2e. Human Nutrition 11/24/10 7:32 PM

2. Structure and Function of Organismse. Human Nutrition

2.23 understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre

2.24 identify sources and describe functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, and the mineral ions calcium and iron, water and dietary fibre as components of the diet.

2.25 understand that energy requirements vary with activity levels, age and pregnancy

2.26 describe the structures of the human alimentary canal and describe in the functions of the mouth, oesophagus, stomach, small intestine, large intestine, and pancreas

2.27 understand the processes of ingestion, digestion, absorption, assimilation and egestion

2.28 explain how and why food is moved through the gut by peristalsis

2.29 understand the role of digestive enzymes to include the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipases

2.30 understand that bile is produced by the liver and stored in the gall bladder, and understand the role of bile in neutralising stomach acid and emulsifying lipids

2.31 describe the structure of a villus and explain how this helps absorption of the products of digestion in the small intestine

2.32 describe an experiment to investigate the energy content in a food sample.

2.23 Balanced Diet 11/24/10 7:32 PM

2.23 understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre

Cambridge bookEdexcel book – page 37-41Ref:Pg. 17 4.3 “Your diet is the food you eat each day”

Pg. 22 4.17 “Diets should provide the right amount of energy” 4.18 “Diets should contain a variety of food”

To do: Read 4.3 on pg. 17. Discuss the importance of the kinds of food needed in the diet. List the 7 nutrients and a brief note on the requirements of each.

2.24 Source and Function of Nutrients 11/24/10 7:32 PM

2.24 identify sources and describe functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, and the mineral ions calcium and iron, water and dietary fibre as components of the diet.

Edexcel book – page 37-39

Cambridge bookRef:Pg. 20 Table 4.1 “Carbohydrates, proteins and fats’

Pg. 21 Table 4.2 “Vitamins”Table 4.3 “Minerals”

To do: Use the information of pg. 20-21 to fill in the table below (make sure you summarise).Complete the questions

Nutrient Source FunctionCarbohydrateProteinLipid

Vitamin AVitamin CVitamin D

CalciumIron

Questions1. Name ONE mineral and ONE vitamin, which should be present in the diet of a young child to encourage the healthy growth of teeth.(2)Mineral ................................Vitamin ................................

2. Cereals are a major part of many people's diet. The diagram shows the parts of a grain of wheat.

(a) Which of the labelled regions acts as an energy store for the plant? (1)

(b) What are proteins broken down to during human digestion? (1)

(c) Why are proteins an important part of the human diet? (2)

3. The table shows the recommended and actual daily intake of minor dietary constituents for a 16 year old girl.

Diet Intake of dietary constituent/mgVitamin C Calcium Iron

Recommended 30 600 12Actual 32 580 5

Use your knowledge and the information in the table to explain why the girl developed anaemia. (2)

4. The drawing shows a human skeleton from 1780.

(a) Which disease did the person suffer from? (1)

(b) Describe one piece of evidence from the drawing, which is typical of the disease. (1)

(c) Name the Vitamin the person lacked in their diet. (1)

(d) Which foods could have provided a source of the deficient Vitamin? (1)

5. Vitamins are an important part of the diet.(a) Give ONE source of vitamin C. (1)

(b) Why are lipids needed in the diet? (1)

(c) Name ONE other component of a healthy diet (apart from vitamins and lipids). (1)

2.25 Energy Requirements 11/24/10 7:32 PM

2.25 Understand that energy requirements vary with activity levels, age and pregnancy.

Edexcel book – page 45

Ref:Pg. 23 4.17 “Diets should provide the right amounts of energy”.

To do: Discuss your ideas on how and why energy requirements may differ with activity levels, age and pregnancy. Jot down some ideas after your discussion.Complete the questions

Activity Levels

Age

Pregnancy

Questions1. Dietary fibre consists of polysaccharides found in plant cell walls. While some polysaccharides are rich sources of energy, dietary fibre has no energy value.The bar graph below shows the mean daily energy intake which people in Japan and the United Kingdom obtain from different foods.

