NCERT Class X Science Class: Chapter –6. Life Processer – Part-7

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Short Answer Questions

Question 36:

Name the following

(a) The process in plants that links light energy with chemical energy

(b) Organisms that can prepare their own food

(c) The cell organelle where photosynthesis occurs

(d) Cells that surround a stomatal pore

(e) Organisms that cannot prepare their own food

(f) An enzyme secreted from gastric glands in stomach that acts on proteins.


(a) Photosynthesis

(b) Autotrophs

(c) Chloroplast

(d) Guard Cells

(e) Heterotrophs

(f) Pepsin

Question 37:

“All plants give out oxygen during day and carbon dioxide during night”. Do you agree with this statement? Give reason.


During daytime, as the rate of photosynthesis is more than the rate of respiration, the net result is evolution of oxygen. At night there is no photosynthesis, so they give out carbon dioxide due to respiration.

Image the photosynthesis

Image the Photosynthesis

Image the photosynthesis

Question 38:

How do the guard cells regulate opening and closing of stomatal pores?


The swelling of guard cells due to absorption of water causes opening of stomatal pores while shrinking of guard cells closes the pores. Opening and closing of stomata occurs due to turgor changes in guard cells. When guard cells are turgid, stomatal pore is open while in flaccid conditions, the stomatal aperture closes.

ImageFigure shown the close and open stoma

ImageFigure Shown the Close and Open Stoma

ImageFigure shown the close and open stoma

Question 39:

Two green plants are kept separately in oxygen free containers, one in the dark and the other in continuous light. Which one will live longer? Give reasons.


Plant kept in continuous light will live longer, because it will be able to produce oxygen required for its respiration by the process of photosynthesis.

Question 40:

If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? Justify your answer.


Release of and intake of gives evidence that either photosynthesis is not taking place or its rate is too low. Normally during day time, the rate of photosynthesis is much more than the rate of respiration. So, produced during respiration is used up for photosynthesis hence is not released.

Question 41:

Why do fishes die when taken out of water?


Fishes respire with the help of gills. Gills are richly supplied with blood capillaries and can readily absorb oxygen dissolved in water. Since fishes cannot absorb gaseous oxygen they die soon after they are taken out of water.

Oxygen taken up by the blood from water

Oxygen Taken up by the Blood from Water

Oxygen taken up by the blood from water

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