unit 6 q 1

June 20101 A student carried out an investigation into the variables affecting the permeability of beetroot cell membranes. Pieces of beetroot were placed into tubes containing distilled water. The student then used a colorimeter to measure the intensity of red colouration in the distilled water. (a) (i) Suggest one factor that affects the permeability of the beetroot cell membrane. Write a hypothesis for this investigation that the student could test.(2)Factor................................................................................................................................................Hypothesis ..................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (ii) Use your biological knowledge and understanding to explain and justify this hypothesis.(3)................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(b) (i) State two factors that need to be controlled in this investigation.(2)1........................................................................................................................................................2........................................................................................................................................................ (ii) Suggest how one of the factors you have stated in (b)(i) could be controlled. If this factor had not been controlled, what effect would it have on the results? (2)How the factor is controlled..........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Effect on the results if this factor is not controlled................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (c) Describe how you could reduce systematic errors in the measurements of the dependent variable in this investigation.(2)................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (Total for Question 1 = 11 marks)

January 20111 Agar plates spread with a suitable culture of bacteria can be used to test the effectiveness of different antibiotics. (a) Describe how to investigate the effect of different types of antibiotic (the independent variable) on bacteria. Include details of a suitable dependent variable and how it can be measured.(6)........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (b) (i) State two variables, other than the dependent and independent variable, which could affect the investigation.(2)1........................................................................................................................................................2........................................................................................................................................................ (ii) Suggest how one of the variables you have stated in (b)(i) could be controlled. (1)............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (c) Give two ways in which this investigation should be carried out safely.(2)..................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(d) To treat a bacterial infection, an antibiotic must be effective against the bacteria. Suggest one other factor that may need to be considered by a doctor when prescribing an antibiotic to treat a patient with a bacterial infection.(1)................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (Total for Question 1 = 12 marks)

May 20111 Many scientists are concerned about the effect climate change could have on the development of organisms. Climate change could have an effect on the yield of many important farmed foods, such as maize, wheat, rice and fish.(a) Describe an experiment to investigate the effect of temperature (the independent variable) on the development of organisms such as seedlings or brine shrimps. Include details of a suitable dependent variable.(5)........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (b) (i) State two variables, other than temperature, which could affect this investigation.(2)1........................................................................................................................................................2........................................................................................................................................................ (ii) Choose one of the variables from (i). Suggest how this variable could have been controlled. Describe what effect it could have had on the results if it had not been controlled.(2)Variable............................................................................................................................................How to control the variable ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Effect on the results if the variable had not been controlled ....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(c) Some plants are adapted to live in low environmental temperatures. When the environmental temperature increases the gross primary productivity increases, but the net primary productivity decreases. This may cause the yield of some crops to decrease. Explain why an increase in environmental temperature causes the yield of some crops to decrease. (4)...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (Total for Question 1 = 13 marks)

January 20121 Seeds contain a plant embryo and a food supply. Cell growth in the seeds will begin when the temperature and moisture conditions are favourable. During cell growth, enzymes break down the stored food supply and ATP is generated by respiration.(a) Describe an experiment to investigate the effect of temperature (the independent variable) on the rate of respiration in seeds.(5)........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) (i) State two variables, other than temperature, which could affect the investigation.(2)1........................................................................................................................................................2........................................................................................................................................................(ii) Choose one of the variables from (b)(i). Suggest how this variable could have been controlled. Describe what effect it could have had on the results if it had not been controlled.(2)Variable.............................................................................................................................................How to control the variable ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Effect on the results if the variable had not been controlled ....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(c) If the seeds had not been exposed to any oxygen during this investigation, suggest the effect this may have on the results. Give an explanation for your answer.(3)...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (Total for Question 1 = 12 marks)

May 20121 The unwanted plants growing in a field of cereal crops are called weeds. Selective weedkillers can be used on fields of cereal crops. These kill broad-leaved weeds, without harming the cereal plants. (a) Describe an experiment to investigate the effect of a new selective weedkiller in a field containing cereal plants and broad-leaved weeds.(6)........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (b) (i) Suggest two abiotic factors that are variables in the investigation.(2)1........................................................................................................................................................2........................................................................................................................................................ (ii) Choose one of the variables from (b)(i). Suggest how this variable could be taken into account or have been controlled. Describe what effect this variable could have had on the results. (2)Variable.............................................................................................................................................How the variable could be taken into account or controlled ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Effect of the variable on the results ............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (c) Suggest how a selective weedkiller, containing a plant growth regulator such as IAA, may be able to kill broad-leaved weeds.(2)................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (Total for Question 1 = 12 marks)

