Human Evolution - Competency-Based Question Bank (with Answers)

Section A: Case-Based Questions

Case Study 1: Fossil skull with small brain and prominent brow ridge (Homo erectus).

1. What does "Homo erectus" mean?
   • Answer: "Upright man" (referring to fully bipedal gait).
2. Cranial capacity comparison.
   • Answer: Homo erectus: 800-1100 cc. Modern man (Homo sapiens): Approx 1450 cc.
3. Designing: Timeline.
   • Answer: Homo habilis -> Homo erectus -> Homo neanderthalensis -> Homo sapiens.
4. Analysis: Significance of bipedalism.
   • Answer: Freed the hands for tool use/carrying, allowed for a higher line of sight, and was more energy-efficient for long-distance travel.
5. Did they use tools?
   • Answer: Yes, they made sophisticated stone tools like hand axes (Acheulean tools) and were the first to use fire.

Case Study 2: Lamarck vs Darwin on giraffe's neck. 6. Lamarck's view.

• Answer: "Acquired Character". He believed the neck stretched during the organism's life and this change was passed to offspring.

7. Darwin's view.
   • Answer: Natural Selection. Giraffes with naturally longer necks survived drought better (as they could reach leaves) and reproduced more.
8. Creating: Comic strip.
   • Answer: [Darwin: "Only the long-necked ones survived." Lamarck: "They just kept stretching until they grew."]
9. Critical Thinking: Why Lamarck rejected?
   • Answer: Experiments showed that changes in somatic cells (like cutting tails of mice) are not inherited; only changes in germ cells (DNA) are.
10. Example of non-inherited trait.
    • Answer: Pierced ears, scars, or knowledge/skills learned during a lifetime.

Section B: Assertion-Reasoning Questions

Directions: (a) Both A/R true, R explains A; (b) Both true, R doesn't explain A; (c) A true, R false; (d) A false, R true.

11. Assertion (A): Appendix is vestigial. Reason (R): Functional in ancestors for cellulose digestion.
    • Answer: (a) Both A and R are true and R is the correct explanation.
12. Assertion (A): Australopithecus is a connecting link. Reason (R): Character of both apes and humans.
    • Answer: (a) Both A and R are true and R is the correct explanation.
13. Assertion (A): Homologous organs show divergent evolution. Reason (R): Same structural origin, different functions.
    • Answer: (a) Both A and R are true and R is the correct explanation.
14. Assertion (A): Neanderthals were first to bury dead. Reason (R): Sense of culture.
    • Answer: (a) Both A and R are true and R is the correct explanation.
15. Assertion (A): Industrial Melanism is Natural Selection. Reason (R): Dark moths survived better in soot.
    • Answer: (a) Both A and R are true and R is the correct explanation.

Section C: Creating and Designing (Application & Analysis)

16. Designing: Cladogram.
    • Answer: [Fish -> Amphibian -> Reptile -> (Bird/Mammal)].
17. Creating: Archaeopteryx poster.
    • Answer: "Missing Link found. Has teeth and tail like a reptile, but feathers and wings like a bird."
18. Analysis: Homologous vs Analogous.
    • Answer: Homologous: Same origin, different function (Common ancestor). Analogous: Different origin, same function (Environment/Convergent evolution).
19. Designing: H. habilis vs H. sapiens table.
    • Answer: [H. habilis: 650-800cc, "Handy man", first tool maker. H. sapiens: 1450cc, complex culture, agriculture].
20. Visualisation: Forelimbs.
    • Answer: [Sketch showing pentadactyl limb pattern across bat, whale, and human].
21. Application: "Goosebumps".
    • Answer: Arrector pili muscles contract to fluff up fur (trapping heat or looking bigger); since we lost our fur, the response is vestigial.
22. Creating: Neanderthal story.
    • Answer: [Focus on group hunting, use of fire for warmth, and caring for the injured].
23. Analysis: Opposable Thumb.
    • Answer: Allowed for a "precision grip," enabling humans to make and use fine tools and eventually write.
24. Designing: CC Quiz.
    • Answer: [650-800: H. habilis. 900: H. erectus. 1450: H. sapiens].
25. Creating: Survival of Fittest for kids.
    • Answer: "Nature chooses the animals that have the best 'superpowers' for where they live."

