Variation and Biodiversity

Question 1

What are the two types of cell division

Answer 1

Mitosis

Meiosis

Question 2

Outline the importance of meiosis

Answer 2

Forms gametes
Which fuse to form a diploid zygote
Halving of DNA allows adult offspring to have same number of chromosomes as parent

Question 3

Outline the process of meiosis1

Answer 3

Homologous chromosomes pair up
Chromatids wrap around eachother
Crossing over sometimes occurs
Chromosomes are pulled to opposite poles
Cell divides

Question 4

Outline the process of meiosis2

Answer 4

The chromatids separate
Chromatids line up in center of cell
Chromosomes are pulled to opposite poles
Cell divides
Forms 4 daughter cells with different chromosomes

Question 5

How does meiosis produce variation

Answer 5

Independent segregation

New combinations of parental chromosomes

Question 6

Outline independent segregation

Answer 6

Homologous pairs line up at random
As do the chromatids
The combination of paternal/maternal chromosomes is random in the gamete

Question 7

Outline variation from genetic combinations

Answer 7

Independent assortment
Of different alleles
Of chromosomes
Each gamete is different

Question 8

Outline crossing over

Answer 8

Chromatid pairs twist around each other
Broken portions of chromatid swap over
Creating new genetic combinations of maternal and paternal
Recombination

Question 9

Outline how fertilisation causes variation

Answer 9

Each gamete is unique
Millions of gametes
Random chance which ones fertilise