Topic – 1.1
What are characteristics of all organisms?
▶️ Answer/Explanation
Ans: C
Excretion (removal of metabolic waste) and nutrition (obtaining energy and nutrients) are universal characteristics of all organisms. Egestion (A/B) is limited to organisms with digestive systems, and photosynthesis (D) is specific to autotrophs like plants. Thus, the correct answer is C (Excretion and Nutrition).
Topic – 1.2
The scientific name for the golden eagle is Aquila chrysaetos. What is the genus of the golden eagle?
A) Aquila
B) chrysaetos
C) eagle
D) golden
▶️ Answer/Explanation
Ans: A
In binomial nomenclature, the scientific name is structured as Genus species. For Aquila chrysaetos, Aquila (A) is the genus, while chrysaetos (B) is the species. “Eagle” (C) and “golden” (D) are common names or descriptors, not taxonomic classifications.
Thus, the correct answer is A (Aquila), as it represents the genus in the given scientific name.
Topic – 1.3
The diagram shows four arthropods.
How many of these arthropods are insects?
A) 1
B) 2
C) 3
D) 4
▶️ Answer/Explanation
Ans: B
The diagram shows four arthropods: Pediculus (lice), Dermacentor (ticks), Anopheles (mosquitoes), and Carcinus (crabs).
Insects are characterized by having three body segments and six legs. Among these, only Pediculus and Anopheles meet these criteria, while Dermacentor is an arachnid (8 legs) and Carcinus is a crustacean (more than 6 legs).
Thus, 2 out of 4 arthropods shown are insects, making B the correct answer.
Topic – 2.1
Which row shows structures that are present in both root hair cells and palisade mesophyll cells?
▶️ Answer/Explanation
Ans: C
Root hair cells and palisade mesophyll cells are both plant cells and share common structures such as a cell wall, nucleus, and vacuole. However, chloroplasts are only present in palisade mesophyll cells for photosynthesis. Row C correctly lists the shared structures (cell wall, nucleus, vacuole) and excludes chloroplasts.
Row A includes chloroplasts (incorrect), Row B excludes the nucleus (incorrect), and Row D excludes the cell wall and vacuole (incorrect). Thus, the correct answer is C (Row C).
Topic – 2.2
The diagram shows a cell at ×1500 magnification.
What is the actual size of the cell?
A) 0.003 mm
B) 0.03 mm
C) 33 mm
D) 333 mm
▶️ Answer/Explanation
Ans: B
The actual size of the cell is calculated using the formula: \[ \text{Actual Size} = \frac{\text{Magnified Size}}{\text{Magnification}} \] Assuming the magnified size of the cell in the diagram is approximately 45 mm, the actual size is: \[ \frac{45\,\text{mm}}{1500} = 0.03\,\text{mm}. \] This matches option B (0.03 mm), which is biologically reasonable for eukaryotic cells (10–100 µm). Options A, C, and D are either too small or implausible for microscopic cells.
Topic – 3.1
The diagram shows a test-tube containing clear jelly. A drop of blue ink is injected into the middle of the jelly. The blue colour of the ink spreads throughout the jelly. By which process does the blue ink spread through the jelly?
A) active transport
B) catalysis
C) diffusion
D) osmosis
▶️ Answer/Explanation
Ans: C
The blue ink spreads through the jelly due to diffusion (C), where molecules move from a region of higher concentration (center of the jelly) to lower concentration (outward). This passive process does not require energy.
Active transport (A) involves energy use, catalysis (B) speeds up reactions, and osmosis (D) is specific to water movement. Since the ink spreads randomly without energy input, the correct answer is C (Diffusion).
Topic – 3.2
The diagram shows some of the apparatus used in an osmosis investigation.
In this investigation a dialysis tubing bag was filled with sucrose solution, sealed and weighed.
The dialysis tubing bag was then immersed in distilled water for one hour.
After one hour the dialysis tubing bag was removed from the beaker, the surface was dried and the bag was reweighed.
Which row explains what will happen during the investigation?
▶️ Answer/Explanation
Ans: C
The dialysis tubing contains a sucrose solution (high solute concentration), while the beaker has distilled water (low solute concentration). Due to osmosis, water moves from the region of higher water concentration (distilled water) to lower water concentration (sucrose solution) across the partially permeable membrane. This increases the mass of the tubing, as described in Row C.
Row A is incorrect because water moves into the bag, not out. Row B is wrong as osmosis occurs due to the concentration gradient. Row D incorrectly suggests sucrose moves out or water moves out, which does not happen.
