Read these statements regarding the transport of gametes in seed plants:
(p) In seed plants, pollen grains are the carriers of male gametes. (q) The female gametes (eggs) are located permanently inside the ovule. (r) Male gametes in seed plants are typically motile and swim through water inside the pistil to reach the ovule. (s) Pollen tubes carry non-motile male gametes to the female gamete for fertilization.
Choose the correct option.
In seed plants, male gametes are non-motile and are transported to the egg through pollen tubes. Therefore statement (r) is incorrect.
Question 62 of 100
📘 CLASS XII
Select the correct post-fertilization transformations in an angiospermic flower:
(1) The zygote undergoes cell divisions to develop into an embryo. (2) The ovules mature to form seeds, while the ovary wall forms a thick protective pericarp. (3) The petals, stamens, and style of the flower remain permanently attached to protect the developing fruit.
Choose the correct option.
After fertilization, the zygote develops into an embryo, ovules become seeds, and the ovary wall forms the pericarp. Petals, stamens and other floral parts usually wither and fall off. Hence statement (3) is incorrect.
Question 63 of 100
📘 CLASS XII
Read the statements below about the role of the zygote in life cycles:
(i) The zygote is the vital biological link ensuring the continuity of species from one generation to the next. (ii) Every sexually reproducing organism, including human beings, begins life as a single cell, the zygote. (iii) In organisms with haplontic life cycles, the diploid zygote divides immediately by mitosis to form a multicellular diploid phase.
Choose the correct option.
The zygote is the continuity link between generations. In haplontic life cycles, the zygote undergoes meiosis, not mitosis, to produce haploid spores. Therefore statement (iii) is incorrect.
Question 64 of 100
📘 CLASS XII
Study the mechanisms of parthenogenesis based on these observations:
(a) The unfertilized female egg cell directly undergoes development to form a complete organism. (b) Parthenogenesis occurs in certain animals like rotifers, honeybees, some lizards, and birds like turkey. (c) It is a type of sexual reproduction since gametes are produced and fused.
Choose the correct option.
Parthenogenesis is the development of an organism from an unfertilized egg. Since fertilization does not occur, fusion of gametes is absent. Hence statement (c) is incorrect.
Question 65 of 100
📘 CLASS XII
Read the statements on cell processes during embryogenesis:
(I) Mitotic cell divisions increase the number of cells in the developing embryo. (II) Cell differentiation helps groups of cells undergo modifications to form specialized tissues and organs. (III) In plants, embryogenesis occurs outside the plant body within the pericarp. (IV) Zygotic cell divisions during embryogenesis are completely amitotic to prevent somatic mutations.
Choose the correct option.
Embryogenesis involves mitotic cell divisions followed by differentiation. In plants, embryogenesis occurs inside the ovule, and the divisions are mitotic, not amitotic. Therefore statements (III) and (IV) are incorrect.
Question 66 of 100
📘 CLASS XII
Examine the sexual classification of organisms based on these terms:
(p) Bisexual conditions are denoted by terms such as homothallic or monoecious. (q) Unisexual conditions are denoted by terms like heterothallic or dioecious. (r) Sweet potato possesses bisexual flowers containing both stamens and pistils. (s) Cockroaches are hermaphrodites containing both testes and ovaries in each individual.
Choose the correct option.
Bisexual and unisexual terminology is correct, and sweet potato bears bisexual flowers. Cockroach is a unisexual animal, not a hermaphrodite. Hence statement (s) is incorrect.
Question 67 of 100
📘 CLASS XII
Read these statements regarding the reproductive behavior of birds:
(1) Wild birds living in natural habitats lay eggs seasonally. (2) Birds in poultry farms can be induced to lay eggs throughout the year. (3) Continuous egg laying in commercial poultry farms is a natural reproductive phenomenon.
Choose the correct option.
Wild birds are seasonal breeders, whereas poultry birds can be induced to lay eggs throughout the year under commercial conditions. Continuous laying is an artificial commercial practice, making statement (3) incorrect.
Question 68 of 100
📘 CLASS XII
Analyze these statements regarding the "Terror of Bengal":
(i) Water hyacinth is an invasive aquatic weed that grows rapidly in standing water. (ii) It causes a depletion of dissolved oxygen in the water body, resulting in fish mortality. (iii) It was introduced in India because of its sweet-scented edible nectar.
Choose the correct option.
Water hyacinth is the "Terror of Bengal" because it rapidly spreads in water bodies and depletes dissolved oxygen, causing fish mortality. It was introduced for its attractive flowers and leaf shape, not for edible nectar. Hence statement (iii) is incorrect.
Question 69 of 100
📘 CLASS XII
Identify the incorrect statement combination regarding sexuality in plants:
(a) Papaya and date palm are dioecious plants. (b) Cucurbits and coconuts are monoecious plants. (c) In unisexual flowering plants, the male flower is staminate and the female is pistillate. (d) Staminate flowers possess only functional carpels.
Choose the correct option.
Staminate flowers are male flowers bearing only stamens. Pistillate flowers bear carpels (pistils). Therefore statement (d) is incorrect.
Question 70 of 100
📘 CLASS XII
Study these statements regarding the lifespan and immortality of organisms:
(I) No individual organism is immortal except single-celled organisms. (II) Natural death is certain for all multicellular organisms. (III) Unicellular organisms undergo natural death because their cellular content decays during division.
Choose the correct option.
Unicellular organisms are considered immortal because the parent cell divides to form daughter cells instead of undergoing natural death. Therefore statement (III) is incorrect.
