ICSE Class 10 Chemistry Sample Paper 2026 with Solutions

SECTION A (40 Marks)

(Attempt all questions from this Section.)

 

Question 1

Choose the correct answers to the questions from the given options.
(Do not copy the question, write the correct answers only.) [15]

 

(i) Allen’s blood report showed an abnormal decrease in the number of R.B.C. He is suffering from: [1 Mark]
(A) Polycythemia
(B) Erythropenia
(C) Glycosuria
(D) Haemophilia

Answer: (B) Erythropenia

Erythropenia refers to a deficiency or abnormal decrease in the count of red blood cells.

Teacher's Note:
a) Recall that the prefix 'erythro' relates to red blood cells and 'penia' means deficiency.
b) Do not confuse with Polycythemia, which is an abnormal increase in R.B.C. count.

 

(ii) A farmer notices that storing ripe mangoes with unripe ones speeds up the ripening process. The phytohormone primarily responsible for this phenomenon is: [1 Mark]
(A) Auxins
(B) Cytokinins
(C) Gibberellins
(D) Ethylene

Answer: (D) Ethylene

Ethylene is a gaseous plant hormone that promotes fruit ripening.

Teacher's Note:
a) Ethylene is unique as it is a gaseous hormone naturally produced by ripening fruits.
b) Remember that commercial fruit ripening often uses artificial sources of ethylene or acetylene gas.

 

(iii) Assertion (A) : Oxygen is produced during light dependent reactions of photosynthesis.
Reason (R) : Oxygen is released as a byproduct during photolysis. [1 Mark]
(A) (A) is true and (R) is false.
(B) (A) is false and (R) is true.
(C) Both (A) and (R) are true and (R) is the correct explanation of (A).
(D) Both (A) and (R) are true but (R) is not the correct explanation of (A).

Answer: (C) Both (A) and (R) are true and (R) is the correct explanation of (A).

Photolysis of water during the light reaction splits water molecules, releasing oxygen as a byproduct.

Teacher's Note:
a) Ensure clear understanding of the Hill reaction and photolysis occurring in the grana during light-dependent reactions.
b) Verify that oxygen evolved comes entirely from water molecules, not carbon dioxide.

 

(iv) Reena gets emotionally stressed when the school examinations are approaching. Which hormone is responsible for this condition? [1 Mark]
(A) Adrenaline
(B) Thyroxine
(C) Insulin
(D) Growth hormone

Answer: (A) Adrenaline

Adrenaline is secreted during emergency or stressful emotional conditions to prepare the body.

Teacher's Note:
a) Adrenaline is known as the hormone of flight or fight secreted by the adrenal medulla.
b) Note that stress, fear, and excitement stimulate the sympathetic nervous system to release this hormone.

 

(v) The diagram given below is that of a Neutrophil.
The function is ___________: [1 Mark]

[Figure: Diagram of a Neutrophil showing a multi-lobed nucleus and dotted cytoplasm.]

(A) secreting hormone
(B) transporting food
(C) phagocytosis
(D) producing antibodies

Answer: (C) phagocytosis

Neutrophils are phagocytic white blood cells that engulf harmful bacteria.

Teacher's Note:
a) Identify neutrophils by their distinct multi-lobed nuclei.
b) Distinguish them from lymphocytes, which produce antibodies.

 

(vi) Assertion (A): Pituitary gland is known as the master gland.
Reason (R): It regulates the activities of other exocrine glands. [1 Mark]
(A) (A) is true and (R) is false.
(B) (A) is false and (R) is true.
(C) Both (A) and (R) are true and (R) is the correct explanation of (A).
(D) Both (A) and (R) are true but (R) is not the correct explanation of (A).

Answer: (A) (A) is true and (R) is false

The pituitary gland regulates other endocrine glands, not exocrine glands.

Teacher's Note:
a) Carefully read the terms endocrine and exocrine in statement reasons.
b) The pituitary secretes tropic hormones that control other endocrine glands like thyroid and adrenals.

