Topic 5.2 - Natural selection

Question 1

Natural selection

Answer 1

Variation - only occurs if there is genetic variation within a species

Competition/selection pressure - Occurs when those with beneficial characteristics that are more suited to the environment live to produce more offspring while those with less beneficial characteristics produce less offspring or die.

Survival - better adapted survive

Reproduction - Those who survive reproduce

Question 2

Sources of genetic variation

Answer 2

• Crossing over in prophase 1 of meiosis
• Random orientation of bivalents during metaphase of meiosis
• Mutations

Question 3

Genetic variation with asexual reproduction

Answer 3

Species that reproduce asexually can only have genetic variation through mutations so their evolution cannot occur at the same rate as species that reproduce sexually.

Question 4

Adaptations

Answer 4

Characteristics that are ideal for an organism’s environment and way of life.

Caused by natural selection.

Question 5

Fastest breeding rate (excluding bacteria)

Answer 5

Calvatia gigantae is a fungus that produces a huge fruiting body (giant puffball) which can produce up to 7 trillion (7,000,000,000,000) spores

Question 6

Overproduction of offspring

Answer 6

Organisms typically produce more offspring than the environment can handle. This leads to competition for resources and natural selection will occur.

Question 7

Acquired characteristics

Answer 7

Characteristics that are caused by the environment (ie missing limb or scars)

Question 8

Inherited characteristics

Answer 8

Characteristics that are caused by genes (ie attached or detached earlobes)

Question 9

Antibiotic-resistant bacteria

Answer 9

Population of bacteria with some containing antibiotic-resistant genes ->

Antibiotics used ->

Antibiotic-resistant bacteria survive and reproduce quicker and easier, likely creating a new generation (generation time of < 1 hour) ->

New antibiotic-resistant population can pass genes to other bacteria through plasmids ->

(If antibiotics stop being used, then non-resistant bacteria are more present than before)