CBSE Class 12 Biology Reproduction In Flowering Plants Worksheet Set C

Important Questions for NCERT Class 12 Biology Sexual Reproduction in Flowering Plants

Question. Ovules generally differentiate a single megaspore mother cell in the
(a) Micropylar region
(b) Chalazal region
(c) Both 1 & 2
(d) Integument region

Answer : A

Question. In Castor plant :
(a) Autogamy is possible
(b) Geitonogamy is possible
(c) Both are possible
(d) Both are not possible

Answer : B

Question. Example of plants, which contains cleistogamous flowers :
(a) Oxalis
(b) Commelina
(c) Viola (Common pansy)
(d) All of the above

Answer : D

Question. In embryosac, three cells are grouped together at the micropylar end to constitute
(a) Antipodals
(b) Synergids
(c) Egg apparatus
(d) Polar nuclei

Answer : C

Question. Cleistogamous flowers are invariably :
(a) Autogamous
(b) Xenogamous
(c) Geitonogamous
(d) All are possible

Answer : A

Question. What would be the ploidy of cells of tetrad ?
(a) n
(b) 2n
(c) 3n
(d) 4n

Answer : A

Question. Which of the following statements are correct ?
(a) Pollen grains are rich in nutrients.
(b) In some cereals like rice and wheat pollen grains lose viability within 30 minutes of their release
(c) In some members of rosaceae, leguminosae and solanaceae, pollen grains maintain viability for months
(d) All of the above

Answer : D

Question. Wind pollinated flowers often have.....ovule in each ovary.
(a) Many
(b) Two
(c) One
(d) Three

Answer : C

Question. Pollen tube enters into the embryosac through :
(a) Chalaza
(b) Integument
(c) Filiform apparatus
(d) Funiculus

Answer : C

Question. Syngamy results in the formation of :
(a) Zygote
(b) Primary endosperm nucleus
(c) Endosperm
(d) Fruit

Answer : A

Questions Based on High Order Thinking Skills (HOTS)

Question. The flask-shaped organ A at the centre of a flower is surrounded by a number of little stalks B having swollen tops which lie just inside the ring of petals.
(a) Name A. What are the various parts of A ?
(b) Which part of A contains gametes ?
(c) Name B. What is the swollen top of B known as ?
(d) What does the swollen top of B contain ?
(e) Out of A and B, which one is (i) male part, and (ii) female part of the flower ?

Answer : (a) A is carpel (or pistil) ; Stigma, Style and Ovary (b) Ovary (c) B is stamen ; Anther (d) Pollen grains (e) (i) B (ii) A

Question. When an insect sits on the flower of a plant then some particles A present in the top of little stalks in the flower attach to its body hair. When this insect now sits on the flower of another similar plant, then particles A attached to the hair of insect are put on the top of a flask-shaped organ at the centre of flower. The particle A grows a long tube B from the top of flask-shaped organ through which C moves down and reaches the bottom part of flask-shaped organ. Here C fuses with the nucleus of D contained in structure E.
The fusion of C and D forms a new cell F which grows and develops into a seed of the plant.
(a) What are particles A ? What is the process of transferring A from one flower to another flower of similar
plant by the insect known as ?
(b) What is the name of tube B ?
(c) What is C which moves down through the tube B ?
(d) Name D and E.
(e) What is F ?

Answer : (a)A are pollen
grains ; Cross-pollination (b) Pollen tube (c) C is male gamete (d) D is female gamete (ovum or egg) ;
E is ovule (e) F is fertilised egg (zygote)

Question. When a human female reaches a certain age then vaginal bleeding occurs for a few days after regular time intervals.
(a) What is this process known as (i) in scientific terms, and (ii) in everyday language ?
(b) At what approximate age this process starts in human females ? What is the human female said to have attained at this stage ?
(c) After how much time is this process repeated ? For how many days this process usually lasts ?
(d) What does the onset of this process in human females signify ?
(e) At which particular event in the life of a human female this process stops temporarily but starts again ?
(f) At which approximate age of human female this process stops permanently ?

