Biology 2025 Objective — Question 1
The Genus into which man is classified is
- A. Chordata
- B. Mammalia
- C. HomoCorrect
- D. Sapiens
Explanation
Human beings belong to the genus Homo, which is part of the family Hominidae and the order Primates.
GCE Biology 2025 Objective Past Questions
All 50 questions from the General Certificate of Education (GCE) Biology 2025 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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Biology 2025 Objective — Question 2
Use the diagram below (the nymph of an insect) to answer this question and the next. The organism illustrated is a stage in the development of
- A. grasshopper
- B. mosquito
- C. termite
- D. cockroachCorrect
Explanation
The diagram is of a cockroach nymph, an immature stage of insects such as cockroaches, which undergo incomplete metamorphosis.
Biology 2025 Objective — Question 3
The growth process that would occur in the organism before it becomes an adult is
- A. respiration
- B. locomotion
- C. moultingCorrect
- D. sensitivity
Explanation
Moulting is a process where an organism sheds its old exoskeleton in order to grow; it is a crucial part of the growth process in arthropods like cockroaches.
Biology 2025 Objective — Question 4
Use the diagram below (a dicot leaf) to answer this question and the next. The parts labelled I, II, III and IV respectively are
- A. vein, apex, midrib, stalk
- B. midrib, petiole, margin, stalk
- C. apex, lamina, blade, axil
- D. apex, midrib, lamina, axilCorrect
Explanation
In the diagram: I is the apex (tip of the leaf), II is the midrib (the central vein), III is the lamina (the broad flat part), and IV is the axil (the angle between the leaf and stem).
Biology 2025 Objective — Question 5
The part that contains the phloem and xylem is labeled
- A. I
- B. IICorrect
- C. III
- D. IV
Explanation
Xylem and phloem are vascular tissues typically found in the vascular bundle, most prominently running through the midrib (II) and veins of the leaf.
Biology 2025 Objective — Question 6
The functions of vacuoles in plants are storage and
- A. protection
- B. strength
- C. supportCorrect
- D. sensitivity
Explanation
The vacuole stores water, nutrients and waste products; this storage of water within the vacuole creates turgor pressure, which maintains the plant's rigidity and contributes to its structural support.
Biology 2025 Objective — Question 7
Four cells each with osmotic potential of about 3% salt solution were immersed respectively into solutions of different concentrations as follows: I - 1% salt solution; II - 3% salt solution; III - 6% salt solution; IV - 10% salt solution. Use the information above to answer this question and the next. Which of the solutions would cause an increase in osmotic pressure within the cell?
- A. ICorrect
- B. II
- C. III
- D. IV
Explanation
When placed in a lower concentration solution (like 1% salt solution), water will move into the cells due to osmosis, causing an increase in osmotic pressure within the cell, since the 1% salt solution has a lower concentration than the cell.
Biology 2025 Objective — Question 8
If the cells are plant cells, what would happen to the cell in solution III? It would become
- A. turgid
- B. crenated
- C. haemolysed
- D. plasmolysedCorrect
Explanation
When plant cells are placed in a solution with a higher solute concentration than the cell's internal fluid (III, 6% salt), water will move out of the cell by osmosis, causing the cell membrane to pull away from the cell wall - a process called plasmolysis.
Biology 2025 Objective — Question 9
How many molecules of oxygen are required for the aerobic respiration of three molecules of glucose?
- A. 3
- B. 6
- C. 12
- D. 18Correct
Explanation
The general equation for aerobic respiration is C6H12O6 + 6O2 -> 6CO2 + 6H2O. From the equation, 1 molecule of glucose takes 6 molecules of oxygen. Thus, for 3 molecules of glucose, the required number of oxygen molecules = 3 x 6 = 18.
Biology 2025 Objective — Question 10
Sclerenchyma tissue in plants is for
- A. water conduction
- B. mechanical supportCorrect
- C. food storage
- D. food transport
Explanation
Sclerenchyma tissue provides structural support to plants; it is composed of cells that have thick, lignified walls, which make them rigid and strong.
