biology jan 2008 6101 question
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6101/01Edexcel GCEBiologyBiology (Human)Advanced SubsidiaryUnit Test 1Wednesday 9 January 2008 – MorningTime: 1 hour
Materials required for examination Items included with question papersRuler Nil
Instructions to CandidatesIn the boxes above, write your centre number, candidate number, your surname, initial(s) and signature.The paper reference is shown above. Check that you have the correct question paper.Answer ALL the questions. Write your answers in the spaces provided in this question paper.Show all the steps in any calculations and state the units. Calculators may be used.Include diagrams in your answers where these are helpful.
Information for CandidatesThe marks for individual questions and parts of questions are shown in round brackets: e.g. (2).There are 8 questions in this question paper. The total mark for this question paper is 60.
Advice to CandidatesYou will be assessed on your ability to organise and present information, ideas, descriptions and arguments clearly and logically, taking account of your use of grammar, punctuation and spelling.
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This publication may be reproduced only in accordance with Edexcel Limited copyright policy. ©2008 Edexcel Limited.
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Answer ALL the questions in the spaces provided.
1. The table below refers to two carbohydrate molecules, glycogen and cellulose. If the statement is correct, place a tick ( ) in the appropriate box and if the statement is incorrect, place a cross ( ) in the appropriate box.
Statement Glycogen Cellulose
Consists of β glucose
Contains 1,4 glycosidic bonds
Is a branched molecule
Is a structural carbohydrate Q1
(Total 4 marks)
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2. Read through the following account of the transport of molecules across a cell surface membrane, then write on the dotted lines the most appropriate word or words to complete the account.
Some molecules cross a cell surface membrane by passing down a
concentration gradient through the phospholipid layer. This process is called
............................................... . Some polar molecules cross the membrane by combining
with transport proteins which can change their shape. When this movement occurs
down a concentration gradient, the process is called ...............................................
and when it occurs against a concentration gradient the process is called
............................................... . Most movement of molecules against a concentration
gradient uses energy in the form of ............................................... . Q2
(Total 4 marks)
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3. (a) Insulin and collagen are both proteins that have a primary structure made up of amino acids joined together by peptide bonds.
(i) Explain what is meant by the term primary structure of a protein.
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(ii) Name the type of reaction that occurs when a peptide bond is broken causing a dipeptide to split into two amino acids.
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(b) Insulin and collagen both contain the amino acids glycine and serine. The diagram below shows a dipeptide formed from these two amino acids. Complete the diagram to show the structure of serine when the peptide bond breaks.
Glycine Serine(1)
N—C—C—N—C—C
H
H CH2
H HO
OH
O
OH
H
H
N—C—C
H
H
O
OH
H
H+
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(c) In the table below give three structural differences between the molecules of collagen and insulin.
Collagen Insulin
1
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3
(3) Q3
(Total 6 marks)
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4. (a) Explain what is meant by the term tissue.
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(b) The photograph below shows a section through part of the digestive system, as seen using the low power of a light microscope.
In the space below, draw a plan of this section. The magnification of your drawing should be ×1.
(3) Q4
(Total 5 marks)
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5. (a) The cell cycle includes interphase and mitosis. Mitosis has four phases: prophase, metaphase, anaphase and telophase. The photograph below shows plant root cells at various stages of the cell cycle.
(i) Draw a line to indicate a cell in the photograph that is undergoing anaphase and label this line A.
(1)
(ii) Draw a line to indicate a cell in the photograph that is undergoing telophase and label this line T.
(1)
(iii) How many of the cells shown in the photograph are in telophase?
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(b) Give an account of the events that take place during prophase and metaphase of mitosis.
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(Total 8 marks)
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6. (a) In the space below, draw and label a diagram to show the structure of a chloroplast, as seen using an electron microscope.
(4)
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(b) The photograph below shows a group of mitochondria in a liver cell, as seen using an electron microscope. The magnification is ×50 000.
(i) Measure the length of the mitochondrion labelled A between X and Y. Calculate the actual length of this mitochondrion in μm. Show your working.
Actual length of A ......................µm.(3)
(ii) Suggest one other structure that might be visible in the cytoplasm of this liver cell if the magnification used was higher.
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(iii) Suggest one reason why the double membrane is not clearly visible all around the mitochondrion labelled A.
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(Total 9 marks)
A
Y
X
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7. Amylase is an enzyme that breaks down starch to maltose. A student carried out an investigation to determine the effect of copper ions on the activity of this enzyme. She added different concentrations of copper ions and timed how long it took the amylase to break down starch.
The results of this investigation are shown in the graph below.
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(a) Describe a test that could be used to show that starch has been broken down.
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(b) Describe the effect that an increase in concentration of copper ions has on the activity of amylase.
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(c) The student suggested that the copper ions were acting as an active site-directed inhibitor at concentrations above 4 arbitrary units. Explain what is meant by the term active site-directed inhibition.
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(d) The student then investigated the initial rate of reaction using amylase and different concentrations of starch. She did this first with copper ions present then with no copper ions present. Her results are shown in the graph below.
(i) Suggest why the initial rate of reaction was measured in this investigation.
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Initial rateof reaction /arbitrary units
Starch concentration / arbitrary units
No copper ions present
Copper ions present
8 –
6 –
4 –
2 –
0
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2 4 6 8 10
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Starch concentration / arbitrary units
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(ii) State why the results do not support the hypothesis that copper ions are an active site-directed inhibitor of amylase.
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(Total 12 marks)
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8. (a) The diagram below shows the structure of a mononucleotide from a DNA molecule.
Name the parts of the mononucleotide labelled A and B.
A ..............................................
B ..............................................(1)
(b) The table below shows the percentage of different bases present in the DNA from two organisms.
OrganismPercentage of each base present
Adenine Guanine Thymine Cytosine
Yeast 31 19 31 19
Cow 29
(i) Complete the table to show the percentage of adenine, guanine and cytosine in the DNA of a cow.
(1)
(ii) Explain how you worked out the percentage of guanine present in the DNA of a cow.
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A
B
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Q8
(Total 12 marks)
(c) DNA and messenger RNA (mRNA) have different properties. DNA is very stable but mRNA breaks down quickly and most of it will be broken down within a day of it being produced. Suggest why it is important for DNA to be more stable than mRNA.
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(d) Protein synthesis involves transcription and translation. Describe the process of transcription.
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TOTAL FOR PAPER: 60 MARKS
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