Answer : (a) (i) Menstruation (ii) Periods (b) 10 to 12 years ; Puberty (c) 28 days ; About 3 to 5 days (d) That the reproductive system of human female has started working (e) Beginning of pregnancy (f) About 45 to 50 years.

Question. X and Y are two human beings. The organ A in the reproductive system of X releases a mature gamete B once a month which goes into a tube-like structure C through a funnel-like opening. The organ D in the reproductive system of Y makes and releases gametes E which pass through a duct F and are introduced by an organ of Y, into the body of X. B and E fuse together in C to form a new cell G. The cell G divides repeatedly to form a ball of cells H which gets embedded in the lining of organ I of reproductive system of X where it grows and develops into a baby.
(a) Name (i) organ A, and (ii) gamete B.
(b) Write two names of tube-like structure C.
(c) Name (i) organ D, and (ii) gamete E.
(d) Write two names of duct F.
(e) Name (i) cell G (ii) ball of cells H, and (iii) organ I.
(f) Out of X and Y, which one is (i) male, and (ii) female ?

Answer : (a) (i) Ovary (ii) Ovum (or Egg) (b) Fallopian tube ; Oviduct (c) (i) Testis (ii) Sperm (d) Sperm duct ; Vas deferens (e) (i) Zygote (Fertilised egg) (ii) Embryo (iii) Uterus (or Womb) (f) (i) Y is male (ii) X is female

Question. When a fertilised egg E formed in the oviduct of a human female divides repeatedly to form an embryo, the embryo gets implanted in the thick and soft lining of the uterus. After this a disc-like special tissue T develops between the uterus wall and embryo through which all the requirements of the developing embryo (and foetus) are met from the mother’s body. The embryo is connected to the tissue T through a string like structure S.
(a) What is the other name of fertilised egg cell E ?
(b) What is the name of tissue T ?
(c) Name the string-like structure S .
(d) Name two substances which pass from mother’s blood to embryo through tissue T and, one type of
substance which passes from embryo to mother’s blood.
(e) What happens to S when the baby is born ? Why ?

Answer : (a) Zygote (b)
Placenta (c) Umbilical cord (d) From mother’s blood to embryo : Oxygen and Nutrients ; From embryo to mother’s blood : Wastes (e) S (umbilical cord) is tied and then cut ; To separate the new born baby from the mother

Question. When a female child is born, her ovaries already contain thousands of immature eggs (or ova) contained in immature structures A. On maturing, A bursts open and an egg shoots out of the ovary in a process called B. The process B starts in the females at puberty and occurs again and again after a time period x. Before every occurrence of process B, the inner lining of uterus becomes thick and soft with lots of blood vessels in it. When the egg cell gets fertilised by a sperm, then an event C occurs in the life of mature human female which lasts for time period y leading to the birth of baby. If, however, the egg cell released by the ovary does not get a sperm to fuse with, then the thick and soft inner lining of uterus breaks down and comes out of the female’s body in an event called D. The occurrence of event D is controlled by chemical substances E.
(a) What are A ?
(b) What is process B ?
(c) What is the time period x ?
(d) Name the event C.
(e) How much is the time period y ?
(f) What is the name of process D ?
(g) Name the chemical substances E.

Answer : (a) Follicles (b) Ovulation (c) 28 days (d) Conception (or Pregnancy) (e) About nine months (f) Menstruation (g) Hormones

Question. In the surgical method of birth control available for males, the structures A in the reproductive system are cut and ligated (tied up) at both ends. This prevents the reproductive cells B from coming out from the organs C where they are made in the male body. Since B cannot come out from the male body, they cannot fuse with cell D in the body of a female and hence pregnancy is prevented.
(a) What are structures A ?
(b) What are cells B ?
(c) Name the organs C.
(d) What is cell D ?
(e) What is the name of this surgical procedure for birth control available to males ?

