Past papers

Question 1

(a) Give two reasons why the data in the table are reliable.
(b) Suggest how the student could modify the apparatus to measure the rate of oxygen production more accurately.
(c) Name the independent variable in this investigation.

(d) The student changed the colour of the light but kept the intensity the same.
Give three other variables that she should keep the same in order to make the comparison of oxygen production valid.

Answer 1

(a) 1. repeated / 3 readings / 3 times / average /
more than once / eq;
2. similar (pattern for red / for green);
3. anomaly ignored in calculation of average for blue light;

(b) measuring cylinder / syringe / scale on the side / eq;
(c) colour / wavelength of light;

(d)

1. mass of plant / size of plant / length of plant /
   amount of plant;
2. species of plant / type of plant / same plant;
3. age of plant;
4. temperature (of water) / room temperature;
5. mass/amount of sodium hydrogen carbonate /
   conc. of carbon dioxide / eq;
6. volume/amount of water / volume of indicator /
   eq;
7. light intensity / light duration / eq;

Question 2

(a) Describe the differences in the appearance of the cells in concentrated salt solution compared with the cells in distilled water.

(b) The student thought that the differences in the cells were caused by osmosis.
What is meant by the term osmosis?

(c) Explain what happens to the cells in concentrated salt solution to change their appearance.

(d) Another student investigated the appearance of red blood cells in distilled water
and in concentrated salt solution.
Use your knowledge of osmosis and the structure of red blood cells to describe
and explain what the red blood cells would look like
(i) in distilled water

(ii) in concentrated salt solution.

Answer 2

(a)

1. not full / less water / flaccid / shrink / eq;
2. cytoplasm does not fill cell / cytoplasm
   away (from cell wall) / membrane away from
   cell wall / membrane irregular shape /
   contents away (from cell wall) / eq;
3. plasmolysed / plasmolysis;
4. darker colour / eq;

(b)

1. (movement of) water;
2. dilute to concentrated / weak solution to a
   strong solution / down water potential
   gradient / high conc of water to low conc of
   water / eq;
3. selectively permeable membrane / eq;

(c)

1. water leaves cell / eq;
2. higher concentration outside cell / dilute to
   concentrated / weak solution to a strong
   solution / down water potential gradient /
   high conc of water to low conc of water / eq;
   eq;
3. cell membrane shrinks from cell wall / cell
   dehydrates / plasmolysis / flaccid / eq;

(d)

(i)

1. cells burst / eq;
2. water enters cells;
3. no cell wall / eq;

(ii)

1. crenated / buckled / shrink / smaller /
   flaccid / eq;
2. water leaves cells;

Question 3

The production of tomatoes is affected by an insect pest called the tomato leaf miner.
The photograph shows a tomato leaf that has been damaged by the tomato leaf miner.

The adult female leaf miner lays eggs on tomato leaves that develop into maggots (larvae). These maggots feed on leaf mesophyll tissue inside the leaf.

Explain how feeding on mesophyll tissue will affect tomato production. (3 marks)

Answer 3

1. lower production / fewer fruit / less growth / eq;
2. (fewer) chloroplasts / less chlorophyll;
3. (less) photosynthesis;
4. (less) carbohydrate / glucose / starch;

Question 4

The diagram shows a section through the root of a plant.

(a) Name two substances that are transported in the xylem.
(b) Draw and label a root hair cell in the following space.

Answer 4

(a)

1. water;
2. minerals / ions / salts / named mineral ion / eq;

(b)

1. shape;

Then max 4 from:

2. cell wall;
3. cell membrane;
4. cytoplasm;
5. nucleus;
6. vacuole;

Question 5

Flowering plants can respond to their environment through tropic responses. These involve root or shoot tips growing towards or away from a stimulus.
A student set up an experiment to investigate how shoots respond to gravity.
He placed a potted plant on its side and looked at its growth after 5 days. The diagram shows what he saw.

(a) (i) Explain the benefit to the plant of this response.

(ii) Give one variable that the student should keep the same in his experiment and suggest how he could do this.

(iii) Suggest a suitable control for this experiment.

