CBSE Class 10 Answered

Amoeba reproduces primarily by binary fission. However, a method known as multiple fission is adopted by the unicellular organism Amoeba to survive and reproduce under unfavourable conditions. When the conditions are unfavourable, Amoeba withdraws its pseudopodia and becomes almost round. It secretes a hard covering called cyst. The cyst forms a thick protective coat around it. Inside the cyst, the nucleus undergoes repeated divisions to form many nuclei. Nuclear division is followed by the division of cytoplasm. Hence, eventually many new daughter cells are formed. On the return of favourable conditions, the cyst bursts open to release these daughter cells.