[3 marks Question Answer]

Question 13 Marks

The following two chemical reactions are supposed to indicate a certain process occurring in the green plants under two different conditions:
(a) $C_6H_{12}O_6 + 6O_2 → 6CO_2$ + _______ + $38$ ATP
(b) $C_6H_{12}O_6$ → ________ + $2 CO_2 + 2 ATP$
(i) Fill in the blank in each reaction.
(ii) Name the process represented by the two reactions.
(iii) What are the conditions under which the two reactions (a) and (b) are occurring respectively?

Answer

(i)
(a) $C_6H_{12}O_6 + 6O_2 → 6CO_2 + 6H_2O + 38$ ATP
(b) $C_6H_{12}O_6 → C_2H_5OH + 2 CO_2 + 2$ ATP
(ii)
(a) Aerobic respiration;
(b) Anaerobic respiration
(iii) Reaction
(a) can be completed only in the presence of oxygen, while reaction
(b) can be completed in the absence of oxygen.

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Question 23 Marks

Explain why respiration is said to be a reversal of photosynthesis?

Answer

Respirationis said to be the reverse of photosynthesis due to the following reasons:
(1) In respiration, the organic food is broken down into its inorganic compounds, i.e., $CO _2$ and $H _2 O$, while in photosynthesis the organic food is synthesized from its inorganic components, i.e., $CO _2$ and $H _2 O$.
(2) In respiration, $CO _2$ is given out, while in photosynthesis $CO _2$ is consumed.
(3) In respiration, $O _2$ is consumed, while in photosynthesis $O _2$ is released or evolved.
(4) In respiration, energy is liberated, while in photosynthesis energy is absorbed.

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BIOLOGY [3 marks Question Answer]

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