Answer : (a) Sperm ducts (or Vas deferens) (b) Sperms (c) Testes
(d) Egg cell (or Ovum) (e) Vasectomy

Question. In the surgical method of birth control available for human females, the structures P in the reproductive
system are cut and ligated (tied up) properly at both ends. This prevents the reproductive cell Q released by an organ R from entering the structures P so that Q is not available to fuse with another reproductive cell S coming from the male reproductive system. In this way, pregnancy is prevented.
(a) What are structures P ?
(b) What is cell Q ?
(c) Name the organ R.
(d) What is the reproductive cell S ?
(e) What is the name of this surgical method of birth control available to females ?

Answer : (a) Oviducts (or Fallopian tubes) (b) Ovum (or Egg cell) (c) Ovary (d) Sperms (e) Tubectomy

Question. The human males use a device X made of a very thin rubber sheet as a covering on the male organ to prevent pregnancy. This device traps the gametes Y in it. In order to prevent pregnancy, the human females use a device Z which is a circle of rubber with a metal spring around it. The device Z is put inside the vagina to cover the cervix. It stops Y from going into the uterus.
(a) What is device X ?
(b) What are Y ?
(c) Name the device Z.
(d) What is the general name of these methods of birth control (or preventing pregnancy) ?
(e) The use of which contraceptive device, X or Z, can protect the persons from sexually transmitted diseases ?

Answer : (a) Condom (b) Sperms (c) Diaphragm (or Cap) (d) Barrier methods (e) X

Question. A woman uses pills A as a method of birth control (or preventing pregnancy). The pills A stop the ovaries from releasing ovum into oviducts. Another woman uses pills B as a method of birth control. The pills B kill the sperms and prevent pregnancy.
(a) What do the pills A contain ?
(b) What is the common name of pills A ?
(c) What do the pills B contain ?
(d) What is the common name of pills B ?
(e) What is the general name of these methods of birth control ?

Answer : (a) Hormones (b) Oral pills (c) Spermicides (d) Vaginal pills (e) Chemical methods

Question. A woman uses a device X made of a common metal for preventing pregnancy. This device works by preventing the implantation of fertilised egg cell (or embryo) in the female organ Y.
(a) What are the two names of device X ?
(b) Name the organ Y.
(c) Can this method of contraception protect a woman from acquiring a STD ?

Answer : (a) Copper-T and IUCD (b) Uterus (or Womb) (c) No

Question. A, B and C are three common STDs. A and C are caused by bacteria whereas B is caused by a virus D. The virus D reduces the immunity of the infected person to such a low level that the person can die of even very mild diseases.
(a) What could A and C be ?
(b) What is B ?
(c) Name the virus D ?
(d) How can A, B and C be caused ?
(e) Out of A, B and C, which one does not have a definite cure as yet ?

Answer : (a) Syphilis and
Gonorrhoea (b) AIDS (c) HIV (d) By sexual contact with an infected person (e) B (AIDS)

Question. The germ cell A produced by a person X is round in shape and it fuses with another germ cell B having a long tail and produced by a person Y. The fusion of A and B produces a new cell C. The cell C divides repeatedly and grows inside the organ D of person X to form E in which the body features of the unborn baby are not much developed. E grows further to form F in which the various body features of the unborn baby (like hands, legs, head, eyes, and ears, etc.) can be identified. F grows further and ultimately forms a baby. What are A, B, C, D, E and F ? Out of the two persons X and Y, which one is male and which one female ?
Answer : A is ovum (or egg cell); B is sperm ; C is zygote (fertilised egg) ; D is uterus ; E is embryo ; F is foetus; Y is male ; X is female

Question. Explain why, a human zygote is more likely to grow into an adult than a frog zygote.
Answer : The human zygote grows inside the uterus of mother so it can grow safely into an adult.

