Q51. The characteristic feature that distinguishes angiosperms from gymnosperms is the presence of:
[A] Seeds
[B] Vascular tissues
[C] Flowers
[D] Roots
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Correct Answer: [C] Flowers
Explanation: While both gymnosperms and angiosperms produce seeds and have vascular tissues, the presence of flowers is the unique characteristic that distinguishes angiosperms. Flowers are the reproductive structures of angiosperms.
Q52. The fruit in angiosperms develops from the:
[A] Ovule
[B] Ovary
[C] Stamen
[D] Petal
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Correct Answer: [B] Ovary
Explanation: After fertilization in angiosperms, the ovary develops into the fruit, which encloses the seeds that develop from the ovules. The fruit provides protection to the seeds and aids in their dispersal.
Q53. Double fertilization is a characteristic feature of:
[A] Algae
[B] Bryophytes
[C] Gymnosperms
[D] Angiosperms
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Correct Answer: [D] Angiosperms
Explanation: Double fertilization is a unique process that occurs only in angiosperms. It involves the fusion of one male gamete with the egg to form the zygote and the fusion of the other male gamete with the central cell to form the triploid primary endosperm nucleus.
Q54. The primary endosperm nucleus in angiosperms is:
[A] Haploid
[B] Diploid
[C] Triploid
[D] Tetraploid
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Correct Answer: [C] Triploid
Explanation: The primary endosperm nucleus (PEN) in angiosperms is formed by the fusion of one male gamete (n) with the diploid secondary nucleus (2n) of the central cell. Therefore, the PEN is triploid (3n).
Q55. Which of the following plant groups exhibits the haplontic life cycle?
[A] Gymnosperms
[B] Angiosperms
[C] Most algae
[D] Bryophytes
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Correct Answer: [C] Most algae
Explanation: In the haplontic life cycle, the dominant phase is the haploid gametophyte. The diploid phase is represented only by the zygote, which undergoes meiosis to form haploid spores. This type of life cycle is characteristic of many algae like Volvox, Spirogyra, and some species of Chlamydomonas.
Q56. Which of the following plant groups exhibits the diplontic life cycle?
[A] Bryophytes
[B] Pteridophytes
[C] Gymnosperms and Angiosperms
[D] Most algae
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Correct Answer: [C] Gymnosperms and Angiosperms
Explanation: In the diplontic life cycle, the diploid sporophyte is the dominant, independent, and photosynthetic phase. The gametophyte is reduced and dependent on the sporophyte. This type of life cycle is characteristic of gymnosperms and angiosperms.
Q57. Which of the following plant groups exhibits the haplo-diplontic life cycle?
[A] Gymnosperms
[B] Angiosperms
[C] Most algae
[D] Bryophytes and Pteridophytes
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Correct Answer: [D] Bryophytes and Pteridophytes
Explanation: In the haplo-diplontic life cycle, both the gametophyte and sporophyte phases are multicellular and often free-living. They alternate with each other. This type of life cycle is characteristic of bryophytes and pteridophytes, although the dominant phase differs between the two groups.
Q58. In bryophytes, the dominant phase is the:
[A] Sporophyte
[B] Gametophyte
[C] Zygote
[D] Embryo
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Correct Answer: [B] Gametophyte
Explanation: In bryophytes, the haploid gametophyte is the dominant, independent, and photosynthetic phase. The diploid sporophyte is dependent on the gametophyte for nutrition and anchorage.
Q59. In pteridophytes, the dominant phase is the:
[A] Gametophyte
[B] Sporophyte
[C] Zygote
[D] Embryo
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Correct Answer: [B] Sporophyte
Explanation: In pteridophytes, the diploid sporophyte is the dominant, independent, and photosynthetic phase. The gametophyte (prothallus) is small, inconspicuous, and short-lived.
Q60. Which of the following algae shows a haplodiplontic life cycle?
[A] Spirogyra
[B] Volvox
[C] Ectocarpus
[D] Chlamydomonas
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Correct Answer: [C] Ectocarpus
Explanation: Ectocarpus, a brown alga, exhibits a haplodiplontic life cycle where both the haploid gametophyte and the diploid sporophyte are multicellular and free-living, although they may differ in morphology (isomorphic or heteromorphi).