Ch 2. Sexual Reproduction in Flowering Plants Flashcards
Name the two end products of sexual reproduction in flowering plants.
Fruits and seeds
What is floriculture?
a discipline of horticulture concerned with the cultivation of flowering plants
Which part of plants is a morphological and embryological marvel to biologists?
Flowers.
Define flower
the specialized part of the shoot found in angiosperms for sexual reproduction.
How many thecae are present in a typical mature anther of angiosperm?
Two thecae
What is a dithecous anther?
An anther with two thecae
How many microsporangia are present in a typical dithecous anther?
Four microsporangia
Write the number of microsporangia in each lobe of an anther.
Two sporangia
Name the innermost wall of microsporangium.
Tapetum
Mention the function of tapetum.
Nourishment of microspores
What is sporogenous tissue?
It is a group of compactly arranged homogenous cells present in the centre of microsporangium of a young anther.
Define microsporogenesis.
The process of formation of haploid microspores from diploid pollen mother cells by meiosis.
Which tissue of microsporangium produces microspores?
Sporogenous tissue.
Name the type of cell division that microspore mother cells undergo
Meiosis
How many microspores are produced from 450 pollen mother cells?
1800 microspores
Which phase of life cycle is represented by pollen grains
Pollen grains represent gametophytic phase.
Name the outer layer of pollen grains? What is it made of?
Outermost layer of pollen grain is exine. It is made of a protein called sporopollenin
What are germ pores?
Germ pores are the openings in the exine, that is the outermost layer of the pollen grain where sporopollenin is absent.
What is intine made up of? (What is the composition of intine)?
Intine is made up of pectin and cellulose.
Name the large and small cells of a pollen grain.
Vegetative or tube cell is large cell while generative cell is the small cell.
Pollen grains are well preserved as fossils. Why?
Pollen grains are well preserved as fossils because of sporopollenin. It is a resistant organic material and can withstand high temperature, acids, alkali, moreover has not been degraded by any enzymes known so far.
How many cells are present in a matured male gametophyte of angiosperms?
three haploid cells.
Which cell of a pollen grain produces pollen tube?
Vegetative cell of a pollen grain
Name the solution used in germination in laboratory.
sucrose solution containing 0.01% boric acid
Give an example of a plant known to cause pollen allergy.
Carrot grass or Parthenium.
How are pollen grains preserved?
Pollen grains are preserved in liquid nitrogen at - 196 °C.
Which external factor play a role in determining pollen viability?
Temperature and humidity.
Name the members of pistil
Carpels
What is syncarpous pistil? Mention one example.
When more than one pistils are fused together it is called syncarpous.
Example: Papaver
What is apocarpous pistil? Mention one example.
When more than one pistils are present and are free is called apocarpous pistil.
Example. Michelia
Name the megasporophyll in flowering plants.
Pistil
Which part of the pistil is called megasporangium?
Ovule
Name the cell in the gynoecium of a flower that undergoes meiosis.
Megaspore mother cell undergoes meiosis, in gynoecium.
What is monosporic development of embryo sac?
The Development of a functional megaspore into embryo sac out of four megasporcs
What is micropyle?
A small opening, uncovered by integuments in an ovule
Name the stalk of the ovule in angiosperms
Funicle
What is hilum
The point of contact (attachment) of the ovule body to funicle
What is nucellus?
A mass of cells enclosed by the integuments of an ovule
Nuclear divisions in functional megaspore not followed immediately by cell wall formation is called ___________ ____________ _____________
free nuclear division
Name the cells present at the micropylar end in the embryosac.
Synergids and a egg
Mention the function of filiform apparatus.
plays an important role in guiding the pollen tubes into the synergid.
Mention the number of nucleii found in a typical mature angiosperm embryosac
8 haploid nucleii.
How many cells are present in the matured embryo sac of angiosperms.
7 haploid cells
Name the female gametophyte of an angiosperm plant.
