I85PREP
⌘ K
VCE Biology study materials
VCE Biology study resources

VCE Biology practice questions

One question at a time. Build your VCE Biology understanding.

First 50 of 194 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Unit 1

Which structure controls the passage of substances into and out of a eukaryotic cell?

  1. The ribosome
  2. The plasma membrane Correct answer.
  3. The Golgi apparatus
  4. The nucleus

Explanation

The plasma membrane forms the outer boundary of the cell and is selectively permeable because of its phospholipid bilayer with embedded proteins, so it regulates which substances enter and leave. The other structures listed carry out different roles inside the cell.

Question 2Unit 1

A cell is placed in a solution and its volume decreases over time. Which description of the surrounding solution best explains this observation?

  1. It is hypertonic, so water leaves the cell by osmosis Correct answer.
  2. It contains active transport pumps that push water out
  3. It is hypotonic, so water enters the cell by osmosis
  4. It is isotonic, so water moves equally in both directions

Explanation

Osmosis moves water from a region of higher water concentration to one of lower water concentration across a semipermeable membrane. In a hypertonic solution the external water concentration is lower, so net water loss causes the cell to shrink.

Question 3Unit 1

Which organelle is the main site of aerobic respiration and ATP production in a eukaryotic cell?

  1. The mitochondrion Correct answer.
  2. The chloroplast
  3. The smooth endoplasmic reticulum
  4. The lysosome

Explanation

Mitochondria contain the enzymes and membranes needed for the later stages of aerobic respiration, including the electron transport chain, which generates most of the cell's ATP. Other organelles perform unrelated functions.

Question 4Unit 1

Which statement best describes the fluid mosaic model of the plasma membrane?

  1. A solid layer of carbohydrate covers the cell surface
  2. A rigid double layer of protein surrounds the cell
  3. Phospholipids are fixed in place with no movement
  4. Proteins are embedded in or attached to a fluid phospholipid bilayer Correct answer.

Explanation

The fluid mosaic model describes a bilayer of phospholipids in which proteins float and are dispersed like tiles in a mosaic. The phospholipids and many proteins can move laterally, giving the membrane a fluid character.

Question 5Unit 1

A student observes a cell with a cell wall, a large permanent vacuole and chloroplasts. To which group does this cell most likely belong?

  1. A fungal cell
  2. A plant cell Correct answer.
  3. A bacterial cell
  4. An animal cell

Explanation

The combination of a cellulose cell wall, a large permanent vacuole and chloroplasts is characteristic of plant cells. Animal cells lack walls and chloroplasts, while fungal and bacterial cells lack chloroplasts and large vacuoles of this type.

Question 6Unit 1

Which process allows a large polar molecule such as glucose to enter a cell down its concentration gradient without direct input of ATP?

  1. Facilitated diffusion through a carrier protein Correct answer.
  2. Simple diffusion through the phospholipid bilayer
  3. Active transport against the gradient
  4. Osmosis through the bilayer

Explanation

Large polar molecules cannot readily cross the hydrophobic core of the bilayer, so they rely on membrane proteins. Facilitated diffusion uses these proteins to move substances down their concentration gradient and does not require ATP.

Question 7Unit 1

Which statement correctly distinguishes prokaryotic from eukaryotic cells?

  1. Prokaryotic cells are always larger than eukaryotic cells
  2. Prokaryotic cells contain mitochondria, whereas eukaryotic cells do not
  3. Prokaryotic cells lack a membrane-bound nucleus, whereas eukaryotic cells have one Correct answer.
  4. Prokaryotic cells have a nucleus, whereas eukaryotic cells lack one

Explanation

The defining difference is the nucleus: prokaryotes keep their DNA in a nucleoid region without a surrounding membrane, while eukaryotes enclose DNA within a nuclear envelope. Prokaryotes also lack membrane-bound organelles such as mitochondria.

