CBSE Class 12 Biology Sexual Reproduction in Flowering Plants Set A

Ques. Meiosis is best observed in dividing
(a) cells of apical meristem
(b) cells of lateral meristem
(c) microspores and anther wall
(d) microsporocytes. 

Answer: D

Ques. Point out the odd one.
(a) Nucellus
(b) Embryo sac
(c) Micropyle
(d) Pollen grain 

Answer: D

Ques. Pollination occurs in
(a) bryophytes and angiosperms
(b) pteridophytes and angiosperms
(c) angiosperms and gymnosperms
(d) angiosperms and fungi. 

Answer: C

Ques. Entry of pollen tube through micropyle is
(a) chalazogamy
(b) mesogamy
(c) porogamy
(d) pseudogamy. 

Answer: C

Ques. Female gametophyte of angiosperms is represented by
(a) ovule
(b) megaspore mother cell
(c) embryo sac
(d) nucellus. 

Answer: C

Ques. Male gametophyte of angiosperms/monocots is
(a) microsporangium
(b) nucellus
(c) microspore
(d) stamen. 

Answer: C

Ques. Which is correct?
(a) Gametes are invariably haploid.
(b) Spores are invariably haploid.
(c) Gametes are generally haploid.
(d) Both spores and gametes are invariably haploid.

Answer: A

Ques. Generative cell was destroyed by laser but a normal pollen tube was still formed because
(a) vegetative cell is not damaged
(b) contents of killed generative cell stimulate pollen growth
(c) laser beam stimulates growth of pollen tube
(d) the region of emergence of pollen tube is not harmed. 

Answer: A

Ques. Total number of meiotic divisions required for forming 100 zygotes/100 grains of wheat is
(a) 100
(b) 75
(c) 125
(d) 50. 

Answer: C

Ques. Male gametophyte of angiosperms is shed at
(a) four celled pollen grain
(b) three celled pollen grain
(c) microspore mother cell
(d) anther.

Answer: B

Ques. What is the fate of the male gametes discharged in the synergid?
(a) One fuses with the egg and other fuses with central cell nuclei.
(b) One fuses with the egg, other(s) degenerates in the synergid.
(c) All fuse with the egg.
(d) One fuses with the egg, other(s) fuse(s) with synergid nucleus. 

Answer: A

Ques. Double fertilisation is
(a) fusion of two male gametes of a pollen tube with two different eggs
(b) fusion of one male gamete with two polar nuclei
(c) fusion of two male gametes with one egg
(d) syngamy and triple fusion. 

Answer: D

Ques. Double fertilisation is exhibited by
(a) algae
(b) fungi
(c) angiosperms
(d) gymnosperms.

Answer: C

Ques. Which one of the following statements is wrong?
(a) When pollen is shed at two-celled stage, double fertilisation does not take place.
(b) Vegetative cell is larger than generative cell.
(c) Pollen grains in some plants remain viable for months.
(d) Intine is made up of cellulose and pectin.

Answer: A

Ques. Through which cell of the embryo sac, does the pollen tube enter the embryo sac?
(a) Egg cell
(b) Persistant synergid
(c) Degenerated synergids
(d) Central cell 

Answer: C

Ques. In angiosperms, pollen tube liberate their male gametes into the
(a) central cell
(b) antipodal cells
(c) egg cell
(d) synergids. 

Answer: D

Ques. Endosperm is formed during the double fertilisation by
(a) two polar nuclei and one male gamete
(b) one polar nuclei and one male gamete
(c) ovum and male gamete
(d) two polar nuclei and two male gametes.

Answer: A

Question: The lengthwise running groove on anther which separate theca is called
a) rupture line
b) line of dehiscence
c) suture of anther
d) None of the above

Answer: b

Question: The outermost wall layer of microsporangium in anther is
a) endothecium
b) tapetum
c) middle layer
d) epidermis

Answer: d

Question: Number of microsporangia in an angiospermic anther is
a) 1
b) 2
c) 3
d) 4

Answer: d

Question: Microsporangium develops into
a) pollens
b) microgametes
c) megagametes
d) pollen sac

Answer: d

Question: Centre of each microsporangium is occupied by
a) sporogenous tissue
b) tapetum
c) central tissue
d) microspore mother cell

Answer: a

Question: Microspore tetrad (pollen grains) is the result of
a) mitotic cell division
b) meiotic cell division
c) Both (a) and (b)
d) None of these