‘Embryosac’
Define pollination.
the process of transfer of the pollen grains from the anther to the stigma of a flower with the help of pollinating agents like wind, water, insects, birds etc.
The distribution of bryophytes and pteridophytes is limjted closer to aquatic/ wet habitats. Why?
Transfer of male gametes to the female gametangia requires water. Hence sexual reproduction cam occur in the absence of aquatic medium. Therefore bryophytes and pteridophytes are limited to aqua habitats.
Transfer of pollen grains from the anther to the stigma of the same flower is called ________________
autogamy
Flowers with exposed anthers and stigma are called ___________
chasmogamous
Define geitonogamy
Transfer of pollen grains from the anther to the stigma of another flower of the same plant.
Geitonogamy is genetically autogamy. Why?
Although geitonogamy is cross pollination functionally, it is genetically self pollination because the pollen grains and pistils belong to the same plant
cross-pollination in which pollen grains from the anther on one flower are transferred to the stigma of flowers on a different plant is called ___________
xenogamy
Pollination by water is called hydrophily is called __________
hydrophily
How are pollen grains protected from wetting in water pollinated species?
by mucilaginous covering.
Mention one important feature of insect pollinated flower.
Brightly coloured, showy, large sized with nectar.
Give an example for a plant that gives floral reward by providing safe place to lay insect eggs.
Amorphophallus flower.
Wind and water pollinated flowers produce enormous amount of pollen when compared to the number of ovules available for pollination. Why?
Pollen grains coming in contact with stigma is a chance factor in both wind and water pollinated flowers. To compensate for these uncertainities and associated loss of pollen grains, the flowers produce enormous amount of pollen.
Name the plant which is known to produce the ta11est flower
Amorphophallus.
Some insects are called ‘pollen robbers’ or nectar robbers. Why?
they consume pollen or nectar without bringing about pollination
Mention one strategy developed by plants to prevent self-pollination.
- Dioecy-male and female plants are separate Eg. Papaya
- Non-synchronised release of pollen grains to the maturity of pistil.
What is self incompatibility?
A genetic mechanism that prevent pollen grains from the same flower or different flower on the sat plant from fertilizing the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
Why are emasculated flowers are covered with bags or butter paper?
To prevent contamination of its stigma with unwanted pollen, an emasculated flower is covered with bags, or butter paper.
What is double fertilization?
Double fertilisation is the process of fusion in angiosperms in which one male gamete fuses with the egg nucleus to form the diploid zygote and another male gamete fuses with the polar nuclei or secondary nucleus to form the triploid primary endosperm nucleus (PEN).
What is triple fusion?
Triple fusion is defined as the fusion taking place between two polar nuclei and the nucleus of one of the male gametes during double fertilization in angiosperms giving rise to a triploid nucleus known as the Primary Endosperm Nucleus (PEN).
What does ‘PEN’ stand for with respect to fertilization in plants?
PEN stands for “Primary Endosperm Nucleus
What does primary endosperm nucleus develop into?
The Primary Endosperm Nucleus, by repeated divisions develops into the endosperm tissue which provides nutrition to the embryo.
Define false fruit? Give an example.
A fruit that develops from the thalamus or any other part of the flower besides the ovary is called a false fruit. E.g., Apple, cashew, strawberry, etc.
What are parthenocarpic fruits? Give examples.
Seedless fruits that develop from the ovary of the flowers without fertilization or from unfertilized ovules are called parthenocarpic fruits.
What is embryogeny?
The early stages of embryo development
the fertilized ovule is called _______
seed
Mention one difference between albuminous and exalbuninous seeds.
Albuminous seeds have residual endosperm even after maturation of embryo whereas endosperm is completely consumed by the embryo and hence it is absent in matured seeds called exalbuninous.
Define a true fruit.
Fruit that develops from the ovary is called a true fruit.
How is parthenocarpy induced?
Parthenocarpy is induced through the application of growth hormones
What is polyembryony?
Occurrence of more than one embryo in a seed
