Genetic Variation

Question 1

What does random fusion of gametes allow for

Answer 1

This random fusion of gametes at fertilization creates genetic variation between zygotes as each will have a unique combination of alleles​

Question 2

During fertilization can any male gamete fuse with any female gamete to form a zygote

Answer 2

Yes - means fusion of gametes is random

Question 3

How does independent assortment increase genetic variation

Answer 3

The different combinations of chromosomes in daughter cells increases genetic variation between gametes​

Question 4

Why is swapping of alleles important in crossing over

Answer 4

it can result in a new combination of alleles on the two chromosomes​

Question 5

What is the number of possible chromosomal combinations resulting from meiosis equal to

Answer 5

2 to the power of n (n is the number of homologous chromosome pairs / haploid number​)

Question 6

What would the calculation and answer be for the number of possible chromosomal combinations in a humans

Answer 6

2^23 = 8 388 608 possible chromosomal combinations​

Question 7

What is the formula to calculate the number of combinations of chromosomes after the random fertilisation of two gametes

Answer 7

(2^n)^2 (N is haploid number and ^2 is the number of gametes.

Question 8

What would the formula be for the number of combinations following fertilisation in humans

Answer 8

(2^23)^2­­ = 70,368,744,177,664

Question 9

Why is there so much genetic variation in meiosis

Answer 9

2^23 is just the number of different possible gametes that one human can make. As sexual reproduction involves the random fusion of two gametes, potentially any one of the > 8 million possible combinations that a male can make following meiosis can fertilise any one of the > 8 million possible combinations that a female could make.​

Question 10

What is genetic variation

Answer 10

The small differences in DNA base sequences between individual organisms within a species

Question 11

What does genetic variation through generations result in

Answer 11

Genetic Diversity

Question 12

What is genetic diversity

Answer 12

The number of different alleles of genes in a population

Question 13

What does mutation result in

Answer 13

The generation of new alleles and contributes to genetic diversity or the size of the gene pool

Question 14

What effect does the genetic code being degenerate have on the effectiveness of an allele

Answer 14

The new allele may be advantageous, disadvantageous or have no apparent effect on phenotype.

Question 15

Are new alleles always presented

Answer 15

No, they can remain hidden (not expressed) within a population for generations

Question 16

Why is genetic diversity important for the development of a species

Answer 16

It allows for natural selection to occur, resulting in differences in phenotype.

Question 17

What are selection pressures and what do they do

Answer 17

Environmental factors that increase the chance of individuals with a specific phenotype surviving and reproducing over others (these organisms have a higher fitness)

Question 18

What is meant by the fitness of an organism

Answer 18

It’s ability to survive and pass on it’s alleles to offspring

Question 19

What are the characteristics of large gene pools

Answer 19

Large gene pools have a strong ability to adapt to change

Question 20

What are the characteristics of small gene pools

Answer 20

Small gene pools have lower genetic diversity = bottle necks = vulnerable to extinction