Answer: b

Question: Exine of pollen is made up of
a) sporopollenin
b) sporogenous tissue
c) spongiform tissue
d) inorganic material

Answer: a

Question: Dehiscence of anther in mesophytes is caused by
a) hydration of anthers
b) dehydration of anthers
c) mechanical injury
d) None of these

Answer: b

Question: Mass of cells enclosed by integuments is called
a) nucellus
b) embryo
c) ova
d) pollen

Answer: a

Question: Pollens have two prominant walls which are …A… and …B… . Here A and B refers to
a) A–intine, B–protein coat
b) A–exine, B–intine
c) A–sporopollenin, B–intine
d) A–sporopollenin, B–exine

Answer: b

Question: Intine is made up of
a) cellulose
b) pectin
c) Both (a) and (b)
d) protein

Answer: c

Question: The sporopollenin is non-degradable because
a) it can withstand strong acids
b) it is resistant at very high temperature
c) no enzyme degrade it
d) All of the above

Answer: d

Question: Which of the following perform microsporogenesis?
a) Microspore mother cell
b) Pollen mother cell
c) Both (a) and (b)
d) None of these

Answer: c

Question: The functions of germ pore is/are
a) emergence of radicle
b) absorption of water for seed germination
c) initiation of pollen tube
d) All of the above

Answer: c

Question: In embryo sac, the number of synergid ®egg cell ®central cell ®antipodal cell follows the order
a) 1–1–2–3
b) 2–1–3–2
c) 2–1–1–3
d) 3–2–1–2

Answer: c

Question: When the pollen grain is mature, it contains two cells, the … A … and … B ….
a) A–generative cell, B–spore mother cell
b) A–vegetative cell, B–spore mother cell
c) A–spore mother cell, B–male gamete
d) A–vegetative cell, B–generative cell

Answer: d

Question: Cleistogamous flowers are strictly autogamous because they remain
a) always open
b) always close
c) always fragrance
d) are brighty coloured

Answer: b

Question: 60% of the angiosperms shed their pollens at the
a) 2-celled stage
b) 3-celled stage
c) 4-celled stage
d) 1-celled stage

Answer: a

Question: Chalazal pole is present
a) opposite to micropyle
b) at the origin of integuments
c) opposite to nucellus
d) near the embryo sac

Answer: a

Question: Megaspore mother cell is found near the region of
a) micropyle
b) chalaza
c) nucellus
d) integuments

Answer: a

Question: Embryo sac is also called
a) female gamete
b) synergids
c) female gametophyte
d) egg of angiosperm

Answer: c

Question: Megasporogenesis is
a) formation of fruits
b) formation of seeds
c) formation of megaspores
d) Both (b) and (c)

Answer: c

Question: An ovule is a
a) differentiated megasporangium
b) dedifferentiated megasporangium
c) integumented megasporangium
d) redifferentiated megasporangium

Answer: c

Question: Single megasporic development is called
a) single sporic
b) unisporic
c) monosporic
d) disporic

Answer: c

Question: Filiform apparatus are
a) special cellular thickenings at antipodal cell
b) special cellular thickenings at the micropylar end
c) special cellular thickenings at synergid cells
d) special cellular thickenings at nuclear end

Answer: c

Question: The most common abiotic pollinating agency in flowering plant is/ are
a) water
b) wind
c) Both (a) and (b)
d) None of these

Answer: b

Question: Autogamy stands for
a) pollination in same flower
b) pollination between different plants
c) pollination in two flowers of same plant
d) division in embryo

Answer: a

Question: In chasmogamy pollination takes place in
a) open flower
b) closed flower
c) large flower
d) geitonogamy flower

Answer: a

Question: Characteristic of wind pollinated pollens is, they are
a) non-sticky
b) light
c) produced in large number
d) All of the above

Answer: d

Question: The innermost layer of microsporangium is
a) tapetum
b) endothecium
c) middle layer
d) epidermis

Answer: a

Question: Double fertilisation is
a) fusion of two male gametes with one egg
b) fusion of one male gamete with two polar nuclei
c) fusion of two male gametes of pollen tube with two different eggs
d) syngamy and triple fusion

Answer: d

Asexual Reproduction Questuons and Answers

Question : Vegetative reproduction a type of asexual reproduction ? How can justify?

Ans. Yes. Since the formation of the new individual does not involve two parents,the process involved is asexual

Question :  Answer the following in one word:
a) An unicellular organism which reproduce by budding.
b)Special hyphae on which spore formation takes place in Penicillium.
c) A multicellular organism which reproduce by budding.

