B3 - Cell division

Question 1

When do cells divide?

Answer 1

Whenever the body needs to:

• grow
• replace worn out cells
• repair damaged tissue

Question 2

Why do all new cells have the same chromosomes?

Answer 2

Because when cells divide they are copied.

Question 3

What is a unicellular organism?

Answer 3

Contains only one cell.

Question 4

Why is multicellular better?

Answer 4

It allows:

• The organism to be larger
• Cell differentiation (having different types of cells with different functions)
• The organisms to be more complex

Question 5

What is a homologous pair?

Answer 5

pairing at meiosis and having the same structural features and pattern of genes.

Question 6

What is a diploid cell?

Answer 6

When a cell has pairs of chromosomes.

Question 7

What are the systems that ensure all cells get enough nutrients and oxygen?

Answer 7

• nervous system to communicate between cells
• transport systems to supply cells with nutrients
• respiratory systems for exchange of gases

Question 8

What are the stages of mitosis?

Answer 8

1) each chromosome is copied
2) spindle forms, chromosomes arranged along the equator
3) chromosomes move to opposite sides of the cell
4) two genetically identical cells are produced

Question 9

What is a haploid?

Answer 9

A haploid is when the gametes have half a set of chromosomes.

Question 10

What is a zygote?

Answer 10

A diploid cell resulting from the fusion of two haploid gametes.

Question 11

What is meiosis?

Answer 11

Meiosis is the production of gametes.

Question 12

How are sperm cells adapted to their function?

Answer 12

• a sperm has large numbers of mitochondria to release energy for motion
• acrosome allowing enzymes to digest the egg
• tail for swimming

Question 13

What are the stages of meiosis?

Answer 13

1) chromosomes pair up
2) they move to each pole
3) the separate to four corners
4) four new haploid cells form