Que 68. Which one of the following is an egg-laying mammal?

(A) Duck-billed platypus
(B) Kangaroo
(C) Bandicoot
(D) Sloth

Answer - (A) Duck-billed platypus

Explanation: The platypus (Ornithorhynchus anatinus) also known as the duck-billed platypus is a semi aquatic egg-laying mammal (Monotreme) endemic to eastern Australia, including Tasmania. 

Que 67. Pleura is the covering of

(A) Liver
(B) Kidney
(C) Heart
(D) Lung

Answer - (D) Lung

Explanation: Pleura - A thin serous membrane in mammals that envelops each lung and folds back to make a lining for the chest cavity.

Que 66. Leaves of many grasses are capable of folding and unfolding because

(A) they have stomata on both sides of the leaf

(B) they have high levels of silica

(C) they have specialised bulliform cells

(D) their mesophyll is not differentiated into palisade and spongy parenchyma

Answer - (C) they have specialised bulliform cells

Explanation: In monocot leaves of grass plants, on the upper epidermis, bulliform cells are present. They help in the rolling or folding and unfolding of leaves. They also help in the process of transpiration.