Natural Selection

Question 1

Definition of evolution

Answer 1

Gradual change in the inheritable characteristics of a population over time

Question 2

Why does evolution happen?

Answer 2

Driven by variation (of traits) and competition (for resources) between individuals (of the same species) of a population, leading to differential survival of and reproduction by, organisms which are best fitted to the environment

-mutation creates new alleles and increases the genetic variation in a population results in variation (traits / phenotypes) between individuals
-organisms with selectively advantageous traits are more likely to survive and reproduce
- individuals produce many offspring which results in competition

Question 3

Examples of environmental factors that can exert a selection pressure

Answer 3

1. Biological factors
   a. presence of predators
   b. presence of pathogens / disease
2. Resource availability
   a. availability of food / water
   b. availability of shelter
3. Physical factors
   a. temperature
   b. weather conditions
   c. natural disasters

Question 4

Template answer

Answer 4

• selection pressure is exerted by [environmental factor]
• individuals with selective advantageous [traits] are more likely to survive than individuals which do not
• these individuals can reproduce, and pass down their alleles to their offspring
• over many generations there are more individuals with the [advantageous phenotype] in the population