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Important Questions and choose the correct answer - Botany - Reproduction in Plants: Evaluation | 12th Botany : Chapter 1 : Asexual and Sexual Reproduction in Plants

Chapter: 12th Botany : Chapter 1 : Asexual and Sexual Reproduction in Plants

Reproduction in Plants: Evaluation

Botany : Asexual and Sexual Reproduction in Plants - Important Questions and choose the correct answer - Botany

Asexual and Sexual Reproduction in Plants


Evaluation

 

1. Choose the correct statement from the following

a) Gametes are involved in asexual reproduction

b) Bacteria reproduce asexually by budding

c) Conidia formation is a method of sexual reproduction

d) Yeast reproduce by budding

 

2. An eminent Indian embryologist is

a) S.R.Kashyap

b) P.Maheswari

c) M.S. Swaminathan

d) K.C.Mehta

 

3. Identify the correctly matched pair

a) Tuber - Allium cepa

b) Sucker - Pistia

c) Rhizome - Musa

d) Stolon - Zingiber

 

4. Pollen tube was discovered by

a) J.G.Kolreuter

b) G.B.Amici

c) E.Strasburger

d) E.Hanning

 

5. Size of pollen grain in Myosotis

a) 10 micrometer

b) 20 micrometer

c) 200 micrometer

d) 2000 micrometer

 

6. First cell of male gametophyte in angiosperm is

a) Microspore

b) megaspore

c) Nucleus

d) Primary Endosperm Nucleus

 

7. Match the following

I) External fertilization

II) Androecium

III) Male gametophyte

IV) Primary parietal layer

i) pollen grain

ii)anther wall

iii)algae

iv)stamens

a)I-iv;II-i;III-ii;IV-iii

b)I-iii;II-iv;III-i;IV-ii

c)I-iii;II-iv;III-ii,IV-i

d)I-iii;II-i;III-iv;IV-ii

 

8. Arrange the layers of anther wall from locus to periphery

a) Epidermis,middle layers, tapetum, endothecium

b) Tapetum, middle layers, epidermis, endothecium

c) Endothecium, epidermis, middle layers, tapetum

d) Tapetum, middle layers endothecium epidermis

 

9. Identify the incorrect pair

a) sporopollenin - exine of pollen grain

b) tapetum – nutritive tissue for developing microspores

c) Nucellus – nutritive tissue for developing embryo

d) obturator – directs the pollen tube into micropyle

 

10. Assertion : Sporopollenin preserves pollen in fossil deposits

Reason : Sporopollenin is resistant to physical and biological decomposition

a) assertion is true; reason is false

b) assertion is false; reason is true

c) Both Assertion and reason are not true

d) Both Assertion and reason are true.

 

11. Choose the correct statement(s) about tenuinucellate ovule

a) Sporogenous cell is hypodermal

b) Ovules have fairly large nucellus

c) sporogenous cell is epidermal

d) ovules have single layer of nucellus tissue 

 

12. Which of the following represent megagametophyte

a) Ovule

b)Embryo sac

c)Nucellus

d)Endosperm

 

13. In Haplopappus gracilis, number of chromosomes in cells of nucellus is 4. What will be the chromosome number in Primary endosperm cell?

a)8

b)12

c)6

d)2

 

14. Transmitting tissue is found in

a) Micropylar region of ovule

b) Pollen tube wall

c) Stylar region of gynoecium

d) Integument

 

15. The scar left by funiculus in the seed is

a) tegmen

b) radicle

c) epicotyl

d)hilum

 

17. A Plant called X possesses small flower with reduced perianth and versatile anther. The probable agent for pollination would be

a)water

b)air

c)butterflies

d)beetles

 

18. Consider the following statement(s)

i) In Protandrous flowers pistil matures earlier

ii) In Protogynous flowers pistil matures earlier

iii) Herkogamy is noticed in unisexual flowers

iv) Distyly is present in Primula

a) i and ii are correct

b) ii and iv are correct

c) ii and iii are correct

d) i and iv are correct

 

18. Coelorhiza is found in

a) Paddy

b) Bean

c) Pea

d) Tridax 

 

19. Parthenocarpic fruits lack

a) Endocarp

b) Epicarp

c) Mesocarp

d) seed

 

20. In majority of plants pollen is liberated at

a) 1 celled stage

b) 2 celled stage

c) 3 celled stage

d) 4 celled stage


Answer the following questions


21. What is reproduction?

Answer: (i) It is a process which helps an organism to perpetuate its own species.

