CUET UG Categorised PYQ Biology Unit 1

At shedding, most angiosperm pollen grains are two-celled. They contain a large vegetative cell and a smaller generative cell. The generative cell later divides to produce two male gametes.

Meiocytes undergo meiosis to produce gametes. During meiosis, the chromosome number is reduced from diploid (2n) to haploid (n). Since the meiocyte of maize contains 20 chromosomes (2n = 20), the resulting gametes will contain 10 chromosomes (n = 10).

Tapetum is the innermost layer of the microsporangium wall. It supplies nourishment and essential materials required for pollen grain development. It is metabolically active and often multinucleate.

Albuminous seed retains endosperm (Castor). Non-albuminous seeds consume endosperm during development (Groundnut). Banana develops without fertilization and is parthenocarpic. Apple is a false fruit because the thalamus contributes to fruit formation.

One pollen mother cell undergoes meiosis to produce four microspores. Each microspore develops into a pollen grain that ultimately produces two male gametes. Therefore, maximum male gametes = 4 × 2 = 8.

The embryo of a seed develops from the zygote formed after fertilization. In maize grain, the embryonal axis and associated structures originate from the zygote.

Maize is an endospermic seed. The endosperm persists in the mature seed and serves as the major food reserve supplying nutrients to the developing embryo.

In maize grain, the radicle is enclosed within a protective sheath called coleorhiza. This structure protects the radicle during seed germination.

The scutellum is the single cotyledon present in monocot seeds such as maize. It absorbs nutrients from the endosperm and transfers them to the embryo.

In monocot seeds such as maize, the plumule is enclosed by a protective sheath called coleoptile. It protects the young shoot during germination.

In artificial hybridisation, the emasculated flower is covered with a bag to prevent contamination of the stigma by unwanted pollen grains. This ensures controlled pollination with desired pollen.

Funicle connects ovule to placenta. Hilum is the junction where ovule fuses with stalk. Micropyle is the opening left by integuments. Chalaza is the basal part opposite the micropyle.

In most flowering plants, only one megaspore remains functional and develops into the embryo sac. Such development is called monosporic development.

Statement A is incorrect because the egg apparatus is present at the micropylar end. Statements B, C and D are correct according to the standard Polygonum type embryo sac development.

Based on the standard NCERT megasporogenesis diagram: Nucellus → G Megaspore dyad → C Micropylar end → B Megaspore mother cell → D Hence Option A is correct.

A hypodermal cell in the micropylar region of the nucellus enlarges, develops dense cytoplasm and a prominent nucleus, and differentiates into the archesporial cell, which ultimately forms the megaspore mother cell.

The functional megaspore undergoes three successive mitotic divisions: 1 → 2 nuclei 2 → 4 nuclei 4 → 8 nuclei This results in the typical eight-nucleate embryo sac.

In monocotyledonous seeds such as grasses, the single cotyledon is called the scutellum. It lies between the embryo and endosperm and absorbs nutrients from the endosperm during germination for transfer to the growing embryo.

The megasporangium (ovule) consists of nucellus, integuments, micropyle and funicle. The generative cell is a component of the male gametophyte (pollen grain) and is not associated with the ovule.

The diploid sporogenous tissue inside microsporangia undergoes meiosis to produce haploid microspores. These later develop into pollen grains.

The filiform apparatus is a specialized structure present at the micropylar end of synergid cells. It plays a crucial role in attracting and guiding the pollen tube into the embryo sac. After reaching the embryo sac, the pollen tube enters one synergid through the filiform apparatus and releases the male gametes. Thus, the filiform apparatus acts as the guiding structure during fertilization in angiosperms.

The chalaza is the basal region of the ovule opposite to the micropylar end. It is the area where integuments and nucellus merge. The embryo sac is situated between the micropylar and chalazal ends.

After fertilization, the ovule develops into a seed while the ovary develops into a fruit. Endosperm is a nutritive tissue formed from the primary endosperm nucleus and supplies nutrients to the developing embryo. Therefore, the statement that endosperm develops into seed is incorrect.

Development of a dicot embryo proceeds through stages such as proembryo (pre-embryo), globular embryo, heart-shaped embryo, and mature embryo. "Bird" is not a recognized developmental stage in plant embryology. Hence it is the incorrect option.

In coconut, the liquid found inside tender fruits is free nuclear endosperm. During development, nuclei divide repeatedly without immediate cell wall formation, creating a multinucleate liquid tissue. This liquid later contributes to the nutritive endosperm of the seed.

Syngamy is the fusion of one male gamete with the egg cell. This fusion restores the diploid chromosome number and forms the zygote. Triple fusion forms the primary endosperm nucleus and does not produce the zygote.

A zygote is formed by the fusion of two haploid gametes and therefore contains the diploid chromosome number (2n). If the zygote contains 38 chromosomes, the haploid number is 19. Thus, the egg cell contributing to the zygote would contain 19 chromosomes.