Ans. a) Yeast; b) Conidiophore; c) Hydra.

Question :  Water hyacinth is one of the most invasive weeds found growing wherever there is standing water.How do they grow in water so rapidly?

Ans. They reproduce asexually by their vegetative propagules called offset.

Question :  Are the offsprings derived by asexual reproduction genetically same? How can you say?

Ans. Yes.Since the offspring is a clone,so the offspring are the exact copy of their parent.

Question :  State whether true or false:
a)Amoeba undergoes multiple fission under unfavourable conditions.
b)Conidia produced by Penicillium is motile.
c)There is no meiosis in fungus.

Ans. a)true b)false c)false.

Sexual reproduction Questuons and Answers

Question :  The chromosome no. in the gamete of cat is 19. What will be the no. of chromosomes in their meiocyte?

Ans. 38

Question :  Name the type of gametes that are formed in staminate and pistilate flowers.

Ans. Heterogametes

Question :  Both frog and snake are unisexual animals.How do they differ in their type of gametic fusion?

Ans. In frogs,gametic fusion take place in external medium(external fertilisation); In snakes, fertilisation occurs inside the body of the organism (internal fertilisation).

Question :  Study the following diagram and answer the following question

a) Name the male and female reproductive structures of Chara.
b) Is Chara, an algae, homothallic or heterothallic? Why?

Ans. a) Male –Antheridium; Female- Archegonium.

        b) Homothallic - Because male and female reproductive organs are found in the same individual organism.

Question :  Fill in the blanks:

a) The ploidy of a cell formed after syngamy is_________ and an endosperm formed after triple fusion in a dicot is_______.
b) The sex organs of a dioecious Marchantia are borne in_____________thallus.
c) The turkey usually produces females for many generations ;such a phenomenon is called________.

Ans. a) 2n(diploid);3n(triploid)

        b) same

        c) parthenogenesis.

Flowers Questions and Answers

Ques. State the difference between actinomorphic flower and zygomorphic flower?

Ans. When a flower can be divided into two equal radial halves in any radial plane passing through the centre, it is said to be actinomorphic, e.g., mustard, datura, chilli. When it can be divided into two similar halves only in one particular vertical plane, it is zygomorphic, e.g., pea, gulmohur, bean, Cassia.

Ques. What is a sessile flower? Give 2 examples.

Ans. Sessile flowers are without a supporting stalk where as pedicellate flowers are supported by a stalk.

Ques. What is hypanthium?

Ans. In some flowers, the stamens, petals, and sepals are fused into a "floral tube" or hypanthium.

Ques. Name the branch of biology which deals with flowers and flowering plants.

Ans. Floriculture

Ques. What is the receptive part of the carpel?

Ans. Stigma

Stamen Questions and Answers

Ques. How does a monothecous anther differ from dithecous anther?

Ans. When the anthers are two chambered, they are named as Dithecous and if they are single chambered, they are termed as Monothecous

Ques. What is difference between syngenesious and synandrous stamens?

Ans. Syngenesious – filaments are free but anthers are fused e.g. sunflower

          Synandrous – stamens are fused throughout the length e.g., cocks-comb.

Ques. What are sterile stamens called as?

Ans. Staminodes

Ques. What is pollinia?

Ans. In some plants, notably members of Orchidaceae and Asclepiadoideae, the pollen remains in masses called pollinia

Ques.  What is the difference between Didynamous and Tetradynamous stamens?

Ans. • Didynamous: occurring in two pairs of different length.

         • Tetradynamous: occurring as a set of six filaments with two shorter ones.

Microsporogenesis Questions and Answers

Ques. Name the 4 wall layers of microsporangium.

Ans. Outside to inside. Epidermis, Endothecium, Middle layers and Tapetum

Ques. Name the group of compactly arranged homogenous cells seen in the centre of microsporangium of young anthers

Ans. Sporogenous tissue

Ques. What is the study of pollen grains called as?

Name the common disease caused due to pollen allergy.

What are palynivores?

Ans.   Palynology.

          Hayfever.

          Many insects and some mites are specialized to feed on pollen, and are called palynivores.

Ques. Name the chemical composition of inner wall (intine) of Pollen grains

Ans. Composed of Cellulose and Pectin

Ques. Generative cell in the pollen has two nuclei with different functions. Justify.

Ans. Generative (reproductive) cell containing two nuclei: a tube nucleus (that produces the pollen tube) and a generative nucleus (that divides to form the two sperm cells).