(ii) It can be classified into a sexual and sexual reproduction.


22. Mention the contribution of Hofmeister towards Embryology.

Answer: In the year of 1848, Hofmeister described the structure of pollen tetrad.


23. List out two sub-aerial stem modifications with example.

Answer: (i) Runner - Centella asiatica

        (ii) Stolon - Fragaria and Mentha.


24. What is layering?

Answer:

(i) It is a conventional method of plant propagation.

(ii) The stem of a parent plant is allowed to develop roots while still intact.

(iii) When the root develops, the rooted part is cut and planted to grow as a new plant.

Example : Ixora and jasminum.


25. What are clones?

Answer: The individuals formed by asexual reproduction are morphologically and genetically identical and are called clones.


26. A detached leaf of Bryophyllum produces new plants. How?

Answer: Adventitious buds develop in notches in the leaf margins. These are epiphyllous buds, from which the new plants develop.


27. Differentiate Grafting and Layering.


Answer:

Grafting

1. Parts of two different plants are joined so that they continue to grow as one plant stock is in contact with the soil scion is the grafted part.

2. The plant will show characteristics of scion.

3. Ex. Citrus, Mango and Apple.

Layering

1. The stem of the parent plant is allowed to develop roots while still intact. When the root develops, rooted part is cut and planted to grow as new plant

2. Layering only results in propagation of parent plant.

Ex.  Ixora and Jasminum.


28. “Tissue culture is the best method for propagating rare and endangered plant species”- Discuss.

Answer: The growth of plant tissue in special culture medium under suitable controlled conditions is known as tissue culture.

Micropropagation:

(i) The regeneration of a whole plant from single cell, tissue or small pieces of vegetative structures through tissue culture is called micropropagation.

(ii) This is one of the modern methods used to propagate plants.

Advantages of modern methods:

(i) Plants with desired characteristics can be multiplied rapidly in a short duration.

(ii) Plants produced are genetically identical.

(iii) Tissue culture can be carried out in any season to produce plants.

(iv) Plants which do not produce viable seeds and seeds that are difficult to germinate can be propagated by tissue culture.

(v) Thus this method is ideal to propagate rare and endangered plants.

(vi) Disease free plants can be produced by meristem culture.


29. Distinguish mound layering and air layering.

Answer:


Mound Layering

1. The lower branch with leaves is bent to the ground and part of the stem is buried in the soil and tip of the branch is exposed above the soil.

2. This method is applicable for plants with flexible branches.

3. Hormones are not required to promote rooting

4. A cut is made in parent plant so that the buried part grow into a new plant after root formation.

Air Layering

1. The stem is girdled at nodal region and hormones are applied to this region which promotes rooting.

2. This method is applicable for all types of plants. (flexible and non - flexible branches)

3. Hormones are applied to promote rooting.

4. Branches are removed from the parent plant and grown in a separate pot or ground after root formation.


30. Explain the conventional methods adopted in vegetative propagation of higher plants.

Answer: Conventional methods:

The common methods of conventional propagation are cutting, grafting and layering.

(a) Cutting:

(i) It is the method of producing a newplant by cutting the plant parts such as root, stem and leaf from the parent plant. 

(ii) The cut part is placed in a suitable medium for growth.

(iii) It produces root and grows into a new plant. Depending upon the part used it is called as root cutting (Malus), stem cutting (Hibiscus, Bougainvillea and Moringa) and leaf cutting (Begonia, Bryophyllum).

(iv) Stem cutting is widely used for propagation.

