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WACE ATAR Human Biology study materials
WACE ATAR Human Biology study resources

WACE ATAR Human Biology practice questions

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Question 1Human Biology

Which structure in the human kidney is responsible for the initial filtration of blood to form filtrate?

  1. Loop of Henle
  2. Collecting duct
  3. Glomerulus Correct answer.
  4. Proximal convoluted tubule

Explanation

Filtration occurs in the renal corpuscle, where blood pressure forces water and small solutes through the glomerular capillary walls and into Bowman's capsule. The remaining tubule segments modify the filtrate rather than create it.

Question 2Human Biology

During gas exchange in the lungs, oxygen moves from the alveoli into the blood because

  1. the partial pressure of oxygen is higher in alveolar air than in deoxygenated blood Correct answer.
  2. haemoglobin repels oxygen until it reaches body tissues
  3. carbon dioxide pushes oxygen into the capillaries
  4. oxygen is actively pumped across the alveolar wall

Explanation

Gases diffuse down partial pressure gradients. Alveolar air has a higher oxygen partial pressure than the arriving pulmonary blood, so oxygen diffuses into the capillaries and binds haemoglobin.

Question 3Human Biology

Which blood vessel carries oxygenated blood away from the heart to the body?

  1. Pulmonary vein
  2. Vena cava
  3. Aorta Correct answer.
  4. Pulmonary artery

Explanation

The aorta is the major systemic artery leaving the left ventricle, delivering oxygenated blood to body tissues. Arteries carry blood away from the heart, and in the systemic circuit this blood is oxygen-rich.

Question 4Human Biology

Which part of a neuron receives incoming signals from other neurons?

  1. Axon
  2. Myelin sheath
  3. Axon terminal
  4. Dendrite Correct answer.

Explanation

Dendrites are branched extensions that receive neurotransmitter signals and carry impulses toward the cell body. The axon transmits impulses away, and the myelin sheath insulates it.

Question 5Human Biology

Insulin lowers blood glucose concentration mainly by

  1. increasing glucose reabsorption in the kidney
  2. converting glucose into fatty acids in the blood plasma
  3. stimulating cells to take up glucose and store it as glycogen Correct answer.
  4. breaking down glycogen in the liver

Explanation

Insulin is released by pancreatic beta cells when blood glucose rises. It promotes glucose uptake into cells and stimulates glycogen formation in the liver and muscle, lowering blood glucose.

Question 6Human Biology

Which hormone is released from the posterior pituitary to increase water reabsorption in the kidney?

  1. Adrenaline
  2. Thyroxine
  3. Antidiuretic hormone Correct answer.
  4. Aldosterone

Explanation

Antidiuretic hormone increases the permeability of the collecting duct to water, so more water is reabsorbed and urine becomes more concentrated. It is released when blood osmolarity rises.

Question 7Human Biology

In meiosis, the reduction of chromosome number from diploid to haploid occurs because

  1. crossing over removes chromosomes
  2. DNA is not replicated before meiosis
  3. homologous chromosomes separate during meiosis I Correct answer.
  4. sister chromatids separate in meiosis I

Explanation

Meiosis I separates homologous chromosomes into two daughter cells, halving the chromosome number. Meiosis II then separates sister chromatids, producing four haploid gametes.

Question 8Human Biology

Which component of a reflex arc detects the stimulus and initiates a sensory impulse?

  1. Interneuron
  2. Receptor Correct answer.
  3. Motor neuron
  4. Effector

Explanation

Receptors are specialised structures that detect a stimulus such as heat or pressure and generate an impulse in a sensory neuron. The effector then produces the response.

Question 9Human Biology

A student measures a person's cardiac output as 5 litres per minute and heart rate as 70 beats per minute. What is the stroke volume?

  1. 70 millilitres Correct answer.
  2. 35 millilitres
  3. 50 millilitres
  4. 14 millilitres

Explanation

Cardiac output equals heart rate multiplied by stroke volume. Rearranging gives stroke volume = 5000 mL ÷ 70 beats, which is approximately 71 mL, closest to 70 millilitres.