An average 13 year old in the United Kingdom requires 12500 kJ of energy daily. What percentage of this total is obtained from oils and fats? (Show your working). (2)

2. The table shows the daily amounts of protein and energy recommended for people of different sex and age.

Use the information in the table to answer the following questions.(a) What effect does age have on the recommended intake of protein in the diet? (2)(i) 1 – 20 years (ii) 20 – 30 years

(b) What effect does the sex of the person have on the recommended intake of protein in the diet? (1)

3. A 20 year old man, with an office job, has decided to train to run a marathon. (a) Suggest how his recommended energy intake should change. (1)

(b) Carbohydrates and proteins are two of the foods which can provide energy in a diet. Name one other type of food which provides energy. (1)

4. A sample of beans were examined to see the proportion of foodstuffs they contained.The results are shown below.

On average:1g of protein can produce 17kJ of energy;1g of carbohydrate can produce 17kJ of energy;1g of fat can produce 38kJ of energy.(a) How much energy is provided, by the beans, from carbohydrates and proteins? (2)

(b) Fibre does not supply any energy. What is its importance in the diet? (1)

5. A pupil was monitored during a typical school day to see how he used up most of his time.The result was as follows:cycling to school 10 minsdesk work 240 minsplaying football 60 minscycling home 10 minsUsing the following information work out the answers to the following questions.Show all calculations.cycling uses 25 kJ/mindesk work uses 3 kJ/minfootball uses 35 kJ/min

(a) How much energy did he use working at his desk? (1)

(b) Which used most energy, cycling to and from school or playing football? (2)

6. The bar chart shows the amount of energy, in kJ, used each day by different people.

Use the graph and your knowledge to help answer the following questions.(a) Which adult uses the least amount of energy each day? (1)

(b) How much more energy does Amy use than Anne each day? Show your working. (2)

(c) Give three factors affecting the amount of energy needed by people each day. (3)

(d) Amy became overweight. Suggest two ways she could change her lifestyle to help her lose weight sensibly. (2)

7. The table shows the energy values of some foods and the size of one serving.

Food Size of serving(g)

Energy per 100g(kJ)

Low fat yoghurt 100 150Mandarin orange segments

200 150

Sugar free Angel Delight

100 340

(a) How much energy is there in a serving of 100g of each of the following foods? (2)Low fat yoghurt Mandarin orange segments Sugar free Angel Delight

(b) Which of these foods would you advise Amy to take as a dessert? Explain your answer. (2)Food Explanation

8. A balanced diet is one where you eat the foods that the body needs in the correct proportions. The average person requires about 12,000 kJ of energy. The table shows the daily food intake for two different people.

PERSON A PERSON BEnergy 18 600 kJ Energy 2 100 kJCarbohydrate 270 g Carbohydrate 45 gFat 180 g Fat 2 gProtein 58 g Protein 6 gFibre None Fibre some

(a) Give ONE thing that is wrong with person A’s diet. (1)

(b) Give ONE thing that is wrong with person B’s diet. (1)

(c) What are the proteins used for in the body? (1)

9. The table shows the daily energy and protein requirements of different adults doing the same job.

(a) Why do men have higher energy requirements than women doing the same job? (1)

(b) Why does the pregnant woman need more protein? (1)

(c) How does the calcium requirement of a woman change during pregnancy? (2)Explain why this is necessary.Change:Explanation:

10. The table shows the food value of a meal eaten by a 16-year-old girl.

Food eaten

Protein

(g)

Carbohydrate(g)

Fat (g)

Iron (mg)

Vitamin C

(mg)Sausages 9 5 24 1 0Chips 8 70 20 2 20Beans 10 20 1 3 4

(a) In this meal, which food gave the girl most protein? (1)

(b) How much energy did the girl obtain from carbohydrate, if there are 17 kJ of energy in 1 g of carbohydrate? (2)

(c) If the girl needs 30 mg of Vitamin C each day, how much more will she need after this meal? (1)

11. Calcium and iron are important minerals in the diet. The table shows the amount of each provided by different foods as a percentage of daily requirements.

