Specialised Cells

Question 1

In sexual reproduction, how is a fertilised egg made?

Answer 1

The nucleus of an egg cell fuses with the nucleus of a sperm cell to create a fertilised egg, which then develops into an embryo.

Question 2

What does both the nucleus of an egg cell and of a sperm cell contain?

Answer 2

Half the number of chromosomes that’s in a normal body cell - so they are called ‘haploid’.
When an egg and sperm nucleus combine at fertilisation, the resulting cell will have the right number of chromosomes.

Question 3

What are the main functions of an egg cell?

Answer 3

To carry the female DNA and to nourish the developing embryo in the early stages.

Question 4

How is an egg cell adapted to its function?

Answer 4

• It contains nutrients in the cytoplasm to feed the embryo.
• It has a haploid nucleus.
• Straight after fertilisation, its membrane changes structure to stop any more sperm getting in. This makes sure the offspring end up with the right amount of DNA.

Question 5

What is the function of a sperm cell?

Answer 5

To transport the male’s DNA to the female’s egg.

Question 6

How is a sperm cell adapted to its function?

Answer 6

• Has long tail to swim to egg.
• Has lots of mitochondria in middle section to provide energy to swim the distance.
• Has an acrosome at front of ‘head’; stores enzymes needed to digest its way through membrane of egg cell.
• Has a haploid nucleus.

Question 7

Where are epithelial cells found?

Answer 7

Epithelial cells line the surfaces of organs.

Question 8

What is the function of ciliated epithelial cells?

Answer 8

To move substances - the cilia beat to move substances in one direction along the surface of the tissue.