hkcee bio ch 11_p1_food

HKCEE Food requirement (1990-2008) P. 1 19903. (c) The table below shows the average body weight, the daily requirements of energy and certain

nutrients for four groups of people :

Body weight(kg)

Energy(kJ)

Protein(g)

Vitamin D(μg)

Iron(mg)

Children(4 to 6 years old)

20 7560 30 10 10

Men(23 to 50 years old)

70 11340 56 5 10

Women(23 to 50 years old)

55 8400 44 5 18

Pregnant women 65 9660 74 10 45

(i) (1) Which group of people requires the greatest amount of energy per unit body weight ?

Show how you arrive at your answer. (2 marks)

(2) Suggest a reason why this group of people requires the greatest amount of energy per unit

body weight. (2 marks)

(ii) How do men differ from children in their requirements for vitamin D ? Give a reason for this

difference. (2 marks)

(iii) Of the three adult groups, which group requires the largest amount of protein ? Why is this so ?

(2 marks)

(iv) Account for the difference in iron requirement between men and non-pregnant women.

(3 marks)

Marking Scheme:

3. (c) (i) (1) children -----------------------------------------------------------------------------------------------------1by calculation : --------------------------------------------------------------------------------------------1

(2) children need to maintain a higher metabolic rate in order to -------------------------------1

- support greater growth/muscular activities )

- compensate for the higher rate of heat loss ) any ONE ----------------1

(ii) men require less vitamin D than children -----------------------------------------------------------------1

because they have already well developed bones / teeth --------------------------------------------1

(iii) pregnant women ------------------------------------------------------------------------------------------------1

for the growth and development of the foetus / embryo -----------------------------------------------1

(iv) women require more iron than men ------------------------------------------------------------------------1

for the formation of red blood cells in the blood ---------------------------------------------------------1

which is lost periodically (during menstruation) ---------------------------------------------------------1

Total : 11 Marks

Marker’s report:

3. (c) (i) (1) Many candidates did not present their calculations as required by the question.

(iv) Many candidates could relate the greater demand for iron by women to the loss of blood during menstruation. However, some failed to pinpoint that iron is required for the formation of red

This material was reproduced under the terms of a license granted by THE HONG KONG REPROGRAPHIC RIGHTS LICENSING SOCIETY LIMITED. No further copying permitted.

HKCEE Food requirement (1990-2008) P. 2 blood cells or haemoglobin.


HKCEE Food requirement (1990-2008) P. 3 1991

1. (b) The table below shows the contents and the energy value of human milk and cow’s milk :

Human milk ( per 100 cm3) Cow’s milk ( per 100 cm3)

protein

fat

carbohydrate

1.23 g

3.8 g

7.0 g

3.4 g

3.8 g

4.8 g

vitamin A

vitamin C

vitamin D

0.053 mg

4.30 mg

0.0008 mg

0.034 mg

1.80 mg

0.0002 mg

calcium

phosphorus

iron

0.034 g

0.016 g

0.00021 g

0.126 g

0.100 g

0.00015 g

water 87.6 g 87.2 g

energy value 300 kJ 290 kJ

WITH REFERENCE TO THE TABLE ABOVE, answer the following questions :

(i) (1) Which mineral is present in the least amount in both types of milk ? (1 mark)

(2) In the absence of this mineral, what deficiency symptom would develop ? (1 mark)

(ii) A one-year-old baby requires 5100 kJ of energy a day. How much human milk should the baby

take in one day to meet its energy requirements ? (1 mark)

(iii) Give ONE advantage of breast feeding a baby over bottle feeding with cow’s milk. Explain your

answer. (2 marks)

(iv) Suggest TWO reasons why cow’s milk is better for the growth of children and youths. Explain

your answer. (4 marks)

Marking scheme:

1. (b) (i) (1) iron ----------------------------------------------------------------------------------------------------------1

(2) symptoms associated with anaemia ----------------------------------------------------------------1

(ii) 1700 cm3 (N.B. no unit, no mark) -------------------------------------------------------------------------1

(iii) in human milk,

- more vitamins good for general health / prevents deficiency diseases -----------1+1

(iv) in cow’s milk

- more protein for the production of protoplasm / body growth ----------------------1+1

- more calcium and / or phosphorus for the growth of bones and teeth ------------------1+1

Total : 9 marks

Marker’s report:

1. (b) (ii) It is encouraging to see that most candidates could correctly extract numerical data from the

question and could readily perform simple calculations to obtain the right answer.