Question 10Human Biology

A person breathes rapidly during strenuous exercise. Which change best explains the increased rate of carbon dioxide removal from the blood?

  1. A decrease in the surface area of the alveoli
  2. A rise in the oxygen partial pressure of body tissues
  3. A steeper partial pressure gradient for carbon dioxide between blood and alveolar air Correct answer.
  4. Reduced blood flow through pulmonary capillaries

Explanation

Rapid breathing keeps alveolar carbon dioxide partial pressure low, maintaining a steep diffusion gradient from blood to alveoli. Diffusion rate depends on this gradient, so removal is faster.

Question 11Human Biology

Which statement best describes the role of the loop of Henle in producing concentrated urine?

  1. It reabsorbs all sodium ions before the filtrate leaves the kidney
  2. It creates a high solute concentration in the medulla that draws water from the collecting duct Correct answer.
  3. It filters large proteins from the blood
  4. It actively secretes glucose into the filtrate

Explanation

The loop of Henle generates an osmotic gradient in the renal medulla by countercurrent multiplication. This gradient allows water to be reabsorbed from the collecting duct when antidiuretic hormone is present.

Question 12Human Biology

If a person's diet is very low in calcium, which hormonal response would be expected?

  1. Increased secretion of parathyroid hormone to release calcium from bone Correct answer.
  2. Increased insulin release from the pancreas
  3. Decreased secretion of parathyroid hormone
  4. Increased secretion of calcitonin to deposit calcium in bone

Explanation

Low blood calcium stimulates the parathyroid glands to release parathyroid hormone. This hormone increases calcium release from bone, reabsorption in the kidney and absorption in the gut.

Question 13Human Biology

A synapse between two neurons ensures one-way transmission because

  1. action potentials travel faster backwards along the axon
  2. neurotransmitter is released only from the presynaptic terminal and receptors are on the postsynaptic membrane Correct answer.
  3. the synaptic cleft is too wide for any chemical to cross
  4. both neurons release neurotransmitter at the same time

Explanation

Synaptic vesicles and release sites are confined to the presynaptic terminal, while receptors sit on the postsynaptic membrane. This arrangement allows signals to pass in one direction only.

Question 14Human Biology

Two parents are both heterozygous for a recessive condition. What is the probability that a child will express the recessive condition?

  1. 50 percent
  2. 25 percent Correct answer.
  3. 0 percent
  4. 75 percent

Explanation

A cross between two heterozygotes gives genotype ratios of 1 homozygous dominant : 2 heterozygous : 1 homozygous recessive. Only the homozygous recessive genotype expresses the condition, so the probability is one in four.

Question 15Human Biology

A woman with blood group AB and a man with blood group O have children. Which blood groups are possible in their offspring?

  1. AB only
  2. A or B Correct answer.
  3. A, B, AB or O
  4. O only

Explanation

The AB mother can pass either the A or B allele, while the O father passes only the O allele. Offspring therefore have genotype AO or BO, giving blood groups A or B.

Question 16Human Biology

Which feature of the alveoli most directly increases the efficiency of gas exchange?

  1. Cartilage rings surrounding each alveolus
  2. A large total surface area with a thin, moist lining Correct answer.
  3. A thick, muscular wall
  4. A small blood supply to each alveolus

Explanation

Gas exchange is more efficient when surface area is large and the diffusion distance is short, which the thin moist alveolar lining provides. A rich capillary network also maintains steep gradients.

Question 17Human Biology

During a marathon, a runner's body temperature rises. Which response would help dissipate heat?

  1. Shivering of skeletal muscles
  2. Increased secretion of thyroxine
  3. Dilation of skin arterioles and increased sweating Correct answer.
  4. Constriction of skin arterioles and reduced sweating

Explanation

Vasodilation of skin arterioles increases blood flow near the surface, so more heat is lost by radiation. Sweating adds evaporative cooling, both of which lower body temperature.

Question 18Human Biology

Which sequence correctly describes the pathway of an action potential through a reflex arc?