Pistil Questions and Answers

Ques. With reference to Gynoecium in a flower, what is staminate?

Ans. Flowers that bear a gynoecium but no androecium are called carpellate. Flowers lacking a gynoecium are called staminate.

Ques. State a difference between Apocarpous and Syncarpous ovary

Ans. If a gynoecium has multiple, distinct (free, unfused) carpels, it is apocarpous. If a gynoecium has multiple carpels fused into a single structure, it is syncarpous

Ques.  Are Carpel and Pistil synonymous? If no justify

Ans. Each pistil is constructed of from one to many enrolled leaflike structures, or carpels.

The carpel is a single megasporophyll, or modified seed-bearing leaf.

A pistil then may be composed of one carpel (simple pistil), as in the sweet pea, or of two or more carpels (compound pistil) partially or completely joined, as in the mustard (two carpels) or lily (three carpels). Pistils in the collective sense form the gynoecium.

Ques. What is placentation?

Identify the types of placentations

Ans. If the ovary is divided, with the ovules born on a line of placentation at the inner angle of each locule, this is axile placentation.

An ovary with free central placentation, on the other hand, consists of a single compartment without septae and the ovules are attached to a central column.

Ques. What is the cavity of ovary called?

Ans. Locule

Ovule Questions and Answers

Ques. . What does the word Ovule derived from latin word Ovulum mean?

Ans. The ovule is derived from Latin word ovulum meaning small egg

Ques. 

Identify the types of ovules given above.

Ans. Anatropous, Orthotropous, Hemitropous,Camylotrophous, Amphitrophous

Ques. Give the ploidy of the following in angiosperm plant.
a. Nucellus
b. MMC (Megaspore Mother Cell)
c. Functional megaspore
d. Female gametophyte

Ans. Nucellus – Diploid (2n)
        MMC (Megaspore Mother Cell) – Diploid (2n)
        Functional megaspore – Haploid (n)
        Female gametophyte – Haploid (n)

Ques. In angiosperms, the female gametophyte develops from the megaspore. Typically, the mature female gametophyte consists of how many cells and how many nuclei?

Name this type too.

Ans. 7 celled -8 nucleate embryo sac (mature female gametophyte), Polygonum type of embryo sac

Ques. If the Pollen tube enters through integuments or funiculus then what is this process called?

How does it differ from Porogamy?

Ans. Entry of pollentube into the ovule: The pollen tube enters the ovule in 3 ways.

1. Porogamy -Pollen tube enters through micropyle. Eg: Ottelia.

2. Chalazogamy – Pollen tube enters through chalaza. This was discovered by Treub. Eg.Casuarinas

3. Mesogamy – Pollen tube enters through integuments or funiculus. Eg-cucurbita.

Pollination Questions and Answers

Ques. What is the name given to the pollination by humans?

Ans. Anthropophily pollination by humans

Ques. Brief the terms "pollinator" and "pollenizer".

Ans. The terms "pollinator" and "pollenizer" are often confused: a pollinator is the agent that moves the pollen, whether it be bees, flies, bats, moths, or birds; a pollenizer is the plant that serves as the pollen source for other plants.

Ques. Give examples of 2 bat pollinated plants.

Ans. Sausage tree(Kiglia pinnata), Musa,Cactus

Ques. What is co-evolution?

Ans. The term coevolution is used to describe cases where two (or more) species reciprocally affect each other’s evolution.

Eg- Orchid plant Ophrys apifera pollination by the solitary bee Eucera occurs in the Mediterranean area

Ques. Snails pollinate flowers. Name the type of pollination.

Ans. Malacophilly.

Outbreeding devices / Pollen Pistil Interaction / Artificial Hybridisation Questions and Answers

Ques. Differentiate between Herkogamy and heterostyly?

Ans. Herkogamy: arrangement of male and female flowers at different heights to prevent self pollination is called Herkogamy.

Heterostyly: presence of styles in different lengths in the flowers of the same species is called Heterostyly.

Ques. How does protandry differ from protogyny?

Ans. This is a phenomenon which takes place in a bisexual / monoecious / hermaphrodite organisms (plant / animal) to avoid self-fertilisation / autogamy .In this phenomenon either male or female reproductive organ develope earlier then the other .When its the female reproductive organ that develope first the condition is protogyny whenever its the male reproductive organ which develope first then it is said to be protandry.

Ques. What is Pollen-pistil interaction?

