Question 1: Define natural selection in your own words.

Answer: The process where organisms with advantageous traits are more likely to survive and reproduce, passing those traits to their offspring.

Question 2: Explain how genetic variation within a population influences natural selection.

Answer: Genetic variation provides different traits in a population, some of which may be better suited to the environment, allowing those traits to be selected for.

Question 1: List the four main stages of natural selection.

Answer: Variation, Competition, Selection of advantageous traits, Reproduction of suited organisms.

Question 2: Describe how environmental changes can affect natural selection.

Answer: Environmental changes alter which traits are advantageous, leading to different traits being selected for over time.

Question 1: In a population of 1000 birds, 600 have a particular allele for beak shape. Calculate the frequency of this allele in the population.

Answer: Allele frequency = (Number of alleles in individuals with the trait) / (Total number of alleles). Since each bird has 2 alleles, total alleles = 2000. Number of alleles with trait = 600 * 2 = 1200. Frequency = 1200 / 2000 = 0.6.

Question 1: Describe a basic experimental setup to investigate how predator presence affects prey size in a pond ecosystem.

Answer: Set up two ponds with similar environmental conditions. In one pond, introduce a predator species (e.g., fish). Observe and record the sizes of prey species over time. Variables include predator presence (independent), prey size (dependent), and pond conditions (controlled). Ensure safety by handling predators carefully and avoiding contamination.

Question 1: A study shows that in a population of moths, the proportion of dark-coloured moths increased from 20% to 70% over 50 years. Explain how natural selection could have caused this change.

Answer: The environment likely became darker, making dark moths less visible to predators. These moths had a survival advantage and reproduced more successfully, increasing their proportion in the population.

Question 1: Describe how natural selection can lead to the development of antibiotic resistance in bacteria. Include the key steps involved. (6 marks)

Answer: Initially, some bacteria have a genetic mutation that confers resistance to antibiotics. When antibiotics are used, susceptible bacteria die, but resistant bacteria survive. These resistant bacteria reproduce, passing on the resistance genes. Over time, the population becomes dominated by resistant strains, leading to antibiotic resistance.

Question 1: Explain how understanding natural selection has helped in developing conservation strategies for endangered species.

Answer: By understanding natural selection, conservationists can maintain genetic diversity, manage habitats to support advantageous traits, and prevent environmental changes that could favour less adaptable traits, helping species survive.