10. Evolution and Natural Selection

Question 1

Evolution definition

Answer 1

is the change in genetic makeup of biological populations over successive generations

Question 2

Changes in gene pools can be caused by :

Answer 2

• mutations
• environmental selection pressures
• genetic drift
• gene flow immigration
• artificial selection pressures

Question 3

characteristics of mutations in DNA

Answer 3

• the only way new genetic material can be made
• almost always harmful to the individual
• can only be passed on if they happen in germ-line cells that make gametes
• can be very small mistakes ( a single DNA base) or very large ( part or whole chromosomes)

Question 4

Definition of environmental selective pressures

Answer 4

select individuals best adapted to a specific environment, promoting their survival and passing on genes through natural selection
eg. competition for water, food and oxygen
deforestation
changing temperature predation

Question 5

population def

Answer 5

a group of organisms of the same species living in the same area

Question 6

heritable

Answer 6

transmissible from parent to offspring (encoded in DNA)

Question 7

Struggle (for survival)

Answer 7

the battle for organisms to survive and reproduce in their environment, caused by selective pressures and limited resources

Question 8

advantageous phenotype

Answer 8

a biochemical, physical or behavioral trait that increases an individual’s fitness in its local environment

Question 9

disadvantageous phenotypes

Answer 9

a biochemical, physical or behavioural trait that lowers an individual’s fitness in its local environment

Question 10

fitness def

Answer 10

a measure of how well an organisms survives and reproduces on its environment

Question 11

species

Answer 11

a group of interbreeding organisms that produce viable and fertile offspring in nature

Question 12

natural selection def

Answer 12

is a mechanism for evolution where individuals best adapted to the selection pressures in their environment survive and pass on their alleles

Question 13

Process of natural selection

Answer 13

1. there is a physical, biochemical or behavioural variation in phenotypes between individuals in a popualtion
2. This variation is heritable
3. A specific selection pressure exists that causes a struggle for survival. Some individuals survive and reproduce better as they have an advantageous phenotype that helps them overcome the selection pressure
4. Organisms with the ‘fitter’ or advantageous - phenotype pass their alleles onto the next generation. This changes the allele makeup of the population as the trait becomes more common

Question 14

allele def

Answer 14

each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Question 15

phenotype

Answer 15

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment