Introduction to Genes and Evolution

Genes are segments of DNA that determine the traits (characteristics) an organism inherits, such as eye colour, height, and even certain behaviours. Evolution is the process through which species change over long periods due to natural selection, where beneficial traits become more common in a population. Together, genes and evolution explain how organisms inherit traits and adapt to their environment over generations.

Key Concepts

1. Genes and Inheritance: Genes are passed from parents to offspring. Each parent contributes half of their genes to their child, meaning we inherit our traits from both parents.
2. DNA and Chromosomes: Genes are made up of DNA, and DNA is organised into structures called chromosomes. Humans have 23 pairs of chromosomes.
3. Natural Selection: A process where organisms with traits that help them survive and reproduce are more likely to pass these traits to their offspring.
4. Adaptation: Over time, species develop traits that help them survive in their specific environments, such as the long necks of giraffes to reach high leaves.
5. Evolutionary Theory: Developed by Charles Darwin, this theory explains how species evolve through the process of natural selection.

Understanding genes and evolution helps us explain why we look like our family members, why certain traits are common in populations, and how species adapt to their environments over time.

Exam Questions on Genes and Evolution

Here are 20 questions each at easy, medium, and hard levels to test your understanding of the topic.

Easy Level Questions

Basic Understanding of Genes and Evolution

1. What are genes?
2. What do genes determine in an organism?
3. What is DNA?
4. Who is known as the ‘father of evolution’?
5. What is the process by which species change over time?
6. How are genes passed from parents to offspring?
7. What is an example of a trait that genes can determine?
8. What are chromosomes?
9. How many pairs of chromosomes do humans have?
10. What does the term ‘inheritance’ mean?
11. What is a species?
12. What is the purpose of natural selection?
13. What is an adaptation?
14. What helps animals survive in their environment?
15. What is evolution?
16. Name an example of a characteristic passed down through genes.
17. Who developed the theory of natural selection?
18. What structure contains DNA in cells?
19. What is the basic unit of inheritance?
20. What term describes changes in species over time?

Medium Level Questions

Intermediate Knowledge of Genetic Inheritance and Evolution

1. Explain the relationship between DNA and genes.
2. What is natural selection, and why is it important?
3. Describe how an adaptation can help an organism survive.
4. What are the advantages of inheriting helpful traits?
5. Explain why offspring resemble their parents.
6. How do genes cause variation within a species?
7. Why is adaptation important for survival?
8. What is the difference between a gene and a chromosome?
9. Explain how giraffes’ long necks are an example of evolution.
10. How can a change in the environment affect a species?
11. What role do mutations play in evolution?
12. How does natural selection lead to evolution?
13. What does ‘survival of the fittest’ mean?
14. What happens to organisms that are not well adapted to their environment?
15. What is a genetic mutation?
16. Why do some traits become more common in a population?
17. What is an example of natural selection in nature?
18. How does selective breeding differ from natural selection?
19. What is a genetic trait?
20. What is the role of genes in physical appearance?

Hard Level Questions

Advanced Concepts in Genetic Variation, Adaptation, and Evolution

1. Explain how mutations contribute to genetic diversity.
2. Describe the process by which natural selection can change a population.
3. How do environmental changes drive evolution?
4. Explain why genetic variation is important in evolution.
5. How does selective pressure influence gene frequency?
6. Why might some genetic traits decrease in a population over time?
7. Describe how a beneficial mutation might spread in a population.
8. Explain the difference between dominant and recessive genes.
9. Why do only certain individuals survive to pass on their genes?
10. How does sexual reproduction increase genetic diversity?
11. Describe the process of speciation.
12. What is the role of gene flow in evolution?
13. How might an organism’s niche affect its evolution?
14. What is genetic drift and how does it affect evolution?
15. Explain how environmental factors can lead to extinction.
16. How do organisms with favourable traits influence a gene pool?
17. What is convergent evolution, and give an example.
18. Describe how camouflage is an example of adaptation.
19. How does isolation contribute to the formation of new species?
20. Explain the role of DNA mutations in antibiotic resistance.

