SexualReproduction

1 Mark Questions

1. Give one example of an animal which exhibits oestrus cycle. [Delhi 2014 c] Ans. Example of an animal that exhibits oestrus cycle is cow.
2. Write the two pre-fertilisation events from the list given below: Syngamy, Gametogenesis, Embryogenesis, Pollination[All India 2014 C] Ans. Gametogenesis and pollination are pre-fertilisation events from the list.

3.In which two of the following organisms is the fertilisation external? Bony fishes, Ferns, Frogs, Birds.[Delhi 2014 C] Ans. Bony fishes and frogs are two organisms with external fertilisation.

4.Differentiate between oviparous and viviparous animals. [Delhi 2014 c] Ans. In oviparous animals, embryo develops outside the body of female in eggs, e.g. reptiles On the contrary in viviparous animals, embryo develops inside body of female. They give birth to babies, e.g. humans.

5.Name the phenomenon and one bird, where the female gamete directly develops into a

new organism.[All India 2013]

Ans. Parthenogenesis is the phenomenon in which a female gamete directly develops into a new organism. It is seen in some birds (Turkey), rotifers and honeybee.

1. Give the name of the common phenomenon with reference to reproduction in rotifers, honeybees and Turkeys. [Delhi 2013 c]

Ans. Parthenogenesis is the common phenomenon of with reference to reproduction in rotifers, honeybees and Turkeys.

1. Cucurbits and papaya plants bear staminate and pistillate flowers. Mention the categories

they are put under separately on the basis of the type of flowers they bear. [HOTS; Delhi 2012] Ans. Papaya is dioecious because the staminate and pistillate flowers are borne on two different plants, while cucurbits such as cucumber is monoecious because it bears both staminate and pistillate flowers on the same plant.

8.A list of three flowering plants is given below. Which ones out of them are:

(i)monoecious

(ii)bearing pistillate flowers

List Date palm, Cucurbits and Pea [Foreign 2011]

Ans. (i) Cucurbits are monoecious.

1. Date palm is dioecious, in which an individual plant bears pistillate flowers
2. Name the type of cell division that takes place in the zygote of an organism exhibiting haplontic life cycle. [Delhi 2011]

Ans. Meiosis is the type of cell division that takes place in zygote of an organism exhibiting haplontic life cycle.

10.A moss plant produces a large number of antherozoids but relatively only a few egg cells. Why? [Delhi 2010]

Ans. The antherozoids or male gametes in moss plants are motile and depend on water for transport towards female gametes (non-motile). During gamete transfer, large number of male gametes are lost. Thus, to ensure fertilisation, large number of male gametes are released to reach the non-motile female gametes.

1. Why are papaya and date palm plants said to be dioecious, whereas cucurbits and

coconut palms monoecious, inspite of all of them bearing unisexual flowers?[HOTS; Foreign 2010]

Ans. Papaya and date palm plants are said to be dioecious because male and female flowers are borne on separate plants, whereas cucurbits and coconut palms are monoecious because male and female flowers are borne on the same plant.

1. What is the major difference you observe in the offsprings produced by asexual

reproduction and in the progeny produced by sexual reproduction? [Delhi 2008]

Ans. Offsprings -produced by asexual reproduction are genetically identical to parents and to each other. On the contrary, progeny produced as a result of meiosis and gametic fusion in sexual reproduction show variations and differences from the two parents as well as among themselves.

2 Marks Questions

13.Coconut palm is monoecious, while date palm is dioecious. Why are they so called? [Delhi 2014]