(iii) Many candidates did not refer to the table given and so gave the presence of antibodies as an

advantage of cow’s milk over breast feeding.

(iv) This was the most well answered part of the whole question paper showing students’ increased

awareness of the daily applications of human nutrition.



3. (a) The diagrams below show he steps involved in preparing a filtrate from green peppers :

The pale green filtrate collected was tested for the presence of four types of food substances. The results are shown below :

Test ResultBenedict's test

Biuret testIodine testDCPIP test

orange precipitateblue solution

brown solutionpale green solution

(i) Name the pigment responsible for the green colour of the extract. (1 mark)

(ii) With reference to the above diagrams, explain why filtration is important in this experiment.

(2 marks)

(iii) The residue left on the filter paper contained mostly an indigestible substance. Name this substance and explain the importance of its presence in our diet. (3 marks)

(iv) Deduce the types of food substances present in the filtrate. Give reasons for your answers. (4 marks)

Marking Scheme:3. (a) (i) * chlorophyll ------------------------------------------------------------------------------------------------------1

(ii) to remove the residue / green chloroplasts ---------------------------------------------------------------1so that results / any colour changes of subsequent food tests can be easily observed ---------------------------------------------------------------------------------1

(iii) * cellulose ---------------------------------------------------------------------------------------------------------1- it increases the bull of the indigestible material )- and stimulates the muscular movements along )

the alimentary canal / peristalsis ) any TWO -------------------------------1,1- to prevent constipation )

(iv) The presence of reducing sugar is shown by the -------------------------------------------------------1formation of orange precipitate in the Benedict’s test --------------------------------------------------1The presence of vitamin C is shown by the decolorization of the DCPIP solution ----------1+1N.B. If more than 2 food tests are mentioned, deduct 1 mark for every additional food substance wrongly deduced. No deduction below 0.

Total : 10 marks

Marker’s report:

3. (a) (i) The term "chlorophyll" was often misspell. Many candidates mistook "chloroplast" as the pigment responsible for the green colour of the green pepper.

(iii) Some candidates confused excretion with egestion of undigested food substances.(iv) Some candidates were not aware that the presence of vitamin C could still be deduced although

the decolorisation of DCPIP was masked by the pale green colour of the original filtrate. A considerable number of candidates wrongly thought that Benedict’s test was a test for the presence of glucose. They failed to note that Benedict’s test is only a test for the presence of reducing sugar.


HKCEE Food requirement (1990-2008) P. 5 19971. (b) The bar chart below shows the composition of food eaten by an overweight child for lunch :

(i) (1) What is food substance Q ? (1 mark)(2) Explain its importance to the body. (2 marks)

(ii) The child often eats milk chocolate as a snack.(1) Explain how it may contribute to his weight problem. (3 marks)(2) Explain how it may cause tooth decay. (3 marks)

(iii) Explain why food from animals, such as pork and fish, is an important part of a child's diet. (2 marks)

Marking scheme:

1. (b) (i) (1) dietary fibre-------------------------------------------------------------------------------------------------1(2) It adds bulk to food, )

promotes peristalsis of the intestine ) any TWO----------------------------------------1,1and prevents constipaton )

(ii) (1) Milk chocolate contains large proportion ofenergy-rich food substances / carbohydrates / fat------------------------------------------------1If the energy intake of the child is greater than the energy needed ,------------------------1the excess energy-rich food substances will be stored in the body as fat------------------1which lends to overweight.