(a) Which foods can provide all the calcium needed daily? (1)

(b) Which food is the best source of iron? (1)

(c) What is calcium used for in plants? (1)

12. The bar chart shows the daily energy needs of a group of people.

Use the bar chart to help answer the following questions.(a) Calculate the difference in the daily energy needs of a teenage boy and a man, who are both doing light work. (2)

(b) Give two factors, other than age, which affect energy needs. (2)

2.26 Digestive System 11/24/10 7:32 PM

2.26 describe the structures of the human alimentary canal and describe in the functions of the mouth, oesophagus, stomach, small intestine, large intestine, and pancreas

Edexcel book – page 46 – 50

Ref:Pg. 29 Diagram 4.16: ‘The human alimentary canal’

Pg. 30 4.34 ‘In the mouth, food is mixed with saliva’ 4.35 ‘The oesophagus carries food to the stomach’ 4.36 ‘The stomach stores food and digests proteins’ 4.37 ‘The small intestine is very long’ 4.38 ‘Pancreatic juice flows into the duodenum’ 4.39 ‘Bile helps to digest fats’ 4.40 ‘Digestion in completed in the small intestine’ 4.41 ‘Digested food is absorbed in the small intestine’ 4.42 ‘The colon absorbs water’ 4.43 ‘The rectum temporarily stores undigested food’

To do: Read one chapter at a time from the above list. After you have read that chapter, label the part on the diagram below and fill in the relevant section of the table (keep it short). The chapter reference has been added into the table to help you.

A.

B.

H.

I. C.

D.

G.

F.

E.

Letter

Name Function

A4.34

B 4.35

C4.36

D4.38

E4.42

F4.43

G4.374.404.41

H4.39

I4.39

Questions1. When food is taken into the body it is digested.(a) Why must food be digested? (1)

(b) What happens to the digested food? (2)

2. The diagram shows the digestion of starch, a large carbohydrate molecule.

Use the diagram to help answer the following questions.(a) What does the enzyme do to the starch molecule? (1)

(b) Explain why starch cannot be absorbed into the blood but glucose can. (1)

(c) Why do muscle cells need a supply of glucose?(1)

3. The diagram shows part of a human digestive system.

(a) Complete the diagram by drawing in the colon. (2)

(b) Name parts A, B and C. (3)

(c) On the diagram, use a line labeled (2)(i) X to show where the products of digestion are absorbed.(ii) Y to show where bile is stored.

(d) How does bile help in the process of digestion? (1)

4. On the diagram of the digestive system:

(a) Label the Liver with an L. (1)

(b) Label the structure which contains acid with an A. (1)

(c) At what temperature do human enzymes work best? (1)

5. The diagrams show a human torso (body) and two organs.

(a) Which letter best represents the position of organs A and B on the torso?(2)

(b) To what system does organ B belong? (1)

(c) To what system does organ A belong? (1)

6. Complete the flow chart to show the passage of food through the digestive system, using the parts given.

Oesophagus : Large Intestine : Small Intestine : Stomach

7. The diagrams show two organ systems.

Name the systems and give their functions. (4)System A Function System B Function

8. The diagram shows part of the human digestive system.

(a) Name parts A, B, C and D. (4)

(b) Explain why the small intestine is long and folded. (1)

2.27 Processes 11/24/10 7:32 PM

2.27 Understand the processes of ingestion, digestion, absorption, assimilation and egestion.

Label the diagram below without looking back at the previous document.

Use the information provided to decide which parts of the digestive system are involved in the processes of ingestion, digestion, absorption, assimilation and egestion.

A.

B.

C. D. E.

G.

H. I.

F.

Process Description Part of Digestive System involved

Ingestion Taking food into the body (very start of the digestive system).