Section D: Competency & Critical Thinking

26. Speciation.
    • Answer: Formation of new species. Isolation prevents interbreeding; separate mutations and selection lead to different traits until they can no longer mate.
27. Scenario: Antibiotic resistance.
    • Answer: Some bacteria have a natural mutation for resistance. When antibiotics are used, only these "fit" ones survive and reproduce, creating a resistant population.
28. Critical Thinking: Are humans still evolving?
    • Answer: Yes (e.g., lactose tolerance, wisdom teeth disappearing), but cultural/medical evolution is now faster than biological evolution.
29. Application: Carbon Dating.
    • Answer: Measures the decay of Carbon-14 in organic fossils to determine their age (up to 50,000 years).
30. Ontogeny vs Phylogeny.
    • Answer: Ontogeny: Development of an individual embryo. Phylogeny: Evolutionary history of a species.
31. Diagram Based: Galapagos Finches.
    • Answer: Different beaks evolved from a common ancestor to exploit different food sources (seeds, insects, nectar) on different islands.
32. Role of Mutation.
    • Answer: It is the primary source of new genetic variations upon which natural selection acts.
33. Analysis: Cro-Magnon.
    • Answer: They were identical to modern humans in anatomy, had advanced art (cave paintings), and used complex bone/stone tools.
34. Competency: "Living Fossils".
    • Answer: Species that have remained largely unchanged for millions of years (e.g., King Crab).
35. Case: Mountain isolation.
    • Answer: Geographical isolation leads to reproductive isolation over time.
36. Creating: Dinosaur extinction hypothesis.
    • Answer: True; the mass extinction of dinosaurs cleared ecological niches, allowing small mammals to diversify and grow.
37. Designing: Vestigial visual aid.
    • Answer: [Sketch pointing to tailbone (Coccyx), wisdom teeth, and nictitating membrane (eye corner)].
38. Application: Embryology evidence.
    • Answer: Early embryos of fish, birds, and humans look almost identical, suggesting a common vertebrate ancestor.
39. Critical Thinking: "Out of Africa" theory.
    • Answer: Suggests all modern humans originated in Africa and migrated to other continents. Supported by DNA evidence.
40. Analysis: Gene Pool.
    • Answer: The total set of unique alleles in a population.

Section E: Advanced Competency

41. Scenario: Artificial vs Natural Selection.
    • Answer: Artificial: Humans choose traits (fast). Natural: Environment chooses traits (slow).
42. Designing: Camouflage model.
    • Answer: Use green and brown colored buttons on a green lawn; birds (students) will pick up more brown ones.
43. Application: Embryo gill slits.
    • Answer: Remnants of our aquatic ancestry; in humans, they develop into parts of the ear and throat.
44. Creating: Timeline.
    • Answer: [Cenozoic Era: Age of Mammals and Humans].
45. Case Study: Sickle Cell Heterozygote advantage.
    • Answer: People with one sickle-cell gene (carriers) are resistant to Malaria, so the gene stays in the population where malaria is common.
46. Genetic Drift.
    • Answer: Random changes in gene frequency in small populations (by chance, not selection).
47. Critical Thinking: Man from monkeys?
    • Answer: No, both evolved from a common ancestor that was neither a modern monkey nor a modern man.
48. Analysis: Ape vs Human jaw.
    • Answer: Ape: U-shaped, protruding (Prognathous). Human: Semi-circular, flatter (Orthognathous).
49. Designing: Brain size chart.
    • Answer: [Australopithecus (450) -> H. habilis (700) -> H. erectus (900) -> H. sapiens (1450)].
50. Creating: Future Human.
    • Answer: [E.g., Larger head, smaller jaw, longer fingers for typing, weaker muscles].