Reproduction
- Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R).Assertion (A) : Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus.Reason (R) : Presence of more than one nuc… Answer: 1. Both A and R are true and R is the correct explanation of A Key idea: The tapetum is the innermost wall layer of the anther and n... 1
- How many meiotic and mitotic divisions need to occur for the development of a mature female gametophyte from the megaspore mother cell in an angiosperm plant? Answer: 3. 1 Meiosis and 3 Mitosis Key idea: Count divisions from megaspore mother cell (MMC) to the 7-celled, 8-nucleate embryo sac. MMC un... 1
- Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R).Assertion (A) : A typical unfertilised, angiosperm embryo sac at maturity is 8 nucleate and 7-celled.Reason (R) : The egg apparatus has 2 polar… Answer: 3. A is true but R is false Key idea: The mature embryo sac is 7-celled and 8-nucleate, so A is true. The reason is false: the egg a... 1
- Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R).Assertion (A) : Both wind and water pollinated flowers are not very colourful and do not produce nectar.Reason (R) : The flowers produce enormou… Answer: 2. Both A and R are true but R is NOT the correct explanation of A Key idea: Both A and R are true, but R does not explain A. Wind a... 1
- Identify the correct description about the given figure: Answer: 2. Wind pollinated plant inflorescence showing flowers with well exposed stamens. Key idea: a dense spike with many long, well-expos... 1
- Identify the set of correct statements:A. The flowers of Vallisneria are colourful and produce nectar.B. The flowers of waterlily are not pollinated by water.C. In most of water-pollinated species, the pollen grains are protected from wetting.D. Poll… Answer: 1. B, C, D and E only Key idea: only some aquatic plants are water pollinated, and these flowers are inconspicuous. A is false: Vall... 1
- In angiosperm, the haploid, diploid and triploid structures of a fertilized embryo sac sequentially are : Answer: 4. Synergids, Zygote and Primary endosperm nucleus Key idea: In a fertilised embryo sac, count ploidy for each structure. Synergids:... 1
- What is the function of tassels in the corn cob? Answer: 3. To trap pollen grains Key idea: In maize (corn) the tassels are the long, silky styles and stigmas of the female inflorescence (c... 1
- Large, colourful, fragrant flowers with nectar are seen in : Answer: 2. insect pollinated plants Key idea: Insect-pollinated flowers are large, colourful and fragrant, and offer nectar as a reward. Win... 1
- Identify the incorrect statement related to Pollination : Answer: 1. Moths and butterflies are the most dominant pollinating agents among insects Bees are the dominant insect pollinators, not moths... 1
- Given below are two statements :Statement I :Cleistogamous flowers are invariably autogamousStatement II :Cleistogamy is disadvantageous as there is no chance for cross pollinationIn the light of the above statements, choose the correct answer from t… Answer: 2. Both Statement I and Statement II are correct Statement I: cleistogamous flowers never open, so pollen falls on the stigma of the... 1
- In some members of which of the following pairs of families, pollen grains retain their viability for months after release ? Answer: 4. Rosaceae ; Leguminosae Pollen viability depends on the family. In cereals such as Poaceae it is lost within 30 minutes. In some m... 1
- A typical angiosperm embryo sac at maturity is : Answer: 1. 8-nucleate and 7-celled A typical (Polygonum-type) embryo sac forms from the megaspore by three mitotic divisions, giving 8 nucle... 1
- The term used for transfer of pollen grains from anthers of one plant to stigma of a different plant which, during pollination, brings genetically different types of pollen grains to stigma, is : Answer: 1. Xenogamy Pollen transfer from the anther of one plant to the stigma of a genetically different plant is xenogamy, and it brings g... 1
- The body of the ovule is fused within the funicle at : Answer: 1. Hilum The ovule is attached to the funicle (stalk) at the hilum, where the body of the ovule fuses with the funicle. The micropyl... 1
- In water hyacinth and water lily, pollination takes place by : Answer: 1. insects or wind Water hyacinth and water lily are aquatic plants but their flowers rise above water, so they are pollinated by in... 1
- The plant parts which consist of two generations - one within the other :(a) Pollen grains inside the anther(b) Germinated pollen grain with two male gametes(c) Seed inside the fruit(d) Embryo sac inside the ovule Answer: 4. (a) and (d) Key idea: Two generations one inside the other means a gametophyte developing inside a sporophyte structure, i.e., a... 1
- In some plants, the female gamete develops into embryo without fertilization. This phenomenon is known as : Answer: 4. Parthenogenesis Development of an egg or female gamete into an embryo without fertilisation is parthenogenesis. Autogamy is self-... 1
- What is the fate of the male gametes discharged in the synergid ? Answer: 4. One fuses with the egg and other fuses with central cell nuclei. Key idea: Double fertilisation: both male gametes released into... 1
- Persistent nucellus in the seed is known as : Answer: 2. Perisperm In most seeds the nucellus is used up. In some, such as black pepper and beet, a part of it persists and is called peri... 1
- Which one of the following statements regarding post-fertilization development in flowering plants is incorrect ? Answer: 4. Ovules develop into embryo sac After fertilisation: ovary becomes fruit, ovule becomes seed, zygote becomes embryo, and the prima... 1
- Double fertilization is Answer: 4. Syngamy and triple fusion Double fertilisation is syngamy (one male gamete with the egg) plus triple fusion (the other male gamet... 1
- Pollen grains can be stored for several years in liquid nitrogen having a temperature of Answer: 2. – 196°C Pollen can be cryopreserved in liquid nitrogen at -196^° C for years. The other temperatures are not that of liquid nitro... 1
- Offsets are produced by Answer: 3. Mitotic divisions Offsets are vegetative propagules formed by mitosis, so the new plants are clones. They are seen in aquatic pla... 1