Reproduction in Organisms

Q1. What is parthenogenesis?

Ans: The phenomenon of development of female gamete directly into an individual without
fertilization is called parthenogenesis.

Q2. What is meant by meiocytes?

Ans: A potential diploid gamete mother cell which undergo meiosis to produce haploid
gametes is called meiocyte.

Q3. What are hermaphrodites?

Ans: The animals bearing both male and female sex organs are called hermaphrodites.
E.g., Earthworm, sponges and tapeworms.

Q3. What is the fate of ovary and ovule after fertilization?

Ans: After fertilization, ovary is transformed into fruit and ovule is transformed into seed.

Q5. What are the differences between external fertilization and internal fertilization? (Any two)

External fertilization:
1. Fusion of gametes occurs outside the body of an organism.
2. Large number of both male and female gametes are released into the surrounding medium (e.g., water) in order to enhance chances of syngamy.
3. Chances of fertilization is less.
4. The offspring are extremely vulnerable to predators, threatening their survival.
5. Examples: Bony fishes, frogs and majority of algae.

Internal fertilization:
1. Fusion of gametes occurs inside the body of an organism.
2. The number of sperms produced are very large and number of eggs produced are less.
3. Chances of fertilization is more.
4. The offspring are well protected comparatively.
5. Examples: Birds, mammals, etc.

Q6. Differentiate between menstrual cycle and oestrous cycle.

Menstrual cycle:
1. It occurs in primates only (Monkeys, apes and human beings)
2. It involves loss of blood.
3. Menstrual cycle consists of menstrual phase, proliferative phase, and the secretory phase.

Oestrous cycle:
1. It occurs in non-primates such as cow, sheep, rats, deer, dogs etc…
2. Loss of blood is not involved.
3. It consists of a short period of oestrous or heat.

Q7. Distinguish between oviparous and viviparous animals.

Oviparous animals:
1. Oviparous animals lay fertilized eggs.
2. The fertilized eggs have calcareous shell and young ones hatch out after a period of incubation.
3. Chances of survival of young one is less as the female lays egg in the environment.
For example, reptiles, birds, etc.

Viviparous animals
1. Viviparous animals give birth to young ones.
2. The fertilized egg (zygote) has no shell and develops into a young one inside the body of the female organism.
3. Chances of survival of young one is more because of proper embryonic care and protection inside the mother's body.
For example, majority of mammals including humans.

Q8. Distinguish between seasonal breeders and continuous breeders.

Seasonal breeders:
1. These are the organisms which mate or breed during particular seasons of the year.
2. These organisms possess the changes in reproductive organs only during favourable conditions.
Example: Dogs, frogs, lizards.

Continuous breeders:
1. These are the organisms which mate or breed throughout the year irrespective of the season.
2. These organisms possess changes in their reproductive organs throughout their reproductive phase.
Example: Human, Rabbit, cattle

Q9. List any four vegetative propagules.

Bulbil – Agave
Bulbs – Onion, Garlic
Eyes – Potato
Leaf buds – Bryophyllum
Offset – Hyacinth and Pistia
Rhizome – Ginger
Runner – Oxalis
Sucker – Mint