Choose the most appropriate answer.
(a) Internal fertilisation occurs
(i) in female body.
(ii) outside female body.
(iii) in male body.
(iv) outside male body.
(b) A tadpole develops into an adult frog by the process of
(i) fertilisation
(ii) metamorphosis
(iii) embedding
(iv) budding
(c) The number of nuclei present in a zygote is
(i) none
(ii) one
(iii) two
(iv) four

AcademicBiologyNCERTClass 8

Correct Answer:

(a) Internal fertilization occurs (i) in the female body.

(b) A tadpole develops into an adult frog by the process of (ii) metamorphosis.

(c) The number of nuclei present in a zygote is (ii) one.


Internal fertilization: Fertilization that takes place inside the female's body and is known as internal fertilization. Male gametes are deposited inside or near the female's reproductive tract and fertilization occurs inside the organ.

The number of gametes produced in internal fertilization is less as fertilization takes place effectively inside the body. Animals with an internal fertilization process completely live their life on land. Examples: Mammals, Birds, Reptiles, etc.

Metamorphosis is a biological process by which animals such as insects, amphibians, and aquatic animals undergo physical development after birth or hatching. It involves rapid and abrupt changes in the body structure caused by cell growth and differentiation, maturation of enzymes and blood cells, and and remodeling of the nervous systems and digestive systems.

The main advantage of the metamorphosis process is that it avoids the food competition between larval insects and adult insects as they both consume different types of food and belong to different ecological niches.

Zygote: When two gametes fuse, a zygote is formed. A zygote is a fertilized egg cell which forms by the union of a female gamete (egg, or ovum) with a male gamete (sperm).

Updated on 10-Oct-2022 12:46:33