Question 1

Among the terms listed below, those that of are not technically correct names for a floral whorl are :(i) Androecium (ii) Carpel (iii) Corolla (iv) Sepal(A) (i) and (iv)(B) (iii) and (iv)(C) (ii) and (iv)(D) (i) and (ii)

Accepted Answer

(C) All the four whorls of the plant with their relative position in flower can be indicated through following diagram. Sepals collectively form a whorl, called as calyx while technically the carpel is known as gynoecium. The floral whorls formed by petals and stamens are called as corolla and androecium, respectively.

Question 2

Embryo sac is related to ovule as is related to an anther.(A) Stamen(B) Filament(C) Pollen grain(D) Androecium

Accepted Answer

(C) The pollen grains represent the male gametophytes. As the anthers mature and dehydrate, the microspores dissociate from each other and develop into pollen grains. So, embryo sac is to ovule as pollen grain is to an anther.

Question 3

In a typical complete, bisexual and hypogynous flower the arrangement of floral whorls on the thalamus from the outermost to the innermost is:(A) Calyx, corolla, androecium and gynoecium(B) Calyx, corolla, gynoecium and androecium(C) Gynoecium, androecium, corolla and calyx(D) Androecium, gynoecium, corolla and calyx

Accepted Answer

(A) In a typical complete, bisexual and hypogynous flower the arrangement of floral whorls on the thalamus from the outermost to the inner most is as follows :(i) Calyx: It is the outermost whorl of sepals.(ii) Corolla : It is a whorl of petals inside the calyx.(iii) Androecium : It is a whorl of stamens inside the corolla.(iv) Gynoecium : It is a whorl of pistils (in the centre of the flower forming inner most whorls).

Question 4

A dicotyledonous plant bears flowers but never produces fruits and seeds. The most probable cause for the above situation is:(A) Plant is dioecious and bears only pistillate flowers(B) Plant is dioecious and bears both pistillate and staminate flowers(C) Plant is monoecious(D) Plant is dioecious and bears only staminate flowers

Accepted Answer

(D) In dioecious plants, the unisexual male flower is staminate, that is, bearing stamens only, while the female is pistillate or bearing pistils only. For the production of fruits and seeds fertilization must take place, which is possible only in the presence of both male and female flowers. When the plant is dioecious, it will give rise to the following situations :(i) If the plant is dioecious and bears only pistillate flowers, fertilization can take place with the help of pollinators.(ii) If the plant is dioecious and bears only staminate flowers, fertilization cannot take place, because female gamete is nonmotile which can't reach the male gamete in order to fuse with it. When the plant is monoecious, that is, carrying both stamen and pistil together, it may lead to self fertilization and production of seed.

Question 5

The outermost and innermost wall layers of microsporangium in an anther are respectively:(A) Endothecium and tapetum(B) Epidermis and endodermis(C) Epidermis and middle layer(D) Epidermis and tapetum

Accepted Answer

(D) The outermost and innermost wall layers of microsporangium in an anther are respectively, epidermis and tapetum. A typical microsporangium is generally surrounded by four-wall layers, that is, the epidermis, (outermost protective layer), endothecia, (middle fibrous layers) and the tapetum (innermost nutritive layer).

Question 6

During microsporogenesis, meiosis occurs in:(A) Endothecium(B) Microspore mother cells(C) Microspore tetrads(D) Pollen grains.

Accepted Answer

(B) During microsporogenesis, meiosis occurs in microspore mother cells. As the anther develops, the microspore mother cells of the sporogenous tissue undergo meiotic divisions to form microspore tetrads. The microspore tetrad after dehydration is separated into pollen grains.

Question 7

From among the sets of terms given below, identify those that are associated with the gynoecium.(A) Stigma, ovule, embryo sac, placenta(B) Thalamus, pistil, style, ovule(C) Ovule, ovary, embryo sac, tapetum(D) Ovule, stamen, ovary, embryo sac

Accepted Answer

(A) Gynoecium indicates the female reproductive part of the flower which consists of pistil. Each pistil has three parts, that is, stigma, style and ovary. Inside the ovarian cavity, the placenta is located. Arising from the placenta there are the megasporangia, commonly called ovules.The functional megaspore undergoing the meiotic division develops into the female gametophyte or embryo sac. Thalamus, tapetum and stamen are not a part of gynoecium. Thalamus is the part of flower which form the base on which all the floral whorls rest up on. Tapetum is the inner most nutritive layer or microsporangium and stamens are male reproductive part (androecium) of plant.

