The proximal end of the filament of a stamen is attached to which part of the flower?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Thalamus or petal
Explanation: A typical stamen consists of a long and slender stalk called the filament. The proximal end of the filament is attached to the thalamus or the petal of the flower.
Which of the following best describes the structure of a typical angiosperm anther?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Bilobed and dithecous
Explanation: A typical angiosperm anther is bilobed with each lobe having two theca, meaning they are dithecous. Often a longitudinal groove runs lengthwise separating the theca.
Which layer of the microsporangium wall performs the function of nourishment for 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. Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus.
The process of formation of microspores from a pollen mother cell (PMC) is termed as:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Microsporogenesis
Explanation: The process of formation of microspores from a pollen mother cell (PMC) through meiosis is called microsporogenesis.
The hard outer layer of the pollen grain, the exine, is composed of which highly resistant material?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Sporopollenin
Explanation: The hard outer layer called the exine is made up of sporopollenin which is one of the most resistant organic material known. It can withstand high temperatures and strong acids and alkali.
What is the specific area on the pollen grain exine called where sporopollenin is absent?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: A
Answer: Germ pore
Explanation: Pollen grain exine has prominent apertures called germ pores where sporopollenin is absent. Pollen tubes exit through these pores during germination.
In over 60 per cent of angiosperms, pollen grains are shed at which stage?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 2-celled stage
Explanation: In over 60 per cent of angiosperms, pollen grains are shed at the 2-celled stage, containing a vegetative cell and a generative cell.
Which plant species introduced as a contaminant in imported wheat has become ubiquitous in India and causes pollen allergy?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Parthenium
Explanation: Parthenium or carrot grass that came into India as a contaminant with imported wheat has become ubiquitous in occurrence and causes pollen allergy.
At what temperature are pollen grains stored in liquid nitrogen for pollen banks?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: -196 degrees C
Explanation: It is possible to store pollen grains of a large number of species for years in liquid nitrogen (-196 degrees C). Such stored pollen can be used as pollen banks.
Which of the following represents the basal part of the ovule?
[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.