Question 8Unit 1

An enzyme-catalysed reaction slows sharply when the temperature is raised well above the optimum. What is the best explanation?

  1. The enzyme's active site changes shape as bonds break, so substrate no longer fits Correct answer.
  2. The enzyme is used up in the reaction
  3. The substrate molecules stop moving at high temperature
  4. The activation energy of the reaction increases permanently

Explanation

High temperatures disrupt the hydrogen bonds and other interactions that maintain an enzyme's three-dimensional shape. The active site loses its complementary shape, substrate binding falls and the rate of reaction declines.

Question 9Unit 1

Which statement best explains why enzymes are described as highly specific?

  1. Enzymes are consumed and must be replaced after each reaction
  2. The active site is complementary in shape and chemistry to a particular substrate Correct answer.
  3. Enzymes can catalyse any reaction in the cell
  4. Enzymes lower the activation energy of all reactions equally

Explanation

Specificity arises because the active site has a shape and chemical environment that only certain substrates can bind to, forming an enzyme-substrate complex. A mismatched substrate cannot bind effectively, so the enzyme acts on a narrow range of reactions.

Question 10Unit 1

A competitive inhibitor is added to an enzyme-catalysed reaction. Which change would restore the reaction rate?

  1. Lowering the temperature below the optimum
  2. Adding more inhibitor
  3. Removing the enzyme's cofactor
  4. Increasing the substrate concentration Correct answer.

Explanation

A competitive inhibitor binds to the active site, competing with the substrate. Raising substrate concentration increases the chance that substrate, rather than inhibitor, occupies the active site, so the rate can be restored.

Question 11Unit 1

Which molecule stores genetic information in most cells and has the sugar deoxyribose?

  1. ATP
  2. A monosaccharide
  3. DNA Correct answer.
  4. A phospholipid

Explanation

DNA is a nucleic acid built from nucleotides containing deoxyribose sugar, a phosphate group and a nitrogenous base. It carries the hereditary instructions for the cell.

Question 12Unit 1

In a DNA molecule, adenine pairs with which base, and how many hydrogen bonds form between them?

  1. Guanine, with three hydrogen bonds
  2. Uracil, with two hydrogen bonds
  3. Thymine, with two hydrogen bonds Correct answer.
  4. Cytosine, with two hydrogen bonds

Explanation

Base pairing in DNA follows complementary rules: adenine pairs with thymine and guanine pairs with cytosine. Adenine-thymine pairs are held by two hydrogen bonds, while guanine-cytosine pairs have three.

Question 13Unit 1

A DNA strand has the sequence 5'-ATGCC-3'. What is the sequence of the complementary strand?

  1. 3'-UACGG-5'
  2. 3'-GCAAT-5'
  3. 3'-ATGCC-5'
  4. 3'-TACGG-5' Correct answer.

Explanation

Complementary base pairing means A pairs with T, T with A, G with C and C with G, and the two strands run antiparallel. Applying this to ATGCC gives TACGG, written antiparallel to the original strand.

Question 14Unit 1

Which statement best describes the relationship between a gene and a protein?

  1. Each protein is made of many genes joined together
  2. A gene carries the sequence information used to build a specific protein Correct answer.
  3. One gene always produces many unrelated proteins
  4. Genes are made of protein and stored in the cytoplasm

Explanation

A gene is a length of DNA whose base sequence encodes the amino acid sequence of a polypeptide. The information is copied and translated by the cell's machinery to build the protein.

Question 15Unit 1

During which stage of the cell cycle is DNA replicated?

  1. S phase of interphase Correct answer.
  2. Cytokinesis
  3. Prophase of mitosis
  4. G1 phase of interphase

Explanation

Interphase consists of G1, S and G2 phases, and DNA synthesis occurs during S phase. Replication ensures each daughter cell receives a complete set of chromosomes after division.

Question 16Unit 1

What is the main purpose of mitosis in a multicellular organism?

