Reproduction In Plants

Question 1

What is asexual reproduction?

Answer 1

The process resulting in the production of genetically identical offspring from one parent, without the fusion of gametes

Question 2

What is sexual reproduction?

Answer 2

The process involving the fusion of two haploid gametes to form a diploid zygote. It produces genetically dissimilar offspring

Question 3

What happens during asexual reproduction and how many chromosomes does the daughter cell have

Answer 3

The cell divides to produce two identical daughter cells through mitosis. Each daughter cell has the same number of chromosomes as the parent plant

Question 4

What happens during sexual reproduction and how many chromosomes does the daughter cell have

Answer 4

A haploid male gamete fuses with the haploid female gamete in a process called fertilisation. The nuclei of the two haploid gametes fuse to form a diploid zygote. Gametes are formed when a cell divides to produce 4 daughter cells through meiosis. Each daughter cell has half the number of chromosomes as the parent cell

Question 5

What are the parts of a flower

Answer 5

Sepal
Petal
Receptacle
Pedicel

Question 6

What is a sepal

Answer 6

A modified leaf that protects the flower in the bud stage

Question 7

What is a petal

Answer 7

A modified leaf that forms the most obvious part of the flower. All petals together make up the corolla. And in insect pollinated flowers the petal is brightly coloured to attract insects for pollination and provide a landing platform for insects

Question 8

What is a receptacle

Answer 8

The enlarged end of the flower stalk

Question 9

What is a pedicel

Answer 9

The flower stalk

Question 10

What is the stamen and what are its parts

Answer 10

Male part of the flower; consists of filament and anther

Question 11

What is the function of the filament

Answer 11

To hold the anther in a suitable position to disperse pollen grains

Question 12

What is the function of the anther

Answer 12

To produce pollen grains for pollination.it is made up of two lobes , each containing 2 pollen sacs. Male gametes in pollen grains produced by meiosis has a haploid set of chromosomes.

Question 13

What is in each pollen grain?

Answer 13

A male gamete( generative nucleus; involved in fertilisation) and the pollen tube nucleus

Question 14

What are the parts of a carpel/pistil?

Answer 14

Stigma
Style
Ovary
Ovule

Question 15

What is the function of the stigma ?

Answer 15

Receives pollen grains. A mature stigma secretes sugary fluid to stimulate the germination of pollen grains

Question 16

What is the function of the style?

Answer 16

Holds the stigma at a suitable position to trap pollen grains

Question 17

What is the function of the ovary?

Answer 17

Produces and protects one or more ovules. Will develop into a fruit after fertilisation

Question 18

What is pollination?

Answer 18

The transfer of pollen grains from the anther to the stigma

Question 19

What is the importance of pollination?

Answer 19

It helps bring together the male and female gametes to enable fertilisation to take place

Question 20

What are the two types of pollination

Answer 20

Self pollination and cross pollination

Question 21

What is self pollination?

Answer 21

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

Question 22

What are the characteristics of self-pollinated plants?

Answer 22

Flowers are bisexual with the anthers and stigmas maturing at the same time
Stigma is situated directly below the anther

Question 23

What are the advantages of self-pollination?

Answer 23

• beneficial qualities are passed down from the parent to the offspring
• only one parent is required
• less pollen and energy is wasted
• more likely to take place as stigmas are closer to the anthers
• not dependent on external actions for pollination

Question 24

What are the disadvantages of self-pollination?

Answer 24

Offspring produced are genetically similar to parents causing fewer varieties of offspring
Probability of harmful recessive alleles being expressed in offspring are higher as compared to cross pollination

Question 25

What is cross pollination?

Answer 25

The transfer of pollen grains from the anther to the stigma of a flower of another plant of the same species

Question 26

What are the advantages of cross-pollination?

Answer 26

Offspring can inherit beneficial qualities from both parents
More varieties of offspring are produced which leads to a greater genetic variation
Increased probability of offspring being heterozygous
Seeds produced are capable of surviving longer before germination
Probability of harmful recessive alleles being expressed in offspring are lower as compared to self-pollination

Question 27

What are the disadvantages of cross-pollination?

Answer 27

Two different plants of the same species are required
Dependent on external factors like wind and insects for pollination
More energy and pollen are wasted
Less likely to occur as compared to self-pollination

Question 28

What is an example of an insect-pollinated flower?

Answer 28

Clitoria

Question 29

What are the characteristics of the clitoria

Answer 29

The filaments of 9 stamens are fused to form a trough that encloses the pistil
Nectar of the flowers collects at the bottom of the stamen trough, only insects with a long tubular mouth can reach it
The stigma is small and compact
The style is long, curved and hairy
It contains nectar guides

Question 30

What happens when the insect lands on the standard petal of the clitoria

Answer 30

It follows the nectar guides into the flower
And forces its way in between te 2 wing petals to collect nectar
The insects back forces the keel petal upwards to expose the anthers and stigma.
Pollen grains from the anther stick to the back of the insect and get transferred to a stigma
When the insect leaves the flower, the keel petals spring back to its original position

Question 31

What is an example of a wind-pollinated flower?

Answer 31

Ischaemum muticum

Question 32

What are the characteristics of the ischaemum muticum

Answer 32

It’s flowers come in pairs
Each flower is enclosed by 2 flowering bracts
The upper bisexual flower consists of an ovary, 2 long feathery stigmas, 3 stamens and 2 lodicules
When ready to reproduce the lodicules swell and force the two flowering bracts apart
The lower male flower contains only 3 stamens with long filaments and 2 lodicules
Mature stamens have long filaments that hangs downwards and can swing freely(pendulous)
When the filaments sway the pollen is shaken free and carried away by the wind
A mature stigma is large extended and feathery to provide a large surface area for the capture of pollen floating in the air

Question 33

What are the differences between insect ad wind pollinated flowers?

Answer 33

Petals : large and brightly coloured (insect) l small dull-coloured and without petals (wind)
nectar: is present (insect) l is absent (wind)
Scent: fragrant and sweet-smelling (insect) l scent is absent in flowers (wind)
Stigmas: small compact and do not protrude out of flowers (insect) l large feathery and protrude out of flowers (wind)
Stamens: not pendulous and do not protrude out of flowers(insect) l long and pendulous filaments with protruding anthers (wind)
Pollen: fairly abundant. Pollen grains are larger with rough surfaces (insect) l more abundant. Pollen grains are tiny with smooth surfaces
Nectar guides: present (insect) l absent (wind)

Question 34

What happens during fertilisation in plants?

Answer 34

Pollen grain germinates in response to the sugary fluid secreted by the mature stigma
A pollen tube grows out of the pollen grain
The male gamete (generative nucleus) enters the pollen tube
The pollen tube secretes enzymes that digests the tissues of the stigma and style. Thus the pollen tube grows down the style into the ovary
Pollen tube enters the ovule through the micropyle
When the pollen tube reaches the ovule, its tip absorbs sap and bursts, releasing the male gamete
The haploid male gamete fuses with the ovum to form the diploid zygote. This is fertilisation. The zygote divides and develops into the embryo