The suspensor in angiosperm embryos functions primarily to:
Answer: A
The suspensor absorbs nutrients from the endosperm and pushes the developing embryo deeper into the embryo sac for better nourishment.
Q.24Medium
In bryophytes, the sperm require water for fertilization. Which adaptation in pteridophytes partially overcame this limitation?
Answer: B
Pteridophytes still require water as sperm are flagellated, but the prothallus provides a moist environment. True water independence came with seeds in gymnosperms.
Q.25Medium
The phenomenon of apomixis in plants results in:
Answer: A
Apomixis is asexual reproduction in seeds where offspring are genetically identical to the parent, bypassing meiosis and fertilization.
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Q.26Medium
Which structural adaptation in angiosperms represents the most advanced reproductive strategy?
Answer: B
Double fertilization is unique to angiosperms where one sperm nucleus fertilizes the egg (embryo) and another fertilizes the polar nuclei (endosperm), providing efficient nutrition for the developing embryo.
Q.27Medium
The phenomenon where a single flower produces both viable pollen and functional ovules is termed:
Answer: D
This represents a hermaphroditic flower with the potential for self-fertilization. Dichogamy prevents this by temporal separation, heterostyly by spatial separation.
Q.28Medium
The microsporophyll in angiosperms is equivalent to which structure?
Answer: C
The stamen is the microsporophyll of angiosperms that bears microsporangia (pollen sacs). Carpels are megasporophylls.
Q.29Medium
The transition from aquatic to terrestrial life in plants required which critical innovation?
Answer: B
Vascular tissue (xylem and phloem) was essential for water transport in terrestrial environments, enabling plants to grow upright and away from moisture sources.
Q.30Medium
Which character distinguishes Selaginella from Lycopodium among pteridophytes?
Answer: B
Selaginella exhibits heterospory (producing two types of spores) and possesses a ligule (a small appendage), which are absent in Lycopodium.
Q.31Medium
Which of the following statements about double fertilization in angiosperms is correct?
Answer: B
In double fertilization, one sperm nucleus fuses with the egg nucleus to form diploid zygote (embryo), while the second sperm fuses with the two polar nuclei to form triploid endosperm.
Q.32Medium
The integument in a gymnosperm ovule develops into which structure?
Answer: B
The integument of the ovule develops into the seed coat (testa), which protects the embryo and endosperm in seeds of both gymnosperms and angiosperms.
Q.33Medium
A botanist finds a plant with the following features: vascular bundles arranged in a ring, presence of cork cambium, and woody stem. This is likely a:
Answer: B
Ring arrangement of vascular bundles, cork cambium, and secondary growth are characteristics of dicot gymnosperms like Pinus and Cedrus.
Q.34Medium
Which of the following is the correct sequence of sporophyte development in angiosperms?
Answer: B
After fertilization, the zygote undergoes mitosis to form suspensor and embryo proper, which together develop into a seedling after germination.
Q.35Medium
In a typical angiosperm flower, the number of nucellate cells in the ovule is:
Answer: B
The nucellus is a multi-cellular tissue surrounding the embryo sac that provides nutrition to the developing female gametophyte.
Q.36Medium
Which plant group shows a transition from water to land by developing a cuticle and stomata?
Answer: B
Bryophytes were the first plants to develop adaptations for land, including a cuticle (though thin) and stomata for gas exchange, though some bryophytes retain both.
Q.37Medium
In gymnosperms, the male gametophyte at maturity contains:
Answer: C
The mature male gametophyte (pollen grain) in gymnosperms contains two sperm cells (after mitosis of generative cell) and one tube cell.
Q.38Medium
Which of the following is characteristic of the embryo sac in angiosperms?
Answer: A
The typical angiosperm embryo sac (Polygonum type) is 7-celled and 8-nucleate consisting of egg apparatus, central cell, and synergid cells.
Q.39Medium
The endosperm in angiosperms is triploid because:
Answer: B
The central cell of the female gametophyte contains two polar nuclei (2n total). When one sperm nucleus (n) fuses with this central cell, the resulting endosperm is triploid (3n).
Q.40Medium
Which tissue in gymnosperms provides mechanical support and conducts water without the presence of vessels?
Answer: B
Gymnosperms lack true vessels and rely on tracheids for water conduction and mechanical support in the xylem.
