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14

Which of the following will release more energy on oxidation? Arrange them in ascending order.

(a) 1 gm of fat

(b) 1 gm of protein

(c) 1 gm of glucose

(d) 0.5 gm of protein +0.5 gm glucose

Explanation

The ascending order of substrate that will release more energy on oxidation will be as follows

1 gm protein $<0.5 \mathrm{gm}$ In protein $<1 \mathrm{gm}$ glucose $<1 \mathrm{gm}$ fat +0.5 gm glucose

15
The product of aerobic glycolysis in skeletal muscle and anaerobic fermentation in yeast are respectively ............. and ............ .
Explanation

The product of aerobic glycolysis in skeletal muscles is pyruvic acid while in anaerobic fermentation in yeast ethanol and $\mathrm{CO}_2$ are produced.

16
If a person is feeling dizzy, glucose or fruit juice is given immediately but not a cheese sandwich, which might have more energy. Explain.
Explanation
The glucose as absorbed and reaches blood, giving instant energy. Whereas, cheese sandwich will require time for digestion, and absorption. Sick person requires immediate energy supply, so glucose or fruit juices contains glucose are given to them.
17
What is meant by the statement 'aerobic respiration is more efficient'?
Explanation

In the process of aerobic respiration, a single molecule of glucose can yield up to 36 ATP molecules. However, in fermentation or anaerobic respiration there is net gain of only 2 molecules of ATP from each glucose molecule, which is comparatively much less than that of aerobic respiration.

Hence, aerobic respiration is more efficient process.

18

Pyruvic acid is the end product of glycolysis. What are the three metabolic fates of pyruvic acid under aerobic and anaerobic conditions? Write in the space provided in the diagram.

Explanation

The three metabolic products formed under aerobic and anaerobic conditions are

(i) Lactic acid (ii) Ethanol (iii) Acetyl Co -A

Lactic acid is formed by the oxidation of pyruvic acid in under anaerobic condition in skeletal muscles.

Ethanol is formed by the oxidation of pyruvic acid in yeast under anaerobic condition.

Acetyl Co-A is formed by the oxidation of pyruvic acid that take place within the mitochondria under aerobic condition.

Pyruvic acid $+\mathrm{Co}-\mathrm{A}+\mathrm{NAD}^{+} \frac{\mathrm{Mg}^{2+}}{\text { Pyruvate dehydrogenase }}$ Acetyl $\mathrm{Co}-\mathrm{A}+\mathrm{CO}_2+\mathrm{NADH}+\mathrm{H}^{+}$