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Twenty representative CLEP Biology questions, each with the answer and a short explanation of why the wrong choices trap test-takers.
By Alex Stone5 min readLast fact-checked January 1970
Twenty practice questions for CLEP Biology, in the real exam's style. Score 16 of 20 here and you are in passing range. Miss more than four, and the pattern of your misses points straight at the topic to review next. Every question below is explained on video, including why the wrong answers trap most test-takers.
What students preparing for this exam tell us is that steady practice in the exam's format, with an explanation for every miss, is what moves a score. Use these the same way: answer, check, and read why the wrong choices are tempting. For the full plan around them, see the CLEP Biology pillar guide.
Watch the full video walkthrough above, then test yourself on the twenty questions below. Each one is explained on the video, including why the wrong answers trap most test-takers.
1. The basic structural and functional unit of all living things is the: Cell. The cell is the basic unit of life. All organisms, from bacteria to humans, are made of one or more cells.
2. The part of the cell that contains its genetic material is the: Nucleus. The nucleus houses the cell's DNA. The mitochondrion, by contrast, produces energy, and ribosomes build proteins.
3. The organelle that produces most of the cell's energy is the: Mitochondrion. The mitochondrion produces most of the cell's usable energy through cellular respiration, which is why it is called the powerhouse of the cell.
4. The process by which plants convert sunlight into chemical energy is called: Photosynthesis. Photosynthesis uses sunlight, water, and carbon dioxide to make sugar and release oxygen. It takes place in the chloroplasts of plant cells.
5. Proteins that speed up chemical reactions in living things are called: Enzymes. Enzymes are biological catalysts that speed up reactions without being used up. Each enzyme fits a specific substrate, like a lock and key.
6. The molecule that carries genetic information in living cells is: Dna. DNA carries the genetic code, stored as a sequence of four bases. Its double-helix structure was described by Watson and Crick in 1953.
7. The monk whose pea-plant experiments founded the study of heredity was: Gregor Mendel. Gregor Mendel's experiments with pea plants revealed how traits pass from parents to offspring, earning him the title father of genetics.
8. A version of a gene, such as for brown or blue eyes, is called an: Allele. An allele is one version of a gene. Offspring inherit one allele from each parent, and the combination determines the trait.
9. An organism's observable physical traits make up its: Phenotype. The phenotype is the set of observable traits, like height or eye color. The genotype, by contrast, is the underlying genetic makeup.
10. The cell division that produces sex cells with half the normal chromosomes is: Meiosis. Meiosis produces egg and sperm cells, each with half the chromosomes, so fertilization restores the full number. Mitosis, by contrast, makes identical body cells.
11. The process by which organisms better suited to their environment tend to survive and reproduce is: Natural Selection. Natural selection is the mechanism of evolution Darwin described: heritable traits that improve survival and reproduction become more common over generations.
12. A heritable change in a DNA sequence, which can introduce new traits, is a: Mutation. A mutation is a change in DNA. Most are neutral or harmful, but some create new traits that natural selection can act on, fueling evolution.
13. Structures with a shared origin, like a whale's flipper and a human arm, are called: Homologous Structures. Homologous structures share a common evolutionary origin even when they serve different functions, evidence that the species share an ancestor.
14. The two-part Latin naming system for species was developed by: Carl Linnaeus. Carl Linnaeus created binomial nomenclature, the two-part Latin naming system, for example Homo sapiens, still used to classify every species.
15. The broadest level in the modern classification of living things is the: Domain. Modern classification runs from the broadest level, domain, down to the most specific, species. The three domains are Bacteria, Archaea, and Eukarya.
16. All the living and nonliving things interacting in an area make up an: Ecosystem. An ecosystem includes all the organisms in an area plus their physical environment, like soil, water, and climate, all interacting together.
17. Organisms that make their own food, like green plants, are called: Producers. Producers, mainly plants and algae, make their own food through photosynthesis and form the base of the food chain. Consumers must eat other organisms.
18. The human body system that transports blood, oxygen, and nutrients is the: Circulatory System. The circulatory system, driven by the heart, transports blood carrying oxygen and nutrients to cells and carries wastes away.
19. The process by which organisms maintain a stable internal environment is called: Homeostasis. Homeostasis is the maintenance of a steady internal state, like body temperature or blood sugar, despite changes in the outside environment.
20. The part of a plant where photosynthesis mainly occurs is the: Leaf. Leaves are the main site of photosynthesis, packed with chloroplasts. Roots anchor the plant and absorb water, while flowers handle reproduction.
The point of twenty questions is not the twenty, it is the pattern. Mark which topic each miss came from, then spend your next session on that topic alone. None of it requires starting over, only tightening the spots that cost you points.
A single twenty-question set is a snapshot, not a study plan. To pass with margin you need volume: enough questions, in the exam's format, with explanations that turn a wrong answer into a correction. That is what Flying Prep's CLEP Biology practice is built for: every question explained, with a free trial before you decide.
About 16. A passing score works out to roughly 80 percent, so clearing 16 of 20 consistently across a few sets puts you in passing range.
No. These are representative practice questions in the exam's style. The real exam draws from a much larger pool, which is why practice volume, not memorizing any single set, is what moves your score.
The Flying Prep CLEP Biology question bank has every question explained and reviewed against the current outline. Start a free trial and drill the topics your misses point to.
Alex Stone founded Flying Prep after earning her bachelor's degree from Thomas Edison State University using 27 CLEP and DSST exams to test out of 99 credits. She built Flying Prep to help working adults and returning students take the same path.
See the full CLEP Biology study guide for the practice quiz, study plan, and credit details.