Answers and Explanations

Easy Level Answers

1. Segments of DNA – Genes are units of inheritance in DNA.
2. Traits or characteristics – Genes determine eye colour, height, etc.
3. The molecule that carries genetic information – DNA contains instructions for life.
4. Charles Darwin – Known as the ‘father of evolution.’
5. Evolution – The process of change in species over time.
6. Through inheritance – Genes are passed from parents to offspring.
7. Eye colour, hair type – Examples of traits determined by genes.
8. Structures made of DNA – Chromosomes hold genes.
9. 23 pairs – Humans have 46 chromosomes in total.
10. Passing traits from parents to offspring – Inheritance is the transfer of genes.
11. A group of organisms that can breed together – A species is a group with similar traits.
12. To help species survive and reproduce – Natural selection favours helpful traits.
13. A trait that helps an organism survive – Adaptations improve survival.
14. Adaptations and inherited traits – Traits help animals survive in their environment.
15. Change in species over time – Evolution is how species develop new traits.
16. Hair colour, eye colour – Examples of genetic characteristics.
17. Charles Darwin – He developed natural selection theory.
18. Chromosomes – DNA is found in chromosomes in the cell.
19. The gene – Genes are units of inheritance.
20. Evolution – The term for changes in species over time.

Medium Level Answers

1. Genes are segments of DNA – DNA holds genetic information.
2. Natural selection allows the best-adapted organisms to survive.
3. An adaptation, like fur for warmth, helps an organism in its environment.
4. Helpful traits improve survival and reproduction.
5. Genes are inherited from both parents.
6. Genes vary slightly between individuals, causing differences.
7. Adaptation helps species survive in changing environments.
8. A gene is a segment of DNA; a chromosome is a structure of DNA.
9. Giraffes with long necks could reach food, which helped them survive.
10. Environmental changes can make survival difficult.
11. Mutations introduce new traits – Some mutations can be beneficial.
12. Natural selection favours traits that improve survival.
13. Survival of the fittest means the best-adapted survive and reproduce.
14. Poorly adapted organisms struggle to survive and may not reproduce.
15. A mutation is a change in DNA.
16. Traits that help survival become more common.
17. For example, peppered moths changing colour to blend in.
18. Selective breeding is human-controlled, while natural selection occurs naturally.
19. A characteristic controlled by genes.
20. Genes determine physical traits like height, eye colour.

Hard Level Answers

1. Mutations create new genetic traits, increasing variation.
2. Natural selection favours beneficial traits, changing gene frequencies.
3. Species adapt or die if the environment changes.
4. Variation allows species to adapt to environmental changes.
5. Selective pressures increase the frequency of beneficial genes.
6. Unhelpful traits decrease as affected organisms don’t survive as well.
7. A beneficial mutation spreads as affected organisms survive better.
8. Dominant genes show their trait with one copy; recessive need two copies.
9. Those better adapted survive and pass on genes.
10. Sexual reproduction combines genes from two parents, increasing diversity.
11. Speciation is when a species evolves into a new one.
12. Gene flow mixes genes, supporting diversity.
13. A niche affects survival needs, shaping evolution.
14. Genetic drift randomly changes gene frequencies.
15. Harsh environments can cause species to die out.
16. Favourable traits spread in a population.
17. Convergent evolution is when different species develop similar traits – e.g., wings in bats and birds.
18. Camouflage helps organisms blend into their surroundings.
19. Isolation prevents breeding, leading to new species.
20. Mutations allow bacteria to resist antibiotics, leading to antibiotic resistance.

These questions and answers provide Year 8 students with a solid understanding of the effects of genes and evolution, helping them grasp fundamental biology concepts and preparing them effectively for their Key Stage 3 exams.