MDCAT Biology chapter 7: Biology · Evolution MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
31 exam-style questions on Biology · Evolution, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. Charles Darwin published 'On the Origin of Species', setting out his theory of evolution by natural selection, in
A
1809
B
1859
C
1865
D
1900
Show answer
Answer: B. The Origin of Species appeared in 1859. 1809 is the year of Lamarck's 'Philosophie Zoologique' (and of Darwin's birth), 1865 the year Mendel presented his work, and 1900 the year Mendel's work was rediscovered.
2. The wing of a bird and the wing of an insect are both used for flight, but the insect wing contains no bones and develops in a completely different way. These wings are
A
homologous organs, produced by convergent evolution
B
homologous organs, produced by divergent evolution
C
analogous organs, produced by convergent evolution
D
analogous organs, produced by divergent evolution
Show answer
Answer: C. Analogous organs do the same job but differ in structure and origin; they arise when unrelated groups evolve similar solutions to the same need, which is convergent evolution. Homologous organs, such as the forelimbs of a bird and a bat, share a basic plan from a common ancestor and reflect divergent evolution.
3. From Malthus's essay on population, Darwin took the idea that
A
the earth is very old and changes slowly over long periods
B
characters acquired during life are passed to the offspring
C
populations tend to increase faster than their food supply
D
traits are inherited as separate units from each parent
Show answer
Answer: C. Malthus argued that populations grow faster than their food supplies, so there must be a struggle for existence; Darwin applied this to all living things. The great age of the earth came from Lyell's geology, and inheritance in units from Mendel.
4. According to the biological species concept, two populations belong to different species when they
A
differ clearly in body size, shape or colour
B
live in different geographical areas
C
feed on different kinds of food plants
D
cannot interbreed to give fertile offspring
Show answer
Answer: D. A species is a group of interbreeding (or potentially interbreeding) organisms that produce fertile offspring and are reproductively isolated from other groups. Populations can look different or live apart and still be one species.
5. The number of amino acid differences between a protein of humans and the same protein in four other species, W, X, Y and Z, is 1, 9, 17 and 31 respectively. Which conclusion is best supported?
A
Z must have evolved from humans, since it differs from them the most
B
W shared a common ancestor with humans more recently than Z did
C
W is the direct ancestor from which humans evolved
D
X and Y are as closely related to humans as W is
Show answer
Answer: B. The fewer the differences in amino acid (or DNA) sequence, the more recently two species shared a common ancestor, so W is the closest relative and Z the most distant. A close relative is not an ancestor, and living species did not evolve from one another.
6. A patient stops taking a course of antibiotics after two days. The infection returns a week later and the same antibiotic no longer clears it. The best explanation is that
A
the bacteria learnt to resist the drug during treatment
B
the few resistant bacteria survived and then multiplied
C
the antibiotic caused the mutations needed to resist it
D
the patient's body became immune to the antibiotic
Show answer
Answer: B. Resistant variants arise by chance mutation before the drug is used. The antibiotic kills the susceptible bacteria and leaves the resistant ones to multiply: natural selection in action. Bacteria do not 'learn', and the drug does not produce the mutations it selects.
7. The finches of the Galápagos Islands have different beak shapes suited to different foods, although they are thought to have descended from one mainland species. This is an example of
A
adaptive radiation
B
convergent evolution
C
artificial selection
D
inheritance of acquired characters
Show answer
Answer: A. One ancestral species spread into different islands and food niches and gave rise to several species, each adapted to its own niche: adaptive radiation (divergent evolution). Convergent evolution is the opposite, unrelated groups coming to look alike.
8. A horse and a donkey can mate and produce a mule, but mules are sterile. This shows that horses and donkeys
A
are a single species, since they are able to interbreed
B
are separate species, isolated by hybrid sterility
C
are kept apart only by geographical barriers
D
are kept apart by different courtship behaviour
Show answer
Answer: B. Members of one species interbreed to give fertile offspring. Because the mule is sterile, genes cannot flow between horses and donkeys; this post-zygotic barrier (hybrid sterility) keeps them separate species.
9. In undisturbed layers of sedimentary rock, fossils found in the deeper layers are generally
A
younger than those in the upper layers
B
the same age as those in the upper layers
C
more complex than those in the upper layers
D
older than those in the upper layers
Show answer
Answer: D. Sediments settle in order, so lower layers were laid down first and their fossils are older. Older layers also tend to hold simpler forms, which supports gradual change over time.
10. Which of these is a vestigial organ in humans?
A
the patella (knee cap)
B
the coccyx (tail bone)
C
the sternum (breast bone)
D
the clavicle (collar bone)
Show answer
Answer: B. The coccyx, a few small fused vertebrae at the end of the backbone, is the remnant of a tail present in our ancestors (and in the early human embryo). The kneecap, breastbone and collar bone all have clear supporting roles.
31, each with the answer and a short explanation, across 2 topics: Theories of evolution, Evidence and speciation. Every chapter test draws ten of them, so you can take it many times.
Is the MDCAT Biology chapter 7 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