Biology 2025 Objective — Question 11
Use the diagram below (a cell carrying out a biological process) to answer this question and the next. The process is referred to as
- A. phagocytosisCorrect
- B. pinocytosis
- C. endocytosis
- D. exocytosis
Explanation
Phagocytosis is a type of endocytosis where a cell takes in large particles like bacteria, dead cells or other foreign materials by engulfing them with its cell membrane.
Biology 2025 Objective — Question 12
The biological system that contains cells that carry out the illustrated biological process in humans is
- A. Reproduction
- B. circulatoryCorrect
- C. respiratory
- D. nervous
Explanation
The biological system that contains the cells carrying out phagocytosis in humans is the circulatory system, which includes white blood cells like macrophages and neutrophils that defend the body by removing pathogens.
Biology 2025 Objective — Question 13
Which of the following statements is not correct about respiration in plants?
- A. It occurs in all plant tissues
- B. Light and chlorophyll must be present for it to occurCorrect
- C. Energy is produced as the end product
- D. It occurs in the presence of oxygen
Explanation
Light and chlorophyll are required for photosynthesis, not respiration; respiration occurs continuously in plant cells regardless of light, making this statement the incorrect one.
Biology 2025 Objective — Question 14
Urine, when compared with blood in mammals is hypertonic because
- A. urine contains high percentage of all cells
- B. all traces of sugar have been removed from urine
- C. urea is actively secreted into the renal tubules
- D. much water has been removed from urineCorrect
Explanation
Urine is hypertonic compared to blood because the kidneys have concentrated the waste products, including salts and urea, by reabsorbing water back into the bloodstream, making the urine more concentrated (much water has been removed).
Biology 2025 Objective — Question 15
The naturally produced auxin in plants is
- A. indole acetic acidCorrect
- B. dichlorophenoxyacetic acid
- C. aldone
- D. florigen
Explanation
Indole Acetic Acid (IAA) is the primary auxin produced naturally in plants; auxins are plant hormones that regulate various aspects of growth.
Biology 2025 Objective — Question 16
The sympathetic nervous system causes
- A. constriction of the arteriesCorrect
- B. heartbeat to slow down
- C. increase in the secretion of saliva
- D. contraction of the bladder
Explanation
The sympathetic nervous system is responsible for the 'fight or flight' response, which includes constricting the arteries to increase blood pressure, helping the body respond to stressful situations by directing blood to vital organs and muscles.
Biology 2025 Objective — Question 17
Long sightedness could be corrected using a
- A. biconvex lens
- B. convex lensCorrect
- C. biconcave lens
- D. concave lens
Explanation
To correct long-sightedness (hypermetropia), a convex lens is needed to converge light rays, allowing them to focus correctly on the retina.
Biology 2025 Objective — Question 18
During the process of hearing in mammals, the structure in the middle ear which receives the first vibration is the
- A. oval window
- B. round window
- C. incus
- D. malleusCorrect
Explanation
Sound waves first hit the eardrum (tympanic membrane), causing it to vibrate; these vibrations are transmitted to the ossicles, small bones in the middle ear. The malleus (also known as the hammer) is the first bone to receive the vibrations from the eardrum.
Biology 2025 Objective — Question 19
An important characteristic of fruits dispersed by water is the presence of
- A. fibrous coveringCorrect
- B. smooth surface
- C. water content
- D. pericarp
Explanation
Fruits dispersed by water typically have a fibrous covering to help them float and be carried by water.
Biology 2025 Objective — Question 20
Plants which grow and produce fruits within a year are called
- A. biennials
- B. perennials
- C. annualsCorrect
- D. herbs
Explanation
Annual plants complete their life cycle within one year, growing, flowering and producing seeds in a single season, often dying after flowering and seed production.