Question 8

From the statements given below choose the option that are true for a typical female gametophyte of a flowering plant:(i) It is 8-nucleate and 7-celled at maturity(ii) It is free-nuclear during the development(iii) It is situated inside the integument but outside the nucellus(iv) It has an egg apparatus situated at the chalazal end(A) i and iv(B) ii and iii(C) i and ii(D) ii and iv

Accepted Answer

(C) Statement (i) and (ii) are correct regarding female gametophyte of flowering plant. The female gametophyte or embryo sac is located inside the nucellus, enclosed within the integuments. In a majority of flowering plants, one of the megaspore is functional while the other three degenerates. Three repeated mitotic divisions of the functional megaspore results in the formation of seven-celled or eight nucleate embryo sac. Six of the eight nuclei are organised at the two poles. Three cells grouped at micropylar end forms egg apparatus and 3 at the chalazal end form antipodal cells. The large central cell at the centre has two polar nuclei. The meiotic divisions in the formation of embryo sac are strictly free nuclear, that is nuclear divisions are not followed immediately by cell-wall formation. Gametophyte is situated at micropylar end not at chalazal end.

Question 9

Autogamy can occur in a chasmogamous flower if:(A) Pollen matures before maturity of uvule(B) Ovules mature before maturity of pollen(C) Both pollen and ovules mature simultaneously(D) Both anther and stigma are of equal lengths

Accepted Answer

(C) Autogamy is a method of self-pollination. It is a process in which the stigma of a flower receives pollens from the anther of same flower. For autogamy both the sex organs of a chasmogamous flower should mature at the same time. As chasmogamous flowers open at maturity, pollen release and stigma receptivity should be synchronised for the process of autogamy. In such flowers, the length of anther and stigma plays secondary role in autogamy, e.g., in case of protandry (in which pollens mature early) and protogyny (in which stigma matures early) leads to cross-pollination.

Question 10

Choose the correct statement from the following:(A) Cleistogamous flowers always exhibit autogamy(B) Chasmogamous flowers always exhibit geitonogamy(C) Cleistogamous flowers exhibit both autogamy and geitonogamy(D) Chasmogamous flowers never exhibit autogamy

Accepted Answer

(A) The pollination that occurs in opened flowers is called chasmogamy. It is of two types, that is, self-pollination (autogamy) and cross-pollination. Cross-pollination is of two types, that is, geitonogamy and xenogamy. So, we can say that chasmogamous flowers exhibit both autogamy (self-pollination) and allogamy (cross pollination).While, in cleistogamous flower the anthers and stigma lies close to each other within the closed flowers. When anthers dehisce in the flower buds, pollen grains come in contact with the stigma for effective pollination. Thus, these flowers are invariably autogamous as there is no chance of cross-pollen landing on the stigma.

Question 11

A particular species of plant produces light, non-sticky pollen in large numbers and its stigmas are long and feathery. These modifications facilitate pollination by:(A) Insects(B) Water(C) Wind(D) Animals

Accepted Answer

(C) Plants use two abiotic (wind and water) and one biotic (animals) agent to achieve pollination. Majority of plants use biotic agents for pollination. Pollination by wind is more common amongst abiotic pollination. It requires the light and non-sticky pollen grains so that, they can be transported in wind currents. They often possess well exposed stamens (so that the pollens are easily dispersed into wind currents) and large often feathery stigma to easily trap air-borne pollen grains. Wind pollination is common in grasses. Pollination by water is called hydrophily which is quite rare in flowering plants but occurs in aquatic plants. Zoophily is pollination through the agency of animals. Entomophily (pollination by insects) is the most common type of zoophily which occurs through the agency of animals.

Question 12

From among the situations given below, choose the one that prevents both autogamy and geitonogamy.(A) Monoecious plant bearing unisexual flowers(B) Dioecious plant bearing only male or female flowers(C) Monoecious plant with bisexual flowers(D) Dioecious plant with bisexual flowers

Accepted Answer

(B) Dioecious plants (bearing only male or female flowers) prevent both autogamy and geitonogamy. Autogamy is a method of self-pollination in which the transfer of pollen grains from anther to stigma of the same flower takes place. Geitonogamy is the transfer of pollen grains from anther to stigma of another flower of the same plant. It is ecologically crosspollination which is supposed to be equivalent to self-pollination because all flowers on a plant are genetically identical.

