Life on earth Key Area 3 – Photosynthesis

Exercise 1

1.What must be present in leaf cells for photosynthesis to take place?

Acarbon dioxide and water

Boxygen and water

Ccarbon dioxide and oxygen

Doxygen and hydrogen1

2.The word equation for photosynthesis is

Acarbon dioxide + water  glucose + oxygen

Boxygen + water  glucose + carbon dioxide

Cglucose + oxygen carbon dioxide + water

Dcarbon dioxide + oxygen  glucose + water1

3.Plants growing close to each other compete mainly for

Awater, light and soil nutrients

Bwater, food and soil nutrients

Clight, water and food

Dlight, food and soil nutrients1

4. The bar chart below shows the number of cells of different lengths in

a sample of onion skin.

The percentage of cells with a length greater than 55 micrometres is

A10%

B15%

C20%

D30% 1

5. The table below shows the rate of photosynthesis by a plant measured at different light intensities.

Light intensity
(kilolux) / Rate of photosynthesis
(units)
10 / 2
20 / 27
30 / 51
40 / 73
50 / 82

What change in light intensity produces the greatest increase in the rate of photosynthesis?

An increase in light intensity from

A10 to 20 kilolux

B20 to 30 kilolux

C30 to 40 kilolux

D40 to 50 kilolux 1

6. The diagram below shows a plant cell.

(a)Which letter shows the structure that is the site of photosynthesis?

1

(b)Name the chemical that this structure contains. 1

(c)What is the function of this chemical in the photosynthesis process?

1

(d)Plant cells convert the sugars made in photosynthesis into other

substances.

Copy and complete the table below by naming two of these substances. 2

Role of substance
in plant cells / Name of substance
Storage of energy
Forms cell walls
  1. A scientist grew some cereal plants in a field.

During the course of the day, she removed 2 plants every 4 hours

and measured the concentrations of sugar in the leaves of the

plants.

The results are shown in the table below.

Present theaverageresults as a line graph on graph paper. (3)

Total 13 marks

Exercise 2

Questions1 and 2 refer to the accompanying diagram which shows some of

the steps carried out to test a leaf for the presence of starch.

1. The correct sequence of the steps is 1

A Y, W, Z, X

B Z, W, Y, X

C Y, W, X, Z

D Z, Y, W, X

1

2. The reason for carrying

out step W is to

A kill the leaf cells

B soften the leaf discs

C remove chlorophyll from

the leaf cells

D extract oxygen bubbles

from the leaf discs

1

Questions3 and 4 refer to the accompanying diagram. The plant was left in sunlight for two days and then leaf discs W, X, Y and Z were tested for the presence of starch.

3. The leaf disc found to contain starch was

A W

B X

C Y 1

D Z

4. This experiment proves that in order to photosynthesise, a plant must

have

A sunlight and carbon dioxide

B carbon dioxide and water

C chlorophyll and sunlight 1

D carbon dioxide and chlorophyll

5. A variegated leaf on an ivy plant was treated as shown in the accompanying

diagram.

Which of the following shows the appearance of the leaf after testing

it for starch?

1

6. The diagram below shows an investigation into photosynthesis.

Which of the following statements is correct?

AP, Q and R make food

Bonly P and Q make food

Conly P makes

Donly R makes food 1

7. The energy conversion that takes place during photosynthesis is

A Chemical to light

B Heat to chemical

C Light to chemical

D Chemical to heat 1

.

8. An experiment was carried out to investigate the growth of pea

plants kept in a high light intensity following germination.

The graph shows the average shoot length of the pea plants.

During which 5 day period is there the greatest increase in average shoot length?

ADay 10 – 15

BDay 15 – 20

CDay 20 – 25

DDay 25 – 30

1

9. Groups of students carried out an investigation into the effects of

competition in plants.

Trays containing seeds were set up as shown below.

The trays were watered regularly to allow germination to take place. After several days the seedlings were observed and the number with healthy green leaves was noted.

The results are shown in the table below.

Number of seeds in each tray / Number of seedlings with
healthy green leaves / Percentage of seedlings with healthy green leaves
15 / 12 / 80
30 / 18 / 60
45 / 23 / 51
60 / 24 / 40

(a) Predict the percentage of seedlings with healthy green leaves if 75 seeds were sown in a seed tray.

1

(b)State two factors for which the seedlings could be competing in this investigation.

