B3d - Cell Division

Question 1

What are the advantages of being multicellular?

Answer 1

• allows organisms to be larger
• allows for cell differentiation
• allows organisms to be more complex

Question 2

Becoming multicellular requires the development of specialised organ systems. Limited to:

Answer 2

• communications between cells
• supplying cells with nutrients
• controlling exchanges with the environment

Question 3

What is cell growth?

Answer 3

Mitosis

Question 4

Why are mitosis cells genetically identical?

Answer 4

Mitosis creates diploid cells which are genetically identical (two copies are made)

Question 5

Where does mitosis occur?

Answer 5

Only in body cells

Question 6

How does DNA replication occur?

Answer 6

• unzipping to form single strands

- new double strands forming by complementary base pairing

Question 7

Mitosis in chromosomes?

Answer 7

• line up along the centre of the cell
• they then divide
• the copies move to opposite poles of the cell

Question 8

How are gametes produced?

Answer 8

Meiosis

Question 9

Why are gametes haploid?

Answer 9

Contains only one Chiron is one from each pair

Question 10

Why does fertilisation result in genetic variation?

Answer 10

Limited to:

• gametes combine to form diploid zygote
• genes on chromosomes combine to control the characteristics of zygote

Question 11

How is the structure of a sperm cell adapted to its function?

Answer 11

• many mitochondria to provide energy

- an acrosome that releases enzymes to digest the egg membrane

Question 12

Why, in meiosis is the chromosome number halved and each cell is genetically different?

Answer 12

• one chromosome from each pair separate to opposite poles of the cell in the first division
• chromosomes divide and the copies move to opposite poles of the cell in the second division

Question 13

Why do they have to half the number of cells in meiosis?

Answer 13

Because they are sex cells