4.7 Sexual and Asexual Reproduction

Question 1

What happens in sexual reproduction?

Answer 1

Sexual reproduction is where genetic information from two organisms (a father and a mother) is combined to produce offspring which are genetically different to either parent.
- The father and mother produce gametes - in animals these are sperm and egg cells.
- Gametes only contain half the number of chromosomes of normal cells.
- At fertilisation, a male gamete fuses with a female gamete to produce a fertilised egg, known as a zygote. -Chromosomes from the mother pair up with the chromosomes from the father, so the zygote ends up with the full set of chromosomes.
- The zygote then undergoes cell division (mitosis) and develops into an embryo
- The embryo inherits characteristics from both parents as it’s received a mixture of chromosomes (and therefore genes) from its mum and dad.

Question 2

Why are egg cells bigger than sperm cells?

Answer 2

They contain all the subcellular structures and nutrients needed for the zygote to grow and develop.

Question 3

During sexual reproduction in plants, which two gametes fuse together?

Answer 3

Pollen & Eggs

Question 4

How many chromosomes does each human gamete have?

Answer 4

23 chromosomes

Question 5

In asexual reproduction, are the clones identical or different?

Answer 5

Identical

Question 6

How many parents does asexual reproduction include?

Answer 6

One parent

Question 7

When eukaryotic organisms reproduce asexually, which process do they use?

Answer 7

Mitosis

Question 8

When bacteria reproduce asexually, which process do they use?

Answer 8

Binary Fission

Question 9

How does sexual reproduction differ from asexual reproduction? (3)

Answer 9

• In sexual reproduction, two parents are needed, whilst in asexual reproduction, only one is needed.
• In sexual reproduction, there is mixing of genetic material whilst in asexual reproduction there is not.
• In sexual reproduction, there is genetic variation, whilst in asexual reproduction there is not.

Question 10

Do animals usually reproduce via sexual or asexual reproduction?

Answer 10

Sexual reproduction

Question 11

Which process is used to create gametes?

Answer 11

Meiosis

Question 12

Sperm and egg cells are h______ cells and only have ___ chromosomes. When a sperm fertilises the egg, they form a d______ cell that has ___ chromosomes.

Answer 12

Haploid, 23, diploid, 46