1.

Digestion Large insoluble molecules are broken down into small soluble molecules.Starch digestion begins.Protein digestion begins.All types of digestion occur.

1.2.3.

Absorption The transfer of digested substances from the intestine into the blood.Majority of absorption.Water absorption

1.2.

Assimilation The soluble products of digestion are taken to cells and used to make structures in the cells. E.g. glucose converted to glycogenAmino acids built up into proteinsFatty acids and glycerol turned into lipid for storage.

Liver cellsMuscle cellsFatty tissue under skin

Egestion Removable of waste material that could not be digested.

1.

Questions1. The diagram below summarises some of the processes which occur in part of the body.

Use the diagram to help explain the processes which are taking place at A, B and C.AProcess (1)Explanation (2)

BProcess (1)Explanation (2)

CProcess (1) Explanation (2) 2. The diagram shows the human digestive system.

(a) Which labelled structures are concerned with ingestion and egestion? (2)Ingestion Egestion

(b) Name the region labelled E. (1)

(c) Give one function of C. (1)

3. The diagram summarises the stages of digestion.

(a) Name processes A and B. (2)

(b) Why do foods need to be digested? (1)

(c) On the diagram, mark with an X where bile is produced. (1)

(d) Bile breaks the large fat droplets into smaller droplets. Explain how this helps in the digestion of fats. (2)

(e) The process of digestion is brought about by enzymes. What is an enzyme?(2)

(f) Complete the table. (4)Food type Enzyme ProductsLipids Fatty acids +

glycerolAmylase

Protein Protease

4. The diagram shows the action of an enzyme on starch.

(a) What is an enzyme? (1)

(b) Use the diagram to help describe what is happening at 1, 2 and 3. (3)

5. The graph shows the effect of temperature on the amount of glucose produced by the action of the enzyme on starch.

(a) What is the optimum temperature for the action of this enzyme? (1)

(b) Calculate the increase in the amount of glucose produced between 20ºC and 30ºC. (2)

(c) Explain the result obtained at 60C.

6. The diagram shows several processes A, B, C and D. (2)

Complete the table by matching the correct letter with the process.Process LetterAbsorptionDigestionEgestion

2.28 Peristalsis 11/24/10 7:32 PM

2.28 Explain how and why food is moved through the gut by peristalsis

Edexecel book – page 46

Ref:Pg. 29 4.33 ‘The alimentary canal is a muscular tube’

Pg. 30 Diagram 4.17: ‘Peristalsis’

Watch the animation:http://health.howstuffworks.com/adam-200088.htm

Movement of Food along the GutAfter the food is swallowed, it is driven down the oesophagus by peristalsis, a wave of muscular contraction that pushes the bolus ahead of it. The circular muscle behind the bolus constricts and pushes it downwards. Ahead of the bolus, the circular muscle relaxes.

Contractions of the small intestine serve three functions:

to mix food with intestinal juices, bile and pancreatic juice, allowing these fluids to neutralize acid and digest nutrients more effectively.

to churn food and bring it into contact with the intestinal for further digestion and nutrient absorption

to move undigested material towards the large intestine.

Importance of FibreFibre gives food more bulk and this helps to give the intestines more ‘grip on it’. The intestines can therefore move the food more efficiently by peristalsis if there is plenty of fibre present in the diet.

Questions1. The diagram shows food in the intestine.

(a) Use the diagram to help explain how food is moved further along the intestine. (2)

(b) Name the process causing this movement. (1)

2. The diagram shows food being swallowed.

(a) Name the process of taking food into the mouth. (1)

(b) Name part A. (1)

(c)The ball of food is moved along part A to the stomach by muscular contractions. Give the term used to describe these muscular contractions. (1)

3. The diagram shows the movement of food (peristalsis) in the oesophagus.

(a) Use the diagram and your knowledge to suggest how peristalsis occurs. (2)

(b) Which organ does the food enter when it leaves the oesophagus? (1)

2.29 Digestive Enzymes 11/24/10 7:32 PM

2.29 Understand the role of digestive enzymes to include the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipases.

Edexcel book – page 48Ref:Pg. 33 Table 4.7: ‘Summary of chemical digestion in the human alimentary canal’

Use the table on pg. 33 to fill in the following table. The table in the book is too detailed, the one below covers all the information you need.