Biology 2025 Objective — Question 21
Chemical digestion in organisms is the
- A. breakdown of starch into carbohydrates
- B. breakdown of complex molecules into simple moleculesCorrect
- C. build up of simple insoluble molecules into complex soluble molecules
- D. build up of simple soluble molecules into complex insoluble molecules
Explanation
Chemical digestion involves breaking down complex, insoluble molecules into simple, soluble molecules that can be absorbed by the body.
Biology 2025 Objective — Question 22
Excessive bleeding from an injury could be due to the lack of vitamin
- A. KCorrect
- B. E
- C. B
- D. A
Explanation
Vitamin K is essential for the blood clotting process; a deficiency can lead to excessive bleeding from an injury.
Biology 2025 Objective — Question 23
Use the diagram below (a system in humans) to answer this question and the next. Enzymatic digestion of protein begins in the part labeled
- A. I
- B. II
- C. IIICorrect
- D. IV
Explanation
Enzymatic digestion of protein begins in the stomach, where pepsin acts on proteins in the presence of hydrochloric acid. (Note: this question depends on a diagram that was not fully legible in the source scan; the answer given is a best estimate.)
Biology 2025 Objective — Question 24
The parts that secrete substances involved in the digestion of fats are labeled
- A. I, II and III
- B. I and IIICorrect
- C. II and III
- D. I, III and IV
Explanation
Fat digestion involves bile (secreted by the liver, stored/released via the gall bladder) and lipase (secreted by the pancreas); these correspond to the labelled parts associated with those organs. (Note: this question depends on a diagram that was not fully legible in the source scan; the answer given is a best estimate.)
Biology 2025 Objective — Question 25
If the small intestine of an organism does not have villi, the organism will have a problem with
- A. digestion of food only
- B. absorption of water only
- C. absorption of nutrients onlyCorrect
- D. digestion of food and absorption of nutrients
Explanation
Villi in the small intestine greatly increase the surface area for absorption; without them, the main problem would be reduced absorption of nutrients, not digestion itself.
Biology 2025 Objective — Question 26
Which of the following statements is not correct about the dental formula of humans?
- A. One pair of canines and three pairs of premolars are on the upper jawCorrect
- B. Two pairs of incisors are on the upper jaw and three pairs of premolars are on the lower jaw
- C. Two pairs of incisors are on the upper jaw and three pairs of molars are on the lower jaw
- D. One pair of canines is on the upper jaw and four pairs of molars are on the lower jaw
Explanation
The standard adult human dental formula has two pairs of premolars per jaw (not three), making the statement claiming three pairs of premolars on the upper jaw incorrect.
Biology 2025 Objective — Question 27
The relationship between a bean plant and a Tridax plant on a farmland is
- A. CompetitionCorrect
- B. predation
- C. Parasitism
- D. epiphytism
Explanation
A bean plant and a Tridax (weed) plant growing on the same farmland compete for the same resources, such as light, water and nutrients.
Biology 2025 Objective — Question 28
The following ecological factors affect all habitats except
- A. temperature
- B. Humidity
- C. light
- D. pressureCorrect
Explanation
Temperature, humidity and light affect virtually all habitats, whereas pressure (e.g. water/atmospheric pressure) is a factor whose relevance varies more specifically by habitat type.
Biology 2025 Objective — Question 29
Use the diagram below (an ecological instrument used in a habitat) to answer this question and the next. The ecological instrument is a
- A. wind vane
- B. Six's thermometerCorrect
- C. Secchi disc
- D. hygrometer
Explanation
The instrument shown is a Six's thermometer, used to record maximum and minimum temperatures in a habitat. (Note: this question depends on a diagram that was not fully legible in the source scan; the answer given is a best estimate.)
Biology 2025 Objective — Question 30
The instrument is used to measure a factor
- A. in the atmosphereCorrect
- B. in water
- C. on land
- D. on grasses
Explanation
A Six's thermometer measures temperature, an atmospheric factor.
