Reproduction

Question 1

What happens in sexual reproduction?

Answer 1

The mother and father produce egg and sperm (which are both gametes) by meiosis

Question 2

What is significant about gametes?

Answer 2

Gametes contain half the number of chromosomes, 23 instead of 46.

Question 3

What happens in fertilisation? How does this result in variation?

Answer 3

Egg and sperm fuse together to form a cell with the full number of chromosomes. This is why offspring inherit features from both parents. The mixture of genetic information produces variation.

Question 4

What happens in asexual reproduction?

Answer 4

There is only one parent so the offspring are genetically identical.

Question 5

How does it happen?

Answer 5

It occurs via mitosis.

Question 6

What produces asexually?

Answer 6

Some animals and plants, bacteria

Question 7

What are the advantages of sexual reproduction?

Answer 7

Sexual reproduction results in variation, meaning the population is more likely to withstand environmental changes, diseases or an introduction of a new predator because they can adapt

Question 8

What are the disadvantages of sexual reproduction?

Answer 8

It requires energy and time to find a partner, it also takes longer

Question 9

What are the advantages of asexual reproduction?

Answer 9

Asexual reproduction is fast, meaning bacteria can produce colonies quickly in favourable conditions such as abundance of a food source. It uses less energy and there only needs to be one parent.

Question 10

What are the disadvantages of asexual reproduction?

Answer 10

Asexual reproduction cannot be used for selective breeding as it does not produce variation or a gene pool, therefore we cannot use it to increase food production for example

Question 11

Which 3 examples of organisms can reproduce asexually and sexually?

Answer 11

Malaria, fungus, plants

Question 12

Malaria

Answer 12

The parasite reproduces sexually between mosquitos and asexually in a human host

Question 13

Fungus

Answer 13

It produces spores which become new fungi when in a suitable place, spores can be produced sexually and asexually

Question 14

Plants

Answer 14

Plants can reproduce asexually and sexually, such as strawberry plants. They produce runners which are horizontal stems along the soil and at various points a new strawberry plant is made (asexual) or seeds (sexual)

Question 15

Inherited diseases

Answer 15

Some disorders can be inherited from a person’s parents, most of these diseases can be screened for in embryos

Question 16

Name a genetic disorder caused by a recessive allele

Answer 16

Cystic fibrosis

Question 17

What is cystic fibrosis?

Answer 17

It is a genetic disorder in the cell membranes which results in the body producing lots of sticky mucus in the air passages, lungs and pancreas.

Question 18

Recessive meaning

Answer 18

Two copies of the allele are needed in order for it to be expressed

Question 19

What is a carrier?

Answer 19

A person who only has one copy of the allele

Question 20

What are the names for a person with two of the same and two different alleles?

Answer 20

Homozygous and heterozygous

Question 21

An example of a genetic disorder caused by a dominant allele

Answer 21

Polydactyly

Question 22

What is polydactyly?

Answer 22

A genetic disorder where a baby is born with extra fingers or toes, it usually doesn’t pose any problems

Question 23

What does dominant mean?

Answer 23

Only one allele is needed for the gene to be expressed

Question 24

What are the two main types of embryo screening?

Answer 24

During in vitro fertilisation (IVF) or during pregnancy by taking a sample from the placenta

Question 25

IVF screening

Answer 25

The embryo has a cell removed and its genes analysed before being implanted into the mother, embryos with defects are discarded or used in stem cell research

Question 26

Embryonic screening in the womb

Answer 26

A cell is taken and its genes analysed, the mother may choose to terminate the pregnancy or keep the child if it has a genetic disorder

Question 27

Arguments for screening

Answer 27

Helps to stop people suffering, treating disorders costs the government a lot of money, there are laws to stop it going too far (not allowed to choose sex for example)

Question 28

Arguments against screening

Answer 28

Implies that people with genetic disorders are undesirable which may increase prejudice, it is expensive, may go too far and people may try to choose characteristics