Part of Digestive System

Enzyme secreted from

Enzyme Name

Substrate Product

Mouth Salivary glands

Amylase starch maltose

Stomach Stomach wall

Pepsin proteins peptides

Small intestine

Villi Amylase Starch maltosepeptidases peptides Amino acidsLipase lipids fatty acids

and glycerol

2.30 Bile 11/24/10 7:32 PM

2.30 Recall that bile is produced by the liver and stored in the gall bladder, and understand the role of bile in neutralizing stomach acid and emulsifying lipids.

Edexcel book – page 48Ref:Pg. 31 4.39 ‘Bile helps to digest fats’

Bile is made in the liver and stored in the gall bladder. It is a greenish yellow alkaline liquid. The function of bile is to neutralize the acidic contents, which come out of the stomach and enter the small intestine, it also breaks lipids into small droplets to increase the surface area for digestion by lipases.

In the diagram above the lipase enzymes can only digest around the outside of the large lipid drop, this does not provide a very large surface area for them to work on and so digestion will be slow.

In the diagram below the bile is emulsifying the lipid into small droplets.This provides a much larger surface area for lipases to act on and digestion is much quicker.

Lipase - Enzyme

Large Lipid Drop

Small Lipid Drop

Bile

2.31 Villi 11/24/10 7:32 PM

2.31 describe the structure of a villus and explain how this helps absorption of the products of digestion in the small intestine

Edexcel book – page 49 -50

Ref:Pg. 31 4.40 ‘Digestion is completed in the small intestine’

Diagram 4.19: ‘Longitudinal section through a villus’Diagram 4.20: ‘Detail of villus structure’

Pg. 32 Table 4.6 ‘How the small intestine is adapted for absorbing digested food’ Diagram 4.21: ‘Diagrammatic section through a villus to show how food is absorbed’

Use the information provided on the page references above to complete the following table.

Feature How it helps absorptionPresence of microvilliBlood capillariesLactealsOne cell thick

Questions

1. The diagram shows a section through the wall of part of the digestive system.

(a) Name the region of the digestive system from which this section was taken.(1)(b) Give one function of the muscle layers. (1)

(c) Give two ways the wall of the digestive system is adapted for absorption. (2)

2. The diagram shows a section through the small intestine.

(a) What are the finger-like projections labelled X called? (1)

(b) Give one advantage in having the lining of the intestine folded into these finger-like projections. (1)

(c) Name the enzyme that breaks down protein during digestion. (1)

3. The diagram shows the human digestive system and a section through the small intestine.

(a) In which part of the digestive system does starch digestion begin? (1)

(b) Give the function of the small intestine (ileum) and suggest how its structure helps it to carry out this function. (2)

2.32 Calorimeter 11/24/10 7:32 PM

2.32 Describe an experiment to investigate the energy content in a food sample

Edexcel book – page 45

A Calorimeter is a simple device used to determine the energy content of food. It takes 4.2 joules of energy to heat 1g or 1ml of water by 1OC. Using this information, food can be burnt and the heat energy used to heat water. The increase in temperature of the water can be calculated to determine how much energy was contained in the food.

The equation used is:energy released in joules = temperature increase × volume of water × 4.2

Questions A pupil carried out an experiment to see how much energy was released from a sample of food. These are some results below the diagram.

Temperature of water at the start – 20°Temperature of water at the end – 70°Volume of water – 20 ml

The following formula was used to calculate the number of joules released.

temperature increase × volume of water × 4.2 = energy released in joules

(a) How many joules of energy were released by this sample? (2)

(b) How many kilojoules of energy were released?(1)