In which of the following plants does Polyembryony commonly occur?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Citrus
Explanation: In many Citrus and Mango varieties, nucellar cells develop into embryos. Occurrence of more than one embryo in a seed is referred to as polyembryony.
Removal of anthers from a flower bud before dehiscence is called:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Emasculation
Explanation: If the female parent bears bisexual flowers, removal of anthers from the flower bud before the anther dehisces is necessary. This step is referred to as emasculation.
The innermost wall layer of a microsporangium is usually:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: D
Answer: Tapetum
Explanation: The microsporangium is generally surrounded by four wall layers. The innermost wall layer is the tapetum.
Which cell of the pollen grain has abundant food reserve and a large irregularly shaped nucleus?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Vegetative cell
Explanation: The vegetative cell is bigger, has abundant food reserve and a large irregularly shaped nucleus.
The generative cell of a pollen grain is:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Small and spindle shaped
Explanation: The generative cell is small and floats in the cytoplasm of the vegetative cell. It is spindle shaped with dense cytoplasm and a nucleus.
Pollen viability in Rice and Wheat is approximately:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: A
Answer: 30 minutes
Explanation: In some cereals such as rice and wheat, pollen grains lose viability within 30 minutes of their release.
Which family typically maintains pollen viability for months?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Rosaceae
Explanation: In some members of Rosaceae, Leguminoseae and Solanaceae, they maintain viability for months.
A multicarpellary, apocarpous gynoecium is found in:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Michelia
Explanation: The pistils may be free (apocarpous) as in Michelia. Papaver has a syncarpous pistil.
The protective envelopes of the ovule are called:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Integuments
Explanation: Each ovule has one or two protective envelopes called integuments.
The mass of cells enclosed within the integuments having abundant reserve food material is:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Nucellus
Explanation: Enclosed within the integuments is a mass of cells called the nucellus. Cells of the nucellus have abundant reserve food materials.