10. State four ways how glucose is utilised in a plant after it is made during photosynthesis.

LL. Photosynthesis is an important process taking place in plants. Give two reasons why this process isimportant to ensure the survival of all living organisms.

Section A: Multiple-Choice Questions

L. The graph shows the results of an investigation into oxygen release and oxygen intake by a greenplant in different light conditions.

start ofinvestigation in dark

lightturned on

end ofinvestigation

I I I

increasingoxygenrelease

increasingoxygen

intake

timeihour6 7I910

For how many hours did respiration and photosynthesis take place during the investigation?

respiration hours photosynthesis hours

4 4

4 6

5 5

1_0 6

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B

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2. The diagram shows an experiment set up to investigate photosynthesis

waterbubblesof gas

plant

Which conditions would cause the plant to produce most bubbles?

carbon dioxide in water light temperature

A present bright warm

B present bright cool

C absent dim warm

D present dim cool

Questions 3 and 4 refer to the diagram showing the arrangement of cells inside a leaf of a green plant.

3

4

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2

3 Which type of cell contains the largest number of chloroplasts?

A1 82C3 D4

4. Which cells are mesophyllcells?

A 1and4 B 2and3 D 3and4

D transpiration

C 4and5

5. Which feature helps plants to make most food by the process of photosynthesis?

A variegated leaves B shiny-surfaced leaves

C broad and flat leaves D spiky leaves

6. How does oxygen pass out through the stomata of leaves?

A active transport B diffusion C osmosis

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7 The cells of green plants make starch from simple inorganic materials. Which of the following bestexplains the important of chlorophyll in this process?

A to capture light energy B to absorb carbon dioxide

C to break down carbon dioxide and water D to release oxygen

Which graph shows the effect of temperature on the rate of photosynthesis?

ABC

temperature temperature temperature temperature

Which equation represents the chemical change which take place during photosynthesis?

A carbon dioxide + oxygen -+ glucose + water

B carbon dioxide + water --> glucose + oxygen

C glucose + oxygen --> carbon dioxide + water

D glucose + water -+ carbon dioxide + oxygen

10. Which of the following features is not found in guard cells?

A absence of chloroplasts B bean-shaped in surface view

C wall thicker near the stoma D size of pores changes

Section B: Short Answer Questions

1. A student set up the following experiment to investigate how light intensity affects the rate ofphotosynthesis. He varied the distance between the lamp and the beaker every 5min.

bubble

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pond weed

distance

lamp

(a) ln the space below and using appropriate axes, sketch a graph to show the likely result of thisexperiment. [3m]

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(b) Give two assumptions that the student has to make in this experiment. [2m]

(c) His teacher advised him to place the lamp at a minimum distance of 10cm from the pond weedExplain why she gave this piece of advice. l2ml

(d) (i) sketch a graph to show the likely result if the student placed the lamp at a distance of 5cmfrom the pond weed at the start of the experiment. [3m]

(ii) Explain the shape of your graph [2m]

(e) The pond weed was washed with a mild disinfectant at the start of the experiment. Explain whythis was necessary. [2m]

A young plant was destarched for two days before being used for an experiment. Four leaves wereplucked from the plant at 9am and measured for their dry weight. The same procedure was carried

out at 3pm and 9pm of the same day.

(a) State two assumptions that must be made in order for this experiment to be a fair one. [2m]

(b) Explain why the plant has to be destarched before the experiment and describe how destarching

is carried out. [2m]

(c) (i) Arrange the three different sets of leaves, starting with the lightest to the heaviest in terms

of dry weight. [1m]

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(ii) Explain the changes in dry weight of the three sets of leaves at the different times in theexperiment. [6m]

(d) (i) Why is the dry weight taken instead of the weight of the whole, fresh leaf? [2m]

(ii) Transpiration was constantly taking place during the experiment. Does this have anyeffect on the results of the experiment? [1m]

(e) Sketch a graph to show the oxygen concentration around the plant during a 24hr period.Does the oxygen concentration peak at 3pm just like the dry weight of the plant? Explain youranswer. [5m]

The diagram below illustrates the chemical process of photosynthesis.

AB

light

3

D E

(b)

(c)

(a) Where in the plant does this process take place? [1m]

State what do the letters A-E represent. [sm]

Using the materials which you have identified in (b), describe what happens during the light-dependent and light-independent reactions of photosynthesis. [2m]

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(d) Suppose only green light were to reach the earth. State one consequence this would have ongreen plants and other life on Earth. [3m]

Several leaves were exposed to sunlight and radioactive carbon dioxide for varying amounts of time.Each leaf was then killed and placed on a photographic plate for observation. The radioactive isotopeL4C showed up in the various leaves as follows.

variegated leaf treated leaves

untreated leaf15 hours of light

'oco, for15 seconds

'oco, for15 minutes

'ocortor15 hours

(a) Name the compound containing the radioactive isotope 14C that was first formed in the leaf

[1m]

(b) Explain why the distribution of L4C was as shown in the three leaves of the diagram above.

[3m]

(c) The leaf used in the control experiment had no traces of radioactive 14C in its carbohydratecompounds. State one conclusion that you can draw from this experiment. [1m]

Section C: Free Response Questions

L. lmagine you are a molecule of carbon dioxide. Trace the processes involved in your journey from theatmosphere and into the plant, until you finally become incorporated as part of a glucose molecule.

[6m]

Explain how energy is trapped by a plant, stored, and then released and used by an animal severaldays later. [6m]

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