(b) Grafting:

(i) In this, parts of two different plants are joined so that they continue to grow as one plant.

(ii) Of the two plants, the plant which is in contact with the soil is called stock and the plant used for grafting is called scion. Examples are Citrus, Mango and Apple. There are different types of grafting based on the method of uniting the scion and stock.

(iii) They are bud grafting, approach grafting, tongue grafting, crown grafting and wedge grafting.

(c) Layering:

(i) In this method, the stem of a parent plant is allowed to develop roots while still intact.

(ii) When the root develops, the rooted part is cut and planted to grow as a new plant. Examples: Ixora and Jasminum.

(iii) Mound layering and Air layering are few types of layering.


31. Highlight the milestones from the history of plant embryology.

Answer: 1682 - Nehemiah Grew mentioned stamens as the male organ of a flower.

1694 - R.J. Camerarius described the structure of a flower, anther, pollen and ovule.

1761 - J.G. Kolreuter gave a detailed account on the importance of insects in pollination.

1824 - G.B. Amici discovered the pollen tube.

1848 - Hofmeister described the structure of pollen tetrad.

1870 - Hanstein described the development of embryo in Capsella and Alisma

1878 - E.Strasburger reported polyembryony.

1884 - E. Strasburger discovered the process of Syngamy.

1898 - S.G. Nawaschin and L. Guignard independently discovered Double fertilization.

1904 - E. Hanning initiated embryo culture.

1950 - D. A. Johansen proposed classification for embryo development.

1964 - S. Guha and S.C. Maheswari raised haploids from Datura pollen grains.

1991 - E.S. Coen and E. M. Meyerowitz proposed the ABC model to describe the genetics of initiation and development of floral parts.

2015 - K.V. Krishnamurthy summarized the molecular aspects of pre and post fertilization reproductive development in flowering plants.


32. Discuss the importance of Modern methods in reproduction of plants.

Answer: Technology is being used for propagation to produce large number of plants in a short period of time. The methods are based on the property of Totipotency shown by plant cells. Modern methods such as tissue culture and micropropagation play a significant role in propagation of plants.

Advantages of modern methods:

(i) Plants with desired characteristics can be multiplied rapidly in a short duration.

(ii) Plants produced are genetically identical.

(iii) Tissue culture can be carried out in any season to produce plants.

(iv) Plants which do not produce viable seeds and seeds that are difficult to germinate can be propagated by tissue culture.

(v) Rare and endangered plants can be propagated. 

(vi) Disease free plants can be produced by meristem culture.

(vii) Cells can be genetically modified and transformed using tissue culture.

The methods also have some disadvantages like high cost, skilled labour undesirable genetic changes etc.


33. What is Cantharophily.

Answer: The cross pollination of flowers by beetles is called cantharophily. The beetles feed the pollen or on some of the juicy tissues of the flowers.


34. List any two strategy adopted by bisexual flowers to prevent self-pollination.

Answer: Dichogamy: In bisexual flowers anthers and stigmas mature at different times, thus checking self-pollination. It is of two types.

(1) Protandry:

The stamens mature earlier than the stigmas of the flowers.

Examples: Helianthus and Clerodendrum.

(2) Protogyny:

The stigmas mature earlier than the stamens of the flower.

Examples: Scrophularia nodosa and Aristolochia bracteata.

Self sterility/ Self- incompatibility:

In some plants, when the pollen grain of a flower reaches  the stigma of the same, it is unable to germinate or prevented to germinate on its own stigma.

Examples: Abutilon, Passiflora. It is a genetic mechanism.


35. What is endothelium.

Answer: (i) It is otherwise known as integumentary tapetum.

(ii) In some species the inner layer of integument may become specialized to perform nutritive function for the embryosac and is called endothelium.

Example: Asteraceae.


36. ‘The endosperm of angiosperm is different from gymnosperm’. Do you agree. Justify your answer.