  1. Sensory neuron, receptor, effector, interneuron, motor neuron
  2. Receptor, motor neuron, interneuron, sensory neuron, effector
  3. Effector, motor neuron, interneuron, sensory neuron, receptor
  4. Receptor, sensory neuron, interneuron, motor neuron, effector Correct answer.

Explanation

A stimulus is detected by a receptor, and the impulse travels along a sensory neuron to the central nervous system. An interneuron relays it to a motor neuron, which activates the effector.

Question 19Human Biology

A person with damaged glomeruli loses protein in their urine. Which consequence is most likely?

  1. Increased oxygen-carrying capacity of the blood
  2. Reduced urine volume due to increased water reabsorption
  3. Reduced blood osmotic pressure and increased tissue fluid accumulation Correct answer.
  4. Increased blood osmotic pressure and reduced tissue fluid formation

Explanation

Plasma proteins maintain the colloid osmotic pressure that draws water back into capillaries. Losing them lowers blood osmotic pressure, so more fluid remains in tissues, causing oedema.

Question 20Human Biology

In a population, a recessive allele causes a condition in 1 in 10 000 individuals. Assuming Hardy-Weinberg equilibrium, what is the approximate frequency of carriers?

  1. 0.0001
  2. 0.0198 Correct answer.
  3. 0.01
  4. 0.99

Explanation

The affected frequency q² = 0.0001, so q = 0.01 and p = 0.99. Carrier frequency is 2pq = 2 × 0.99 × 0.01 ≈ 0.0198, about 2 percent of the population.

Question 21Human Biology

A mutation changes a single base in a gene so that a premature stop codon is produced. What is the most likely effect on the protein?

  1. A polypeptide with all amino acids replaced
  2. A shortened, non-functional polypeptide Correct answer.
  3. No change to the polypeptide sequence
  4. A polypeptide with one extra amino acid

Explanation

A premature stop codon terminates translation early, producing a truncated polypeptide that usually cannot function normally. This is a nonsense mutation.

Question 22Human Biology

An athlete at high altitude has a lower oxygen partial pressure in the air. Which long-term response would best improve oxygen delivery to tissues?

  1. Decreased capillary density in muscles
  2. Increased red blood cell production stimulated by erythropoietin Correct answer.
  3. Reduced ventilation rate
  4. Decreased red blood cell production

Explanation

Low oxygen availability stimulates the kidneys to release erythropoietin, which increases red blood cell production. More red cells raise the oxygen-carrying capacity of the blood.

Question 23Human Biology

A drug blocks calcium channels in the sinoatrial node. Which immediate effect on the heart is most likely?

  1. Reversal of blood flow through the heart valves
  2. Increased stroke volume due to stronger ventricular contraction
  3. Reduced rate of spontaneous depolarisation and slower heart rate Correct answer.
  4. Increased heart rate due to faster pacemaker firing

Explanation

Calcium influx contributes to the pacemaker potential in the sinoatrial node. Blocking these channels slows spontaneous depolarisation, reducing the rate at which the heart generates impulses.

Question 24Human Biology

In a pedigree, a condition appears in every generation and affects both males and females equally, with affected individuals always having an affected parent. Which mode of inheritance is most consistent with this pattern?

  1. Mitochondrial
  2. Autosomal recessive
  3. Autosomal dominant Correct answer.
  4. X-linked recessive

Explanation

Autosomal dominant conditions appear in every generation because one copy of the allele is sufficient, and affected individuals have an affected parent. Both sexes are affected equally because the gene is on an autosome.

Question 25Human Biology

Which molecule stores the genetic instructions that are passed from a parent cell to its daughter cells during mitosis?

  1. DNA Correct answer.
  2. Glucose
  3. ATP
  4. Haemoglobin

Explanation

Deoxyribonucleic acid carries the coded base sequence of genes, and this sequence is copied and distributed to daughter cells during mitosis. The other molecules serve energy transfer, fuel supply or oxygen transport rather than information storage.

Question 26Human Biology

Which process moves oxygen from the alveolar air into the blood of the pulmonary capillaries?