  1. To produce genetically identical cells for growth and repair Correct answer.
  2. To produce gametes with half the chromosome number
  3. To halve the DNA content before fertilisation
  4. To create genetic variation through crossing over

Explanation

Mitosis produces two daughter cells with the same chromosome number and genetic information as the parent cell. This supports growth, replacement of damaged cells and asexual reproduction.

Question 17Unit 1

Which event occurs during prophase of mitosis?

  1. Chromosomes line up along the cell equator
  2. The cytoplasm divides to form two cells
  3. Chromosomes condense and the nuclear envelope breaks down Correct answer.
  4. Sister chromatids separate and move to opposite poles

Explanation

In prophase the chromatin coils and condenses into visible chromosomes, the nucleolus disappears and the nuclear envelope breaks down as the spindle begins to form. Chromosome alignment and chromatid separation occur in later stages.

Question 18Unit 1

How does meiosis contribute to genetic variation among offspring?

  1. It prevents mutation from occurring in gametes
  2. Crossing over and independent assortment create new combinations of alleles Correct answer.
  3. It doubles the chromosome number in each gamete
  4. It produces daughter cells identical to the parent cell

Explanation

During meiosis, homologous chromosomes exchange segments by crossing over and then assort independently into gametes. Together these processes shuffle alleles into many different combinations, increasing variation in offspring.

Question 19Unit 1

A cell with a diploid number of 24 undergoes meiosis. What chromosome number will each resulting gamete have?

  1. 24
  2. 48
  3. 6
  4. 12 Correct answer.

Explanation

Meiosis is a reduction division that halves the chromosome number, producing haploid gametes. Half of a diploid number of 24 is 12 chromosomes per gamete.

Question 20Unit 1

Which type of cell division produces four genetically different haploid cells?

  1. Cytokinesis
  2. Meiosis Correct answer.
  3. Mitosis
  4. Binary fission

Explanation

Meiosis involves two successive divisions after a single round of replication, yielding four haploid cells. Crossing over and independent assortment make these cells genetically different from one another.

Question 21Unit 1

Which feature is shared by all cells, whether prokaryotic or eukaryotic?

  1. A plasma membrane enclosing cytoplasm Correct answer.
  2. A membrane-bound nucleus
  3. Chloroplasts for photosynthesis
  4. Mitochondria for respiration

Explanation

All cells are bounded by a plasma membrane that encloses cytoplasm and genetic material. The other structures listed are found only in certain groups of cells, not universally.

Question 22Unit 1

A plant wilts on a hot day because its cells lose water. Which change best explains the wilting?

  1. Chloroplasts move out of the cells
  2. Cells gain turgor pressure as water enters
  3. The cell walls dissolve in the heat
  4. Cells lose turgor pressure as the central vacuole shrinks Correct answer.

Explanation

Turgor pressure from water pressing the vacuole against the cell wall keeps plant tissues firm. When water is lost by osmosis, the vacuole shrinks, turgor pressure falls and the tissue becomes limp.

Question 23Unit 1

An enzyme is added to a substrate solution and the reaction rate is measured. After some time the rate levels off even though substrate remains. What is the most likely reason?

  1. The substrate has become a competitive inhibitor
  2. The enzyme has been completely used up
  3. All active sites are occupied, so the enzyme is working at maximum rate Correct answer.
  4. The temperature has fallen to zero

Explanation

When substrate is plentiful, the rate is limited by the number of enzyme active sites available. Once all active sites are occupied, the enzyme is saturated and cannot increase the rate further.

Question 24Unit 1

Which statement about the structure of a phospholipid explains why it forms a bilayer in water?

  1. A single hydrophobic head repels water on all sides
  2. A hydrophilic head and hydrophobic tails cause two layers to face water at both surfaces Correct answer.
  3. Phospholipids are charged at both ends and repel each other
  4. Two hydrophobic heads attract each other in water

Explanation

A phospholipid has a polar phosphate head that interacts with water and two non-polar fatty acid tails that are repelled by water. In water the tails turn inward and the heads face outward, producing a bilayer with hydrophilic surfaces.

