Some students investigated the effect of light intensity ...

[Pages:18]Q1. Some students investigated the effect of light intensity on the rate of photosynthesis. They used the apparatus shown in Diagram 1. Diagram 1

The students: ? placed the lamp 10 cm from the pondweed ? counted the number of bubbles of gas released from the pondweed in 1 minute ? repeated this for different distances between the lamp and the pondweed.

(a) The lamp gives out heat as well as light. What could the students do to make sure that heat from the lamp did not affect the rate of photosynthesis? ........................................................................................................................ ........................................................................................................................

(1)

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(b) The table shows the students' results.

Distance in cm 10 15 20 40 50

Number of bubbles per minute 84 84 76 52 26

(i) At distances between 15 cm and 50 cm, light was a limiting factor for photosynthesis.

What evidence is there for this in the table?

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

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

(1)

(ii) Give one factor that could have limited the rate of photosynthesis when the distance was between 10 cm and 15 cm.

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

(1)

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(c) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

Diagram 2 shows a section through a plant leaf.

Diagram 2

Describe the structure of the leaf and the functions of the tissues in the leaf. You should use the names of the tissues in your answer. ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................

(6) (Total 9 marks)

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## (a) Complete the table to give one site where digestive substances are made.

Digestive substance

One site of production

bile

amylase

lipase

protease

(4)

(b) Describe two ways that the mouth can break down starchy foods. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................

(2)

(c) Describe how the liver helps to digest fats.

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

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

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

(2) (Total 8 marks)

Q3.

(a) (i) What name is given to an enzyme which catalyses the breakdown of protein?

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

(1)

(ii) What product is formed when protein is broken down by the enzyme?

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

(1)

The table shows the effect of pH on the activity of an enzyme which catalyses the breakdown of protein.

pH

1.0

2.0

3.0

4.0

5.0

Rate of formation of product

10.5

23.0

10.5

2.5

0.0

in mmol per minute

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(b) Draw a graph of the data in the table.

(3)

(c) The enzyme is produced by the human digestive system. (i) At what pH does this enzyme work best? ........................................................

(1)

(ii) Suggest which part of the digestive system produces this enzyme. ...........................................................................................................................

(1)

(d) Why is it necessary to break down proteins in the digestive system? ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................

(3) (Total 10 marks)

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Q4.

Marathon runners are recommended to have a high carbohydrate diet prior to a race. Three

athletes tried out three dietary regimes prior to a marathon race.

These three dietry regimes were as follows.

Athlete A Up to 7 days before the race -

7 days before the race

-

6-3 days before the race

-

2 and 1 days before the race -

Normal mixed diet Prolonged extreme physical activity Protein and fat diet; no carbohydrate Large carbohydrate intake

Athlete B Up to 5 days before race 5 days before the race 4-1 days before the race

-

Normal mixed diet

-

Prolonged extreme physical activity

-

Large carbohydrate intake

Athlete C Up to 4 days before the race -

4-1 days before the race

-

Normal mixed diet Large carbohydrate intake

The graph below shows the effect of each of these dietary regimes on glycogen levels in the athletes' muscles

(a) (i) What is the immediate effect of extreme physical activity on the glycogen content of muscles?

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

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

(1)

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(ii) Describe how this effect occurs. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................

(3)

(b) (i) Evaluate the three regimes as preparation for a marathon race. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................

(3)

(ii) Suggest a possible explanation for the different effects of the three regimes. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................

(2) (Total 9 marks)

Q5.

This is a diagram of a belt transect showing the major types of plants growing on the bottom

of a lake.

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(a) Suggest, and explain, two reasons why a much smaller population of Nitella plants is found amongst the Potamogeton plants than further down in the lake. 1. ................................................................................................................................ .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... 2. ................................................................................................................................ .................................................................................................................................... .................................................................................................................................... ....................................................................................................................................

(4)

(b) Describe how you would use the belt transect technique to measure the abundance and distribution of plants which live on the bottom of a shallow lake. .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... ....................................................................................................................................

(3) (Total 7 marks)

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