2

(c) Name one factor that should be kept the same in this investigation to ensure that the results are valid.

1

Total 12 marks

Exercise 3

1.The light reactions involve

Acombining of water with carbon dioxide

Buse of water by chlorophyll to split light

Crelease of energy from water using light energy

Dsplitting of water using light energy1

2. The products of the above process in the light reaction are

Aglucose and hydrogen

Bcarbon dioxide and hydrogen

Cwater and oxygen

Dhydrogen and oxygen 1

3.ATP synthesised during the light reactions provides the second stage of photosynthesis with

Aglucose

Bcarbondioxide

Cenergy

Dhydrogen1

Questions 4,5 and 6 refer to the accompanying diagram which shows the light reactions. Choose from the following possible answers.

A oxygen

B hydrogen

C water

D carbon dioxide

4. What is substance X? 1

5. What is substance Y? 1 1

6. What is substance Z? 1

7. The diagram below shows the second stage of photosynthesis.

Look at the table on the next page. Which line correctly identifies X and Y?

X / Y
A / hydrogen / starch
B / starch / ADP
C / starch / oxygen
D / water / starch

1

8. The following stages occur during photosynthesis.

Wglucose is formed

Xwater is broken down to produce hydrogen

Yglucose is converted to starch

Zhydrogen is combined with carbon dioxide

The correct order for these stages is

AW Z X Y

BZ Y X W

CX Z W Y

DY X Z W 1

9. (a)Name the two substances produced in the light reactions that

arerequired for the second stage. 2

(b) Name the second stage. 1

(d) Name the other substance required for the second stage which is

absorbed by the leaves of the plant. 1

Total 12 marks

Exercise 4

  1. Which of the following are all limiting factors in photosynthesis?

ACarbon dioxide concentration, temperature and light intensity.

BCarbon dioxide concentration, oxygen concentration and light

intensity.

COxygen concentration, temperature and light intensity.

DOxygen concentration, carbon dioxide concentration and temperature. 1

2.The graph below shows the effect of increasing light intensity on

the rate of photosynthesis.

Light intensity (units)

Which factor is limiting the rate of photosynthesis at point X on

the graph?

Acarbon dioxide concentration

Btemperature

Clight intensity

Doxygen concentration 1

  1. The graph below shows the effect of increasing temperature on

the rate of photosynthesis.

Rate of

photosynthesis

1015

Temperature (oC)

A correct conclusion would be that

Aas the temperature increases, the rate of photosynthesis increases

Bas the temperature increases, the rate of photosynthesis decreases

Cas the temperature increases, the rate of photosynthesis remains constant

Das the temperature decreases, the rate of photosynthesis increases 1

3. Some students were asked to design an investigation to compare the rate of production of oxygen gas by two different

species of water plant. The diagrams below show the proposed procedure.

Identify two changes to the procedure that should be made to ensure that a valid conclusion can be made. 2

  1. The following word equation shows the first stage of photosynthesis.

water oxygen + hydrogen + ATP

(a)Name this stage of photosynthesis. 1

(b)Name the substance which captures the light energy. 1

(c)Describe what happens to each of the following

products.

(a)Oxygen 1

(b)Hydrogen 1

(c)ATP 1

  1. The diagram below represents a summary of part of the process of photosynthesis.

Reaction

X

Name the following:

Reaction X; Substance Y; Substance Z

3

  1. The graph below shows how the rate of photosynthesis is affected

bylight intensity at different concentrations of carbon dioxide.

(a)What factor was limiting the rate of photosynthesis at points

1 and 2?

2

(b) Name one other factor that may limit the rate of

photosynthesis. 1

7.An experiment was set up to measure the effect of light intensity

on the rate of photosynthesis in the water plantElodea.

The light intensity was varied using a dimmer switch on the bulb.

The rate of photosynthesis was measured by counting the number

of bubbles released per minute.

1

The results of the experiment are shown in the table below.

Light intensity
(units) / Rate of photosynthesis
(number of bubbles per minute)
1 / 2
3 / 10
5 / 23
8 / 45
10 / 45
12 / 45

(a)On graph paper, plot a line graph to show rate of photosynthesis against

light intensity. 2

(b)Name the gas collected. 1

(c)Explain why the rate of photosynthesis remained constant at light intensities greater than 8 units. 1

Total 20 marks