Summative Practice Chapter 2 – Question 4 – 6 (Form 5 Biology Textbook Exercise and Answer)

Question 4:
Figure 1.1 and Figure 1.2 show the average of stomata size in two different types of plants in a 24-hour duration. One of the plants is placed in a humid surrounding whereas another plant is placed in a hot and dry surrounding.

(a) Which graph shows the plant that has been placed in a hot and dry surrounding?

(b) Explain your answer in 4(a).

(c) Why is the average of stomata size at night smaller than day time?

(d) Predict two characteristics of the plant structures which have been placed in a hot and dry surrounding in order to continue living.

(a) Graph in Figure 1.2

(b) At noon, the weather is hot and dry and this reduces the average number of stomata that is open. This in turn reduces excessive loss of water.

(c) The guard cells do not carry out photosynthesis and are straight.

(d) Stems or succulent leaves store water, has thick cuticle layers and fibrous roots.

Question 5:
(a) Name two types of reactions in photosynthesis.
(b) In which reaction is chlorophyll needed? Explain.

(a) Light-dependent reactions and light-independent reactions

(b) Light-dependent reactions. Light energy is absorbed by chlorophyll to excite electrons or for photolysis.

Question 6:
Aizat keeps a few fish in an aquarium which is decorated with plastic aquatic plants. However, those fish die because there is no electrical supply. Suggest one way for Aizat to overcome the problem.

He can switch plastic plants with real aquatic plants. Real plants carry out photosynthesis and release oxygen. This will increase the concentration of dissolved oxygen in the water.

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