Question

Refer to the given figure showing life cycle of an insect and statements associated with it.


(a) Commercial silk is obtained from ___(i)__ stage.
(b) _(ii)__stage undergoes four moults to become__(iii)__.

Select the option which correctly fills blanks (i), (ii) and (iii).

• A. (i) - S; (ii) - Q; (iii) - R
• B. (i) - R; (ii) - Q; (iii) - R
• C. (i) - S; (ii) - R; (iii) - Q
• D. (i) - Q; (ii) - R; (iii) - S

Answer 1

The correct option is B (i) - R; (ii) - Q; (iii) - R

• The figure represents the life cycle of a silkworm, where P represents the egg stage, Q represents the larva stage, R represents the pupa stage and S represents the moth stage.
• Silk is obtained by unwinding the silk fibres from the cocoons of silkworms. It is done by boiling cocoons which softens the cocoons, reduces the stickiness, and loosens the fibres. This is done during the pupa stage of the silkworm. Hence, commercial silk is obtained from the pupa stage (R).
• Moulting is the process when silkworms stop feeding, become immobile and prepare themselves for shedding their old skin to accommodate the fast growth. Four moults take place during the entire larval period after which the silkworm forms cocoons and enters the pupa stage. Hence, larva (Q) undergoes four moults to become pupa(R).
• On matching the blanks given in the statements with the different stages in the life cycle of the silkworm, the correct option is (b).