 

(vii) Aruna went to a theatre to watch a movie on a bright sunny morning. As she came out of the theatre, she felt a dazzling effect and could not open her eyes. After a few minutes her vision became normal. This is due to: [1 Mark]

[Figure: A person shielding eyes from bright sunlight outdoors.]

(A) Accommodation of eye
(B) Mutation
(C) Polarisation
(D) Adaptation of eyes

Answer: (D) Adaptation of eyes

The eyes take time to adapt from dark adaptation inside the theatre to bright light outside.

Teacher's Note:
a) Light adaptation and dark adaptation involve changes in pupil size and retinal sensitivity (rhodopsin/iodopsin).
b) Do not confuse with accommodation, which is focusing on objects at different distances.

 

(viii) Reflex actions provide a survival advantage because they: [1 Mark]
(A) are controlled by the cerebrum.
(B) are controlled by the medulla oblongata.
(C) require no conscious thought, allowing rapid responses.
(D) always involve the spinal cord.

Answer: (C) require no conscious thought, allowing rapid responses.

Reflex actions are involuntary and instantaneous, protecting the body from immediate danger.

Teacher's Note:
a) Reflex arcs bypass conscious brain processing to ensure instantaneous reaction.
b) Remember that cerebral involvement would delay response times.

 

(ix) Industrial melanism is the phenomenon by which the peppered moth: [1 Mark]
(A) die due to industrial growth.
(B) in polluted areas, became darker in colour for better camouflage.
(C) became lighter in colour due to natural selection.
(D) became resistant to industrial pollution.

Answer: (B) in polluted areas, became darker in colour for better camouflage.

Dark-colored moths survived better against soot-covered tree trunks due to natural selection.

Teacher's Note:
a) Industrial melanism is a classic textbook example of natural selection.
b) Ensure students understand that pollution darkened the environment, favoring the dark variant (carbonaria).

 

(x) The hormone that maintains the thickening of the endometrium during pregnancy is: [1 Mark]
(A) Oestrogen
(B) ACTH
(C) Progesterone
(D) Oxytocin

Answer: (C) Progesterone

Progesterone secreted by the corpus luteum maintains the uterine lining for implantation and pregnancy.

Teacher's Note:
a) Progesterone is known as the pregnancy hormone.
b) Oestrogen promotes the initial proliferation of the endometrium, but progesterone maintains it.

 

(xi) The onset of menstruation in a human female is called: [1 Mark]
(A) Menopause
(B) Menarche
(C) Ovulation
(D) Oogenesis

Answer: (B) Menarche

Menarche marks the beginning of the first menstrual cycle during puberty.

Teacher's Note:
a) Menopause is the permanent cessation of menstruation.
b) Spell terms carefully to avoid confusion between menarche and menopause.

 

(xii) The number of autosomes and allosomes present in a human cell: [1 Mark]
(A) 22 allosomes, 1 autosome
(B) 22 pairs of autosomes, 1 pair of allosome
(C) 22 autosomes, 1 allosome
(D) 22 pairs of allosomes, 1 pair of autosome

Answer: (B) 22 pairs of autosomes, 1 pair of allosome

Human somatic cells contain 23 pairs of chromosomes comprising 22 pairs of autosomes and 1 pair of sex chromosomes (allosomes).

Teacher's Note:
a) Note the word "pairs" in the correct option.
b) Total chromosomes equal 44 autosomes and 2 allosomes (46 individual chromosomes).

 

(xiii) Cultural revolution favours a steep rise in human population. Identify the correct sequence of revolution: [1 Mark]
(A) Tool making, Scientific and Industrial, Agricultural
(B) Agricultural, Tool making, Scientific and Industrial
(C) Scientific and Industrial, Agricultural, Tool making
(D) Tool making, Agricultural, Scientific and Industrial

Answer: (D) Tool making, Agricultural, Scientific and Industrial

Human cultural evolution progressed chronologically from tool making to agriculture and then to scientific and industrial advancements.

Teacher's Note:
a) Chronological order of cultural milestones explains the population explosion.
b) Agriculture provided steady food supplies, while science reduced mortality rates.