Biology 2025 Objective — Question 31
When Tilapia population in a pond reaches the carrying capacity, the population
- A. alternately increases and decreasesCorrect
- B. remains unchanged
- C. increases only
- D. decreases only
Explanation
At carrying capacity, a population tends to fluctuate (alternately increase and decrease) around the maximum sustainable level rather than staying perfectly constant.
Biology 2025 Objective — Question 32
Which of the following statements about the pyramid of energy is correct?
- A. Energy remains constant across trophic levels
- B. Energy decreases from the base to the apex of the pyramidCorrect
- C. Energy increases from the base to the apex of the pyramid
- D. Each trophic level is an independent energy source
Explanation
In a pyramid of energy, the amount of available energy decreases progressively from the producers at the base to the top predators at the apex, due to energy loss at each trophic transfer.
Biology 2025 Objective — Question 33
Which of the following sequences represents the trend in eutrophication?
- A. Heavy mineralization -> lack of oxygen -> massive algal growth
- B. Excessive nitrates -> massive algal growth -> lack of oxygen -> death of aquatic organismsCorrect
- C. Excessive phosphates -> lack of oxygen -> massive algal growth -> death of aquatic organisms
- D. Massive algal growth -> excessive nitrates -> lack of oxygen -> excessive nitrates
Explanation
Eutrophication follows the sequence: excess nutrients (like nitrates) enter the water, causing massive algal growth, which subsequently depletes oxygen, leading to the death of aquatic organisms.
Biology 2025 Objective — Question 34
Which of the following statements correctly describes the term population? The number of
- A. Tilapia in a lakeCorrect
- B. fungus and snail on leaf litter
- C. bees and butterflies on a flower
- D. flatworms and roundworms in the gut of an animal
Explanation
A population refers to the number of individuals of the SAME species in a given area; Tilapia in a lake represents a single species, fitting the definition of a population, unlike the other options which mix different species.
Biology 2025 Objective — Question 35
What is the population density of Ageratum sp. of frequency 1,850 on a land area measuring 100m2?
- A. 18.50/m2Correct
- B. 8.05/m2
- C. 0.50/m2
- D. 0.05/m2
Explanation
Population density = frequency / area = 1,850 / 100m2 = 18.50/m2.
Biology 2025 Objective — Question 36
Which of the following activities does not control pathogens?
- A. Exposure to ultraviolet radiation
- B. Use of disinfectants
- C. Eating balanced dietCorrect
- D. Destroying the habitats of pathogens
Explanation
While a balanced diet supports overall immune health, it does not directly control or eliminate pathogens the way UV exposure, disinfectants, or habitat destruction do.
Biology 2025 Objective — Question 37
Which of the following diseases could be prevented by a BCG vaccination?
- A. Malaria
- B. Cholera
- C. TuberculosisCorrect
- D. Diphtheria
Explanation
The BCG (Bacillus Calmette-Guerin) vaccine is specifically used to prevent tuberculosis.
Biology 2025 Objective — Question 38
The main effect of deforestation is
- A. creation of new habitats
- B. loss of soil particlesCorrect
- C. survival of more species
- D. reduction of carbon (IV) oxide in the atmosphere
Explanation
Deforestation removes vegetation cover that would otherwise hold soil in place, leading to loss of soil particles through erosion.
Biology 2025 Objective — Question 39
Which of the following resources cannot be conserved?
- A. Mineral resources
- B. Soil and water
- C. Forests and wildlife
- D. Domestic wastesCorrect
Explanation
Domestic wastes are not a resource to be conserved; rather, they are managed/disposed of, unlike minerals, soil/water, and forests/wildlife which are conservable natural resources.
Biology 2025 Objective — Question 40
Which of the following activities is not suitable for forest conservation?
- A. Felling of treesCorrect
- B. Planting seedlings
- C. Preventing bush fires
- D. Planting tree crops
Explanation
Felling (cutting down) of trees directly reduces forest cover and is not a conservation activity, unlike planting seedlings, preventing bush fires, or planting tree crops.
Biology 2025 Objective — Question 41
Which of the following pairs of features is an example of discontinuous variation?
