Biology Questions Biological Resources

8/12/2019 Biology Questions Biological Resources

1/14

Biological resources questions (overall section c)

Biology (AQA)January 2008Advanced Subsidiary ExaminationBIOLOGY/HUMAN BIOLOGY (SPECIFICATION A) BYA1

Unit 1 Molecules, Cells and Systems

6) Catalase is an enzyme. It catalyses the following reaction.

Hydrogen peroxide water + oxygen

Catalase can be obtained from the potato tissue. A student ground potato tissue with water and

sand, and then filtered the mixture. The liquid contained catalase.

In an investigation, the student mixed this liquid with hydrogen peroxide and measured the volumeof oxygen produced at 10- second intervals. The results are shown in the graph.

(a) (i) How much oxygen was produced between 120 and 130 seconds?...................................................................................................................................

(1 mark)

(ii) Less oxygen was produced between 80 and 90 seconds than between 10 and 20

seconds. Use your knowledge of the way enzymes work to explain why.

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

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

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

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

(2 marks)


2/14


(b) Sketch a curve on the graph to show how the rate of reaction changed over the time

shown.

(2 marks)

(c) Describe how you could test the catalase preparation to show that it contained protein.

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

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

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

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

(2 marks)

(d) When scientists measure the activity of an enzyme, they make sure that the enzyme isat its optimum pH. Explain why.

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

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

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

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

(2 marks)


3/14


9) The table below shows the mass of certain food components in 100 g of liquid milk and

in 100 g of dry powdered milk.

(a) (i) How much carbohydrate would be in 50 g of liquid milk?

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

(1)

(ii) How much more fat is contained in 100 g of powdered milk than in 100 g liquid

milk?

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

(1)

(iii) Which of the food components listed in the table contains all the elements carbon,

hydrogen, oxygen, nitrogen and sulphur?

................................................................................................................................(1)

(iv) The food components in the table are all needed in a balanced diet. Name two

other food components, not listed in the table, that are needed in a balanced

diet.

1 .............................................................................................................................

2 .............................................................................................................................

(2)

(b) Describe a simple test you could carry out to test a food sample for fat (lipid).

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

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

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

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

(2)


4/14


(c) Mothers feed their babies on milk. Describe what happens to the fat in milk in the

gut of a baby.

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

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

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

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

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

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

(3)


5/14


7. (a) The table below gives some of the components required in a balanced diet. Complete

the table to show a suitable source of the component and give one function for each

Component.

(b) Humans also require vitamins as additional substances in their diet

.

Name one vitamin and describe the symptoms associated with a diet lacking enoughof this vitamin.

Name .............................................................................................................................

Symptoms .....................................................................................................................

(2)

(c) Some individuals may become so overweight that it adversely affects their health.

This condition is known as obesity.

(i) Describe the dangers of being obese.

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

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

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

(2)

(ii) How might obesity be prevented?

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

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

(1)


6/14



7/14



8/14



9/14



10/14



11/14


Mark SchemeAQA paper Jan 2008 q6

Question 6

(a) (i) 0; 1

(ii) Amount of substrate/hydrogen peroxide less;

Fewer collisions with active site (of enzyme)/ fewer E-S complexes

formed; 2 marks

(b) Allow 1 mark for a curve showing a decrease but no increase

Allow 2 marks for a curve showing a decrease with maximum at start and falling

to zero; 2 marks

(c) Add biuret;

Lilac/purple/mauve; 2 marks

Ignore references to precipitate; do not accept blue or pink although blue-purplewould be acceptable.

(d) Rate of reaction will be lower if pH not at optimum/ works best at optimum;

Shape/charge on active site changed/ enzymes denatured/

loses tertiary structure;

Substrate will not fit/bind/form E-S complexes; 2 marks

Total marks: 9


12/14



13/14



14/14


Biology Questions Biological Resources

Documents

Transcript of Biology Questions Biological Resources