Question

Which of the following statements are true/false?

I. In Torpedo, the electric organs are capable of generating strong electric shock.
II. Claspers are found in cartilaginous fishes.
III. Amphibian skin is moist and has thick scales.
IV. Birds are poikilothermic animals.
V. The most unique mammalian characteristic is the presence of milk-producing mammary glands by which the young ones are nourished

Answer 1

True statements:

Statement I: In Torpedo, the electric organs are capable of generating strong electric shock.

Torpedo is also called electric ray. They are cartilaginous fishes included in class Chondrichthyes which contain electric organs. It can produce electric shock which helps them in defence and capturing prey. Hence the statement I is correct.

Statement II: Claspers are found in cartilaginous fishes.

Claspers are the male copulatory organs. The cartilaginous fishes included in class Chondrichthyes possess claspers in the pelvic fins of males. Hence statement II is correct.

Statement V: The most unique mammalian characteristic is the presence of milk-producing mammary glands by which the young ones are nourished

The skin of animals in class Mammalia have sweat glands and sebaceous glands. In mammalian females, the sweat gland in the breast are modified into mammary glands which are milk-producing glands. The presence of mammary gland is the characteristic feature of class Mammalia. This gland is used to nourish the young ones. Hence the statement V is correct.

False statements

Statement III: Amphibian skin is moist and has thick scales.

Amphibian skin is glandular and it is moist. The skin is thin and vascular and not covered by scales. It is a respiratory organ for some amphibians such as frogs. Hence statements III is incorrect.

Statement IV: Birds are poikilothermic animals.

In some organisms, body temperature varies with that of the envirnment and such animals are called poikilotherms. Fishes, amphibians, reptiles etc., are examples of poikilothermic animals.

Birds are warm-blooded animals. Thus they are homeotherms which can maintain a constant body temperature. Hence statement IV is incorrect.