reproduction in plants

Question 1

types of reproduction

Answer 1

asexual and sexual reproduction

Question 2

what is asexual reproduction?

Answer 2

process which only involves one parent and does does not involve fusion of gametes. daughter cell is genetically identical to parent cell (same amount and type of genes)

Question 3

what is sexual reproduction?

Answer 3

the fusion of nuclei of two gametes to form a zygote and produce a genetically dissimilar offspring

Question 4

what is fertilisation in plants?

Answer 4

it is the fusion of male nucleus found in the pollen grain and female nucleus found in the ovule to form a zygote

Question 5

what is pollination?

Answer 5

it is the transfer of pollen grains from the anther to the stigma

Question 6

what are the parts of the flower?

Answer 6

sepal, petal, receptacle, pedicel

Question 7

what is the sepal?

Answer 7

modified leaves to protect the other parts of flower at the bud stage. all sepals tgt make up the calyx

Question 8

what is the petal?

Answer 8

modified leaves. insect-pollinated plants: brightly coloured and act as a landing platform. all petals make up the corolla

Question 9

what is the receptacle?

Answer 9

enlarged end of the flower stalk

Question 10

what is the pedicel?

Answer 10

flower stalk

Question 11

what is the stamen?

Answer 11

it is the anther and filament

Question 12

what is the anther?

Answer 12

it has two lobes, each lobe contains pollen sacs which has pollen grains. anthers produce pollen grains, when they are mature they will split open to release pollen grains. it also contains a vascular bundle of a phloem and a xylem

Question 13

what is the filament?

Answer 13

stalk that holds the anther in a suitable position to disperse pollen grains

Question 14

what do the pollen grains contain?

Answer 14

male gametes. each pollen grains contains 2 nuclei, pollen tube nucleus and generative nucleus

Question 15

what is the style?

Answer 15

stalk that connects the stigma to the ovary, holds the stigma in a suitable position for it to trap pollen grains

Question 16

what is the stigma?

Answer 16

it is the swollen structure at the end of the style that receives pollen grains. when it matures, it secretes sugary fluid which stimulates pollen grains to germinate

Question 17

what is the ovary?

Answer 17

it contains one or more ovule, and one mature ovule contains a female gamete which is the ovum and a definitive nucleus

Question 18

what is self-pollination?

Answer 18

it is the transfer of pollen grains from anther to stigma of the same flower or to a different flower of the same plant

Question 19

what are the advantages of self-pollination?

Answer 19

1. requires only one parent plant
2. beneficial qualities likely to be passed down to offsrpings as they inherit genes from parent plant
3. does not rely on external factors for pollination
4. higher probability that self-pollination will occur as reproductive parts of the plant are close to each other compared to cross-pollination
5. less pollen grains and energy wasted compared to cross-pollination

Question 20

what are the disadvantages of self-pollination?

Answer 20

1. fewer variations of offspring produced, species less adapted to changes in the environment
2. continued self-pollination produces weaker, smaller and disease-prone offsrpings

Question 21

what is cross-pollination?

Answer 21

the transfer of pollen grain from the anther of one plant to the stigma of another plant that is of the same species

Question 22

what are the disadvantages of cross-pollination?

Answer 22

two parent plants req, depends on external factors, lower probability of it occuring, more energy and pollen grains wasted as compared to self-pollination

Question 23

what are the advantages of cross-pollination?

Answer 23

1. beneficial qualities inherited from both parents

2. more varieties of offspring produced, higher chances of species’ survival

Question 24

insect-pollinated vs wind-pollinated flowers

stigmas, stamens, pollen

Answer 24

insect: small and compact stigma that does not protrude out of the flower
not pendulous and do not protrude out of the flower
fairly abundant, larger pollen grains with rought surfaces
wind: large and feathery stigma and usu protrude out of the flower
long and pendulous filaments with protruding anthers
more abundant, pollen grains smaller and smoother

Question 25

what happens during fertilisation?

Answer 25

1. pollen grains germination in response to secretion of sugary fluid of mature stigma
2. pollen tube grows from the pollen grain. the growth of pollen tube is controlled by pollen tube nucleus
3. the two nuclei and cytoplasm pass into the pollen tube
4. pollen tube secretes enzymes to digest the surrounding tissues of stigma and style
5. pollen tube enters the ovule through the micropyle
6. the generative nucleus divides into two male gametes and the pollen tube nucleus disintegrates
7. when the pollen tube reaches the ovule, its tip absorbs sap and bursts, releasing two male gametes into the ovule
8. one male gamete fuses with the ovum to form a zygote while the other fuses with the generative nucleus to form the endosperm nucleus
9. zygote divides and develops into the embryo while the endosperm nucleus gives rise to endosperm