Consider the following statements about Marchantia (a liverwort) sexuality based on NCERT descriptions:
(i) Marchantia is a dioecious plant where male and female sex organs are borne on separate thalli. (ii) The female thallus of Marchantia bears a specialized structure called the antheridiophore. (iii) The male thallus of Marchantia possesses archegoniophores that produce female gametes.
Which of the following is correct?
Marchantia is dioecious. The female thallus bears archegoniophores, while the male thallus bears antheridiophores. Hence statements (ii) and (iii) are incorrect.
Question 52 of 100
📘 CLASS XII
Examine the statements regarding the taxonomic and educational contributions of Prof. Panchanan Maheshwari:
(a) He popularized the integration of embryological traits with systematic botany for plant classification. (b) He established the famous research center at the Department of Botany, University of Delhi, to focus on embryology and tissue culture. (c) His landmark research on test-tube fertilization and intra-ovarian pollination won worldwide acclaim. (d) He led the NCERT initiative that published the very first Biology textbooks for Higher Secondary Schools in 1964.
Select the correct combination.
All four statements are correct historical facts regarding Prof. Panchanan Maheshwari as described in NCERT.
Question 53 of 100
📘 CLASS XII
Read the following statements on the chromosome numbers of different organisms during gamete formation:
(p) The diploid chromosome number of a dog's meiocyte is 78. (q) The haploid chromosome number of a cat's gamete is 19. (r) The meiocyte chromosome number of a housefly is 12. (s) The gamete of a fruit fly contains 4 chromosomes.
Choose the correct set of statements.
All statements are correct according to NCERT Table 1.1. Dog: 2n = 78, Cat: n = 19, Housefly: 2n = 12, Fruit fly: n = 4.
Question 54 of 100
📘 CLASS XII
Study these statements about sexuality in Chara (a green alga):
(I) Chara is a monoecious plant showing both male and female reproductive structures. (II) The male sex organ in Chara is called the oogonium and is located globally below the female sex organ. (III) The female reproductive structure in Chara is termed the antheridium.
Which combination correctly identifies the valid statement(s)?
In Chara, the female sex organ is the oogonium (nucule) and the male sex organ is the antheridium (globule). Statements (II) and (III) are incorrect because the names are interchanged.
Question 55 of 100
📘 CLASS XII
Analyze the morphological features of gametes in lower plants:
(i) In algae like Cladophora, the gametes are homogametes because they are morphologically indistinguishable. (ii) In Fucus (an alga), the male and female gametes are heterogametes because they differ morphologically. (iii) In all algae, the female gamete is strictly non-motile and stored in multicellular archegonia.
Choose the correct option.
Cladophora has homogametes and Fucus has heterogametes. Statement (iii) is incorrect because algae do not possess archegonia and several algae have motile female gametes.
Question 56 of 100
📘 CLASS XII
Read these statements concerning the reproductive phases of annual, biennial, and perennial plants:
(a) Annual and biennial plants display clear-cut vegetative, reproductive, and senescent phases of life. (b) Perennial plant species exhibit highly complex life phases that are difficult to define clearly. (c) The inter-flowering period in perennial plants that flower multiple times is considered a juvenile phase.
Choose the correct option.
Annuals and biennials show clear-cut developmental phases, whereas perennials do not. The inter-flowering period belongs to the mature reproductive phase and is not a juvenile phase.
Question 57 of 100
📘 CLASS XII
Examine the mechanical and evolutionary differences of external syngamy in amphibians and bony fishes:
(p) Both amphibians and bony fishes exhibit external fertilization in an aquatic medium. (q) To maximize fertilization success, these organisms show remarkable synchronization in the release of gametes. (r) A key survival advantage is that their offspring are fully protected from environmental predators.
Which of the statements given above is/are correct?
Amphibians and bony fishes exhibit external fertilization and synchronized gamete release. Their offspring are highly vulnerable to predators, making statement (r) incorrect.
Question 58 of 100
📘 CLASS XII
Evaluate the biological characteristics of the plant Strobilanthus kunthiana (Neelakuranji):
(1) It is an unusual perennial plant that flowers once every 12 years. (2) Its mass flowering has historically transformed hills in Kerala, Karnataka, and Tamil Nadu into spectacular blue stretches. (3) It produces large numbers of toxic fruits immediately after flowering and dies. (4) Its flowering cycle is regulated strictly by temperature changes rather than hormones.
Choose the correct option.
Neelakuranji flowers once every 12 years and covers hills with blue flowers. It does not die immediately after flowering like bamboo, and its developmental phases are hormonally regulated. Hence statements (3) and (4) are incorrect.
Question 59 of 100
📘 CLASS XII
Study the comparison of chromosome counts in the meiocytes of various plants:
(i) In Apple, the diploid chromosome number is 34. (ii) In Rice, the haploid chromosome number (n) is 12, representing a diploid count (2n) of 24. (iii) In Potato, the meiocyte contains 48 chromosomes. (iv) In Onion, the meiocyte has 8 chromosomes.
Choose the correct option.
According to NCERT Table 1.1, the gamete of Onion has 8 chromosomes, so the meiocyte contains 16 chromosomes. Therefore statement (iv) is incorrect.
Question 60 of 100
📘 CLASS XII
Analyze the differences in vegetative propagules in the plants listed below:
(a) Offset of water hyacinth is a horizontal branch of stem that can propagate vegetatively. (b) Rhizomes of ginger and banana possess nodes and internodes that give rise to roots and new shoots. (c) Bulbils of Agave represent modified adventitious roots used for propagation.
Choose the correct option.
Offsets and rhizomes are stem modifications. Bulbils of Agave are modified vegetative buds (shoot origin), not root modifications. Hence statement (c) is incorrect.
