Ten questions on how living things are built and how they change, each connected to the level above and below it.
This quiz moves through biology at several scales: the parts of a cell and what they do, how genetic information is stored and copied, and the mechanism that explains the diversity of life. It sticks to well-established science and to the terms that recur across the whole subject. The explanations link each answer upward and downward, from molecule to cell to organism, because the connections are what make biology cohere rather than fragment into lists.
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: C. The cell
Why: Every living organism is made of one or more cells, and all cells come from existing cells. This is the central claim of cell theory.
Answer: D. In the nucleus
Why: The nucleus holds the chromosomes containing most of the cell's DNA. A small separate amount sits in the mitochondria.
Answer: A. The chloroplast
Why: Chloroplasts contain chlorophyll and convert light into chemical energy. Mitochondria do roughly the reverse, releasing energy from food.
Answer: D. The mitochondrion
Why: Mitochondria release usable energy from nutrients through respiration. They carry their own small genome, evidence they were once separate organisms.
Answer: C. Charles Darwin
Why: Darwin published On the Origin of Species in 1859. Alfred Russel Wallace arrived at the same mechanism independently and they presented jointly.
Answer: C. 23
Why: Humans have 23 pairs, making 46 chromosomes in total. Confusing the pair count with the total is the most common error here.
Answer: B. Single-celled organisms
Why: Bacteria are single cells without a nucleus, and most are harmless or useful. Viruses are not cells at all and cannot reproduce alone.
Answer: D. Two genetically identical cells
Why: Mitosis is ordinary cell division for growth and repair. Meiosis is the separate process producing sex cells with half the chromosomes.
Answer: A. An autotroph
Why: Autotrophs, such as plants, build food from simple inputs using light or chemicals. Heterotrophs, including all animals, must consume other organisms.
Answer: C. The circulatory system
Why: The circulatory system moves blood, carrying oxygen, nutrients and waste. It works closely with the respiratory system, which handles gas exchange.
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