Question 13

While planning for an artificial hybridization programme involving dioecious plants, which of the following steps would not be relevant:(A) Bagging of female flower(B) Dusting of pollen on stigma(C) Emasculation(D) Collection of pollen

Accepted Answer

(C) Artificial hybridisation is one of the major methods of crop improvement programme.This cross will make sure that only the desired pollen grains are used for pollination and the stigma is protected from contamination (from unwanted pollen). This is achieved by emasculation and bagging techniques. If the female parent produces unisexual flowers; there is no need for emasculation (a process of removal of anther). The female flower buds are bagged before the flowers open. When the stigma becomes receptive, pollination is carried out using the desired pollen and the flower rebagged. This protects them from contamination by unwanted pollen grains. When the female parent bears bisexual flowers, removal of anthers from the flower bud before the anther dehiscence is necessary.

Question 14

In a flower, if the megaspore mother cell forms megaspores without undergoing meiosis and if one of the megaspores develops into an embryo sac, its nuclei would be:(A) Haploid(B) Diploid(C) A few haploid and a few diploid(D) With varying ploidy.

Accepted Answer

(B) In some species, the diploid egg cell is formed without reduction division and develops into an embryo without fertilization. It is an a sexual reproduction which occurs in the absence of pollinators or in extreme environments. In some species like citrus plants, nucellar cells surrounding the embryo sac start dividing and develop into embryos. It occurs in the megaspore mother cell without undergoing meiosis and produces diploid embryo sac through of desirable characters for indefinite period. Thus, it can be concluded that apomictic species produce diploid cells. Haploid cells will be formed during sexual reproduction when cell will undergo meiosis.

Question 15

Which one of the cell in an embryo-sac produce endosperm after double fertilization?(A) Synergids cell(B) Antipodal cell(C) Central Cell(D) Egg

Accepted Answer

(C) In female gametophyte, central cell is involved in the double fertilisation that help in the endosperm development While antipodal cells provides nourishment to the egg cell, and synergid cell help in pollen tube growth.

Question 16

Starting from the innermost part, the correct sequence of parts in an ovule are,(A) egg, nucellus, embryo sac, integument(B) egg, embryo sac, nucellus, integument(C) embryo sac, nucellus, integument, egg(D) egg, integument, embryo sac, nucellus.

Accepted Answer

(B) Starting from the innermost part, the correct sequence of parts in an ovule is egg, embryo-sac, nucellus, and integument.

Question 17

In a fertilised embryo sac, the haploid, diploid and triploid structures are:(A) Synergid, zygote and primary endosperm nucleus(B) Synergid, antipodal and polar nuclei(C) Antipodal, synergid and primary endosperm nucleus(D) Synergid, polar nuclei and zygote.

Accepted Answer

(A) In a fertilised embryo sac, the haploid, diploid and triploid structures are synergids, zygote and primary endosperm nucleus respectively.

Question 18

In an embryo sac, the cells that degenerate after fertilisation are:(A) Synergids and primary endosperm cell(B) Synergids and antipodals(C) Antipodals and primary endosperm cell(D) Egg and antipodals.

Accepted Answer

(B) In unfertilised embryo sac, the antipodal sand synergids are distinctly present at chalazal end and micropylar end respectively while, in fertilised embryo sac, antipodals and synergids gradually degenerate after the formation of zygote.

Question 19

In the embryos of a typical dicot and a grass, true homologous structures are :(A) Coleorhiza and coleoptile(B) Coleoptile and scutellum(C) Cotyledons and scutellum(D) Hypocotyl and radicle.

Accepted Answer

(C) A typical dicotyledonous embryo consists of two cotyledons. While, embryos of monocotyledons possess only one cotyledon and it is called scutellum (in grass). Cotyledons of dicots, are simple structures generally thick and swollen due to storage of food reserves (as in legumes) and embryo of monocots consists of one large and shield shaped cotyledon known as scutellum situated towards one side (lateral) of the embryonal axis.

Question 20

The phenomenon observed in some plants wherein parts of the sexual apparatus is used for forming embryos without fertilisation is called:(A) Parthenocarpy(B) Apomixis(C) Vegetative propagation(D) Sexual reproduction.

Accepted Answer

(B) Apomixis refers to the formation of seeds without fertilization. The embryos are genetically identical to the parental plant.

Filters

Filters

book

topic

difficulty

Solutions for Oswaal CBSE MCQs Chapterwise For Term I II, Class 12, Biology by Oswaal Editorial Board

Found the solution, but did not understand the concept?

Ask my first question