Q21. The life cycle in which the sporophyte is the dominant, independent, photosynthetic phase and alternates with a small, inconspicuous gametophyte is called:
[A] Haplontic
[B] Diplontic
[C] Haplo-diplontic
[D] Isomorphic
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Correct Answer: [B] Diplontic
Explanation: In a diplontic life cycle, the diploid sporophyte is the dominant and photosynthetic phase. The gametophyte is typically small and dependent on the sporophyte or exists for a very short duration. This type of life cycle is characteristic of gymnosperms and angiosperms.
Q22. The life cycle in which the gametophyte is the dominant, free-living, photosynthetic phase and alternates with a short-lived sporophyte that is dependent on the gametophyte is called:
[A] Haplontic
[B] Diplontic
[C] Haplo-diplontic
[D] Heteromorphic
Show Answer
Correct Answer: [A] Haplontic
Explanation: In a haplontic life cycle, the haploid gametophyte is the dominant and photosynthetic phase. The diploid sporophyte is usually represented only by the zygote, which undergoes meiosis to form haploid spores that develop into the gametophyte. This type of life cycle is characteristic of many algae like Volvox and Spirogyra.
Q23. The life cycle in which both the gametophyte and sporophyte phases are multicellular and often free-living, but may differ in morphology, is called:
[A] Haplontic
[B] Diplontic
[C] Haplo-diplontic
[D] Autotrophic
Show Answer
Correct Answer: [C] Haplo-diplontic
Explanation: In a haplo-diplontic life cycle, both the haploid gametophyte and the diploid sporophyte are multicellular and often free-living. They alternate with each other. This type of life cycle is characteristic of bryophytes and pteridophytes.
Q23. The life cycle in which both the gametophyte and sporophyte phases are multicellular and often free-living, but may differ in morphology, is called:
[A] Haplontic
[B] Diplontic
[C] Haplo-diplontic
[D] Autotrophic
Show Answer
Correct Answer: ([C] Haplo-diplontic
Explanation: In a haplo-diplontic life cycle, both the haploid gametophyte and the diploid sporophyte are multicellular and often free-living. They alternate with each other. This type of life cycle is characteristic of bryophytes and pteridophytes.
Q24. Alternation of generation refers to the:
[A] Alternation of different modes of nutrition in a plant
[B] Alternation of sexual and asexual phases in a plant’s life cycle
[C] Alternation of haploid and diploid phases in a plant’s life cycle
[D] Alternation of dominant and recessive genes in a plant
Show Answer
Correct Answer: ([C] Alternation of haploid and diploid phases in a plant’s life cycle
Explanation: Alternation of generation is a characteristic feature of plant life cycles, where there is an alternation between a haploid gametophyte generation that produces gametes and a diploid sporophyte generation that produces spores.
Q25. In algae, the zygote undergoes meiosis to produce haploid spores. This type of life cycle is:
[A] Haplontic
[B] Diplontic
[C] Haplo-diplontic
[D] Sporophytic
Show Answer
Correct Answer: ([A] Haplontic
Explanation: In many algae with a haplontic life cycle, the diploid zygote is the only diploid stage. It undergoes meiotic division (zygotic meiosis) to form haploid spores, which then develop into the dominant haploid gametophyte.
Q26. Which of the following algae is used as food?
[A] Spirogyra
[B] Ulothrix
[C] Laminaria
[D] Chlamydomonas
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Correct Answer: ([C] Laminaria
Explanation: Laminaria (kelp), a type of brown alga, is used as food in many parts of the world, especially in East Asian countries. It is rich in iodine and other nutrients.
Q27. Agar, a commercially important substance, is obtained from:
[A] Green algae
[B] Brown algae
[C] Red algae
[D] Blue-green algae
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Correct Answer: ([C] Red algae
Explanation: Agar is obtained from certain red algae, particularly Gelidium and Gracilaria. It is widely used as a solidifying agent in culture media, in the food industry, and in the preparation of jellies and ice creams.
Q28. Carrageenan, another commercially important polysaccharide, is obtained from:
[A] Chlorella
[B] Spirogyra
[C] Chondrus
[D] Volvox
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Correct Answer: [C] Chondrus
Explanation: Carrageenan is a polysaccharide extracted from certain red algae, such as Chondrus crispus (Irish moss). It is used as a thickening, stabilizing, and gelling agent in various food products, cosmetics, and pharmaceuticals.
Q29. Which of the following algae is unicellular and rich in proteins, used as a food supplement even by space travelers?
[A] Spirogyra
[B] Chlamydomonas
[C] Chlorella
[D] Ulothrix
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Correct Answer: [C] Chlorella
Explanation: Chlorella is a unicellular green alga that is rich in proteins, vitamins, and minerals. Its high nutritional value and ability to grow efficiently have made it a popular food supplement, even used by space travelers.
Q30. The plant body of a bryophyte is more differentiated than that of algae and is thallus-like, prostrate or erect, and attached to the substratum by:
[A] Roots
[B] Rhizoids
[C] Stems
[D] Leaves
Show Answer
Correct Answer: [B] Rhizoids
Explanation: Bryophytes lack true roots, stems, and leaves. They have root-like structures called rhizoids, which are unicellular or multicellular filaments that help in anchoring the plant body to the substratum and absorbing water and minerals.