Also called: TEAS-style biology · HESI A2-style biology · pre-nursing biology
Free Biology for nursing entrance exams multiple-choice practice questions with hints and explanations, at three levels: key terms and facts, applying the concepts, cases and analysis.
What is the single most important way to prevent the spread of infection in hospitals?
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The cell theory says that all living things are made of cells, the cell is the basic unit of life, and every cell comes from an existing cell.
Prokaryotes (bacteria) have no nucleus: their DNA lies in the cytoplasm. Eukaryotes (plants, animals, fungi) keep their DNA in a nucleus and have membrane-bound organelles.
Answer: Mitochondria. Mitochondria release most of the cell’s ATP. Chloroplasts and cell walls belong to plant cells, and lysosomes digest waste rather than supply energy.
The cell membrane is a phospholipid bilayer with proteins in it. It is selectively permeable.
A red blood cell in a hypertonic solution (saltier outside) shrinks; in a hypotonic solution (pure water) it swells and may burst; in an isotonic solution it stays the same.
Answer: Water leaves the cell and it shrinks. Water moves by osmosis towards the side with more solute, so it leaves the cell. Swelling would happen in a hypotonic solution, the opposite situation.
Mitosis makes two identical diploid cells for growth and repair: prophase, metaphase (chromosomes line up in the middle), anaphase (chromatids pulled apart), telophase. DNA is copied earlier, in the S phase of interphase.
Meiosis makes four genetically different haploid gametes (23 chromosomes in humans) through two divisions. Crossing over in prophase I mixes alleles.
DNA is a double helix of nucleotides with the bases A, T, G and C. A pairs with T and G with C. RNA is single-stranded and uses uracil (U) instead of thymine.
Protein synthesis: transcription copies a gene into mRNA in the nucleus; translation at the ribosome reads mRNA codons (three bases each) and joins amino acids.
Answer: Meiosis. Meiosis halves the chromosome number. Mitosis keeps all 46, binary fission is how bacteria divide, and transcription makes RNA, not cells.
Each person has two alleles of each gene, one from each parent. A dominant allele (A) shows even with one copy; a recessive allele (a) shows only as aa. AA and aa are homozygous; Aa is heterozygous. The genotype is the alleles; the phenotype is the trait you see.
Use a Punnett square. Aa × Aa gives 1 AA : 2 Aa : 1 aa, a 3 : 1 phenotype ratio. Aa × aa gives 1 : 1.
Special cases: incomplete dominance blends (red × white → pink); codominance shows both (blood type AB); X-linked recessive traits such as haemophilia are more common in males, who have one X.
Two parents who are both Aa have a child. What is the chance that the child shows the recessive trait?
Each parent gives A or a, each with probability ½.
The four equally likely cells are AA, Aa, aA and aa.
Only aa shows the recessive trait: 1 of 4 cells.
1/4, or 25%.
Enzymes are protein catalysts that lower the activation energy. Each fits its substrate at the active site; heat or a wrong pH changes the shape (denaturation) and stops it working.
Bacteria are prokaryotic cells that divide by binary fission and can be treated with antibiotics. Viruses are DNA or RNA in a protein coat; they need a host cell and are not affected by antibiotics. Fungi include yeasts and moulds.
Answer: Colds are caused by viruses, which lack the structures antibiotics attack. Antibiotics target bacterial cell walls, ribosomes and enzymes. Viruses have none of these, so antibiotics cannot stop them.
A hypothesis is a testable prediction (“If plants get more light, then they grow taller”). The independent variable is what you change; the dependent variable is what you measure; controlled variables stay the same. A control group gives a baseline.
Good experiments use large samples, repeat measurements, random assignment and, in trials, placebos and double blinding. Results support a hypothesis but never prove it absolutely.
Correlation is not causation: two things can rise together because a third factor drives both.
Answer: Plant height. Height is measured, so it is the dependent variable. Fertiliser is the independent variable, and soil and water should be controlled.
Read every option before choosing: the wrong answers are often true statements that do not answer the question asked.
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What is the SI base unit of mass?
The kilogram (kg) is the SI base unit of mass. The gram is a smaller unit (1 kg = 1000 g), the pound is not metric, and the litre measures volume.
A study finds a positive correlation between hours of exercise and lung capacity. What does this mean?
A positive correlation means both variables tend to rise together. Correlation alone does not prove that one causes the other; a controlled experiment is needed for that.
Sucrose is broken down into glucose and fructose during digestion. What type of reaction is this?
Hydrolysis breaks a bond by adding water across it, as when sucrase splits sucrose. Dehydration synthesis is the reverse: it joins monomers and releases water.
The cell theory says that all living things are made of cells, the cell is the basic unit of life, and every cell comes from an existing cell.
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