Plant Development and Morphogenesis Questions and Answers

Q: What do you understand by 'Chiropterophily' ?

Chiropterophily means pollination by bats.The word comes from Chiroptera, the order of bats, and -phily, 'love of'. Bat-pollinated flowers usually open at night, are large and pale, have a strong musty smell and produce plenty of nectar, as in Kigelia, baobab and some bananas.Pollination by insects is entomophily, by snails malacophily, and by air (wind) anemophily.Other pollination terms follow the same pattern: ornithophily is pollination by birds, hydrophily by water, and zoophily is the general term for pollination by animals.

Q: Female reproductive part of a flower is

The female reproductive part of a flower is the gynoecium.The gynoecium is made up of one or more carpels (pistils), each with stigma, style and ovary; the ovules inside the ovary develop into seeds after fertilisation.The stamens form the androecium, the male part, and produce pollen grains, which carry the male gametes. The endosperm is the nutritive tissue of the seed formed after fertilisation, not a part of the flower.

Q: The role of double fertilization in angiosperms is to produce :

Double fertilization produces the endosperm.In angiosperms one male gamete fuses with the egg to form the diploid zygote, which develops into the embryo, while the second fuses with the two polar nuclei (or the secondary nucleus) of the central cell. That triple fusion gives the triploid primary endosperm nucleus, from which the endosperm, the food store for the developing embryo, grows.Cotyledons are part of the embryo, formed from the zygote. The mesocarp and endocarp are layers of the fruit wall, which develops from the ovary wall without any fertilization event of its own.

Q: In viviparous plants, the seeds have :

In viviparous plants the seeds have no dormancy period.Vivipary is the germination of seeds while still attached to the parent plant. It is typical of mangroves such as Rhizophora, whose seedlings grow a long hypocotyl on the tree and then drop into the mud, ready to root before the tide carries them away. Because germination follows directly on maturation, there is no resting period.Longer dormancy is the opposite of vivipary. Viability is not the defining feature: viviparous seeds are viable but cannot be stored, so neither 'low viability' nor 'high viability' describes what makes them viviparous.

Q: In Cucurbitaceae, during fertilization entry of the pollen tube occurs through integuments. This type of fertilization is referred as :

Entry of the pollen tube through the integuments is mesogamy.The route of the pollen tube into the ovule is classified into three types. In porogamy, the common type, it enters through the micropyle. In chalazogamy, first described in Casuarina, it enters through the chalaza. In mesogamy it enters through the middle of the ovule, through the integuments (as in Cucurbita) or the funicle (as in Pistacia).Isogamy is not a route of pollen tube entry at all. It is the fusion of gametes that look alike, as in some algae.

Q: For direct shoot regeneration from leaf explants, requirement of growth hormones will be :

The key gives Auxin : Kinetin (1 : 2), a ratio in which cytokinin exceeds auxin.Skoog and Miller's tobacco work (1957) showed that the ratio of the two hormones steers the fate of cultured tissue: a high cytokinin to auxin ratio favours shoots, a high auxin to cytokinin ratio favours roots, and a balanced ratio favours callus. Direct shoot regeneration from a leaf explant, with no callus stage, is therefore taught as needing more cytokinin than auxin, which is option D.Auxin alone (1 : 0) favours roots or callus, not shoots. Equal amounts (1 : 1) give callus, the usual textbook result. The choice B (0 : 1, cytokinin alone) is the one a reader might defend, since some species do form shoots on cytokinin alone; but the question asks for the general requirement and a ratio rule needs both hormones present, so we keep the key. The rule is a general tendency and the best ratio depends on species and explant, so the question is a recall of the textbook ratio and nothing more.

Q: Nucellar polyembryony is common in species of :

Nucellar polyembryony is common in Citrus.In Citrus, cells of the nucellus around the embryo sac divide and grow into extra embryos, alongside the zygotic one. These nucellar embryos are genetically identical to the mother plant, which is why citrus seedlings raised from seed come true to type and are used as uniform rootstocks. Mango is another well-known example.Citronella, Croton and Crotalaria (printed Crotallaria) are not known for nucellar polyembryony; they are the near-name distractors.

Q: In tender coconut, initially the endosperm is :

In tender coconut the endosperm is initially free nuclear.Coconut has free-nuclear endosperm: the primary endosperm nucleus divides repeatedly without cell walls, giving thousands of free nuclei suspended in fluid. This is the coconut water of a tender nut. Later, cell walls form from the periphery inwards, producing the cellular white kernel, while the centre stays liquid.So the endosperm becomes partly cellular only later. Helobial endosperm, where the first division gives two unequal chambers, is typical of monocots such as the Alismatales, not of coconut.