(2) Milk chocolate contains high proportion of carbohydrates / It sticks easily tothe tooth surface------------------------------------------------------------------------------------------1Sugars in the chocolate are broken down by the bacteria in the plaque--------------------1to form acid which dissolves the enamel and causes tooth decay --------------------------1Effective communication (C)------------------------------------------------------------------------1

(iii) Foot from animals is rich in protein--------------------------------------------------------------------------1which is necessary for the growth of the child------------------------------------------------------------1

Total : 11 + 1 marks

Marker’s report:

1. (b) (i) The performance in this part was quite good.(1) Most candidates gave the correct answer. However, there were many spelling mistakes,

such as 'diary' or 'daily' for 'dietary', and 'cellose' for 'cellulose'.(2) Some candidates answered wrongly that dietary fibre helps in digestion. There were many

wrong spellings for 'peristalsis' such as 'peristalsis', 'peristalisis' etc.(ii) (1) Very few candidates could relate the weight problem of the child to the excessive energy

intake in food. Many candidates answered wrongly that the increase in weight was due to the conversion of excess carbohydrates into glycogen which was stored in the liver and the muscles. In fact, tile increase in weight was due to the storage of fat, not glycogen. Some candidates had the misconception that fat was digested into fatty acid and glycerol which were stored in the body; others answered wrongly that fat in food was stored under the skin. In fact, fat in food is digested into fatty acid and glycerol first before absorption. These are resynthesised into fat in the epithelial cells of villi before being transported to the body organs for storage.

(2) Most candidates understood the concept but some could not express themselves clearly using appropriate wording. Many candidates wrongly said that bacteria in the plaque digested / fed on / reacted with sugars in the chocolates to form acid. In fact, the conversion of sugars to acid by the metabolism of bacteria should not be viewed as a feeding or digestion process. It is also wrong to consider the bacteria as a reactant.

(iii) Many candidates just listed all food substances that can be found in pork and fish without

realizing that the main difference between these two types of food and the others was the high

proportion of protein they contained.



(2) (a) In order to lose weight, an 18-year-old girl, Jane, had a diet as shown in the table below:

(i) If the average daily energy requirement for Jane is about 9200kJ, explain why this diet will be

effective in helping her to lose weight. (3 marks)

(ii) Protein in the diet can be absorbed into the body as amino acids. Explain how amino acids can

provide energy for Jane’s daily activity. (3 marks)

(iii) If Jane continues this diet for several months, what disease will she probably develop as a

result of mineral deficiency? (1 mark)

(iv) Describe a food test to show that fat is present in ham. (3 marks)

Marking Scheme:

2. (a) (i) The daily energy intake of Jane is 6620 kJ ----------------------------------------------------------------1

which is less than her daily energy requirement ---------------------------------------------------------1

Thus she has to consume / mobilize the fat / food reserve in her body ----------------------------1

Leading to a loss in her body weightEffective communication (C) 1

(ii) Amino acids are broken down in the liver ------------------------------------------------------------------1

to form carbohydrate / a part without nitrogen (and urea) ---------------------------------------------1

which will be oxidized / used in respiration to release energy ----------------------------------------1

(iii) anaemia ------------------------------------------------------------------------------------------------------------1

(iv) Rub a piece of ham on a filter paper

------------------------------------------------------------------

A translucent spot will remain after drying -----------------------------------------------------------

Immerse the paper in an organic solvent and the spot will disappear -----------------------

OR any one set

Add alcohol to a piece of ham and obtain a clear solution

--------------------------------------

Add water to the clear solution -------------------------------------------------------------------------


HKCEE Food requirement (1990-2008) P. 7 The solution will turn milky ------------------------------------------------------------------------------

Total: 10+1 marks

Marker’s report:

2. (a) (i) This part was well answered. Most candidates pointed out correctly that Jane could lose weight

because her daily energy intake was less than her daily energy requirement, and this led to a

mobilization of the fat reserve in her body.

(ii) Many candidates did not know that excess amino acids taken into the body can be an energy

source as they are broken down in the liver and form carbohydrates.

(iii) Some candidates stated scurvy as a disease caused by mineral deficiency. This suggests that

they could not distinguish between minerals and vitamins.

(iv) The grease spot test is a standard food test, but many candidates did not seem to understand

how it worked. For instance, some did not emphasize that the translucent spot should remain

after drying. Many did not understand that it is necessary to immerse the paper in an organic

solvent in order to check whether the spot is formed by fat or other substances. Some

candidates showed a poor understanding of the emulsion test, as they stated that a mixture of

fat and water would give a milky emulsion when ethanol was added to the mixture.