- A. Height and blood group
- B. Height and sex
- C. Colour and weight
- D. Fingerprint and blood groupCorrect
Explanation
Height, colour and weight are examples of continuous variation, while fingerprint and blood group are examples of discontinuous variation.
Biology 2025 Objective — Question 42
The ability of some individuals to taste phenylthiocarbamide (PTC) is an example of
- A. morphological variation
- B. morphological adaptation
- C. physiological variationCorrect
- D. physiological adaptation
Explanation
The ability to taste phenylthiocarbamide (PTC) is an example of physiological variation - a variation in a functional/physiological trait among individuals.
Biology 2025 Objective — Question 43
Alleles are found on
- A. nucleus
- B. Nucleolus
- C. chromosomesCorrect
- D. tissues
Explanation
Alleles are different versions of a gene, and they are located on chromosomes. Each individual has two alleles for each gene (one from each parent), which determine specific traits.
Biology 2025 Objective — Question 44
A couple heterozygous for albino genes have normal skin colour. What is the probability that their child would be an albino?
- A. 1/2
- B. 1/3
- C. 1/4Correct
- D. 1
Explanation
When both parents are heterozygous (Aa), where A is the dominant normal skin colour allele and a is the recessive albino allele, there is a 1 in 4 chance that their child will inherit two recessive alleles (aa) and thus be albino.
Biology 2025 Objective — Question 45
The process occurring in the illustrated molecule below (a DNA-like double helix structure) is
- A. protein synthesis
- B. gene coding
- C. DNA replicationCorrect
- D. gene mutation
Explanation
The process occurring in the illustrated molecule is DNA replication - the process by which a cell copies its DNA to ensure that each daughter cell receives an identical set of genetic instructions.
Biology 2025 Objective — Question 46
If the percentage of adenine in the DNA of a human is 32%, what will be the percentage of thymine?
- A. 10%
- B. 16%
- C. 27%
- D. 32%Correct
Explanation
In DNA, adenine (A) pairs with thymine (T). So, the percentage of adenine is always equal to the percentage of thymine. If adenine is 32%, then thymine is also 32%.
Biology 2025 Objective — Question 47
Which of the following statements is not correct about colour blindness?
- A. It is a sex-linked trait
- B. Males are often carriersCorrect
- C. Females are not carriers
- D. The trait is controlled by a recessive gene
Explanation
A male cannot be a carrier of a sex-linked trait; he either suffers from the trait or is normal. A female may be a sufferer, carrier or normal - if one X-chromosome of a female is defective, the female is a carrier, so 'males are often carriers' is the incorrect statement.
Biology 2025 Objective — Question 48
Lamarck's theory of evolution states that
- A. characteristics of organisms are not the sum of the characters of their parents
- B. characteristics of organisms are determined by mutation
- C. organisms transfer acquired characters to their offspringCorrect
- D. organisms acquire genes from their parents
Explanation
Lamarck proposed the idea of inheritance of acquired characteristics, which suggests that traits developed during an organism's lifetime could be passed on to offspring.
Biology 2025 Objective — Question 49
The castes of the organisms found in a beehive are
- A. drones, queen and workersCorrect
- B. workers, soldiers and reproductives
- C. soldiers, workers and reproductives and king
- D. king, queen, workers and soldiers
Explanation
In a beehive, the primary castes are: Drones (male bees whose sole purpose is to mate the queen), Queen (the reproductive female that lays eggs), and Workers (non-reproductive females who perform tasks in the hive, such as foraging and caring for larvae).
Biology 2025 Objective — Question 50
The theory of natural selection in evolution was formulated by
- A. Mathias Schleiden
- B. Louis Pasteur
- C. Charles DarwinCorrect
- D. Jean Lamarck
Explanation
Charles Darwin was a British naturalist who formulated the theory of natural selection as a mechanism for evolution. His groundbreaking book, 'On the Origin of Species,' laid the foundation of modern evolutionary biology.
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