Topic: 3.3
Which row describes active transport of ions?
▶️ Answer/Explanation
Ans: D
Active transport moves ions against the concentration gradient (low to high) and requires energy (ATP). Option D matches this description.
Option A is incorrect because high to low movement describes passive transport, despite mentioning energy. Option B is wrong as energy is required. Option C describes diffusion, a passive process.
Thus, the correct answer is D.
Topic – 4.1
The diagram shows part of a protein molecule.
What does X represent?
A) amino acid
B) fatty acid
C) glycerol
D) sugar
▶️ Answer/Explanation
Ans: A
The diagram depicts a segment of a protein molecule, where X represents an amino acid (A). Proteins are polymers formed by peptide bonds linking amino acids. Fatty acids (B) and glycerol (C) are lipid components, while sugar (D) is a carbohydrate. Since proteins are exclusively made of amino acids, the correct answer is A.
Topic – 5.1
What is true of all enzymes?
▶️ Answer/Explanation
Ans: D
Enzymes are biological catalysts made of proteins, not sugars (A and B are incorrect). Their optimal pH varies—for example, pepsin works best at pH 2, while amylase is most effective at pH 7 (C is incorrect). Thus, D is correct because neither statement applies universally to all enzymes.
Topic: 5.1
What is the substrate for enzyme X?
▶️ Answer/Explanation
Ans: D
The substrate is the molecule upon which an enzyme acts. In the diagram, option D is the correct substrate for enzyme X, as it fits into the enzyme’s active site, initiating the reaction.
Options A, B, and C do not match the shape or specificity of enzyme X’s active site, making them incorrect. Thus, the correct answer is D.
An experiment is set up to investigate gas exchange in aquatic plants. The hydrogencarbonate indicator solution is orange at the start. Which colour is it after three hours?
▶️ Answer/Explanation
Ans: C
The hydrogencarbonate indicator starts orange (neutral CO₂ levels). During photosynthesis, aquatic plants absorb CO₂, reducing its concentration in the solution. This makes the solution more alkaline, turning the indicator purple (C). Yellow (D) indicates high CO₂ (respiration), while orange (B) implies no change. Blue-black (A) is irrelevant to this indicator.
A) They have a large surface area and are thick.
B) They have a large surface area and are thin.
C) They have a small surface area and are thick.
D) They have a small surface area and are thin.
▶️ Answer/Explanation
Ans: B
Leaves are adapted for photosynthesis by having a large surface area to capture maximum sunlight and being thin to allow efficient gas exchange (CO₂ in, O₂ out) and light penetration to chloroplasts.
Thick leaves (A) would hinder gas diffusion, while small surface areas (C, D) reduce light absorption. Thus, the correct adaptation is B (large surface area and thin).
Topic: 7.1
The haemoglobin concentration in the blood of a person is 80 g/dm³. The accepted normal concentration is 120 g/dm³ or above. Which substance may be lacking in their diet?
A) calcium
B) fats
C) fibre
D) iron
▶️ Answer/Explanation
Ans: D
Haemoglobin is an iron-containing protein in red blood cells responsible for oxygen transport. A low concentration (80 g/dm³ vs. the normal ≥120 g/dm³) indicates iron deficiency anaemia.
Iron (D) is essential for haemoglobin synthesis, while calcium (A) supports bones, fats (B) provide energy, and fibre (C) aids digestion. Thus, the deficient nutrient is iron.
Topic: 7.3
Which statement about physical digestion is correct?
A) It increases the surface area of food.
B) It involves enzymes.
C) It takes place in the mouth only.
D) It produces smaller molecules.
▶️ Answer/Explanation
Ans: A
Physical digestion mechanically breaks down food into smaller pieces, increasing its surface area (A) for efficient chemical digestion. This occurs in multiple locations, including the mouth (chewing) and stomach (churning).
Enzymes (B) are part of chemical digestion, not physical digestion. Option C is incorrect because physical digestion is not limited to the mouth. Option D describes chemical digestion, where molecules are broken down, not physical digestion.
Thus, the correct answer is A.
Solid food enters the mouth at P and enters the oesophagus at Q. How does the food at Q differ from the food at P?
A) It contains less fibre.
B) It contains less water.
C) It contains less protein.
D) It contains less starch.
▶️ Answer/Explanation
Ans: D
In the mouth (P), food mixes with saliva containing salivary amylase, which breaks down starch into simpler sugars. By the time food reaches the oesophagus (Q), some starch has been digested, reducing its quantity. Thus, the food at Q contains less starch (Option D).