Q: Female gametophyte in Gnetum at later stage is :

At a later stage, the female gametophyte of Gnetum is multinucleate.In Gnetum the functional megaspore undergoes repeated free-nuclear divisions, giving a large female gametophyte with many free nuclei and no archegonia. At the time of fertilisation the micropylar part is still free-nuclear and its nuclei act as eggs; the chalazal part becomes cellular, but the gametophyte as a whole remains a multinucleate structure.It never stays uninucleate or binucleate. The eight-nucleate gametophyte is the Polygonum-type embryo sac of flowering plants, not that of Gnetum.

Q: The term anthesis refers to :

Anthesis is the opening of a flower.Anthesis is the period when a flower is fully open and functional, with the anthers shedding pollen and the stigma receptive. The time of anthesis matters to plant breeders, who must emasculate or pollinate flowers at the right stage.Formation of the anther and development of the flower happen before anthesis, and dehiscence of the anther is the splitting that releases pollen, which usually occurs at anthesis but is a separate term.

11.

What do you understand by 'Chiropterophily' ?

A.Pollination by insects
B.Pollination by snails
C.Pollination by air
D.Pollination by bats

Exam Year(s)

MPPSC Forest Service - 2022,

Answer: D

Chiropterophily means pollination by bats.

The word comes from Chiroptera, the order of bats, and -phily, 'love of'. Bat-pollinated flowers usually open at night, are large and pale, have a strong musty smell and produce plenty of nectar, as in Kigelia, baobab and some bananas.

Pollination by insects is entomophily, by snails malacophily, and by air (wind) anemophily.

Other pollination terms follow the same pattern: ornithophily is pollination by birds, hydrophily by water, and zoophily is the general term for pollination by animals.

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12.

Female reproductive part of a flower is

A.Stamen
B.Pollengrain
C.Endosperm
D.Gynoecium

Exam Year(s)

MPPSC Forest Service - 2024,

Answer: D

The female reproductive part of a flower is the gynoecium.

The gynoecium is made up of one or more carpels (pistils), each with stigma, style and ovary; the ovules inside the ovary develop into seeds after fertilisation.

The stamens form the androecium, the male part, and produce pollen grains, which carry the male gametes. The endosperm is the nutritive tissue of the seed formed after fertilisation, not a part of the flower.

Discuss in Forum

13.

The role of double fertilization in angiosperms is to produce :

A.Cotyledons
B.Mesocarp
C.Endosperm
D.Endocarp

Exam Year(s)

MH SET - 2018, SET Exam - 2018,

Answer: C

Double fertilization produces the endosperm.

In angiosperms one male gamete fuses with the egg to form the diploid zygote, which develops into the embryo, while the second fuses with the two polar nuclei (or the secondary nucleus) of the central cell. That triple fusion gives the triploid primary endosperm nucleus, from which the endosperm, the food store for the developing embryo, grows.

Cotyledons are part of the embryo, formed from the zygote. The mesocarp and endocarp are layers of the fruit wall, which develops from the ovary wall without any fertilization event of its own.

Discuss in Forum

14.

In viviparous plants, the seeds have :

A.Longer dormancy period
B.No dormancy period
C.Low viability
D.High viability

Exam Year(s)

MH SET - 2018, SET Exam - 2018,

Answer: B

In viviparous plants the seeds have no dormancy period.

Vivipary is the germination of seeds while still attached to the parent plant. It is typical of mangroves such as Rhizophora, whose seedlings grow a long hypocotyl on the tree and then drop into the mud, ready to root before the tide carries them away. Because germination follows directly on maturation, there is no resting period.

Longer dormancy is the opposite of vivipary. Viability is not the defining feature: viviparous seeds are viable but cannot be stored, so neither 'low viability' nor 'high viability' describes what makes them viviparous.

Discuss in Forum

15.

In Cucurbitaceae, during fertilization entry of the pollen tube occurs through integuments. This type of fertilization is referred as :

A.Porogamy
B.Mesogamy
C.Chalazogamy
D.Isogamy

Exam Year(s)

MH SET - 2018, SET Exam - 2018,

Answer: B

Entry of the pollen tube through the integuments is mesogamy.

