Biology Test Cheat Sheet 2026

The 30 highest-yield Biology Test facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What does the Hardy-Weinberg principle predict about allele frequencies in a population? → They remain constant in the absence of evolutionary forces
2. A sarcomere is defined as the region between two consecutive: → Z discs
3. Which stage of cellular respiration produces the most ATP per glucose molecule? → Oxidative phosphorylation
4. Which of the following organelles contains its own DNA and ribosomes, supporting the endosymbiotic theory? → Mitochondria and chloroplasts
5. Which type of RNA carries amino acids to the ribosome during translation? → tRNA
6. What is a keystone species? → A species that greatly affects ecosystem balance
7. What is the term for the movement of water across a semipermeable membrane from low to high solute concentration? → Osmosis
8. What is the primary mechanism by which NK (natural killer) cells recognize and kill target cells? → Detecting absence of MHC class I ('missing self')
9. Which germ layer gives rise to the central nervous system, including the brain and spinal cord? → Ectoderm
10. What is the primary function of lysosomes? → Digesting cellular waste and foreign material
11. In fermentation, what serves as the final electron acceptor? → An organic molecule
12. What process describes the movement of water across a selectively permeable membrane? → Osmosis
13. The exchange of gases between the blood and body tissues is called: → Internal respiration
14. What does 'r-selected' reproductive strategy describe in ecology? → Species that produce many offspring with little parental investment
15. In a secretory cell like a pancreatic acinar cell, what is the correct order of organelles a newly synthesized digestive enzyme passes through before secretion? → Rough ER → Golgi → Secretory vesicle → Plasma membrane
16. Which organelle is unique to plant cells and is responsible for photosynthesis? → Chloroplast
17. How does a testcross help determine whether an organism showing a dominant phenotype is homozygous or heterozygous? → Cross it with a homozygous recessive organism and observe offspring
18. A researcher observes that a cell has an unusually high number of mitochondria. This cell most likely: → Has very high energy demands, such as a cardiac muscle cell
19. What is the primary function of the cerebellum in motor control? → Coordinating movement and maintaining balance and fine motor precision
20. What is neurulation? → The process by which the neural plate folds and fuses to form the neural tube
21. In marine conservation, what does the term 'no-take zone' refer to? → Marine protected areas where all extractive activities including fishing are prohibited
22. What term describes a species’ role in its environment? → Niche
23. Which of the following best describes an r-selected species? → Rapid reproduction, many offspring, little parental care, unstable environments
24. A cell has the genotype AaBb. If the two genes assort independently, what fraction of offspring from self-fertilization will be AABB? → 1/16
25. Which type of muscle tissue is characterized by involuntary control and intercalated discs? → Cardiac muscle
26. The bicuspid (mitral) valve controls blood flow between which two chambers? → Left atrium and left ventricle
27. Resource partitioning among competing species in the same habitat is an example of → Character displacement reducing direct competition
28. What is the primary function of the lymphatic system? → Return interstitial fluid to the bloodstream
29. Which vitamin is a precursor to the coenzyme NAD+? → Vitamin B3 (Niacin)
30. What is a food chain? → A series of steps in which organisms transfer energy by eating and being eaten