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

Explanation

Oxygen moves down its partial pressure gradient from the higher concentration in alveolar air to the lower concentration in capillary blood. This passive movement of a dissolved gas across a thin membrane is simple diffusion and requires no energy input.

Question 27Human Biology

A cell in the human body has 46 chromosomes. After completing meiosis, each gamete normally contains how many chromosomes?

  1. 46
  2. 23 Correct answer.
  3. 12
  4. 92

Explanation

Meiosis halves the chromosome number so that each gamete receives one chromosome from each homologous pair. In humans this gives 23 chromosomes, and fertilisation restores the diploid number of 46 in the zygote.

Question 28Human Biology

Which part of the nephron filters small molecules such as glucose and urea out of the blood while retaining blood cells and large proteins?

  1. Collecting duct
  2. Glomerulus Correct answer.
  3. Ureter
  4. Proximal convoluted tubule

Explanation

The glomerulus is a knot of capillaries where high pressure forces water and small solutes into the capsule, while cells and large proteins remain in the blood. The tubules and ducts mainly reabsorb or secrete substances after this initial filtration.

Question 29Human Biology

Which type of blood vessel carries blood away from the heart under high pressure?

  1. Venule
  2. Vein
  3. Artery Correct answer.
  4. Capillary

Explanation

Arteries have thick muscular and elastic walls that withstand the pressure created by ventricular contraction and carry blood away from the heart. Veins and venules return blood at low pressure, while capillaries are exchange vessels.

Question 30Human Biology

Which part of the nervous system controls involuntary functions such as heart rate and digestion?

  1. Sensory nervous system
  2. Skeletal nervous system
  3. Somatic nervous system
  4. Autonomic nervous system Correct answer.

Explanation

The autonomic nervous system regulates smooth muscle, cardiac muscle and glands without conscious control, maintaining internal homeostasis. The somatic division instead controls voluntary skeletal muscle movement.

Question 31Human Biology

Which type of immunity results from receiving antibodies through breast milk rather than producing them after exposure to an antigen?

  1. Passive artificial immunity
  2. Active artificial immunity
  3. Active natural immunity
  4. Passive natural immunity Correct answer.

Explanation

Passive immunity occurs when ready-made antibodies are transferred rather than produced by the recipient's own immune system. Because the transfer happens naturally through breast milk, it is classified as passive natural immunity.

Question 32Human Biology

Which structure produces the hormone testosterone in the male reproductive system?

  1. Interstitial cells of the testes Correct answer.
  2. Epididymis
  3. Seminal vesicles
  4. Prostate gland

Explanation

Interstitial cells, located between the seminiferous tubules of the testes, secrete testosterone under stimulation by luteinising hormone. The other structures contribute secretions or store sperm but do not produce this hormone.

Question 33Human Biology

A person's blood pressure is measured as 120 mm Hg systolic and 80 mm Hg diastolic. What does the systolic value represent?

  1. Pressure in the arteries during ventricular contraction Correct answer.
  2. Pressure in the arteries during ventricular relaxation
  3. Pressure in the veins during atrial contraction
  4. Pressure in the capillaries during gas exchange

Explanation

Systolic pressure is the peak arterial pressure reached when the ventricles contract and force blood into the aorta and pulmonary arteries. Diastolic pressure is the lower value recorded while the ventricles relax and refill.

Question 34Human Biology

During vigorous exercise, a muscle cell has insufficient oxygen for aerobic respiration. Which product accumulates in the muscle as a result of anaerobic respiration?

  1. Ethanol
  2. Carbon monoxide
  3. Pyruvate only
  4. Lactic acid Correct answer.

Explanation

When oxygen is limiting, human muscle cells convert pyruvate to lactic acid to regenerate NAD+ so glycolysis can continue. Ethanol is produced in yeast and some plants, not in human muscle.

Question 35Human Biology

A mutation in a gene causes a transport protein in the kidney tubule to be non-functional. As a result, glucose appears in the urine. Which process has been directly affected?

