HESI A2 biology practice questions
- free questions here
- 10 free questions here
- topics covered
- 7 topics covered
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- October 2026 last updated
Ten free HESI A2 biology practice questions are below, each with an explanation. Biology is one of the optional science sections; your school decides whether you take it. It covers biological molecules, cell structure and organelles, cellular respiration and photosynthesis, mitosis and meiosis, genetics, the scientific method, and classification of organisms.
Biology
10 free biology questions
Answer, check, and read the explanation before you move on.
HESI A2 Biology
Question 1 of 10
Why can most animals not digest cellulose although they digest starch?
Not quite. The answer is B
Key takeaway
Cellulose is joined by β-1,4 glycosidic bonds, whose geometry most animal enzymes cannot hydrolyze. Starch has α-1,4 linkages.
Smooth endoplasmic reticulum is most active in which of the following functions?
Not quite. The answer is A
Key takeaway
Smooth ER lacks ribosomes and is active in lipid synthesis, Ca²⁺ storage and detoxification, as in liver hepatocytes. Protein synthesis on bound ribosomes belongs to rough ER.
The molecular oxygen released during photosynthesis comes from the splitting of which molecule?
Not quite. The answer is A
Key takeaway
Photolysis of water at Photosystem II releases O₂. Carbon dioxide is reduced into sugar and is not the source of the oxygen gas.
Which of the following best describes the result of meiosis?
Not quite. The answer is C
Key takeaway
Meiosis ends in four haploid cells derived from a diploid cell. Two identical cells is the product of mitosis.
In a dihybrid cross AaBb × AaBb with independent assortment and complete dominance, the phenotypic ratio is ________.
Not quite. The answer is A
Key takeaway
Two independently assorting genes each giving 3:1 combine to produce 9:3:3:1. The 3:1 ratio belongs to a monohybrid cross.
Which of the following statements is unfalsifiable and so cannot be a scientific hypothesis?
Not quite. The answer is D
Key takeaway
Beauty is an aesthetic judgement that cannot be observed and measured, so it cannot be falsified. The other statements can be tested.
Which statement correctly describes the writing of a binomial name such as Homo sapiens?
Not quite. The answer is B
Key takeaway
In a binomial, the genus is capitalized and the species name is lowercase, with both italicized. Reversing the capitalization is a common error.
Carbohydrates contain carbon, hydrogen and oxygen in approximately which ratio?
Not quite. The answer is B
Key takeaway
Carbohydrates follow the general formula CnH2nOn, giving a C:H:O ratio of about 1:2:1. Glucose, C6H12O6, is an example.
Which organelle is the site of ribosomal RNA synthesis and ribosomal subunit assembly?
Not quite. The answer is C
Key takeaway
The nucleolus is a dense, non-membrane-bound region of the nucleus that makes rRNA and assembles ribosomal subunits. The Golgi modifies and sorts proteins instead.
Glycolysis occurs in which part of the cell, and what is its net ATP yield?
Not quite. The answer is D
Key takeaway
Glycolysis takes place in the cytoplasm and nets 2 ATP per glucose. The much larger ATP yield comes later from oxidative phosphorylation.
Coverage
What HESI A2 biology covers
The topics our practice questions for this section are written to.
- Describe biological molecules (carbohydrates, lipids, proteins, nucleic acids)
- Describe cell structure and organelle function
- Describe cellular respiration and photosynthesis
- Describe cell division (mitosis and meiosis)
- Apply genetics and heredity (Mendelian inheritance, DNA, RNA)
- Describe the scientific method and basic biology terminology
- Describe classification of organisms and microbiology basics
Tips
How to score higher on biology
- Match each organelle to one job: ribosomes make protein, the nucleolus builds ribosomes, smooth ER makes lipids.
- Know where each stage of cellular respiration happens and roughly what it yields.
- Practise Punnett squares until a dihybrid cross takes under a minute.
- Mitosis keeps the chromosome number; meiosis halves it.
FAQ
HESI A2 biology FAQ
Is biology on the HESI A2?
Biology is one of the science sections Elsevier offers. Each school decides which sections its applicants take.
What biology topics are on the HESI A2?
Biological molecules, cells and organelles, cellular respiration and photosynthesis, cell division, genetics, the scientific method, and classification.
How many questions are in HESI A2 biology?
We have not found an official count we can cite. Your school or testing center can confirm the section length.
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