All Free Biology MCQs with Answers

621. 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.

622. 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.

623. 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.

624. 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.

625. Lamarck published his theory of evolution in 1809 in the book

• A. The Origin of Species
• B. Principia Mathematica
• C. Philosophie Zoologique
• D. Zoonomia

Explanation: Philosophie Zoologique set out the first complete theory of evolution, fifty years before Darwin. The Origin of Species is Darwin's 1859 work, a confusion the options invite on purpose.

626. Lamarck explained the loss of functional eyes in cave dwelling animals as the result of

• A. sudden mutation
• B. natural selection
• C. hybridisation
• D. disuse over many generations

Explanation: By his law of use and disuse, an organ that stops being used wastes away and the loss is then inherited. Modern genetics rejects the inheritance, but disuse was Lamarck's consistent explanation for disappearing structures.

627. The scientist who cut off the tails of mice for twenty two generations to test Lamarck's idea was

• A. August Weismann
• B. Charles Darwin
• C. Gregor Mendel
• D. Louis Pasteur

Explanation: Every generation was still born with a tail, proving that injuries acquired during life are not transmitted. Weismann's experiment was a landmark in refuting the inheritance of acquired characters.

628. Acquired characteristics such as a blacksmith's strong arms are not passed to his children because they

• A. are always harmful
• B. do not alter the genes in the gametes
• C. are dominant traits
• D. affect only the nervous system

Explanation: Only changes in the DNA of eggs or sperm can be inherited, and exercise reshapes muscle without touching the germ line. This separation of soma from germ line is the fundamental objection to Lamarckism.

629. The first complete theory of evolution was proposed by

• A. Darwin
• B. Wallace
• C. Lamarck
• D. Aristotle

Explanation: Although wrong in mechanism, Lamarck was the first to offer a coherent, published explanation of how species change. Aristotle classified life but believed species were fixed, and Darwin came half a century later.

630. An acquired characteristic is

• A. a trait inherited from both parents
• B. a mutation in the germ cells
• C. a sex linked trait
• D. a change produced during an individual's lifetime by use, disuse or the environment

Explanation: Acquired traits develop within one lifetime, such as a tan or a learned skill, and vanish with the individual unless written into the gametes. Inherited traits, by contrast, arrive already coded in the DNA.