  1. Filtration at the glomerulus
  2. Secretion into the distal tubule
  3. Reabsorption from the proximal tubule Correct answer.
  4. Filtration in the collecting duct

Explanation

Glucose is normally filtered freely and then recovered by active transport carriers in the proximal convoluted tubule. If these carriers fail, glucose remains in the filtrate and is excreted, producing glycosuria.

Question 36Human Biology

A person's tidal volume is 500 mL and their breathing rate is 12 breaths per minute. What is their pulmonary ventilation?

  1. 42 mL per minute
  2. 512 mL per minute
  3. 6000 mL per minute Correct answer.
  4. 60 mL per minute

Explanation

Pulmonary ventilation equals tidal volume multiplied by breathing rate, so 500 mL times 12 breaths gives 6000 mL per minute. This measures the total volume of air moved into and out of the lungs each minute.

Question 37Human Biology

A child inherits a sex-linked recessive allele on the X chromosome from the mother and a Y chromosome from the father. Why does the child express the condition?

  1. The Y chromosome carries a dominant suppressor allele
  2. The condition requires two copies of the allele
  3. The allele is masked by the father's Y chromosome
  4. The child has no second X chromosome carrying a normal allele Correct answer.

Explanation

Males have only one X chromosome, so a recessive allele on that X is expressed directly because there is no homologous X carrying a normal copy. Females with two X chromosomes usually need two copies to express such a condition.

Question 38Human Biology

In a dihybrid cross between two individuals heterozygous for both unlinked genes (AaBb x AaBb), what proportion of offspring is expected to show both recessive phenotypes?

  1. 9/16
  2. 3/16
  3. 1/16 Correct answer.
  4. 1/4

Explanation

Because the genes are unlinked, each recessive phenotype appears in one quarter of offspring independently. Multiplying 1/4 by 1/4 gives 1/16 for the double recessive combination.

Question 39Human Biology

Which change would increase the rate of diffusion of oxygen across the alveolar membrane?

  1. Increasing the partial pressure gradient of oxygen Correct answer.
  2. Reducing blood flow through the pulmonary capillaries
  3. Increasing the thickness of the alveolar wall
  4. Decreasing the surface area of the alveoli

Explanation

Fick's law states that diffusion rate is proportional to the concentration gradient, so a steeper oxygen gradient increases the rate of transfer. Thickness and surface area also matter, but increasing thickness or decreasing area slows diffusion.

Question 40Human Biology

A person living at sea level travels to a high-altitude city where the air contains less oxygen. Which immediate response helps maintain oxygen delivery to tissues?

  1. Decreased heart rate
  2. Constriction of the bronchioles
  3. Reduced red blood cell production
  4. Increased breathing rate Correct answer.

Explanation

Lower oxygen partial pressure at altitude stimulates chemoreceptors, which increase ventilation to raise oxygen uptake in the lungs. Heart rate also rises, while red cell production increases only over days to weeks.

Question 41Human Biology

A person with type 1 diabetes does not produce enough insulin. Which effect on blood glucose regulation is most likely?

  1. Glycogen storage in the liver increases
  2. Blood glucose remains high after a meal Correct answer.
  3. Blood glucose falls dangerously low after a meal
  4. Cells take up glucose more rapidly

Explanation

Insulin normally stimulates cells to take up glucose and the liver to store it as glycogen, so its deficiency leaves glucose in the blood after eating. This produces the persistent hyperglycaemia characteristic of untreated type 1 diabetes.

Question 42Human Biology

A woman has a regular menstrual cycle. On about which day of a typical 28-day cycle does ovulation usually occur?

  1. Day 1
  2. Day 26
  3. Day 14 Correct answer.
  4. Day 7

Explanation

In a typical 28-day cycle, the follicular phase occupies roughly the first half and ovulation occurs near the middle, around day 14. The luteal phase then follows for about 14 days before menstruation.

Question 43Human Biology

Which statement best explains why the wall of the left ventricle is thicker than that of the right ventricle?

