Cells, Genes & Evolution
From the inside of a cell to the logic of natural selection.
What is generally considered the basic unit of life?
Natural selection is easy to state and easy to get slightly wrong. These ten questions cover the mechanism itself and the observations that support it.
Natural selection needs only three things to be true: individuals vary, some of that variation is inherited, and it affects how many offspring they leave. Given those, the makeup of a population has to shift over generations. The logic is simple enough that Darwin's supporters were reportedly annoyed at not having thought of it first. The common misunderstandings are worth knowing too. Individuals do not evolve, populations do. Selection cannot plan ahead. Fitness is measured in surviving offspring rather than strength. This quiz works through the mechanism, the classic evidence from finches and fossils, and the version of the story that Lamarck got wrong.
Every question in this quiz is listed below with its correct answer and the reasoning behind it. Play first if you would rather not see the answers — or read through as a study sheet.
Play it insteadAnswer: D. HMS Beagle
Why: Darwin sailed from 1831 to 1836, invited largely as a dining companion for captain Robert FitzRoy. The specimens and notebooks from those five years supplied him with material for the rest of his life.
Answer: C. Inherited variation that affects survival and reproduction
Why: Only heritable differences can be passed on, so selection works by changing which variants are common in the next generation. An individual never evolves during its life; the population it belongs to does.
Answer: B. That traits acquired during life are passed to offspring
Why: Lamarck suggested a giraffe stretching for high leaves would pass a longer neck to its young. He was right that species change over time, which put him well ahead of most of his contemporaries, but wrong about how.
Answer: A. Analogous structures
Why: Both are wings, but they are built from completely different tissue and evolved separately for the same job, which is convergent evolution. Homologous structures, such as a bat wing and a human arm, share the same underlying bone plan inherited from a common ancestor.
Answer: D. Beak size and shape
Why: Beaks range from heavy seed-crushers to fine probes for insects, with each form suiting the food available on its island. Peter and Rosemary Grant later measured average beak size shifting within a couple of years on Daphne Major as drought changed which seeds were left.
Answer: C. Resistant individuals survive the drug and pass on their genes
Why: A few cells in any large population already carry a resistance mutation or a plasmid picked up from elsewhere; the drug clears out the rest and leaves them room to multiply. It is natural selection running fast enough to watch across a weekend in a lab.
Answer: B. Success in leaving surviving offspring
Why: Fitness is counted in descendants, not muscle, so a small short-lived animal that breeds prolifically is fitter than a powerful one that leaves none. This is why the phrase "survival of the fittest", which Darwin borrowed from Herbert Spencer, misleads so many people.
Answer: A. A population becoming separated so the groups stop interbreeding
Why: Once gene flow stops, mutation and selection accumulate differently in each group until they can no longer produce fertile offspring together. Rivers changing course, mountains rising and sea levels cutting off islands have all done this.
Answer: D. Random change in how common gene variants are between generations
Why: Drift is chance rather than advantage deciding which variants get passed on, and it dominates in small populations. A founder group settling a new island can end up with a strange mix of variants purely because of who happened to be aboard.
Answer: C. A body part that has lost most of its original function
Why: The hip bones buried in a whale and the stunted wings of flightless birds are leftovers from ancestors that used them fully. They shrink rather than vanish because once a structure costs almost nothing there is little pressure to remove it.
Evolution & Natural Selection has 10 questions and takes about 8 minutes to finish. It is rated Medium and sits in our Biology category.
Each of the 10 correct answers adds 10 XP, up to 100 XP for a clean run. Wrong answers cost you nothing, and your full question-by-question review is shown at the end.
Yes. All 10 questions carry a written explanation of why the correct answer is right, so the quiz works as a study sheet as well as a test.
Yes, as often as you like. The questions and the answer options are reshuffled on each run, and you can use Practice Mistakes afterwards to retry only the ones you missed. No account is needed to play.
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