What is the main advantage of apomictic seeds in agriculture?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: They prevent segregation of hybrid characters
Explanation: If these hybrids are made into apomicts, there is no segregation of characters in the hybrid progeny. Then the farmers can keep on using the hybrid seeds.
Which layer of the anther wall nourishes the developing pollen grains?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: D
Answer: Tapetum
Explanation: The innermost wall layer is the tapetum. It nourishes the developing pollen grains.
The generative cell of a pollen grain is characterized by:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Being small and spindle-shaped
Explanation: The generative cell is small... It is spindle shaped with dense cytoplasm and a nucleus.
The vegetative cell of a pollen grain is characterized by:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Having a large irregularly shaped nucleus
Explanation: The vegetative cell is bigger, has abundant food reserve and a large irregularly shaped nucleus.
In over 60 percent of angiosperms, pollen grains are shed at which stage?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 2-celled
Explanation: In over 60 per cent of angiosperms, pollen grains are shed at this 2-celled stage.
The inner wall of the pollen grain (intine) is composed of:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Cellulose and pectin
Explanation: The inner wall of the pollen grain is called the intine. It is a thin and continuous layer made up of cellulose and pectin.
Germ pores on the pollen grain are areas where:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Sporopollenin is absent
Explanation: Pollen grain exine has prominent apertures called germ pores where sporopollenin is absent.
The basal part of the ovule is represented by the:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: D
Answer: Chalaza
Explanation: Opposite the micropylar end, is the chalaza, representing the basal part of the ovule.
Which insect group is the dominant biotic pollinating agent?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Bees
Explanation: Among the animals, insects, particularly bees are the dominant biotic pollinating agents.
Flowers pollinated by flies and beetles typically secrete:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Foul odours
Explanation: The flowers pollinated by flies and beetles secrete foul odours to attract these animals.