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Science · 2024 · 3 marks
CBSE 2024 · Region 2 · Set 3 · Q30
(a) Give reasons for the following: (i) Alveoli in lungs are richly supplied with blood capillaries. (ii) Respiratory pigment in the blood takes up…
(a)
Give reasons for the following :
(i)
Alveoli in lungs are richly supplied with blood capillaries.
(ii)
Respiratory pigment in the blood takes up oxygen and not carbon dioxide.
(iii)
During anaerobic respiration, a $\displaystyle 3$ -carbon molecule is formed as an end product instead of $\displaystyle \mathrm{CO}_{2}$ in human beings.
OR 30. (b) (i) Name the movements that occur all along the gut in human digestive system. How do they help in digestion?
(ii)
Where is bile juice stored in human body ? List two roles of bile juice.
Marking-scheme solution
(i) To facilitate efficient exchange of gases.
(ii) It has high affinity for oxygen.
(iii) Lack of oxygen does not oxidise glucose completely and forms a $\displaystyle 3$-Carbon molecule or lactic acid.
(i) • Peristaltic movements
Muscles contract rhythmically in order to push the food forward in a regulated manner to be digested properly.
(ii) • Gall bladder
Two roles:
Emulsification of fats
Makes the acidic medium alkaline.
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CBSE Class 10 Science past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.