Answer 5

(a) (i) obtain light for photosynthesis;

(ii) 1. light / lamp;
2. dark room / even illumination / same light intensity everywhere / eq;

(iii) plant upright / clinostat / not on its side / eq;

Question 6

Plants can respond to drought by closing their stomata.
(i) Suggest how a plant benefits from closing its stomata when less water is available in the soil.

(ii) Explain the disadvantages to the plant of closing its stomata.

Answer 6

(i)

less/no transpiration / less water loss /
less evaporation / prevent wilting /
prevent flaccid cells / eq;

(ii)

1. less/no carbon dioxide;
2. photosynthesis;
3. less glucose / starch / carbohydrate;
4. less cooling /
   less transport of water /
   less transport of mineral ions;

Question 7

Plants need water to survive.

** (a) ** Name the two parts of a plant cell where most water is found.

• *(b) ** Plants absorb water from the soil through their roots.
• *(i) ** In the space draw a labelled diagram of a root hair cell.

**(ii) ** Explain how the structure of the root hair cell is adapted to absorb water from the soil.

Answer 7

(a)

cytoplasm;
vacuole;

(b) Draw the root hair cell with followings labeled.

1. shape;
   Then three from:
2. cell wall;
3. cell membrane;
4. nucleus;
5. vacuole;
6. cytoplasm;

(ii)

1. large surface area;
2. permeable membrane;
3. osmosis / diffusion;

Question 8

Plants also absorb mineral ions from the soil.
(i) What are magnesium ions used for in plants?

(ii) What are nitrate ions used for in plants?

Answer 8

(i) chlorophyll / chloroplast;

(ii)

1. amino acids / protein / enzymes;
2. growth;
3. DNA / bases;
4. chlorophyll / eq;

Question 9

An experiment is set up to find out if carbon dioxide is needed by plants for photosynthesis. Two plants were destarched and then put in glass containers A and B
as shown in the diagram.
After two days in the containers the plant leaves are tested for starch.

(a) (i) Suggest why the pots were covered with clear-plastic bags.
(ii) What is the purpose of container B?

(iii) The plant species and the time were kept the same in the experiment.
Suggest two other variables that should be kept the same for the experiment to be valid.

Answer 9

(a) (i)

1. stop release of carbon dioxide;
2. respiration;
3. bacteria / fungi / microorganisms /
   decomposers / soil organisms / eq;

(ii) control / to make a comparison / to show
photosynthesis needs carbon dioxide / to show
plants need carbon dioxide / difference due to
carbon dioxide / eq;

• *(iii)** 1. (sun)light;
  2. water / moisture / humidity;
  3. temperature;
  4. soil / minerals / nutrients / ions / eq;
  5. number of leaves / mass of plant / eq;

Question 10

The table describes the stages used to test the leaves for starch. It also gives the reason for each stage.
(i) Complete the table by describing stage 2 and giving the reason for stage 4.

(ii) Explain how stage 1 will prevent any starch digestion.
(iii) What is meant by the term diffusion mentioned in stage 3?
(iv) Describe the colour of the leaves you would expect after a starch test on

a leaf from container A

a leaf from container B

Answer 10

• *(i)** 1. boil/heat/warm in ethanol / alcohol;
  2. test for starch;

(ii) denature enzymes / eq; (reject/ignore kill enzymes )

(iii) high to low concentration / down concentration
gradient / eq; (ignore along concentration gradient)

(iv) a leaf from container A = yellow / brown / orange; (ignore green / white red )

a leaf from container B = blue / black / blue black / eq; (ignore purple)

Question 11

Some of the carbon in plants is found in the form of carbohydrates.
Name two carbohydrates found in plants.

Answer 11

Any two:

1. starch;
2. glucose;
3. cellulose;
4. sucrose;
5. fructose;

Question 12

The table shows some of the levels of organisation within an organism.

Complete the table by inserting a tick (9) to show the level of organisation of each example. The first one has been done for you.

Answer 12

Question 13

A student wants to investigate osmosis using potato tissue.
(a) What is meant by the term osmosis?