Meiosis and Mitosis

Question 1

Explain the role of independent segregation in meiosis.

Answer 1

1. To provide genetic variation;
2. Allows different combinations of maternal and paternal chromosomes/ alleles;
3. To produce haploid cells/half the chromosome number;
4. Allows homologous chromosomes/ homologous pairs to arrange randomly / separate;

Question 2

What joins chromosomes together

Answer 2

Centromeres

Question 3

Describe the 3 roles of centromeres in mitosis.

Answer 3

Holds chromatids together
Attaches chromatids to spindle;
Allows chromatids to be separated/move to opposite
poles

Question 4

Homologous chromosomes carry the same genes but they are not genetically identical. Explain why.

Answer 4

They carry different alleles

Question 5

Other than independent segregation, give one way in which meiosis allows the production of genetically different cells.

Answer 5

Crossing over

Question 6

DNA helicase is important in DNA replication. Explain why

Answer 6

Separates the strands by breaking H-bonds so nucleotides can attach

Question 7

Explain how a change in a sequence of DNA bases could result in a non-functional enzyme.

Answer 7

A change in the base sequence will cause a change in sequence of amino acids which can alter the shape of the active site so the substrate can not bind

Question 8

Explain how a change in the DNA base sequence for a protein may result in a change in the structure of the protein.

Answer 8

Can lead to a change in amino acids which will create a change in the ionic bonds which alters the tertiary structure

Question 9

Describe what happens in metaphase

Answer 9

The spindles begin to form and the chromosomes line along the middle

Question 10

Cells lining the human intestine complete the cell cycle in a short time. Explain the advantage of these cells completing the cell cycle in a short time.

Answer 10

cells can be replaced quickly

Question 11

Mikanolide is a drug that inhibits the enzyme DNA polymerase. Explain why this drug may be effective against some types of cancer.

Answer 11

Slows down DNA replication which slows down mitosis