Free Evolution MCQs with Answers

21. Evolution is best defined as

• A. gradual genetic change in populations over successive generations
• B. the growth of an individual from birth to adulthood
• C. the seasonal migration of animals
• D. the extinction of a single species

Explanation: Evolution acts on populations across generations, changing allele frequencies over time. An individual's own growth or a single extinction event is not evolution, since neither involves inherited change passed through a population.

22. The theory of evolution by natural selection was proposed independently by Darwin and

• A. Lamarck
• B. Alfred Russel Wallace
• C. Gregor Mendel
• D. Thomas Huxley

Explanation: Wallace reached the same conclusion while collecting in the Malay Archipelago, and his letter prompted the joint reading of both men's work in 1858. Mendel discovered inheritance, and Huxley defended Darwin, but neither proposed natural selection.

23. The study of the geographical distribution of organisms, such as the concentration of marsupials in Australia, is called

• A. palaeontology
• B. embryology
• C. biogeography
• D. taxonomy

Explanation: Biogeography explains why isolated landmasses evolve their own distinctive faunas, a pattern Darwin and Wallace both used as evidence. Palaeontology is the study of fossils and embryology of development, different branches of the same supporting case.

24. The smallest unit in which evolution occurs is the

• A. individual
• B. cell
• C. organelle
• D. population

Explanation: An individual's genes are fixed for life, so it cannot evolve; what changes is the genetic makeup of populations as generations pass. This is why evolutionary biology always speaks of populations, never of single organisms.

25. The fossil sequence of which animal is one of the most completely documented examples of gradual evolution?

• A. The horse
• B. The pigeon
• C. The frog
• D. The earthworm

Explanation: From the small multi toed Hyracotherium to the single hooved Equus, horse fossils record increasing size, fewer toes and taller teeth as grasslands spread. No other lineage offers so complete a series from North America and Europe.

26. The fact that almost all organisms use the same genetic code is evidence for evolution because it suggests that

• A. all species were created separately
• B. all life shares a common ancestor
• C. mutation is impossible
• D. DNA is chemically unstable

Explanation: A universal code is exactly what common descent predicts: one original system inherited by every branch of life. If organisms had separate origins there would be no reason for bacteria and humans to translate codons identically.

27. Which of the following is NOT used as evidence for evolution?

• A. The fossil record
• B. Comparison of DNA sequences
• C. The growth of an individual from birth to adulthood
• D. The presence of vestigial organs

Explanation: Fossils, molecular comparisons and vestigial structures all reveal change across generations. An individual growing up changes neither its genes nor its species, so ontogeny alone is not evolutionary evidence.

28. Vestigial organs are structures that

• A. are equally useful in every species
• B. appear only in fossils
• C. function better than they once did
• D. have lost most or all of their original function in the course of evolution

Explanation: The human appendix, wisdom teeth and ear muscles persist as reduced remnants of structures that served our ancestors. Their existence is evidence of descent with modification, since a designer would have no reason to include them.

29. The different beak shapes of Darwin's finches on the Galapagos Islands reflect

• A. adaptation to different food sources
• B. random accidents with no cause
• C. differences in the age of the birds
• D. infection by different parasites

Explanation: Seed crackers, insect pickers and cactus feeders each carry a beak matched to their food, descendants of one ancestor that radiated into vacant niches. The pattern shows natural selection shaping a structure to its use.

30. Which feature of natural populations provides the raw material for evolution?

• A. All individuals being genetically identical
• B. Heritable variation among individuals
• C. The absence of competition
• D. Unlimited food supply

Explanation: Without heritable differences there is nothing for selection to choose between, so variation produced by mutation and recombination is the essential fuel. Identical populations, however large, cannot evolve.