On the other hand , a frog zygote grows in the water of pond or stream where it is very unsafe because it may be eaten up by other aquatic animals

Question. In a bisexual flower, inspite of the young stamens being removed artificially, the flower produces fruit. Explain.
Answer : Though stamens have been removed but the female organ ‘carpel’ of the flower is intact. Cross-pollination has occurred in this flower leading to the formation of fruit

Question. In what ways is fertilisation in a plant :
(a) similar to fertilisation in a human ?
(b) different from fertilisation in a human ?

Answer : (a) Similarities : (i) The fusion of gametes occurs in the female part in a plant as well as in a human (ii) the male gamete moves (or is moved) to the female gamete in a plant as well as in a human (iii) A zygote is produced which develops into an embryo in a plant as well as in a human (b) Differences : (i) There is pollination in a plant but copulation ( or mating) in a human to bring the male and female gametes together (ii) There is no equivalent in a plant to the oviducts in a human (iii) In a human, the male gametes (sperms) swim but in a plant self-fertilisation is possible (The fertilisation of a plant with its own pollen is called self-fertilisation)

Question. Differentiate between albuminous and non-albuminous seeds, giving one example of each.
Answer : Albuminous seeds have residual endosperm in them. For example, maize.
Non-albuminous seeds do not have any residual endosperm. For example, pea.

Question. Mention the reasons for difference in ploidy of zygote and primary endosperm nucleus in an angiosperm. 
OR
In angiosperms, zygote is diploid while primary endosperm cell is triploid. Explain.
Answer : A zygote is formed by the fusion of haploid male gamete with the haploid egg to form a diploid cell; whereas, primary endosperm nucleus (PEN) is formed by the fusion of haploid male gamete with two haploid polar nuclei, forming a triploid nucleus.

Question. Some angiosperm seeds are said to be ‘albuminous’, whereas few others are said to have a perisperm. Explain each with the help of an example. 
Answer : Albuminous seeds are those which retain a part of endosperm as it is not completely used up during embryo development. For example, in wheat and maize. In some seeds remnants of nucellus are also persistent. This residual, persistent nucleus is the perisperm. For example, in black pepper and beet.

Question. Double fertilisation is reported in plants of both, castor and groundnut. However, the mature seeds of groundnut are non-albuminous and castor are albuminous. Explain the postfertilisation events that are responsible for it. 
Answer : The development of endosperm (preceding the embryo) takes place from primary endosperm nucleus (PEN) in both, castor and groundnut.
The developing embryo derives nutrition from endosperm.
PEN undergoes repeated division to give free nuclei. Subsequently cell wall is formed and endosperm becomes cellular. At this stage endosperm is retained in castor or is not fully consumed but in groundnut endosperm is consumed by growing embryo.

Question. (a) You are given castor and bean seeds. Which one of the two would you select to observe the endosperm?
(b) The development of endosperm precedes that of embryo in plants. Justify.
Answer : (a) Castor
(b) Endosperm stores reserve food materials. It provides nutrition to the developing embryo,therefore its development precedes that of embryo.

Question. (a) Mature seeds of legumes are non-albuminous. Then, can it be assumed that double fertilisation does not occur in legumes? Explain your Answer :
(b) List the differences between the embryos of dicot (pea) and monocot (grass family).
Answer : (a) No it cannot be assumed so because fertilisation does takes place but the endosperm is consumed during embryo development.

(b) Differences between dicot and monocot embryo
S. No.    Dicot embryo                                            Monocot embryo
(i) It has two cotyledons.                                       It has one cotyledon.
(ii) Radicle and plumule are not covered with       Radicle is covered with coleorhiza and
sheath.                                                                  plumule is covered by coleoptile.

Question. What is pericarp? Mention its functions.
Answer : The wall of the ovary that develops into wall of the fruit is called pericarp.
Functions: (i) Protects the seed till its maturity.
(ii) Helps in seed dispersal.

Question. A non-biology person is quite shocked to know that apple is a false fruit, mango is a true fruit and banana is a seedless fruit. As a biology student how would you satisfy this person?
Answer : In apple only the thalamus (along with ovary) portion contributes to fruit formation. Therefore,it is a false fruit. Mango develops only from the ovary, therefore it is a true fruit. Banana develops from ovary but without fertilisation. The method is known as parthenocarpy.Since there is no fertilisation, no seeds are formed in banana.