Question 25Unit 1

A red blood cell is placed in pure distilled water. What is the most likely outcome?

  1. There is no net movement of water and the cell is unchanged
  2. Water leaves by osmosis and the cell shrinks
  3. The cell wall prevents any change in volume
  4. Water enters by osmosis and the cell swells and may burst Correct answer.

Explanation

Distilled water has a higher water concentration than the cell contents, making it hypotonic to the cell. Water therefore enters by osmosis, and because animal cells lack a cell wall, the cell can swell and burst.

Question 26Unit 1

Which organelle is the main site of ATP production in a eukaryotic cell?

  1. Golgi apparatus
  2. Ribosome
  3. Lysosome
  4. Mitochondrion Correct answer.

Explanation

The mitochondrion carries out aerobic respiration, using the electron transport chain and chemiosmosis to generate most of the cell's ATP. Other organelles perform different roles such as modification, digestion or protein synthesis.

Question 27Unit 1

Which structure controls the movement of substances into and out of a cell?

  1. Plasma membrane Correct answer.
  2. Cytoskeleton
  3. Nuclear envelope
  4. Cell wall

Explanation

The plasma membrane is a selectively permeable phospholipid bilayer with embedded proteins that regulate what enters and leaves the cell. It is the boundary common to all cells and governs transport.

Question 28Unit 1

A solution contains 0.9% salt and a cell's cytoplasm also contains 0.9% salt. How is the solution best described relative to the cell?

  1. Isotonic Correct answer.
  2. Hypotonic
  3. Hydrophobic
  4. Hypertonic

Explanation

When the solute concentration outside equals that inside the cell, there is no net movement of water and the solution is isotonic. Hypotonic and hypertonic describe lower and higher external solute concentrations respectively.

Question 29Unit 1

Which property of the phospholipid bilayer allows small nonpolar molecules such as oxygen to cross a membrane readily?

  1. The presence of many large pores
  2. The negative charge on phosphate heads
  3. The hydrophobic interior of the bilayer Correct answer.
  4. The bilayer is rigid and impermeable

Explanation

The fatty acid tails form a hydrophobic core, so small nonpolar molecules dissolve into and diffuse across it easily. Polar and charged substances are repelled by this core and need transport proteins.

Question 30Unit 1

Which process moves sodium ions out of a cell against their concentration gradient using ATP?

  1. Active transport Correct answer.
  2. Osmosis
  3. Simple diffusion
  4. Facilitated diffusion

Explanation

Moving a substance against its concentration gradient requires energy, which defines active transport. Pumps such as the sodium-potassium pump hydrolyse ATP to drive such movement.

Question 31Unit 1

Which pair of molecules are the monomers that make up a polypeptide?

  1. Nucleotides
  2. Fatty acids
  3. Monosaccharides
  4. Amino acids Correct answer.

Explanation

Polypeptides are polymers built from amino acids joined by peptide bonds. Nucleotides form nucleic acids, monosaccharides form polysaccharides and fatty acids contribute to lipids.

Question 32Unit 1

A student tests a food sample and finds it turns from blue to brick-red when heated with Benedict's solution. Which nutrient is present?

  1. Reducing sugar Correct answer.
  2. Starch
  3. Lipid
  4. Protein

Explanation

Benedict's solution changes from blue to green, yellow or brick-red when heated with reducing sugars such as glucose. The colour change reflects the reduction of copper ions during the test.

Question 33Unit 1

Which statement best describes the role of a coenzyme in an enzyme-catalysed reaction?

  1. It permanently denatures the enzyme
  2. It lowers the activation energy directly
  3. It replaces the substrate at the active site
  4. It assists the enzyme by transferring chemical groups or electrons Correct answer.

Explanation

Coenzymes are non-protein organic molecules that help enzymes by carrying chemical groups or electrons between reactions. They are not permanently altered and do not themselves provide the catalytic site.

