mutations and meiosis 2016-2021

Question 1

what is non dysjucntion

Answer 1

ALL chromosomes not separate equally and change the number of chromosomes in each cell

Question 2

how com the mass of DNA is double at prophase?

Answer 2

DNA replicated in interphase and has become condensed

Question 3

why does the DNA mass half when in telophase?

Answer 3

chromosomes move to either end of pole

Question 4

why is the mass of DNA in telophase double the mass in a gamete?

Answer 4

because in a gamete the chromosomes have uncoiled

Question 5

how come a horse and a dog cant make fertile offspring

Answer 5

• too many chromosomes
  -no homologous paring
  -no meiosis

Question 6

Define ‘gene mutation’ and explain how a gene mutation can have:
* no effect on an individual
* a positive effect on an individual.

Answer 6

-change in the DNA base sequences
-forms new allele
- degenerate- more than one base codes for the same amino acid
- insertion and deletions causes a change in tertiary structure at there is a Fram shift changing the amino acid sequence
- more likely to survive and reproduce

Question 7

Explain how the chromosome number is halved during meiosis.

Answer 7

1. Homologous chromosomes (pair);
2. One of each (pair) goes to each (daughter) cell / to opposite
   poles;