Question.Why are some seeds referred to as apomictic seeds? Mention one advantage and one disadvantage to a farmer who uses them. 
Answer : Seeds that are produced without fertilisation are referred to as apomictic.
Advantage: Desired characters are retained in offspring (progeny) as there is no segregation of characters in offspring (progeny). Seed production is assured even in absence of pollinators.Apomictic seeds are economical as they can be used to grow crops year after year.
Disadvantage: Cannot control accumulation of deleterious genetic mutation. These are usually restricted to narrow ecological niches and lack ability to adapt to changing environment.

Question. Explain any two ways by which apomictic seeds get developed. 
Answer : Ways by which apomictic seeds develop are:
(i) A diploid egg is formed without reduction division which develops into embryo without fertilisation.
(ii) Some cells of the nucellus, which are diploid in nature, start dividing and without fertilisation develop into embryo.

Question. If you squeeze a seed of orange you might observe many embryos of different sizes? How is it possible? Explain. 
Answer : In orange, the nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into a number of embryos of different sizes.

Question. Banana is a parthenocarpic fruit whereas oranges show polyembryony. How are they different from each other with respect to seeds?
Answer : Banana develops from an ovary without fertilisation having non-viable seeds so it is called parthenocarpic fruit. An orange contain seeds with more than one embryo thus, it shows
polyembryony.

Question. (a) How are parthenocarpic fruits produced by some plants and apomictic seeds by some others? Explain.
(b) When do farmers prefer using apomictic seeds? 
Answer : (a) Parthenocarpic fruits are formed when ovary develops into fruit without fertilisation.
Apomictic seeds are formed when formation of seeds take place without fertilisation.
(b) To maintain hybrid characters (year after year in a desired plant) and to avoid buying hybrid seeds every year (expensive seeds) farmers prefer using apomictic seeds.

Question. What is agamospermy? How is agamospermy different from parthenogenesis and parthenocarpy?
Answer : The phenomenon of asexual reproduction that mimics sexual reproduction as it forms seed without fertilisation is called agamospermy.
Parthenogenesis refers to the development of unfertilised egg into an adult individual. On the other hand, parthenocarpy is the phenomenon of formation of fruits without fertilisation of an ovary.

Question. (a) Name the organic material exine of the pollen grain is made up of. How is this material advantageous to pollen grain?
(b) Still it is observed that it does not form a continuous layer around the pollen grain. Give reason.
(c) How are ‘pollen banks’ useful? 
Answer : (a) Sporopollenin
It is most resistant material to high temperature, strong acids on alkali and no enzymes can degrade it.
(b) Germs pores are present to allow pollen tube to emerge out for pollen germination.
(c) Pollen banks help in storing pollen grains for years for crop breeding programmes.

Question. Write the functions of:
(a) Coleoptile (b) Tapetum (c) Scutellum 
Answer : (a) Coleoptile: It protects the plumule of the monocot embryo.
(b) Tapetum: It provides nourishment to developing pollen.
(c) Scutellum: It provides nourishment and protection to the developing embryo.

Question. When and where do tapetum and synergids develop in flowering plants? Mention their functions.
Answer : Tapetum develop during microsporogenesis in the microsporangium (anther). It nourishes the developing pollen grains.Synergids develop during megasporogenesis in the megasporangium (ovule). Synergids have filiform apparatus to guide the pollen tube into it.

Question. Where are the following structures present in a male gametophyte of an angiosperm? Mention the function of each one of them.
(a) Germ pore (b) Sporopollenin (c) Generative cell 
Answer : (a) Germ pore: Exine of pollen grain. It is the site from where pollen tube emerges.
(b) Sporopollenin: Exine of pollen grains. It protects the pollen grains from high temperature, strong acids and alkali, enzymes and adverse conditions.
(c) Generative Cells: These are present in pollen grains. These give rise to two male gametes.