January 20131 Many fruits contain vitamin C. Fruits can decay quickly when stored at room temperature. They are therefore sometimes stored in a refrigerator or freezer. (a) Describe an experiment to investigate the effect of storage temperature on the vitamin C content of one type of fruit.(5).................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (b) (i) State two variables which need to be controlled in this investigation.(2)1........................................................................................................................................................2........................................................................................................................................................ (ii) Choose one of the variables from (b)(i) above. Suggest how this variable can be controlled. Describe what effect it could have on the results if it is not controlled.(2)Variable.............................................................................................................................................How to control the variable ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Effect on the results if the variable is not controlled ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (c) Suggest why storing fruit at low temperature slows down decay.(3)...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (Total for Question 1 = 12 marks)

May 20131 John thought that there was a difference in breathing when lying down compared with when sitting on a chair. He decided to test this, using traces from a spirometer. (a) Describe how he could use data from spirometer traces to compare breathing when lying down and when sitting on a chair.(4)........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) (i) State two variables which need to be controlled to provide valid spirometer traces.(2)1........................................................................................................................................................2........................................................................................................................................................ (ii) Choose one of the variables from (b)(i) above. Suggest how this variable can be controlled. Describe what effect this variable could have on the data from the spirometer traces if it is not controlled.(2)Variable.............................................................................................................................................How to control the variable ......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Effect on the data from the spirometer traces if this variable is not controlled................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (c) Suggest how breathing is controlled by the nervous system in response to changing position from lying down to sitting on a chair.(4)...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (Total for Question 1 = 12 marks)

January 20141 Lemurs are primates found on the island of Madagascar. At least 33 different species of lemur are living on the island today. Scientists would like to know how closely related the different species of lemur are.In one study, the scientists collected tissue samples from several individuals of eachspecies. For each sample, they examined the DNA sequences of five different genes.The polymerase chain reaction (PCR) was used to amplify the DNA in the samples.(a) Describe how to amplify a strand of DNA using the polymerase chain reaction (PCR).(5)....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) An enzyme is used in the amplification process. Describe two properties of this enzyme that are relevant to its biological activity in this process.(2)1............................................................................................................................................................................................................................................................................................................................................................................................................................................................................2............................................................................................................................................................................................................................................................................................................................................................................................................................................................................(c) Temperature is an important variable in the PCR.Choose one step in the process you described in part (a) and explain why changing the reaction temperature might reduce the production of DNA in this reaction.(2)Step...................................................................................................................................................Explanation...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(d) Suggest an explanation for each of the following statements.(i) The scientists collected and analysed samples from more than one individual of each species.(2)................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (ii) For each sample, the scientists examined the DNA sequence of five different genes.(2)................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (Total for Question 1 = 13 marks)

June 20141 Snails can respond to a variety of stimuli, including touch. When a snail experiences an unfamiliar stimulus, it will withdraw into its shell. After repeated exposure to the same stimulus, the snail will stop responding to the stimulus. This behavior is called habituation.

A snail magnification x2(a) Describe how you could investigate the habituation of a snail to a stimulus. (5)...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (b) (i) State two variables, other than the stimulus, which could affect the investigation.(2)1........................................................................................................................................................2........................................................................................................................................................ (ii) Choose one of these variables. Suggest how this variable could be controlled.Describe the effect the variable could have on the results if it is not controlled. (2)Variable.............................................................................................................................................How to control the variable................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Effect on the results if the variable is not controlled ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (c) Suggest how calcium ions are involved in habituation in snails. (4)...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (Total for Question 1 = 13 marks)

January 2015

1 A seed contains an embryo and a food supply. A seed will germinate when it is placed in suitable conditions. The ATP required for growth and germination is provided by respiration. (a) Describe an experiment to determine the effect of temperature on the rate of respiration in germinating seeds. (5) ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) (i) State two variables, other than temperature, that could affect this investigation. (2) 1........................................................................................................................................................ 2........................................................................................................................................................ (ii) Suggest how one of the variables you have stated in (b)(i) could be controlled. Describe what effect it could have on the results if it was not controlled. (2) Variable.............................................................................................................................................How to control the variable................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Effect on the results if the variable is not controlled................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (c) When seeds are placed in conditions suitable for germination, there is a delay of several hours before respiration can be detected. Suggest an explanation, in terms of metabolic processes, that might account for this delay. (3) ...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (Total for Question 1 = 12 marks)