Exercise 2.3
Look at the diagram of a cell in Fig. 2.20. Identify the parts labelled from (a) to (g) and correctly match them with their functions given below: (i) Controlling all the activities of a cell. (ii) Site of cellular respiration. (iii) Storage organelle that also provides rigidity to the cell. (iv) Separates the cell contents from surroundings. (v) Provides structural rigidity to the cell. (vi) Packs and stores materials received from ER. (vii) Helps in manufacturing food.
Not cross-checked
NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.
The cell in Fig. $\displaystyle 2.20$ is a plant cell — the functions listed include a cell wall, a large storage vacuole and food manufacture, and an animal cell has none of these.
(i) Controlling all the activities of a cell — nucleus, the house of coded instructions, holding the chromosomes.
(ii) Site of cellular respiration — mitochondrion, where glucose is broken down and the energy stored as ATP.
(iii) Storage organelle that also provides rigidity to the cell — vacuole; the water it stores keeps up the pressure inside the cell, which keeps the cell firm.
(iv) Separates the cell contents from surroundings — cell membrane.
(v) Provides structural rigidity to the cell — cell wall.
(vi) Packs and stores materials received from ER — Golgi apparatus.
(vii) Helps in manufacturing food — chloroplast, whose chlorophyll absorbs sunlight for photosynthesis.
Now read the seven labels off Fig. $\displaystyle 2.20$ in your book and write the matching letter beside each part named above.