Question. Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. 
Answer : (i) Time of pollen release and stigma receptivity are different (not synchronised). This prevents self-pollination.
(ii) Anther and stigma are placed at different positions, so the pollens cannot come in contact with the stigma of the same flower.
(iii) Self-incompatibility, which is a genetic mechanism to prevent the pollen germination on the stigma of the same flower.

Question. Why are angiosperm anthers called dithecous? Describe the structure of its microsporangium.
Answer : The anthers of angiosperms are called dithecous because they are bilobed and each lobe of anther has two theca.Microsporangium is surrounded by four wall layers named as epidermis, endothecium, middle layer and tapetum. In young anther, a group of compactly arranged homogenous cells called sporogenous tissue occupies the centre of each microsporangium which produce microspores or pollen grains.

Question. The generative cell of a 2-celled pollen divides in the pollen tube but not in a 3-celled pollen.
Give reasons. 
Answer : In a 3-celled pollen, the generative cell has already divided and formed 2 male gametes. Hence, it will not divide again in the pollen tube. As the generative cell has not divided in a 2-celled pollen,it divides in the pollen tube.

Question. During an excavation assignment, scientists collected pollen grains of a plant preserved in deeper layers of soil. Analyse the properties of pollen grains which help in the fossilization.
Answer : Pollen has an outer layer called exine which is made of sporopollenin.It is the most resistant organic material known. It can withstand high temperature, strong acids and alkali as well. No enzyme that degrades sporopollenin is so far known.

Question. What will be the ploidy of the cells of the nucellus, microspore mother cell, the functional megaspore and female gametophyte? 
Answer : Nucellus : Diploid
Microspore mother cell : Diploid
The functional megaspore : Haploid
Female gametophyte : Haploid

Question. Given below are the events that are observed in artificial hybridisation programme. Arrange them in the correct sequential order in which they are followed in the hybridisation programme.
(a) re-bagging; (b) selection of parents;
(c) bagging; (d) dusting the pollen on stigma;
(e) emasculation; (f) collection of pollen from male parent.
Answer : (b); (e); (c); (f); (d); (a).

Question. Explain the process of artificial hybridisation to get improved crop variety in (i) plants bearing bisexual flowers (ii) female parent producing unisexual flowers. 
Answer : (i) In plants bearing bisexual flowers, the anthers are removed from the flower before they dehisce. This is called emasculation. The emasculated flowers are covered with a bag of butter paper to prevent contamination of stigma with unwanted pollen. This process is called bagging. When this stigma attains receptivity, mature pollen grains are dusted on the stigma and the flowers are rebagged to allow the fruits to develop.
(ii) If the female parent produces unisexual flowers, emasculation is not done. The flower buds are bagged before the flowers open. When the stigma becomes receptive, pollen is dusted on stigma and the flower is rebagged.

Question.15. Differentiate between geitonogamy and xenogamy in plants. Which one between the two will lead to inbreeding depression and why? 
Answer : Differences between geitonogamy and xenogamy

Question. Write the differences between wind-pollinated and insect-pollinated flowers. Give an example of each type. 
Answer : Differences between wind-pollinated and insect-pollinated flowers

Question. (i) Write the characteristic features of anther, pollen and stigma of wind-pollinated flowers.
(ii) How do flowers reward their insect pollinators? Explain. 
Answer : (i) The characteristics of wind-pollinated flowers are:
(a) Pollen grains are light in weight, non-sticky, dry and winged, so that they can be easily transported.
(b) Well-exposed stamens for easy dispersal of pollen grains in the wind.
(c) The stigma is sticky, large, feathery to trap pollen grains in air.
(d) Numerous flower are packed together to form inflorescence.
(d) The flowers are small and inconspicuous.
(ii) Insect pollinators are rewarded in following ways:
(a) The flowers offer floral reward like nectar and pollen grain.
(b) In some species floral reward provides safe place to lay eggs.