Fibre (A) remains undigested, water (B) increases due to saliva, and protein (C) digestion begins in the stomach, not the mouth.
Topic – 8.1
Which row shows the functions of xylem and phloem?
▶️ Answer/Explanation
Ans: A
The xylem transports water and minerals upward from roots to leaves and provides structural support, while the phloem transports sugars (like sucrose) and other organic nutrients bidirectionally (from leaves to other parts).
Option A correctly matches these functions. The other options (B, C, D) either reverse the roles or misassign functions (e.g., phloem transporting water or xylem transporting sugars). Thus, the correct answer is A.
Topic: 8.2
What is the effect on a plant of not having any root hairs?
▶️ Answer/Explanation
Ans: A
Root hairs significantly increase the surface area of roots, enhancing water and mineral absorption from the soil. Without root hairs, the plant’s ability to absorb water is reduced due to the decreased surface area, leading to less water uptake (Option A).
Option B is incorrect because root hairs do not increase absorption when absent. Option C is wrong as water loss to the soil is not a direct effect of missing root hairs. Option D is incorrect because mineral ion loss is unrelated to root hair absence.
Topic: 9.1
Which statements describe how the structures in the circulatory system function?
1. A muscular pump to push blood into vessels
2. Valves to ensure one-way blood flow
3. Veins to take blood away from the heart
4. Vessels to return blood to the heart
A) 1, 2 and 3
B) 1, 2 and 4
C) 1, 3 and 4
D) 2, 3 and 4
▶️ Answer/Explanation
Ans: B
1. Correct – The heart (a muscular pump) pushes blood into arteries.
2. Correct – Valves prevent backflow, ensuring one-way circulation.
3. Incorrect – Veins return blood to the heart; arteries carry blood away.
4. Correct – Veins are the vessels that return blood.
Since only statements 1, 2, and 4 are accurate, the correct answer is B.
Topic – 9.2
The diagram shows a section through the heart. Which part is the septum?
▶️ Answer/Explanation
Ans: C
The septum is the muscular wall that divides the left and right sides of the heart, ensuring oxygenated and deoxygenated blood do not mix. In the diagram, C represents the septum, as it is the central partition. Structures A, B, and D correspond to chambers or valves, not the dividing wall. Thus, the correct answer is C.
Topic – 10.1
What is an example of good personal hygiene in the kitchen?
A) Cooking food at a high temperature
B) Disposing of waste food in sealed containers
C) Storing uncooked meat in a fridge
D) Washing hands before eating food
▶️ Answer/Explanation
Ans: D
Washing hands before eating food (D) is a direct example of personal hygiene, as it prevents contamination from hands to food. Options A (cooking temperature) and C (storing meat) are food safety measures, while B (waste disposal) relates to kitchen sanitation. Since the question focuses on personal hygiene, the correct answer is D.
Topic: 11.1
What is the pathway of expired air as it travels out of the body?
A) alveoli → trachea → bronchiole → bronchi
B) alveoli → bronchiole → bronchi → trachea
C) trachea → alveoli → bronchiole → bronchi
D) trachea → bronchi → bronchiole → alveoli
▶️ Answer/Explanation
Ans: B
Expired air follows the reverse pathway of inhaled air. It starts from the alveoli (where gas exchange occurs), moves into bronchioles, then to the bronchi, and finally exits through the trachea.
Option A is incorrect because air does not bypass bronchioles and bronchi. Option C and D describe the inhalation pathway, not exhalation. Thus, the correct sequence is B (alveoli → bronchiole → bronchi → trachea).
▶️ Answer/Explanation
Ans: A
Yeast undergoes anaerobic respiration (fermentation) in the sugar solution, producing carbon dioxide as a byproduct. When CO₂ passes through limewater (calcium hydroxide solution), it reacts to form calcium carbonate, which is insoluble and turns the solution cloudy. This confirms the presence of CO₂ (A). Oxygen (B/D) doesn’t cause this change, and limewater starts colourless, not cloudy (C/D).
A) carbon dioxide + water → glucose + oxygen
B) glucose + oxygen → carbon dioxide + water
C) glycogen + oxygen → carbon dioxide + water
D) water + oxygen → glucose + carbon dioxide
▶️ Answer/Explanation
Ans: B
Aerobic respiration breaks down glucose in the presence of oxygen to release energy, producing carbon dioxide and water as byproducts. The correct equation is:
glucose + oxygen → carbon dioxide + water + energy
Option A describes photosynthesis (the reverse process). Options C and D use incorrect reactants (glycogen/water instead of glucose). Thus, B is the only correct representation of aerobic respiration.
