Reproduction in plants

Question 1

What is Asexual reproduction?

Answer 1

Asexual reproduction is 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

Sexual reproduction is a process involving the fusion of two gametes to form a zygote. It produces genetically dissimilar offspring.

Question 3

Imagine the parts of a flower

Answer 3

Go refer to your notes

Question 4

What is pollination?

Answer 4

Pollination is the transfer of pollen grain from the anther to a stigma.
It is also important to help bring together the male and female gametes to enable fertilization to take place.

Question 5

What are the advantages of self-pollination?

Answer 5

1. Beneficial qualities are passed down from parent plant to offspring
2. More likely for the pollination to occur since the stigma is very close to the anther
3. Not dependent on external factors for pollination
4. Only one parent is required
5. Less pollen and energy is wasted

Question 6

What are the advantages of cross-pollination?

Answer 6

1. More varieties of offspring are produced which leads to greater genetic variation.
2. Offspring can inherit beneficial qualities from both parents
3. Seeds produced are capable of surviving longer before germination.
4. Increased probability of offspring being heterozygous

Question 7

What are the disadvantages of self-pollination?

Answer 7

1. Offspring produced are genetically similar to parents causing fewer varieties of offspring
2. If there is a disease, there will be a high chance that the species goes extinct
3. Probability of harmful recessive alleles being expressed in offspring is high

Question 8

What are the disadvantages of cross-pollination?

Answer 8

1. Two different plants of the same species are required
2. Dependent on external factors for pollination
3. Less likely to occur compared to self- pollination
4. More energy and pollen are wasted

Question 9

Describe all the features of a insect pollinated flower?

Answer 9

1. Large and brightly coloured petals to attract insects
2. Nectar is present
3. Fragrant
4. Usually small, compact and do not protrude out of the flower
5. Stamens are not pendulous and do not protrude out of the flower
6. Pollen is fairly abundant. It is usually large with rough surfaces so that it can readily cling onto the insect’s body
7. Nectar guide is present on the petals to guide the insect towards the nectar

Question 10

Describe all the features of a wind-pollinated flower?

Answer 10

1. Small and dull coloured, without petals
2. Nectar is absent
3. Odourless
4. Stigma are large, feathery and usually protrude out of the flower to provide a large surface area to trap pollen
5. Stamens have long pendulous filaments and protruding anthers.
6. Pollen is abundant. It has smooth surfaces and it is tiny so that it can be carried by the wind.
7. Nectar guide is absent

Question 11

What are the steps of fertilization inside the flower?

Answer 11

1. After pollination, pollen grain germinates in response to sugary fluid secreted by the mature stigma.
2. A pollen tube grows out of the pollen grain.
3. The cytoplasm and the two nuclei pass into the pollen tube.
4. The pollen tube secrete enzymes to digest the surrounding tissue of the stigma and the style
5. The pollen tube enters the ovule through the micropyle.
6. Within the ovule, the tip of the pollen tube absorbs sap and bursts, releasing the two male gametes.
7. The nucleus of the male gamete fuses with the nucleus of the ovum to form a zygote. (This is fertilisation)