Question. (a) Mention any four strategies adopted by flowering plants to prevent self-pollination.
(b) Why is geitonogamy also referred to as genetical autogamy? [CBSE (AI) 2010]
Answer : (a) Refer to Basic Concepts Point 5 [Contrivances for self-pollination (Autogamy)].
(b) Geitonogamy is the transfer of pollen grains from the anther to the stigma of another flower of the same plant. Although geitonogamy is functionally cross-pollination involving a pollinating agent, genetically it is similar to autogamy, since the pollen grains come from the same plant.

Question. State the significance of pollination. List any four differences between wind-pollinated and animal pollinated flowers.
Answer : Pollination is the phenomena of transfer of pollen grains from anthers to the stigma of a pistil. Pollination is prerequisite for the beginning of fertilisation.

Question. (a) How does cleistogamy ensure autogamy?
(b) State one advantage and one disadvantage of cleistogamy to the plant.
Answer : (a) Cleistogamous flowers do not open. Therefore, the pollens have to land on the stigma of the same flower. This ensures autogamy.
(b) Advantage: Self-pollination is assured, thus ensuring seed formation.
Disadvantage: Least variations observed and it leads to inbreeding depression.

Question. (a) Describe the endosperm development in coconut.
(b) Why is tender coconut considered a healthy source of nutrition?
(c) How are pea seeds different from castor seeds with respect to endosperm?
Answer : (a) The primary endosperm nucleus (PEN) undergoes successive nuclear divisions to give rise to free nuclei. Subsequently, cell wall is formed towards the periphery and endosperm becomes cellular, leaving free nuclear endosperm in the central part. This division is followed by cytokinesis and thus endosperm becomes cellular and is called cellular endosperm.
(b) It is rich in many nutrients like fats, proteins, carbohydrates, minerals, vitamins. Hence, tender coconut is considered a healthy source of nutrition.
(c) In peas, the endosperm is used up and there is no endosperm present in the mature seed. In castor, the endosperm remains intact in the mature seed.

Question. Differentiate between perisperm and endosperm by giving one example of each.
Answer : Differences between perisperm and endosperm
S. No. Perisperm                                    Endosperm
(i) It is persistent nucellus.                 It is the nutritive tissue for embryo.
(ii) It is diploid.                                    It is triploid.
(iii) Example: black pepper, beet.      Example: maize, rice, wheat, castor.

Question. Explain any three advantages the seeds offer to angiosperms. 
Answer : (i) Since reproductive process such as pollination and fertilisation are independent of water, seed formation is more dependable.
(ii) Seeds have better adaptive strategies for dispersal to new habitats and help the species to colonise in other areas.
(iii) As they have sufficient food reserves young seedlings are nourished until they are capable of photosynthesis on their own.
(iv) The hard seed coat provides protection to the young embryo.
(v) Being products of sexual reproduction, they generate new genetic combinations or variations.

Question. Differentiate between parthenocarpy and parthenogenesis. Give one example of each.
Answer : Differences between parthenocarpy and parthenogenesis
S. No. Parthenocarpy                                                    Parthenogenesis
(i) It is process of formation of fruit without           It is the process of development of new
fertilisation                                                            organism without fertilisation.
(ii) For example, banana, grapes, etc.                  For example, drones, male honey bee, turkey,
rotifers, etc.

Question. (a) How are parthenocarpic fruits produced by some plants and apomictic seeds by some others? Explain.
(b) When do farmers prefer using apomictic seeds?
Answer : (a) Parthenocarpic fruits are formed when ovary develops into fruit without fertilisation.
Apomictic seeds are formed when formation of seeds take place without fertilisation.
(b) To maintain hybrid characters (year after year in a desired plant) and to avoid buying hybrid seeds every year (expensive seeds) farmers prefer using apomictic seeds.