Question 34Unit 1

A DNA molecule contains 30% adenine. What percentage of its bases is guanine?

  1. 70%
  2. 30%
  3. 40%
  4. 20% Correct answer.

Explanation

By complementary base pairing, adenine equals thymine, so thymine is also 30% and together they make 60%. The remaining 40% is shared equally between guanine and cytosine, giving 20% guanine.

Question 35Unit 1

Which feature of the DNA double helix allows accurate copying during replication?

  1. The sugar-phosphate backbone is negatively charged
  2. The two strands are complementary and can act as templates Correct answer.
  3. The strands are held only by covalent bonds
  4. The bases face the outside of the helix

Explanation

Because each base pairs specifically with its partner, each separated strand carries the information needed to build a new complementary strand. This template mechanism underlies semi-conservative replication.

Question 36Unit 1

Which type of RNA carries amino acids to the ribosome during translation?

  1. Transfer RNA Correct answer.
  2. Ribosomal RNA
  3. Messenger RNA
  4. Small nuclear RNA

Explanation

Transfer RNA molecules bind specific amino acids and deliver them to the ribosome, matching their anticodon to the messenger RNA codon. This ensures the correct amino acid is added to the growing polypeptide.

Question 37Unit 1

A mutation changes a codon from GAA to GAG but the same amino acid is still inserted. What type of mutation is this?

  1. Nonsense mutation
  2. Frameshift mutation
  3. Silent mutation Correct answer.
  4. Missense mutation

Explanation

Because the genetic code is degenerate, several codons specify the same amino acid, so this change does not alter the protein. Such a change is called a silent mutation.

Question 38Unit 1

During which phase of mitosis do sister chromatids separate and move to opposite poles?

  1. Metaphase
  2. Anaphase Correct answer.
  3. Prophase
  4. Telophase

Explanation

In anaphase the centromeres divide and the spindle fibres pull sister chromatids apart towards opposite poles. This ensures each daughter nucleus receives one copy of every chromosome.

Question 39Unit 1

Which process produces gametes with half the chromosome number of the parent cell?

  1. Mitosis
  2. Meiosis Correct answer.
  3. Cytokinesis
  4. Binary fission

Explanation

Meiosis involves two successive divisions that halve the chromosome number, producing haploid gametes. This reduction is essential so that fertilisation restores the diploid number.

Question 40Unit 1

Which process during meiosis creates new combinations of alleles on a single chromosome?

  1. Separation of sister chromatids
  2. Crossing over between homologous chromosomes Correct answer.
  3. Replication of DNA before division
  4. Formation of the spindle apparatus

Explanation

Crossing over exchanges segments between non-sister chromatids of homologous chromosomes, producing recombinant chromosomes with new allele combinations. This recombination adds to the variation generated by independent assortment.

Question 41Unit 1

A cell with 8 chromosomes undergoes mitosis. How many chromosomes will each daughter cell contain?

  1. 16
  2. 4
  3. 2
  4. 8 Correct answer.

Explanation

Mitosis produces two daughter cells that are genetically identical to the parent, so the chromosome number is maintained. Each daughter therefore receives the full set of 8 chromosomes.

Question 42Unit 1

Which statement best describes apoptosis?

  1. Cell swelling and bursting after osmotic damage
  2. Permanent exit of a cell from the cell cycle
  3. Programmed cell death that removes damaged or unwanted cells Correct answer.
  4. Uncontrolled cell division forming a tumour

Explanation

Apoptosis is a controlled, genetically regulated process of cell death that removes cells no longer needed or potentially harmful. It is essential in development and in maintaining tissue health.

Question 43Unit 1

A cell that normally divides rapidly is treated with a drug that blocks spindle fibre formation. What is the most likely immediate consequence?

