High school biology practice test: 8 free questions with worked answers

The daily High School Biology paper has 8 original questions worth 25 to 35 marks. It covers cell structure and transport, cell division, enzymes, photosynthesis, respiration, genetics, evolution, ecology, homeostasis, the nervous and circulatory systems, and disease and immunity: a close match for a first-year high school biology course.

What's on a high school biology test

Courses vary by state. In states that use the Next Generation Science Standards (NGSS), high school life science has four parts: how molecules and cells make organisms work, how ecosystems pass energy and matter around, how traits are inherited, and how evolution produces the variety of life.

Free biology practice test: 8 questions

We wrote these questions for this page. Give yourself 25 minutes, then check the answers below.

1. Which organelle makes proteins, and which releases energy from glucose in aerobic respiration?
2. Some red blood cells are dropped into very salty water. What happens to them, and why?
3. Write the word or symbol equation for photosynthesis.
4. Why does an enzyme stop working when it is heated well above body temperature?
5. One DNA strand reads ATGCCA. What is the base sequence of the matching strand?
6. Brown eyes (B) are dominant to blue (b). Two parents are both Bb. What is the chance their child has blue eyes?
7. Producers in a food chain capture 50,000 kJ of energy. Roughly how much reaches the secondary consumers?
8. Explain how bacteria can become resistant to an antibiotic.

Biology practice test answers

1. Ribosomes and mitochondria. Ribosomes build proteins from amino acids, following instructions copied from DNA. Mitochondria carry out aerobic respiration, releasing the energy cells use. Explore a cell in the Cell Simulator.

2. They shrink. The water outside has a lower concentration of water than the cytoplasm, so water leaves each cell by osmosis, moving across the membrane from where there is more water to where there is less.

3. Carbon dioxide + water → glucose + oxygen, using light energy absorbed by chlorophyll. As symbols: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Aerobic respiration is the same equation in reverse.

4. Strong heating breaks the bonds holding the protein in its folded form. The pocket where the substrate binds is bent out of shape, and the substrate can't bind any more. The enzyme is denatured, and cooling it down again doesn't repair it.

5. TACGGT. A pairs with T and C pairs with G, so each base is swapped for its partner. The DNA Translator shows the matching strand and the protein it codes for.

6. 1 in 4, or 25%. Each parent passes on B or b with equal chance. The Punnett square has four equally likely boxes, and only bb gives blue eyes. The other three, BB, Bb and Bb, give brown, so the ratio is 3 brown to 1 blue.

Try a genetics question from our Genetics and DNA course, then press Mark. The Genetics Cross Calculator draws Punnett squares for any cross.

7. About 500 kJ. Only around 10% of the energy passes from one level to the next, so producers to primary consumers is 5,000 kJ, and on to secondary consumers is about 500 kJ. The rest is used in respiration and lost as heat, or stays in parts that aren't eaten.

8. In any population of bacteria, a few may carry a mutation that lets them survive the antibiotic. The antibiotic kills the rest, the survivors reproduce, and their offspring inherit the resistance. Over many generations most of the population becomes resistant. That is natural selection, which you can watch in the Natural Selection simulator.

Biology Regents and other state tests

Many states give a biology end-of-course exam, so ask your teacher which test you will take. New York's newer Regents exam is Life Science: Biology, with past papers from June and August 2026. The August 2026 paper ran on Wednesday, August 19, from 12:30 to 3:30 p.m., and each past paper comes with a scoring key, rating guide and conversion chart, so you can mark a real paper yourself.

Use the daily paper as a short timed practice test

1. Open today's High School Biology paper and work to the suggested time, 35 to 40 minutes.
2. Answer explain questions with a cause and its effect, linked by "so" or "because".
3. Mark it with the mark scheme and note the topic behind each lost mark.
4. Fill gaps with the Cell Biology, Genetics and DNA and Human Physiology courses.

Common biology mistakes

• Saying cells "want" or "need" water in osmosis: describe where there is more water and where there is less.
• Saying enzymes are killed: they are proteins, not living things, so they are denatured.
• Mixing up genotype and phenotype: Bb is a genotype; brown eyes is the phenotype.
• Saying bacteria choose to become resistant: the mutation is already there, and the antibiotic selects it.
• Writing respiration as only happening in animals: plants respire too.

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