(Q).
Q: What makes toenails and fingernails hard? Choices: - guanine - cellulose - taurine - keratin A:
(A).
keratin

(Q).
Q: What term describes waves that travel through matter? Choices: - replaced waves - water waves - heat waves - mechanical waves A:
(A).
mechanical waves

(Q).
Q: What process can be triggered by a burst of ethylene production in the fruit? Choices: - pickling - hardening - drying - ripening A:
(A).
ripening