DNA replication & variation

Question 1

DNA replication

Answer 1

Before the cell can divide, the DNA inside its nucleus must make a copy of itself and go into the two new cells that will be created.

Question 2

Importance of DNA replication

Answer 2

to produce identical copies of DNA
so that the daughter cells contain the same DNA as parent
allow the cell to function correctly

Question 3

crossing over

Answer 3

a section of chromosomes crosses over another then breaks and rejoins. This results in recombinations of paternal and maternal features

Question 4

random fertilisation increases variation how?

Answer 4

• each gamete has an unique set or combination of genes
• any sperm can fuse with any egg
• as a result each zygote is unique
• variations also occurs due to different combinations of genes from the paternal and maternal gametes

Question 5

independent assortment

Answer 5

chromosomes arrange randomly along the equator of the cell
( metaphase 1 & 2) There is random movement, the homologous pairs moving towards opposite poles awayb from eachother

Question 6

how is sex determined in humans

Answer 6

x and y chromosome

Question 6

karotype

Answer 6

a map of the chromosomes arranged in there homologous pairs from largest to smallest ( sex determining chromosomes last)