Question

Onion bulb is the modification of leaves. Then why is there an absence of chloroplasts in onion cells?

Answer 1

Chloroplast is used by plants in the process of photosynthesis to make their own food. Onion bulb is used as the food storage organ by the onions. Bulb of the onion is generally present under the ground. Hence, it does not need chloroplast which is used in the presence of sunlight. During the modification of leaves, chloroplast vanishes away from the onion.