Ans. All these events–from pollen deposition on the stigma until pollen tubes enter the ovule–are together referred to as pollen-pistil interaction.

Ques. Which structure present at the micropylar part of the synergids guides the entry of pollen tube?

Ans. Filiform apparatus

Ques. 

Why is bagging done in the process of artificial hybridization?

What is heterosis or hybrid vigour? Who coined this term?

Ans. Emasculated flowers have to be covered with a bag of suitable size, generally made up of butter paper, to prevent contamination of its stigma with unwanted pollen.

Heterosis, hybrid vigor, or outbreeding enhancement, is the improved or increased function of any biological quality in a hybrid offspring.

G.H. Shull

Double Fertilisation Questions and Answers

Ques. Name the scientists who discovered
a) Triple fusion
b) Double fertilisation

Ans. a)Nawaschin
        b)Strassburger

Ques. 

Label A, B and C of the developing Dicot embryo

Ans. 

Ques. 

Above is the diagram of dicot and monocot seed. Label

Ans. 

Ques. Give the ploidy of endosperm? How many types of endosperms are noted in flowering plants?

Ans. Triploid

3 types- Cellular, Nuclear and Helobial

Ques. 

Ans. 

Seed Questions and Answers

Ques. What is perisperm? Give 2 examples.

Ans. The persistent nucellus is called the perisperm. Eg.- Black pepper and Beet

Ques. What do epigeal and hypogeal germination mean?

Ans. The bean shows epigeous germination, in which the cotyledons emerge from the soil, following the arch of the hypocotyl.

The pea shows hypogeous germination, in which the cotyledons stay underground because it is the epicotyl that arches out, protecting the delicate meristem--leaving the cotyledons behind.

Ques. What is dormancy?

Ans. A dormant seed is one that is unable to germinate in a specified period of time under a combination of environmental factors that are normally suitable for the germination of the non-dormant seed.

Ques. Give two examples of fruits with fleshy pericarp.

Ans. In fleshy fruits, the outer and often edible layer is the pericarp, which is the tissue that develops from the ovary wall of the flower and surrounds the seeds. Some edible "vegetables" such as the cucumber, squash, and tomatoes are actually botanical fruits.

Ques. 

Name the structure which develops into a fruit in these false fruits?

Ans. Thalamus

Parthenocarpy/Apomixis/Polyembryony Questions and Answers

Ques. Who discovered Polyembryony in plants?

Ans. The polyembryony phenomenon was discovered by Leeuwenhoek in 1719, who observed the formation of two plantlets from the same citrus seed

Ques. Who coined the term Apomixis?

Ans. The term Apomixis was by Hans Winkler

Ques. Parthenocarpy is sometimes claimed to be the equivalent of parthenogenesis in animals. Is it true?

Ans. Parthenocarpy is sometimes claimed to be the equivalent of parthenogenesis in animals. That is incorrect because parthenogenesis is a method of asexual reproduction, and parthenocarpy is not, except in rare cases such as pineapple. The plant equivalent of parthenogenesis is apomixis.

Ques. 

Observe the above pictures.Do they have seeds? Give the term used to describe such fruits and define it.

Ans. Parthenocarpic fruits.

In botany and horticulture, parthenocarpy (literally meaning virgin fruit) is the natural or artificially induced production of fruit without fertilization of ovules. The fruit is therefore seedless

Ques. In the case of polyembryony, an embryo develops from the synergid and another from the nucellus. Which is diploid and which is haploid?

Ans. Synergid embryo is haploid and nucellar embryo is diploid

POINTS TO REMEMBER

Autogamy : When pollen grains of a flower are transferred from anther to stigma of the same flower.

Coleorhiza : A protective sheath of radicle in monocot seed.

Coleoptile : A protective sheath of plumule in monocot seed.

Endothecium : A fibrous layer in the anther next to epidermis.

Geitonogany : Self pollination between flowers of the same plant

Micropyle : A small pore in the ovule through which the pollen tube enters.

Nucellus : Multicellular tissue in the centre of ovule where embryo sac is present.

Tapetum : Inner most layer of cells in pollen sac which provide nutrition tod eveloping pollen grains

Viability of Seed : Ability of seed to retain the power of germination.

1. Microsporangium (Pollen sac) :

Outermost layer = Epidermis

Second layer = Endothecium

Middle layer = 2 – 4 layers of cells

Innermost layer = Tapetum [Nourishes the developing Pollen grains (Microspores)]

2. Microsporogenesis : Process of formation of microspores from a pollen mother cell