Chapter 14 - Asexual And Sexual Reproduction

Question 1

What is Asexual reproduction?

Answer 1

A process which results in the production of genetically identical offspring from one parent

Question 2

What are some examples of asexual reproduction?

Answer 2

Binary fission in bacteria
Budding in yeast
Runners in plant
Potato tubers

Question 3

How are potatoes formed from tubers?

Answer 3

The parent plant produces underground stems eventually forming tubers ( seed potatoes )
Sucrose is transported to the underground stems through the phloem in translocation
Sucrose is converted to starch and the stem swells to form a tuber

Question 4

What is a haploid nucleus?

Answer 4

A nucleus containing only 1 set of chromosomes

Question 5

What is a diploid nucleus?

Answer 5

A nucleus containing 2 complete sets of chromosomes

Question 6

What is fertilisation?

Answer 6

The fusion of gamete nuclei

Question 7

What does it mean when a flower is a hermaphrodite?

Answer 7

It means that flower contains both the male and female reproductive organs

Question 8

What is the function of the sepal?

Answer 8

To protect the unopened flower

Question 9

What is the function of the petals?

Answer 9

To attract insects in insect-pollinated flowers

Question 10

What is the function of the anther?

Answer 10

To produce male gametes in pollen

Question 11

What is the function of the stigma?

Answer 11

Collects pollen from pollinators or wind

Question 12

What is the function of the ovary?

Answer 12

To produce the female gametes in ovules

Question 13

What is pollination?

Answer 13

The transfer of pollen grains from an anther to a stigma

Question 14

What is self-pollination?

Answer 14

The transfer of pollen grains from an anther to the stigma on the same flower or another flower on the same plant

Question 15

What is cross-pollination?

Answer 15

The transfer of pollen grains from an anther to the stigma of a flower on a different plant of the same species

Question 16

What are the advantages and disadvantages of Self-pollination?

Answer 16

Advantages

More chance of fertilisation
No reliance on pollinators

Disadvantages

Less variation
Less able to adapt to environmental change

Question 17

What are advantages and disadvantages of Cross-pollination?

Answer 17

Advantages

Increase variation
More able to adapt to environmental change

Disadvantages

Less chance of fertilisatiion
Reliance on pollinators

Question 18

What is the structure of an insect-pollinated flower like?

Answer 18

Large and colorful petals
Anther and stigma are inside the flower
Stigma is sticky
There is a nectary present

Question 19

What is the structure of a wind-pollinated flower like?

Answer 19

Small, inconspicuous, and green petals
Anther and stigma dangle outside the flower
Stigma is feathery
There is no nectary

Question 20

What is structure of a pollen grain from an insect-pollinated flower like?

Answer 20

Large size
Spiky and sticky
Smaller quantity produced

Question 21

What is the structure of a pollen grain from a wind-pollinated flower like?

Answer 21

Smaller size
Smooth and light
Larger quantity produced

Question 22

Describe the process of fertilisation in a plant

Answer 22

Pollen grain germinated and grows a pollen tube
The pollen tube grows down the style by digesting the style using enzymes released from the pollen tube and reaches through the ovule through the micropyle
The tip of the pollen tube breaks open and the male nucleus enters the ovule
Fertilisation occurs when the male nucleus fuses with the female nucleus inside the ovule
A zygote is formed as a result of fertilisation

Question 23

Describe the changes in the number of chromosomes after pollination

Answer 23

Pollen grains are formed in anthers
During their formation, the number of chromosomes in the nuclei is halved by meiosis ( reduction division )
This means the male nucleus in the pollen tube is described as a haploid nucleus
When the main nucleus fuses with the female nucleus, the chromosome number doubles to form a diploid nucleus this process is called fertilisation
The zygote then divides by mitosis to form an embryo

Question 24

What do the ovule, integuments and ovary become after fertilisation?

Answer 24

Ovule becomes a seed
Integuments become a testa
Ovary becomes the fruit

Question 25

What do the radical and plumule grow into during germination?

Answer 25

The radicle will grow into a root
The plumule will grow into a shoot

Question 26

What is the function of the cotyledons?

Answer 26

To store nutrients

Question 27

What is the function of the micropyle?

Answer 27

Entry of pollen tube during fertilisation
Enter of water and diffusion of gases during germination
The radicle emerges from the seed through the micropyle

Question 28

What are the 3 environmental conditions needed for germination? Give a reason for each condition

Answer 28

Presence of water, to activate the enzymes
Presence of oxygen, to allow for the release of energy from aerobic respiration
Suitable temperature, to increase enzyme activity

Question 29

For a seed kept in the dark, why does the dry mass of the seed decrease because of respiration?

Answer 29

As respiration uses glucose, glucose is used up during respiration in the seed, which decreases its dry biomass

Question 30

For a seed kept in the light, why does the dry mass of the seed increase?

Answer 30

As the seed carries out photosynthesis, the dry biomass of glucose used up for respiration is less then the dry biomass produced in the seed by photosynthesis

Question 31

What are the advantages of asexual reproduction to a species in the wild?

Answer 31

All the offspring produced are genetically identical
If the parent is well adapted, the offspring will be adapted to the surroundings
Only one parent is required
The process is fast
Less energy required as there are no gametes needed

Question 32

What are the advantages of asexual reproduction for crop production?

Answer 32

Population increases rapidly
All the desired features of the parent plants are passed on to the offspring

Question 33

What are the disadvantages of asexual reproduction to a species in the wild?

Answer 33

Little or no variation
Evolution (formation of anew species) takes place slowly
Less able to adapt to a change in the environment
All individuals may be killed by the same disease
Overcrowding causes high competition for resources

Question 34

What are the disadvantages of asexual reproduction for crop production?

Answer 34

Can exploit the same environment quickly as all the plants have the same demand for nutrients so they will exhaust the nutriet supply in the soil

This can be prevented by adding fertiliser to the soil

Question 35

What are the advantages of sexual reproduction to a species in the wild?

Answer 35

Increases genetic variation
Evolution (formation of a new species) takes place more quickly
It easily adapts to a change in the environment
Seed dispersal can reduce competition for resources and allow colonisation of new areas
Less liable to be wiped out by disease

Question 36

What are the advantages of sexual reproduction for crop production?

Answer 36

Can produce new varieties of plants

Question 37

What are the disadvantages of sexual reproduction to a species in the wild?

Answer 37

Two parents are needed
Fertilisation may not happen and many pollens or seeds may be wasted
The loss of lots of energy
The process is slow

Question 38

What are the disadvantages of sexual reproduction for crop production?

Answer 38

Desired features may be lost by cross-breeding
Plants may not be as well adapted to the area where parent grows

Question 39

What is eutrophication?

Answer 39

When too much fertiliser is used so it goes in the river and promotes algae growth.
When algae grows in the river, they use up all the oxygen to decompose dead plants
So the fish cannot breath, so they die and their body is decomposed by the bacteria.