Answer:


Endosperm of Angiosperm

1. It is formed ofter fertilization.

2. It is a triploid tissue.

3. The function is to nourish the developing embryo.

Endosperm of Gymnosperm

1. It is formed before fertilization.

2. It is a haploid tissue.

3. It acts as the female gametophyte and later acts as nutritive tissue.

Thus the endosperm tissue is different in Angiosperms and gymnosperm.


37. Define the term Diplospory.

Answer: A diploid embryo sac is formed from megaspore mother cell without a regular meiotic division.

Example: Eupatorium and Aerva. It is a type of apomixis.


38. What is polyembryony. How it can commercially exploited.

Answer: Occurrence of more than one embryo in a seed is called polyembryony.

(i) The seedlings formed from the nucellar tissue in Citrus are found better clones for Orchards.

(ii) Embryos derived through polyembryony are found virus free.


39. Why does the zygote divides only after the division of Primary endosperm cell.

Answer: (i) Zygote requires nourishment during its development.

(ii) As mature, fertilized embryo sac offers very little nourishment to the zygote, the primary endosperm cell (PEC) divides and generates the endosperm tissue which nourishes the zygote.

(iii) Hence the zygote always divides after division of PEC. 


40. What is Mellitophily?

Answer: Pollination of flowers by bees is known as mellitophily.


41. ‘Endothecium is associated with dehiscence of anther’ Justify the statement.

Answer: (i) Endothecium is a single layer of radially elongated cells below the epidermis of anther wall.

(ii) The inner tangential wall develops bands or thickenings of α cellulose.

(iii) In the cells along the junction of two sporangia, the thickenings are absent and this region is called stomium.

(iv) This along with the hygroscopic nature of endothecium helps in the dehiscence of anther at maturity.


42. List out the functions of tapetum.

Answer: (i) It supplies nutrition to the developing microspores.

(ii) It contributes sporopollenin through ubisch bodies thus plays an important role in pollen wall formation.

(iii) The pollenkitt material is contributed by tapetal cells and is later transferred to the pollen surface.

(iv) Exine proteins responsible for ‘rejection reaction’ of the stigma are present in the cavities of the exine. These proteins are derived from tapetal cells.


43. Write short note on Pollen kitt.

Answer: (i) It is a oily layer forming a thick viscous coating at the surface of the pollen.

(ii) The pollenkitt material is contributed by tapetal cells and made of carotenoids or flavonoids. (Orange or Yellow).

(iii) It attracts insects and protects damage from UV radiation.


44. Distinguish tenuinucellate and crassinucellate ovules.

Answer:


Tenuinucellate type

Sporogenous cell is hypodermal with a single layer of nucellar tissue around in the ovule.

Crassinucellate type

Ovules with subhypodermal sporogenous cell are described as crassinucellate.

Note: These two types of ovules are differentiated based on the position of the sporogenous cell.


45. ‘Pollination in Gymnosperms is different from Angiosperms’ – Give reasons.

Answer:


Gymnosperms – Pollination

1. Direct pollination is seen since pollen are directly deposited on the exposed ovules.

2. Pollination is by anemophilous mode.

Angiosperms – Pollination

1. Indirect pollination is seen since pollens are deposited on the stigma of the pistil.

2. Pollination can be self pollination or cross pollination by various agents like air, water, insects etc.


46. Write short note on Heterostyly.

Answer: It is a contrivance of cross pollenation. Some plants produce two or three different forms of flowers that are different in their length of stamens and style. Pollination will take place only between organs of the same length. (Figure)

(a) Distyly:

(i) The plant produces two forms of flowers, Pin or long style, long stigmatic papillae, short stamens and small pollen grains; Thrum-eyed or short style, small stigmatic papillae, long stamens and large pollen grains.

ExamplePrimula (Figure).

(ii) The stigma of the Thrum-eyed flowers and the anther of the pin lie in same level to bring out pollination.

(iii) Similarly the anther of Thrum-eyed and stigma of pin ones is found in same height. This helps in effective pollination.

(b) Tristyly:

(i) The plant produces three kinds of flowers, with respect to the length of the style and stamens.

(ii) Here, the pollen from flowers of one type can pollinate only the other two types but not their own type.