5. Some vegetarians eat plants foods only.

(a) From the nutritional point of view, explain two advantages of having a diet rich in plant foods over that

with little plant foods. (4 marks)

(b) Most plant foods have a low protein content. Suggest a plant food that can provide a lot of protein to

the vegetarians. (1 mark)

(c)A piece of agricultural land can be used for growing crops, or for growing grass to raise cattle for meat.

Explain why crop-growing can provide more food for human consumption than cattle-raising.

(4 marks)

Total: 9 marks

Marking scheme:

6. (a) A vegetarian diet has low fat content…........................................................................... 1

This will reduce the risk of obesity / heart diseases .................….............................….... 1

A vegetarian diet has a high content of dietary fibre .......................….......……..........…... 1

This helps maintain normal peristalsis / prevent constipation / reduce the risk of

colon cancer / avoid overeating .........................................……......…………………….…. 1

A vegetarian diet has a high vitamin C content...........................................................….... 1

This helps the formation of connective tissue / preventing scurvy .................................. 1

(b) beans / peas / nuts / mushroom (accept other reasonable answers) ................………….............…...1

(c) In the first way, humans feed directly on the crops grown, while in the second way humans feeds on cattle

which in turn feeds on grass / In the first way, humans obtain food through a shorter food chain / a smaller

number of trophic levels .....................…………………………………………………………............... 1

Since energy is lost along the food chain ..........…………………………………………………........... 1

through respiration, death, excretory products, faeces ............................…………….......................... 1

more energy in the form of organic matter will be available to humans in the first way.……………….. 1

Effective Communication (C)------------------------------------------------------------------- 1

Total: 9+1 marks

Marker’s report:

Q.6 (a) Many candidates scored well in this question. Some candidates, however, mentioned that plant foods

contain a lot of vitamins or minerals. Such answers were not accepted as these substances are not

specific to plant foods.

(c) It is a demanding question as it requires candidates to explain why crop-growing can provide more

food for human consumption than cattle-raising. A considerable number of candidates missed the

crux of the question and their answers included a lot of irrelevant points, such as the land can

support the growth of more plants than cattle. Only a small proportion of the candidates could make


Any Two sets

HKCEE Food requirement (1990-2008) P. 9 reference to the difference in energy loss along the two food chains, and relate this to the

subsequent difference in energy transfer to humans.



5. Body mass index (BMI) is a figure used to assess the body weight condition of a person. It is determined by

two factors: weight and height of the person. The BMI chart below allows allows people to check their weight

conditions based on their weight and height:

(a) (i) Mr. Wong weighs 70 kg and his height is 1.7m. Using the descriptions given on the chart, state the body

weight condition of Mr. Wong. (1 marks)

___________________________________________________________________________________

(ii) Mr. Wong’s son is 1.55 m tall. What should be the ideal range of his body weight if he wants to be fit a

healthy? (1 marks)

____________________________________________________________________________________


HKCEE Food requirement (1990-2008) P. 11 (b) According to the deposition of fat in the body, scientists classify body shape into two basic categories: apple

shape and pear shape. To determine the category of body shape, the waist-to-hip ratio (WHR) can be used

and it is represented by the following formula:

The table below shows the categorization of the body shapes of men and women using the WHR:

WHR

Men Women

Apple sharp >0.90 >0.85

Pear shape <= 0.90 <= 0.85

(i) For most people, having extra fat around their waist increases health risk more than having extra fat

around their hip. With reference to this information, which body shape has a higher health risk?

(1 mark)

______________________________________________________________________________________

Mr. and Mrs. Wong have similar BMI, but their body shapes are different. Mr. Wong’s waist and hip

circumferences are 0.87m and 0.97m respectively, whereas Mrs. Wong’s are 0.87m and 0.95m. Who has a

higher health risk? Show how you arrive at your answer. (3 marks)

______________________________________________________________________________________

______________________________________________________________________________________

(c) Dieticians recommend that overweight people should people should have a diet with more vegetables.

