Select the correct combination of statements concerning post-fertilization changes in angiosperms:
(I) In most plants, the zygote develops inside the ovule. (II) The ovary develops into the fruit, which develops a protective wall called the pericarp. (III) The sepals, petals, and stamens usually wither and fall off after fertilization. (IV) The ovules develop into the pericarp, while the ovary develops into seeds.
Choose the correct option.
The ovules develop into seeds, while the ovary develops into the fruit and its wall forms the pericarp. Statement (IV) is incorrect.
Question 82 of 100
📘 CLASS XII
Consider the sex organs and sexuality of Chara and Marchantia:
(p) Chara is monoecious with the globule (antheridium) located below the nucule (oogonium). (q) Marchantia is a dioecious liverwort. (r) The female thallus of Marchantia bears antheridiophores.
Choose the correct set of statements.
Marchantia is dioecious. The female thallus bears archegoniophores, whereas the male thallus bears antheridiophores. Therefore, statement (r) is incorrect.
Question 83 of 100
📘 CLASS XII
Examine the environmental adaptations of fertilization modes:
(i) In external fertilization, a large number of male and female gametes are released into the water. (ii) In internal fertilization, the male gametes are non-motile and must drift by wind to reach the stationary egg. (iii) A major disadvantage of external fertilization is that offspring are highly vulnerable to predators.
Which combination correctly identifies the valid statement(s)?
External fertilization involves release of numerous gametes into water, and the resulting offspring are highly vulnerable to predators. In animals with internal fertilization, male gametes are generally motile and do not drift by wind. Hence statement (ii) is incorrect.
Question 84 of 100
📘 CLASS XII
Identify the correct options regarding vegetative propagules in the plants listed below:
(a) Banana propagates vegetatively through underground rhizomes. (b) Agave produces modified vegetative buds called bulbils. (c) Bryophyllum leaves develop adventitious buds along their margins. (d) Dahlia propagates vegetatively using modified stem tubers called offsets.
Select the correct set.
Dahlia propagates through tuberous adventitious roots, not offsets. Offsets are stem modifications found in aquatic plants like water hyacinth and Pistia. Hence statement (d) is incorrect.
Question 85 of 100
📘 CLASS XII
Compare the cell division patterns of binary fission and budding:
(1) In binary fission, the cell division is equal and produces two equivalent halves. (2) In budding, the division is unequal and a small bud remains attached initially to the parent cell. (3) Budding is typically observed in Amoeba. (4) Binary fission is a common mode of reproduction in Monerans.
Choose the correct statement combination.
Binary fission is an equal division seen in organisms like Amoeba and Monerans. Budding is characteristic of yeast, not Amoeba. Therefore statement (3) is incorrect.
Question 86 of 100
📘 CLASS XII
Read the statements below regarding cyclic changes in female placental mammals:
(I) Non-primate mammals like sheep, cows, and tigers show oestrus cycles. (II) Primate mammals like monkeys, apes, and humans show menstrual cycles. (III) Oestrus cycle differs from menstrual cycle as there is no periodic blood flow in oestrus cycle.
Identify the correct set.
All three statements are correct. In non-primate mammals, the endometrium is reabsorbed rather than shed with menstrual bleeding, which characterizes the oestrus cycle.
Question 87 of 100
📘 CLASS XII
Evaluate these chromosome count facts of gamete mother cells and gametes:
(x) In Ophioglossum (a fern), the meiocyte contains 1260 chromosomes. (y) In a human, the gamete contains 23 chromosomes. (z) In a dog, the gamete contains 78 chromosomes.
Which combination is true?
The diploid chromosome number (2n) of a dog is 78, so its gamete contains 39 chromosomes. Therefore statement (z) is incorrect.
Question 88 of 100
📘 CLASS XII
Assess the characteristics of asexual spores and buds across diverse kingdoms:
(i) Zoospores are thin-walled, motile, and flagellated structures. (ii) Conidia are non-motile asexual spores produced exogenously in Penicillium. (iii) Gemmules are internal buds of freshwater sponges that assist in asexual reproduction.
Select the correct combination.
All three statements are correct according to NCERT. Zoospores are motile, conidia are exogenous non-motile spores, and gemmules are internal buds of sponges.
Question 89 of 100
📘 CLASS XII
Read the statements below regarding the lifespans of different organisms:
(a) A crow lives for about 15 years, while a parrot can live up to 140 years. (b) A crocodile has a lifespan of about 60 years. (c) A tortoise has a lifespan of about 100–150 years. (d) A rose bush has a lifespan of about 200–300 years.
Select the correct set of statements.
A rose bush has a lifespan of about 5–7 years, not 200–300 years. Therefore statement (d) is incorrect.
Question 90 of 100
📘 CLASS XII
Review the academic milestones of Prof. Panchanan Maheshwari:
(I) He was born in November 1904 in Jaipur, Rajasthan. (II) He worked on test-tube fertilization and intra-ovarian pollination. (III) He was elected as a Fellow of the Royal Society of London (FRS). (IV) He established the Botany Department at Delhi University.
Which of these statements are true?
All four statements are presented as correct in the provided source and describe the milestones associated with Prof. Panchanan Maheshwari.
