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Biology > Sexual Reproduction in Flowering Plants > Flashcards

Sexual Reproduction in Flowering Plants Flashcards

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1
Q

Structure of typical anther

A
  • A typical anther has two anther lobes
  • Each anther has two pollen chambers (microsporangia) which has many microspores
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2
Q

Epidermis in anther- structure + function

A

It is the outermost layer in a mature anther and is composed of tangentially stretched cells
The cells are tangentially stretched so that at the time of maturation, the anther can rupture easily and release pollen grains

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3
Q

Endothecium (anther)- structure + function

A

It is the second layer of the mature anther and is composed of columnar cells with fibrous thickened bands
They are fibrous for elasticity and thickened for protection

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4
Q

Middle layers of the anther

A

Third layer of a mature anther and they degenerate before pollen mother cells undergo meiosis

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5
Q

Tapetum- structure + function

A

The tapetum is the 4th and innermost layer of a mature anther

It is composed of cytoplasmic cells which are multinucleate
Serves as nutritive tissue for pollen mother cells and microspores/pollen grains/male gametophyte

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6
Q

Microsporogenesis

A

Formation of microspores from sporogenous tissue.

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7
Q

Name the two walls of the pollen grain

A

Exine and intine

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8
Q

Exine- structure

A

Composed of sporopollenin- oxidative polymer of carotenoid esters. Hardest substance seen in a plant
* Resistant to physical and biological decomposition
* Checks the natural decay of pollen

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9
Q

Give reason why the exine is resistant to heat and acid

A

It is composed of sporopollenin, which is the hardest substance seen in a plant, making the exine resistant to physical and biological decomposition/ heat and acid

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10
Q

Intine- structure + function

A

Structure: Inner layer that is composed of pectin and cellulose
Function: Gives rise to pollen tube at the time of pollen germination

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11
Q

Which two cells does a pollen grain divide into?

A
  1. A larger vegetative cell
  2. And a smaller generative cell which divides mitotically to form 2 non-motile male gametes
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12
Q

Pollination- definition

A

Transger of pollen grains from the anther to the stigma of a flower is called pollination

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13
Q

Self pollination- definition

A

Transfer of pollens from the anther of a flower to the stigma of the same flower (bisexual) (autogamy) or another flower of the same plant (geitonogamy).

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14
Q

Adaptation/contrivances for self pollination

A

Homogamy- Anthers and stigma mature at the same time
Chasmogamous flowers- Flowers with exposed anthers and stigma
Cleistogamous flowers- Completely closed flowers

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15
Q

Cross pollination- definition

A

Transfer of pollens from the anther of a flower to the stigma of another flower of another plant of the same species (allogamy/xenogamy)

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16
Q

Adaptation/contrivances for cross pollination

A
  • Self sterility- Pollens of flowers do not grow or grow slowly
  • Dichogamy- Maturation of pollens and stigma of a flower at different times
  • Herkogamy- In some bisexual flowers, the style is longer than the stamens. Pollens fail to reach the stigma
  • Heterostyly- In dimorphic flowers, the styles are of different lengths (long styled flowers and short styled flowers)
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17
Q

What is the nucellus

A

Parenchymatous body of the ovule/mega sporangium

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18
Q

What are integuments

A

Sheaths that cover the nucellus of the ovule

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19
Q

What is the micropyle

A

Small opening at one end of the ovule that facilitates the entry of the pollen tube

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20
Q

What is the funicle

A

The stalk that attaches the ovule to the placenta

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21
Q

What is the chalaza

A

The basal part of the ovule where the nucellus, integuments and funicle merge

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22
Q

Megasporogenesis

A

Development of megaspore within the ovule is called Megasporogenesis

23
Q

Functions of Antipodal cells

A
  1. They nourish the embryo sac
  2. growth and nourishment of the endosperm
24
Q