The route of the pollen tube into the ovule is classified into three types. In porogamy, the common type, it enters through the micropyle. In chalazogamy, first described in Casuarina, it enters through the chalaza. In mesogamy it enters through the middle of the ovule, through the integuments (as in Cucurbita) or the funicle (as in Pistacia).

Isogamy is not a route of pollen tube entry at all. It is the fusion of gametes that look alike, as in some algae.

Discuss in Forum

16.

For direct shoot regeneration from leaf explants, requirement of growth hormones will be :

A.Auxin : Kinetin (1 : 0)
B.Auxin : Kinetin (0 : 1)
C.Auxin : Kinetin (1 : 1)
D.Auxin : Kinetin (1 : 2)

Exam Year(s)

MH SET - 2018, SET Exam - 2018,

Answer: D

The key gives Auxin : Kinetin (1 : 2), a ratio in which cytokinin exceeds auxin.

Skoog and Miller's tobacco work (1957) showed that the ratio of the two hormones steers the fate of cultured tissue: a high cytokinin to auxin ratio favours shoots, a high auxin to cytokinin ratio favours roots, and a balanced ratio favours callus. Direct shoot regeneration from a leaf explant, with no callus stage, is therefore taught as needing more cytokinin than auxin, which is option D.

Auxin alone (1 : 0) favours roots or callus, not shoots. Equal amounts (1 : 1) give callus, the usual textbook result. The choice B (0 : 1, cytokinin alone) is the one a reader might defend, since some species do form shoots on cytokinin alone; but the question asks for the general requirement and a ratio rule needs both hormones present, so we keep the key. The rule is a general tendency and the best ratio depends on species and explant, so the question is a recall of the textbook ratio and nothing more.

Discuss in Forum

17.

Nucellar polyembryony is common in species of :

A.Citrus
B.Citronella
C.Croton
D.Crotallaria

Exam Year(s)

MH SET - 2019, SET Exam - 2019,

Answer: A

Nucellar polyembryony is common in Citrus.

In Citrus, cells of the nucellus around the embryo sac divide and grow into extra embryos, alongside the zygotic one. These nucellar embryos are genetically identical to the mother plant, which is why citrus seedlings raised from seed come true to type and are used as uniform rootstocks. Mango is another well-known example.

Citronella, Croton and Crotalaria (printed Crotallaria) are not known for nucellar polyembryony; they are the near-name distractors.

Discuss in Forum

18.

In tender coconut, initially the endosperm is :

A.Free nuclear
B.Cellular
C.Helobial
D.Both cellular and helobial

Exam Year(s)

MH SET - 2019, SET Exam - 2019,

Answer: A

In tender coconut the endosperm is initially free nuclear.

Coconut has free-nuclear endosperm: the primary endosperm nucleus divides repeatedly without cell walls, giving thousands of free nuclei suspended in fluid. This is the coconut water of a tender nut. Later, cell walls form from the periphery inwards, producing the cellular white kernel, while the centre stays liquid.

So the endosperm becomes partly cellular only later. Helobial endosperm, where the first division gives two unequal chambers, is typical of monocots such as the Alismatales, not of coconut.

Discuss in Forum

19.

Female gametophyte in Gnetum at later stage is :

A.Uninucleate
B.Binucleate
C.Eight nucleate
D.Multinucleate

Exam Year(s)

MH SET - 2019, SET Exam - 2019,

Answer: D

At a later stage, the female gametophyte of Gnetum is multinucleate.

In Gnetum the functional megaspore undergoes repeated free-nuclear divisions, giving a large female gametophyte with many free nuclei and no archegonia. At the time of fertilisation the micropylar part is still free-nuclear and its nuclei act as eggs; the chalazal part becomes cellular, but the gametophyte as a whole remains a multinucleate structure.

It never stays uninucleate or binucleate. The eight-nucleate gametophyte is the Polygonum-type embryo sac of flowering plants, not that of Gnetum.

Discuss in Forum

20.

The term anthesis refers to :

A.Formation of an anther
B.Opening of a flower
C.Development of flower
D.Dehiscence of anther

Exam Year(s)

MH SET - 2019, SET Exam - 2019,

Answer: B

Anthesis is the opening of a flower.

Anthesis is the period when a flower is fully open and functional, with the anthers shedding pollen and the stigma receptive. The time of anthesis matters to plant breeders, who must emasculate or pollinate flowers at the right stage.

Formation of the anther and development of the flower happen before anthesis, and dehiscence of the anther is the splitting that releases pollen, which usually occurs at anthesis but is a separate term.

Plant Development and Morphogenesis Questions and Answers

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