  1. DNA replication stops before it begins
  2. Chromosomes cannot align at the equator or separate Correct answer.
  3. The cell membrane breaks down during interphase
  4. The nuclear envelope dissolves prematurely

Explanation

Spindle fibres attach to chromosomes and are responsible for aligning them at the metaphase plate and pulling chromatids apart. Without them, chromosome segregation fails and division cannot proceed normally.

Question 44Unit 1

Which comparison of plant and animal cells is correct?

  1. Plant cells have chloroplasts and a cell wall; animal cells do not Correct answer.
  2. Both cell types lack a plasma membrane
  3. Plant cells lack mitochondria; animal cells have them
  4. Animal cells have a nucleus; plant cells do not

Explanation

Plant cells typically possess chloroplasts, a cellulose cell wall and a large central vacuole, whereas animal cells lack these structures. Both cell types are eukaryotic and share nuclei, mitochondria and plasma membranes.

Question 45Unit 1

A protein is secreted from a cell. Which sequence best traces its path from synthesis to release?

  1. Smooth ER, mitochondria, vesicles, cell wall
  2. Rough ER, Golgi apparatus, vesicles, plasma membrane Correct answer.
  3. Nucleus, lysosome, Golgi apparatus, plasma membrane
  4. Golgi apparatus, rough ER, lysosome, nucleus

Explanation

Secretory proteins are synthesised on ribosomes of the rough endoplasmic reticulum, modified and packaged in the Golgi apparatus, then carried in vesicles that fuse with the plasma membrane. This ordered pathway ensures correct processing before release.

Question 46Unit 1

Which feature of the fluid mosaic model describes the movement of phospholipids within a membrane?

  1. Membrane components can move laterally Correct answer.
  2. The bilayer is fixed and static
  3. The bilayer is composed only of protein
  4. Proteins are permanently anchored in place

Explanation

The fluid mosaic model proposes that lipids and many proteins can move sideways within the membrane, giving it fluidity. This dynamic arrangement underlies processes such as vesicle formation and membrane fusion.

Question 47Unit 1

A cell is placed in a solution with a higher solute concentration than its cytoplasm. What is the expected net movement of water?

  1. Out of the cell, causing it to shrink Correct answer.
  2. Into the cell, causing it to swell
  3. No net movement occurs
  4. Water moves equally in both directions with no net change

Explanation

In a hypertonic solution the external solute concentration is higher, so water moves out of the cell by osmosis down its concentration gradient. The cell loses volume and may shrivel.

Question 48Unit 1

Which statement correctly describes the effect of a non-competitive inhibitor?

  1. It permanently destroys the substrate
  2. It increases the rate of the reaction at high substrate concentration
  3. It binds away from the active site and changes enzyme shape Correct answer.
  4. It binds the active site and is overcome by more substrate

Explanation

A non-competitive inhibitor binds at a site other than the active site, altering the enzyme's shape so the substrate fits less well. Adding more substrate does not fully reverse this inhibition, unlike competitive inhibition.

Question 49Unit 1

A student finds that an enzyme works fastest at 37 degrees Celsius and is inactive at 80 degrees Celsius. Which explanation is most consistent with this result?

  1. High temperature denatures the enzyme by disrupting bonds in its active site Correct answer.
  2. The activation energy increases because the enzyme is diluted
  3. The substrate concentration falls to zero at 80 degrees
  4. The enzyme becomes a competitive inhibitor at high temperature

Explanation

Above the optimum, excessive thermal energy breaks the weak bonds maintaining the enzyme's three-dimensional shape, distorting the active site so the substrate no longer binds. This denaturation is usually irreversible.

Question 50Unit 1

A polypeptide has 120 amino acids. How many peptide bonds does it contain, assuming it is a single unbranched chain?

  1. 119 Correct answer.
  2. 60
  3. 120
  4. 121

Explanation

Each peptide bond joins two adjacent amino acids, so a chain of n amino acids contains n minus one bonds. For 120 amino acids this gives 119 peptide bonds.