The diameter of a pollen grain is generally:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: 25-50 micrometers
Explanation: Pollen grains are generally spherical measuring about 25-50 micrometers in diameter.
Which condition prevents autogamy but not geitonogamy?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Monoecy
Explanation: If both male and female flowers are present on the same plant such as castor and maize (monoecious), it prevents autogamy but not geitonogamy.
The stalk attaching the ovule to the placenta is called:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Funicle
Explanation: The ovule is a small structure attached to the placenta by means of a stalk called funicle.
Cells of the nucellus are characterized by:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Abundant reserve food materials
Explanation: Cells of the nucellus have abundant reserve food materials.
In a majority of flowering plants, how many megaspores degenerate?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: C
Answer: Three
Explanation: In a majority of flowering plants, one of the megaspores is functional while the other three degenerate.
Free nuclear endosperm means:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: A
Answer: Nuclear divisions are not immediately followed by cell wall formation
Explanation: PEN undergoes successive nuclear divisions to give rise to free nuclei. This stage... is called free-nuclear endosperm... nuclear divisions are not followed immediately by cell wall formation.
In pea and groundnut, the endosperm is:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Completely consumed
Explanation: Endosperm may either be completely consumed by the developing embryo (e.g., pea, groundnut, beans).
The portion of the embryonal axis above the level of cotyledons is called:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Epicotyl
Explanation: The portion of embryonal axis above the level of cotyledons is the epicotyl.
Which part of the flower contributes to the fruit formation in apple?
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Thalamus
Explanation: In a few species such as apple... the thalamus also contributes to fruit formation.
Parthenocarpy can be induced by the application of:
[Sexual-Reproduction-in-Flowering-Plants] [class-xii]
Correct Option: B
Answer: Growth hormones
Explanation: Parthenocarpy can be induced through the application of growth hormones.