Suggest two reasons to explain why this diet may help these people to reduce the chance of becoming

obese. (4 marks)

______________________________________________________________________________________

______________________________________________________________________________________

______________________________________________________________________________________

______________________________________________________________________________________

______________________________________________________________________________________


HKCEE Food requirement (1990-2008) P. 12 (cont’d [06/5])

Marking scheme:

5.

(a) (i) slightly overweight ----------------------------------------------------------------------------------------------------1

(ii) 49.0 - 56.5 kg ----------------------------------------------------------------------------------------------------------1

(b) (i) apple shape -----------------------------------------------------------------------------------------------------------1

(ii) WHR of Mr. Wong = 0.90, thus he is of pear shape --------------------------------------------------------1

WHR of Mrs. Wong = 0.92, thus she is of apple shape ----------------------------------------------------1

Mrs. Wong has a higher health risk -----------------------------------------------------------------------------1

(calculation 1 mark, shape 1 mark

(c) This diet has low fat content ------------------------------------------------------------------------------------------------1

so that the energy intake will be lowered --------------------------------------------------------------------------------1

This diet has high content of dietary fibre -------------------------------------------------------------------------------1

which is indigestible and thus a low energy value / add bulks to the food to give the sense of fullness

-------------------------------------------------------------------------------------------------------------------------------------1

Hence, the overall energy intake through the diet will be lowered thus reducing the chance of obesity

Total: 10 marks

Marker’s report:

Q5

This question refers to the information about a BMI chart and WHR. It assesses candidates' ability in reading

graph and interpreting of data. The performance is good in general.

(a) Good.

(b) Most candidates correctly calculated the WHR. However, quite a number of the candidates failed to consider

the difference in the standard of classifying male and female body shape with reference to the WHR. As a

result, they were unable to point out the difference in their body shapes as the risk factor.

(c) This question requires candidates to point out two reasons to explain how a diet containing more

vegetations can help reduce the chances of becoming obese. Many candidates able to point out the low

energy content of vegetable, leading to a lower energy input. However, some candidates just focused on the

comparison of vegetable and meat, and thus gave irrelevant answers such as 'vegetable has less fat than

meat', 'vegetable have more vitamin C', etc. some candidates even though that vegetable contained little

carbohydrates or did not contain fat. Many candidates failed to point out that the dietary fibre is indigestible

and add to a sense of fullness, thus leading to less constipation, or assumed that the increased peristalsis

would help remove body fat, thus leading to a decrease I body weight. These misconceptions probably

arose from the advertisement of slimming products of 'detox' products nowadays. Also, candidates confused

the concepts of excretion and egestion. The overall performance of this part was not satisfactory.


- stimulates peristalsis and hence less food / energy is absorbed

Effective Communication (C) ------------------------------------------------1


9. (b) Glycemic Index (GI) is a ranking of foods containing carbohydrates. It is based on their

immediate effect on the blood glucose level after consumption. The higher the GI value of a food,

the quicker the rise of blood glucose level. Below are the major food constituents and the GI

values of some common food items :

Food itemMajor food constituents

GI valueCarbohydrate Fat Protein

Whole milk 27Fat-free milk 32Cornflakes 92Oatmeal 49

Key : '' means present'' means absent

(i) With reference to the major constituents of whole milk and fat-free milk in the above table suggest why whole milk has a lower GI value. (3 marks)

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

(ii) For a diabetic person, which breakfast food item, cornflakes or oatmeal, is more suitable? Explain your choice. (3 marks)

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................

..........................................................................................................................................................(iii) Besides GI values, state and explain two other considerations regarding the nutritional

content of food when you plan a healthy diet to reduce body weight. (4 marks)................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

Total : 10 marks(cont’d [07/9b])

Marking scheme:

9. (b) (i) Whole milk has more fat than fat-free milk 1

Presence of fat slow down the digestion of carbohydrates 1

and hence a slower absorption of glucose 1

(ii) Diabetics cannot lower their blood glucose level if it is too high 1

Oatmeal has slow GI value/ causes a slow rise in blood glucose level 1

Therefore, oatmeal is better than cornflake 1

(iii) The overall energy intake should be less than the overall energy expenditure 1


HKCEE Food requirement (1990-2008) P. 14 so that the food reserve will be mobilized and used 1

The diet should contain sufficient amount and types of nutrient 1

for proper functioning of the body 1

Total: 10

Marker’s report:

9. (b) The performance on this question was fair.