Topic: 13.1
Which part of the body excretes urea, excess water and excess ions?
A) gall bladder
B) heart
C) kidney
D) lungs
▶️ Answer/Explanation
Ans: C
The kidneys (C) are the primary excretory organs that filter blood to remove waste products like urea, regulate water balance, and maintain proper ion concentrations in the body.
The gall bladder (A) stores bile, the heart (B) pumps blood, and the lungs (D) excrete carbon dioxide – none of these handle urea or ion regulation.
Topic: 13.1
The diagram shows the kidneys and associated organs. Which label is the ureter?
▶️ Answer/Explanation
Ans: C
The ureter is a muscular tube that transports urine from the kidney to the bladder. In the diagram, it is correctly labeled as C, connecting the kidney to the bladder.
Other structures in the diagram include:
A: Likely the kidney (produces urine)
B: Likely the renal blood vessels (supply blood to the kidney)
D: Likely the bladder (stores urine)
Thus, the correct answer is C (Ureter).
Topic: 14.1
What is the name of the junction between two neurones?
A) effector
B) receptor
C) gland
D) synapse
▶️ Answer/Explanation
Ans: D
The junction between two neurones is called a synapse (Option D). At the synapse, electrical impulses are converted into chemical signals (neurotransmitters) to cross the gap between neurones.
Effectors (A) are muscles or glands that respond to signals, receptors (B) detect stimuli, and glands (C) secrete substances. These are not junctions between neurones.
Topic – 14.3
Which statement about adrenaline is correct?
A) It decreases the heart rate.
B) It decreases the diameter of the pupil.
C) It increases the breathing rate.
D) It is made in the pancreas.
▶️ Answer/Explanation
Ans: C
Adrenaline, a hormone secreted by the adrenal glands, triggers the “fight or flight” response. It increases breathing rate (C) to supply more oxygen to muscles, preparing the body for action.
Option A is incorrect because adrenaline increases heart rate. Option B is wrong as it dilates (widens) pupils. Option D is false since adrenaline is produced in adrenal glands, not the pancreas. Thus, the correct answer is C.
Plant growth towards light is called ……1…… .
When a plant shoot grows towards a light source, it is showing a ……2…… to light.
Light acts as the ……3…… .
▶️ Answer/Explanation
Ans: C
The correct sequence is: phototropism (1), response (2), and stimulus (3). Phototropism is the specific term for plant growth towards light (1). The directional growth is the plant’s response to light (2), while light itself serves as the stimulus (3) that initiates this response.
Option A and B use “movement” which is too general. Option D reverses the order of response and stimulus. Therefore, C is correct.
Topic: 15.1
Which statements about antibiotics are correct?
1. Antibiotics can be used to treat bacterial infections.
2. Antibiotics can be used to treat viral infections.
3. Antibiotics are not effective against resistant bacteria.
A) 1, 2 and 3
B) 1 and 2 only
C) 1 and 3 only
D) 2 and 3 only
▶️ Answer/Explanation
Ans: C
1. Correct – Antibiotics specifically target bacterial infections by disrupting bacterial cell processes.
2. Incorrect – Viruses have different structures and life cycles, making antibiotics ineffective against them.
3. Correct – Resistant bacteria have evolved mechanisms to survive antibiotic treatment.
Since only statements 1 and 3 are true, the correct answer is C.
Topic – 16.2
Which statement about sexual reproduction is correct?
A) Fertilisation is involved.
B) Zygotes fuse.
C) Offspring are always genetically identical.
D) One female gamete fuses with many male gametes.
▶️ Answer/Explanation
Ans: A
Sexual reproduction requires fertilisation (A), where male and female gametes fuse to form a zygote. This is the defining feature of sexual reproduction. Option B is incorrect because zygotes develop into offspring rather than fusing. Option C is false because meiosis and genetic recombination ensure offspring are genetically unique. Option D is incorrect as typically only one male gamete fertilizes one female gamete. Thus, the correct answer is A.
▶️ Answer/Explanation
Ans: B
Asexual reproduction involves one parent producing genetically identical offspring through mitosis or budding. The offspring are clones of the parent (identical to parent) and to each other. Option B correctly states these characteristics. Options A, C, and D are incorrect because they either describe non-identical offspring (which occurs in sexual reproduction) or involve two parents.