Example : Lythrum.


47. Enumerate the characteristic features of Entomophilous flowers

Answer: (i) Flowers are generally large or if small, they are aggregated in dense inflorescence.

Examples: Asteraceae flowers.

 (ii) Flowers are brightly coloured. The adjacent parts of the flowers may also be brightly coloured to attract insects.

Examples: Poinsettia and Bougainvillea the bracts become coloured.

(iii) Flowers are scented and produce nectar.

(iv) Flowers in which there is no secretion of nectar, the pollen is either consumed as food or used in building up of its hive by honey bees. Pollen and Nectar are the floral rewards for the visitors.

(v) Flowers pollinated by flies and beetles produce foul odour to attract insects.

(vi) In some flowers juicy cells are present which are pierced and the contents are sucked by the insects.


48. Discuss the steps involved in Microsporogenesis.

Answer: The stages involved in the formation of haploid microspores from diploid microspore mother cell through meiosis is called Microsporogenesis.

(i) The primary sporogeneous cells directly, or may undergo a few mitotic divisions to form sporogenous tissue.

(ii) The last generation of sporogenous tissue functions as microspore mother cells.

(iii) Each microspore mother cell divides meiotically to form a tetrad of four haploid microspores (microspore tetrad).

(iv) The microspore tetrad may be arranged in a tetrahedral, decussate, linear, T shaped or isobilateral manner.

(v) Microspores soon separate from one another and remain free in the anther locule and develop into pollen grains.

(vi) In some plants, all the microspores in a microsporangium remain held together called pollinium.

Example: Calotropis. Compound pollen grains are found in Drosera and Drymis.


49. With a suitable diagram explain the structure of an ovule.

Answer: (i) Ovule is also called megasporangium and is protected by one or two covering called integuments.

(ii) A mature ovule consists of a stalk and a body. The stalk or the funiculus is present at the base and it attaches the ovule to the placenta.

(iii) The point of attachment of funicle to the body of the ovule is known as hilum.

(iv) In an inverted ovule, the funicle is adnate to the body of the ovule forming a ridge called raphe.


(v) The body of the ovule is made up of a central mass of parenchymatous tissue called nucellus which has large reserve food materials.

(vi) The nucellus is enveloped by one or two protective coverings called integuments.

(vii) Integument encloses the nucellus completely except at the top where it is free and forms a pore called micropyle.

(viii) The ovule with one or two integuments are said to be unitegmic or bitegmic ovules respectively.

(ix) The basal region of the body of the ovule where the nucellus, the integument and the funicle meet or merge is called as chalaza.

(x) There is a large, oval, sac-like structure in the nucellus toward the micropylar end called embryo sac or female gametophyte.

(xi) It develops from the functional megaspore formed within the nucellus.

(xii) In some species (unitegmic tenuinucellate) the inner layer of the integument may become specialized to perform the nutritive function for the embryo sac and is called as endothelium or integumentary tapetum

Example: Asteraceae.

(xiii) There are two types of ovule based on the position of the sporogenous cell.

(a) If the sporogenous cell is hypodermal with a single layer of nucellar tissue around it is called tenuinucellate type. Normally tenuinucellate ovules have very small nucellus.

(b) Ovules with subhypodermal sporogenous cell is called crassinucellate type. These ovules have fairly large nucellus.

(xiv)  Group of cells found at the base of the ovule between the chalaza and embryo sac is called hypostase and the thick -walled cells found above the micropylar end above the embryo sac is called epistase.


50. Give a concise account on steps involved in fertilization of an angiosperm plant.

Answer: The fusion of male and female gamete is called fertilization.

Events of fertilization:

(i) Germination of pollen to form pollen tube in the stigma.

(ii) Growth of pollen tube in the style.

(iii) Direction of pollen tube towards micropyle of ovule.

(iv) Entry of the pollen tube into embryo sac.

(v) Discharge of male gametes.

(vi) Syngamy.

(vii) Triple fusion.