Functions of Synergid cells

A
  1. It helps in guiding the pollen tube towards the ovule
  2. It releases substances that stop the growth of the pollen tube and help in the release of male gametes from the pollen tube
25
Q

Types of entry of pollen tube (Name)

A
  1. Porogamy
  2. Chalazogamy
  3. Mesogamy
26
Q

Porogamy

A

When the pollen tube wnters through the micropyle, it is the most common type of entry of pollen tube

27
Q

Chalazogamy

A

Entry of pollen tube from the chalazal end.
E.g. plants like Casuarina

28
Q

Mesogamy

A

Entry of pollen tube through integuments
E.g. plants like Cucurbita

29
Q

Syngamy

A

Fusion of gametes is called Syngamy

30
Q

Fertilization

A

Fusion of male and female gametes is called fertilization

31
Q

Triple fusion/Double fertilization

A

In angiosperms, one of the male gametes fuses with the egg cell to form the zygote (2n) and the other fuses with the diploid polar nuclei forming the endosperm (3n). This is known as triple fusion or double fertilization

32
Q

Who discovered triple fusion/double fertilization

A

S.G. Nawaschin

33
Q

What is the endosperm?

A
  • Endosperm (triploid nucleus) is a nutritive tissue formed by 3 halploid nuclei, 2 from the female gametophyte and one from the male gametophyte.
  • It provides nourishment to the growing embryo
34
Q

Nuclear endosperm

A
  • Seen in polypetalous dicots
  • Nucleus division is not followed by wall formation
  • Nuclei formed remain free in the embryo sac
  • Watery endosperm of coconut contains growth promoting coconut milk factor Used as nutrient medium in culture experiments
  • E.g. coconut
35
Q

Cellular endosperm

A
  • Seen in gamopetalous dicots
  • Wall formation begins along with first division of nucleus, transversely.
  • Subsequent divisions are irregular
36
Q

Helobial endosperm

A
  • Seen in members of order- Helobiales of monocots
  • Nucleus division is accompanied by wall formation
  • This is followed by free nuclear and wall divisions
37
Q

Is it n, 2n, 3n-
1. Vegetative parts of a plant
2. Endosperm
3. Antipodal cell, synergid cell, egg cell, male gamete
4. Nucellus

A
  1. Vegetative parts of a plant- DIPLOID (2n)
  2. Endosperm- TRIPLOID (3n)
  3. Antipodal cell, synergid cell, egg cell, male gamete- HAPLOID (n)
  4. Nucellus- DIPLOID (2n)
38
Q

Embryogenesis

A

Development of mature embryo from diploid zygote is called embryogenesis

39
Q

Fate of the ovary

A

fruit

40
Q

Fate of the ovary wall

A

pericarp

41
Q

Fate of the ovule

A

seed

42
Q

Fate of the funicle

A

stalk of seed

43
Q

Fate of the nucellus

A

perisperm

44
Q

Fate of the integuments

A

seed coat

45
Q

Fate of the egg cell

A

embryo

46
Q

Fate of the secondary nucleus

A

endosperm

47
Q

Define fruit

A

Fruit is a ripened ovary

48
Q

True fruit

A

When a fruit develops exclusively from the ovary
E.g. Mango

49
Q

False fruit

A

When other parts like tepals or thalamus take part in the formation of a fruit in addition to the ovary
E.g. Apple (fleshy thalamus)

50
Q

Parthenocarpy

A

Development of fruits without fertilisation

51
Q

Polyembryony

A

The condition where more than one embryo are present in the seed

52
Q

Apomixis

A

Substitution of sexual process by asexual methods

53
Q

Albuminous seeds

A

Endosperm persists to nourish the young seedling
E.g. Dicot: Castor, Custard apple
Monocot- Cereals, pulses

54
Q

Exalbuminous seeds

A

Non-endospermic, cotyledons store food for nourishment
Dicot- Pea, bean, mango
Monocot- Orchids, Vallisneria

Biology (31 decks)

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