Topic: 17.1
What is defined as a length of DNA that codes for a protein?
A) amino acid
B) antibody
C) chromosome
D) gene
▶️ Answer/Explanation
Ans: D
A gene is a specific sequence of DNA that contains the instructions for building one or more proteins. This makes option D correct.
Option A (amino acid) is incorrect because it’s a protein building block, not a DNA segment. Option B (antibody) is a protein product, not DNA. Option C (chromosome) contains many genes but isn’t a single coding unit. Therefore, D (gene) is the correct answer.
▶️ Answer/Explanation
Ans: C
In human reproduction, the father’s sperm carries either an X (producing a daughter) or Y (producing a son) chromosome, with equal probability (50% each). Previous children’s genders don’t affect future probabilities – each conception is an independent event. Thus, despite having three sons, the chance of the next child being a daughter remains 50% (C).
Option A (0%) suggests impossibility, B (25%) underestimates, and D (100%) guarantees a daughter – all incorrect as they violate basic genetic probability.
A) allele
B) genotype
C) mutation
D) phenotype
▶️ Answer/Explanation
Ans: C
A mutation (C) is the only option that represents a genetic change – an alteration in the DNA sequence that can create new alleles or modify existing ones.
Allele (A) is a gene variant, genotype (B) is the genetic makeup, and phenotype (D) is the physical expression of genes. While these are genetic terms, they don’t represent changes in genetic material.
Therefore, the correct answer is C (mutation), as it specifically refers to a change in genetic information.
The diagram shows energy flow from the Sun, through a food chain and into the environment. What is the form of energy for each numbered arrow?
▶️ Answer/Explanation
Ans: C
The energy flow follows this sequence:
1. Arrow 1 (Sun → Producer): Light energy from the Sun is converted by plants during photosynthesis (light → chemical).
2. Arrow 2 (Producer → Consumer): Chemical energy stored in plants is transferred when consumed by animals (chemical remains chemical).
3. Arrow 3 (All organisms → Environment): Heat energy is lost at each trophic level through metabolic processes.
Thus, the correct sequence is light → chemical → heat, matching option C.
Topic: 19.2
In a pyramid of numbers, what does the top of the pyramid represent?
A) carnivores
B) decomposers
C) herbivores
D) Sun
▶️ Answer/Explanation
Ans: A
A pyramid of numbers shows the quantity of organisms at each trophic level. The top represents carnivores (A), specifically apex predators, which are fewest in number due to energy loss (only ~10% transfers between levels).
Why other options are incorrect:
B (Decomposers): Not part of the pyramid’s trophic levels.
C (Herbivores): Found at the middle level (primary consumers).
D (Sun): Energy source but not an organism in the pyramid.
Thus, the correct answer is A (Carnivores).
A few yeast cells were placed in a container of nutrient solution. The graph shows how their population size changed over time. Which row shows when the reproduction rate was greater than the death rate for the numbered phases on the graph?
▶️ Answer/Explanation
Ans: B
The graph shows a typical microbial growth curve with three phases:
- Phase 1 (Lag phase): Cells adapt to environment – reproduction slightly exceeds death (yes)
- Phase 2 (Exponential phase): Rapid growth – reproduction greatly exceeds death (yes)
- Phase 3 (Stationary phase): Resources limited – reproduction equals death (no)
Thus, the correct sequence is yes, yes, no (Option B). Other options incorrectly represent the growth dynamics in these phases.
Topic – 20.3
The bloodworm is an organism that is found in heavily polluted water.
The diagram shows where raw sewage flows into a river.
Where would there be fewest bloodworms?
▶️ Answer/Explanation
Ans: A
Bloodworms thrive in polluted water rich in organic matter. Before the sewage inflow (A), the water is cleanest, making it the area with fewest bloodworms.
At the inflow (B) and just downstream (C), pollution is highest, supporting maximum bloodworm populations. Far downstream (D), pollution disperses but remains higher than upstream. Thus, A is correct as it represents the least polluted (and least favorable) zone for bloodworms.
Topic: 21.3
Which statement about genetic modification is correct?
▶️ Answer/Explanation
Ans: C
Genetic modification (GM) directly alters an organism’s DNA to create new gene combinations, often by inserting genes from different species. This makes option C correct.
Why others are wrong:
• A describes selective breeding, not GM
• B is false (GM commonly uses cross-species genes)
• D describes cloning, not genetic modification
Examples include Bt cotton (containing bacterial genes) or golden rice (with daffodil genes), demonstrating how GM creates novel genetic combinations.