(i) Candidates could point out that the difference in the two types of milk lies in the

absence of fats in fat-free milk and presence of fat in whole milk. They failed to go

further to postulate the presence of fats may slow down the digestion of

carbohydrates or absorption of glucose that will lead to lower GI.

(ii) Most candidates could make the right choice but failed to relate clearly to the

inability of lowering the glucose level in diabetic person. Some answered that

diabetic person discharge urine with glucose, which only occurs when the glucose

level is too high.

(iii) While in the planning of a healthy, weight reduction diet, very few candidates could

master the underlying principles of energy deficit for weight loss and a balanced diet

for maintaining health. Hence, they failed to give a complete answer.



1. A person joined a fitness programme which involved both weight training and cardio-respiratory

training for one month. The table below shows some data about this fitness status and after the

training.

Before training After training

Muscle mass (kg) 30.3 31.4

Mass of body fat (kg) 18.8 17.7

Mass of minerals in bone(kg) 3.15 3.29

Basal metabolic rate* (kcal per day) 1543 1580

Average heartbeat rate (beat per minute) when

running at 6 km per hour for 5 minutes

143 135

(a) With reference to the above data, suggest an explanation for the increased basal metabolic rate

after the training programme. (2 marks)

(b) How does the training result in the decrease in body fat of the person? (3 marks)

(c) During this training, the diet should be changed accordingly. With reference to two changes in

the fitness status shown above, state two nutrients that may require an increased intake.

Explain how the increased intake of these nutrients contributed to the changes in the fitness

status. (4 marks)


HKCEE Food requirement (1990-2008) P. 16 (cont’d [08/7])

(d) There is a change in the person’s stroke volume (volume of blood pumped out of the heart in

each heartbeat) when running at 6 km per hour before and after the training. Suggest the

change in his stroke volume and explain the significance of such a change. (3 marks)

Total: 12 marks

Marking scheme:

7. (a) There is greater muscle mass after the training 1

Muscles are made up of active cells that require more energy 1

(b) There is an increase in the daily expenditure due to increased basal metabolic

rates/

1

energy expenditure also increases during training

Thus the energy expenditure is greater than the energy intake 1

our body has to utilize the stored fat to meet the energy demand 1

Effective Communication (C) (1)

(c) The intake of protein should be increased 1+

as it is the major raw material for building muscles 1

The intake of calcium/ phosphorus should be increased 1+

as it is the major raw material for building bone 1

(d) The stroke volume increases after the training 1

This increases the amount of oxygen and carbon dioxide transported per heartbeat 1

A low heartbeat rate is sufficient to sustain the same intensity of exercise/

Exercise of

higher intensity can be performed by the person 1

Marker’s report:

Q.7 (a) Many candidates correctly stated the increase in muscle mass as the answer. However, only

some of them were able to provide proper explanation to associate this with the increased

basal metabolic rate after the training. They wrongly thought that the increased basl

metabolic rate was ra result of increased muscle activity during training.

(b) Poor. Many candidates were not aware that the lost of body fat implies a consumption of

energy reserve in the body, which is a result of a greater energy expenditure than energy

input. Misconceptions were common as revealed by the answers written. Firstly, candidates

overlooked that fat is also one of the respiratory substrates. Secondly, some candidates still

used ‘burns’ fat instead of oxidation of fat in the respiration. Thirdly, when answering

questions, candidates confused terms such as ‘energy consumption’, ‘energy intake’ and ‘

food consumption’.


HKCEE Food requirement (1990-2008) P. 17

(c) Good. Most candidates were able to answer the question correctly.

(d) Poor. Candidates were unable to relate the cause and consequence, thus unable to state the

significance of the increased stroke volume to a person’s ability to perform more vigorous

exercise.


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