Germination of pollen on stigma:

(i) The events from pollen deposition on the stigma to entry of pollen tube into the ovule is called pollen pistil interaction. This involves recognition of pollen and promotion / inhibition of germination and growth.

(ii) If the pollen is compatible with the stigma it germinates to form a tube. This is facilitated by fluid in wet stigma and pellicle in dry stigma. The compatibility depends on recognition-rejection protein reaction between the pollen and stigma surface. All cytoplasmic contents move to the tip of pollen tube which is hemispherical and transparent. This is called cap block.

Growth of pollen tube in the style:

(i) The growth of the pollen tube through the style depends an the type of style.

(ii) Styles may be hollow; solid or semi-solid.

(iii) The style is lined internally by a single layer of glandular cells called Transmitting tissue.

(iv) This provides nourishment for the pollen tube and also controls the incompatibility between style and pollen tube.

Entry of pollen tube into the ovule:

The pollen tube enters the ovule through the micropyle (Porogamy) or chalaza (Chalazogamy) or integument (Mesogamy).

Entry of pollen tube into embryo sac:

(i) Pollen tube enters the embryo sac at the micropylar end only.

(ii) A structure known as the obturator guides the pollen tube towards micropyle of the ovule. 

(iii) After entering into the embryo sac, a pore is formed in the pollen tube wall behind the apex.

(iv) The content of the pollen tube (two male gametes, vegetative nucleus and cytoplasm) are discharged into the synergids into which pollen tube enters. The tube nucleus disorganizes.


Double fertilization and triple fusion:

(i) Both the male gametes are involved in fertilization.

(ii) The phenomenon is called double fertilization.

(iii) One male gametes fuses with the egg nucleus (syngamy) to form Zygote.

(iv)  The second male gamete fuses with the polar nuclei (secondary nucleus) to form primary endosperm nucleus.

(v) Since this involves fusion of three nuclei, the phenomenon is known as triple fusion. This results in formation of endosperm which is the nutritive tissue for the growing embryo.


51. What is endosperm. Explain the types.

Answer: The primary endosperm nucleus (PEN) divides immediately after fertilization into an endosperm. The primary endosperm nucleus is the result of triple fusion (two polar nuclei and one sperm nucleus) and thus has 3n number of chromosomes. It is a nutritive tissue and regulatory structure that nourishes the developing embryo.

I. Depending upon the mode of development, 3 types of endosperm are recognized in angiosperms. They are:

Nuclear endosperm:

(i) Primary endosperm nucleus (PEN) divides into two without any wall formation.

(ii) The subsequent division of these two nuclei are free nuclear so that the endosperm consists of only free nuclei and cytoplasm around them.

(iii) The nuclei may either remain free or may become separate by walls in later stages.

Example: Coccinia, Capsella and Arachis.

Cellular endosperm:

(i) The primary endosperm nucleus (PEN) divides into 2 nuclei which are immediately followed by a wall formation.

(ii) Subsequent divisions are also followed by walls.

Example: Adoxa, Helianthus and Scoparia.

Helobial endosperm:

(i) The primary endosperm nucleus (PEN) moves towards the base of the embryo sac and divides into two nuclei.

(ii) These 2 nuclei are separated by a wall to form a large micropylar chamber and a small chalazal chamber.

(iii) The nucleus of the micropylar chamber undergoes several free nuclear divisions whereas that of the chalazal chamber may or may not divide.

Example: Hydrilla and Vallisneria.

II. Endospermous and Non-endospermous seeds:

The endosperms may either be completely consumed by the developing embryo or it may persist in the mature seeds.

(i) Those seeds without endosperms are called non- endospermous or ex- albuminous seeds. Examples: Pea, Groundnut and Beans.

(ii) Those seeds with endosperms are called endospermous or albuminous seeds. The endosperms in these seeds supply nutrition to the embryo during seed germination. Example: Paddy, Coconut and Castor.

III. Ruminate endosperm:

The endosperm with irregularity and unevenness in its surface forms ruminate endosperm.

Example: Areca catechu.