  1. The right ventricle pumps blood only during diastole
  2. The left ventricle must pump blood a greater distance at higher pressure Correct answer.
  3. The left ventricle holds a larger volume of blood at all times
  4. The right ventricle contains more cardiac muscle fibres

Explanation

The left ventricle drives blood through the systemic circulation, which has high resistance and requires greater pressure than the pulmonary circuit. Its thicker muscular wall generates that higher pressure, while the right ventricle pumps to the nearby lungs.

Question 44Human Biology

A baby is born with a hole in the septum between the two atria. Which immediate consequence is most likely?

  1. Blood cannot leave the left ventricle
  2. The heart valves fail to close
  3. The pulmonary artery becomes blocked
  4. Oxygenated and deoxygenated blood mix within the heart Correct answer.

Explanation

A septal defect creates a passage between the chambers, allowing oxygenated and deoxygenated blood to mix. This reduces the oxygen content of blood delivered to the body and forces the heart to work harder.

Question 45Human Biology

A person's diet lacks iron over several months. Which effect on the blood is most likely?

  1. Reduced oxygen-carrying capacity of the blood Correct answer.
  2. Increased haemoglobin production
  3. Reduced clotting ability of plasma
  4. Increased number of platelets

Explanation

Iron is a component of the haem group in haemoglobin, so a deficiency limits haemoglobin synthesis and the oxygen-carrying capacity of red blood cells. This produces the fatigue and pallor typical of iron-deficiency anaemia.

Question 46Human Biology

A population of insects is exposed to an insecticide over many generations. Which mechanism best explains the increasing proportion of resistant individuals?

  1. The insecticide causes mutations that make individuals resistant
  2. Individuals acquire resistance during their lifetime and pass it on
  3. All individuals become equally resistant at the same time
  4. Pre-existing resistant variants survive and reproduce more successfully Correct answer.

Explanation

Natural selection acts on variation already present in the population, so individuals with resistance alleles survive and leave more offspring. Over generations these alleles become more common, shifting the population toward resistance.

Question 47Human Biology

Two hormones regulate blood calcium concentration in opposing directions. Which pairing correctly describes their effects?

  1. Parathyroid hormone lowers blood calcium; calcitonin raises it
  2. Parathyroid hormone raises blood calcium; calcitonin lowers it Correct answer.
  3. Both hormones raise blood calcium concentration
  4. Both hormones lower blood calcium concentration

Explanation

Parathyroid hormone increases blood calcium by promoting bone resorption, renal reabsorption and intestinal absorption via vitamin D. Calcitonin opposes it by promoting calcium deposition in bone, so the two act as an antagonistic pair.

Question 48Human Biology

In a Hardy-Weinberg population, the frequency of a recessive allele is 0.3. What proportion of the population is expected to be heterozygous?

  1. 0.49
  2. 0.09
  3. 0.21
  4. 0.42 Correct answer.

Explanation

Heterozygote frequency is calculated as 2pq, where p is 0.7 and q is 0.3, giving 2 x 0.7 x 0.3 = 0.42. The homozygous recessive frequency would be q squared, or 0.09.

Question 49Human Biology

A mutation inserts one extra base into the coding sequence of a gene. Why is the resulting protein often severely affected?

  1. The gene is copied twice during replication
  2. The reading frame shifts, changing every subsequent codon Correct answer.
  3. The chromosome is deleted entirely
  4. Only one amino acid is replaced by another

Explanation

An insertion of a single base shifts the triplet reading frame from that point onward, so all following codons are read differently. This usually produces a non-functional protein because many amino acids are altered or a premature stop codon appears.

Question 50Human Biology

Which tissue type forms the lining of the small intestine and is specialised for absorption?

  1. Simple columnar epithelium Correct answer.
  2. Stratified squamous epithelium
  3. Dense fibrous connective tissue
  4. Smooth muscle tissue

Explanation

Epithelial tissue covers and lines body surfaces, and simple columnar epithelium has tall, closely packed cells with microvilli suited to absorbing nutrients. Stratified squamous epithelium is built for protection against abrasion, not absorption.