Natural Selection

Question 1

what is evolution

Answer 1

• the process in which organisms have developed over time from earlier forms during history
• the slow and continuous change of organisms from one generation to the next

Question 2

what are the four reasons variation can be triggered

Answer 2

• mutation
• random mating
• random fertilisation
• recombination between homologous chromosomes during meiosis

Question 3

how do individuals in a population show genetic variation

Answer 3

with the differences in their alleles

Question 4

how do new alleles arise

Answer 4

through mutations

Question 5

what are the selection pressures and what do they do

Answer 5

• the selection pressures are predation, competition and disease
• they affect an organisms chance of surviving and reproducing

Question 6

how do adaptations contribute to an organisms survival

Answer 6

adaptation causes the organism to develop special characteristics and traits to help them survive in their environment

Question 7

how does the mutation of alleles result in some of a species to survive more than others

Answer 7

there would be organisms who have developed characteristics that make them better adapted to the selection pressures in their environment than other organisms in the species would

Question 8

why does natural selection lead to the evolution of a species

Answer 8

• because more resistant organisms have a higher survival and reproductive rate
• less resistant organisms die more frequently than the more resistant
• leaving the majority of the population being more resistant
• they reproduce and pass on their allele for resistance to their off-spring making them more resistant too
• gradually the population is filled with more resistant organisms

Question 9

what are ultimately responsible for the useful characteristics that are more likely to be passed on to the next generation

Answer 9

alleles, specifically, the mutation of alleles

Question 10

how does anibiotic resistance provide evidence for evolution

Answer 10

• because it makes the bacteria better adapted to an environment in which antibiotics are present
• as a result antibiotic resistance becomes more common in the population overtime

Question 11

what is a fossil

Answer 11

any trace of an animal or plant that lived a long time ago

Question 12

how does arranging fossils in chronological order allow gradual changes in organisms to be observed

Answer 12

• because it shows how species have changed and developed over billions of years
• therefore providing evidence for evolution

Question 13

what is the effect of genetic variation in a species, causing some organisms to be more resistant than others

Answer 13

• the better adapted ones have a better chance of survival so are more likely to breed successfully
• the less well adapted to the selection pressures are less able to compete
• so they are less likely to to survive and reproduce