52. Differentiate the structure of Dicot and Monocot seed.

Answer:


Dicot seed

1. The seed developed from the ovule is found inside the fruit.

2. The seed coat is distinct from the fruit coat or pericarp

3. The seed encloses two cotyledons.

4. The seed coat is differentiated into outer testa and inner tegma.

5. The seeds may or may not possess endosperm. They are known respectively as the endospermic or non-endospermic seeds.

6. The two cotyledons enclose the embryonic axis in between them.

7. In the endospermic seed the endosperm encloses the embryo.

8. The embryonic Root and shoot are not covered by sheaths.

9. Cotyledons store food material, in non-endospermous seeds. In castor the endosperm stores food material, so cotyledons are thin.

Monocot seed

1. The seed known as the grain is represented by the single seeded fruit known as caryopsis.

2. The seed coat is fused with the pericarp.

3. The seed encloses only a single cotyledon which is known as the scutellum.

4. The seed coat is unilayered and is inseparable from the pericarp.

5. Most of the monocot members possess endospermic seeds.

6. The embryo is found in the cotyledon.

7. The endosperm is found above the embryo. The endosperm and the embryo are separated by the epithelium.

8. The radicle is protected by a sheath called coleorhiza and plumule is protected by coleoptile.

9. The scutellum supplies the growing embryo with food material absorbed from endosperm with help of epithelium.


53. Give a detailed account on parthenocarpy. Add a note on its significance.

Answer: Parthenocarpy:

(i) Fruit like structures may develop from the ovary without the act of fertilization. Such fruits are called parthenocarpic fruits.

(ii) Many commercial fruits are made seedless.

Example: Banana, Grapes and Papaya.

(iii) Nitsch in 1963 classified parthenocarpy into following types:

(a) Genetic parthenocarpy:

Parthenocarpy arises due to hybridization or mutation.

Example: Citrus and Cucurbita.

(b) Environmental parthenocarpy: Environmental conditions like frost, fog, low temperature, high temperature etc., induce parthenocarpy. For example, low temperature for 3-19 hours induces parthenocarpy in Pear.

(c) Chemically induced parthenocarpy: Application of growth promoting substances like Auxins and Gibberellins induces parthenocarpy.

Significance:

(i) The seedless fruits have great significance in horticulture.

(ii) The seedless fruits have great commercial importance.

(iii) Seedless fruits are useful for the preparation of jams, jellies, sauces, fruit drinks etc.

(iv)  High proportion of edible part is available in parthenocarpic fruits due to the absence of seeds.


Glossary

Apospory: The process of embryo sac formation from diploid cells of nucellus as a result of mitosis

Budding: A method of asexual reproduction where small outgrowth(Bud) from a parent cell are produced

Callus: Undifferentiated mass of cells obtained through tissue culture.

Clone: Genetically identical individuals.

Endothecium: A single layer of hygroscopic, radially elongated cells found below the epidermis of anther which helps in dehiscence of anther.

Fertilization: The act of fusion of male and female gamete

Grafting: Conventional method of reproduction where stock and scion are joined to produce new plant.

Horticulture: Branch of plant science that deals with the art of growing fruits, vegetables, flowers and ornamental plants.

Nucellus: The diploid tissue found on the inner part of ovule next to the integuments.

Pollenkitt: A sticky covering found on the surface of the pollen that helps to attract insects.

Regeneration: Ability of organisms to replace or restore the lost parts.

Sporopollenin: Pollen wall material derived from carotenoids and is resistant to physical and biological decomposition.

Tapetum: Nutritive tissue for the developing sporogenous tissue

Transmitting tissue: A single layer of glandular canal cells lining the inner part of style.

Tags : Important Questions and choose the correct answer - Botany , 12th Botany : Chapter 1 : Asexual and Sexual Reproduction in Plants
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12th Botany : Chapter 1 : Asexual and Sexual Reproduction in Plants : Reproduction in Plants: Evaluation | Important Questions and choose the correct answer - Botany

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12th Botany : Chapter 1 : Asexual and Sexual Reproduction in Plants


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