Question. (a) How does a farmer use the dormancy of seeds to his advantage?
(b) What advantages a seed provides to a plant? 
Answer : (a) Dormancy of mature seeds are important for storage of seeds which can be used as food throughout the year and also to raise crop in the next season.
(b) Seeds offer several advantages to angiosperms. Firstly, since reproductive processes such as pollination and fertilisation are independent of water, seed formation is more dependable.
Also seeds have better adaptive strategies for dispersal to new habitats and help the species to colonise in other areas. As they have sufficient food reserves, young seedlings are nourished until they are capable of photosynthesis on their own. The hard seed coat provides protection to the young embryo. Being products of sexual reproduction, they generate new genetic combinations leading to variations.

Question. ‘Fertilisation is not an obligatory event for fruit production in certain plants’. Explain the statement. 
Answer : This can be observed in parthenocarpic fruits. The ‘seedless fruits’ that are available in the market, such as pomegranate, grapes, etc., are good examples. Flowers of these plants are sprayed by a growth hormone that induces fruit development even though fertilisation has not occurred. The ovules of such fruits, however, fail to develop into seeds.

Question. Is pollination and fertilisation necessary in apomixis? Give reasons. 
Answer : No, they are not necessary. Apomixis is actually an alternative to sexual reproduction, although the female sexual apparatus is used in the process. In apomicts, embryos can develop directly from the nucellus or synergid or egg. Therefore, there is no need for either pollination or fertilisation.

Question. Embryo sacs of some apomictic species appear normal but contain diploid cells. Suggest a suitable explanation for the condition. 
Answer : Many apomictic species have been seen to have normal looking embryo sacs. The only possibility of the embryo sac possessing diploid cells will be due to failure of meiotic division at the megaspore mother cell stage. Since the megaspore mother cell has a diploid nucleus, if it undergoes mitosis instead of meiosis, all the resulting nuclei and cells will be diploid in nature.

1. Where is sporopollenin present in plants? State its significance with respect to its chemical Nature. 

2. Normally one embryo develops in one seed but when an orange seed is squeezed many embryos of different shapes and sizes are seen. Mention how it has happened. 

3. Name the part of the flower which the tassels of the corn-cob represent. 

4. Name the type of flower which favours cross pollination. 

5. Why is bagging of the emasculated flowers essential during hybridization experiments? 

6. The meiocyteof rice has 24 chromosomes. How many chromosomes are present in its endosperm? 

7. Why is a coconut plant referred to a monoecious? 

8. A bilobed, dithecous anther has 100 microspore mother cells per microsporangium. How many male gametophytes this anther can produce? 

9. Differentiate between albuminous and non-albuminous seeds, giving one example of each. 

10. Why is geitonogamy also referred to as genetical autogamy? 

11. The flower of brinjal is referred to as chasmogamous while that of beans is cleistogamous. How are they different from each other? 

12. Banana is a parthernocarpic fruit whereas oranges show polyembryony. How are they different from each other with respect to seeds . 

13. Draw a vertical section of a maize grain and label i) pericarp ii) scutellum c) coleoptile and iv) radicle.  

14. Write the difference between the tender coconut water and the thick, white kernel of a mature coconut and their ploidy. 

15 i) Write the characteristic features of anther, pollen and stigma of wind pollinated flowers. ii) How do flowers reward their insect pollinators? Explain. 

16 Draw a longitudinal section of post pollinated pistil showing entry of pollen tube into a matureembro-sac. Label filiform apparatus, chalazal end, hilum, antipodals, male gametes and secondary nucleus.

17 Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination. 

18 Why are angiosperm anthers called dithecous ? Describe the structure of its Microsporangium.

19 Draw a diagram of a male gametophyte of an angiosperm. Label any four parts. Briefly describe its structure. 

20 How does the megaspore mother cell develops into 7-celled,8-nulceated embryosac in an angiosperm? Draw labeled diagram of a mature embryo sac. 

21 a) Explain the different ways apomictic seeds can develop. Give an example of each. (b) Mention one advantage of apomictic seeds to farmers.

(c) Draw a labelled mature stage of a dicotyledonous embryo.