 

(xiv) Tanvi tried to match the phases of menstrual cycle with the number of days as given in the table below: [1 Mark]

PHASE	DAYS
P - Follicular Phase	Day 5 - 12
Q - Luteal Phase	Day 15 - 28
R - Menstrual Phase	Day 3 - 5
S - Ovulatory Phase	Day 13 or 14

Identify the correct sequence:
(A) P, Q, R, S
(B) Q, S, R, P
(C) R, P, S, Q
(D) S, R, P, Q

Answer: (C) R, P, S, Q

Chronologically in a 28-day cycle: Menstrual phase (R: Days 3-5), Follicular phase (P: Days 5-12), Ovulatory phase (S: Day 13 or 14), and Luteal phase (Q: Days 15-28).

Teacher's Note:
a) Track the sequence starting from day 1 of the cycle.
b) Ensure students trace the exact day ranges specified in standard human physiology chapters.

 

(xv) Aditya who is fond of roller skating. Identify the correct terms which help him to maintain his body balance: [1 Mark]

[Figure: A boy balancing on roller skates.]

(A) Cerebellum, Semicircular canals, Vestibule
(B) Vestibule, Sclera, Cerebrum
(C) Malleus, Semicircular canals, Utriculus
(D) Sacculus, Stapes, Cochlea

Answer: (A) Cerebellum, Semicircular canals, Vestibule

The cerebellum and the inner ear structures (semicircular canals and vestibule) coordinate muscular activity and dynamic and static balance.

Teacher's Note:
a) Semicircular canals manage dynamic balance, whereas the vestibule manages static equilibrium.
b) The cerebellum coordinates voluntary muscular movements and body posture.

 

Question 2

(i) Give the biological/technical terms for the following: [5 Marks]

(a) A mixture of smoke and fog. [1 Mark]

Answer: Smog.

Teacher's Note:
a) Smog is a severe form of air pollution.
b) Check spelling accuracy.

(b) The inner lining of uterus. [1 Mark]

Answer: Endometrium.

Teacher's Note:
a) The endometrium undergoes cyclic changes during the menstrual cycle.
b) It is richly supplied with blood vessels for implantation.

(c) The pressure that is responsible for the movement of water molecules across the cortical cells of the root. [1 Mark]

Answer: Root pressure.

Teacher's Note:
a) Root pressure pushes water up the xylem vessels to a limited height.
b) It develops due to active absorption of salts by root hairs.

(d) The ground substance present in a chloroplast. [1 Mark]

Answer: Stroma.

Teacher's Note:
a) Stroma is the fluid-filled matrix where dark reactions (Calvin cycle) take place.
b) Do not confuse with stoma (stomatal pore).

(e) The fluid present between the layers of meninges. [1 Mark]

Answer: Cerebrospinal fluid.

Teacher's Note:
a) Cerebrospinal fluid protects the brain and spinal cord from mechanical shocks.
b) It also provides nutrition and oxygen to central nervous tissues.

 

(ii) Given below is the diagram of a human heart. Read the information below the diagram and fill in the blanks: [5 Marks]

[Figure: Diagram of a human heart indicating external features and major blood vessels.]

The human heart pumps blood throughout the body. It is the size of a large fist. The heart is located between the lungs in the thoracic cavity. It has four chambers. The heart functions all through the lifespan of a person and is responsible for the survival of the person.
The heart is enclosed by a membrane called (a) ____________ (Pericardium / Pleura). The ventricles give rise to two large blood vessels called (b) ____________ (Pulmonary vein / Pulmonary artery) and (c) ____________ (Aorta / Venacava). The flaps of the cuspid valves are kept in position by (d) ____________ (Chordae tendinae / Endometrium). (e) ____________ (Hepatic / Coronary) arteries supply oxygenated blood to the walls of the heart.

Answer:
(a) Pericardium
(b) Pulmonary artery
(c) Aorta
(d) Chordae tendinae
(e) Coronary

Teacher's Note:
a) Ensure students choose from the options given in the question text.
b) Pleura is the membrane covering the lungs, whereas pericardium covers the heart.

 

(iii) Choose the odd term out from each of the following set of terms. Mention the category to which the remaining three belong: [5 Marks]

(a) Sulphur dioxide, Oxygen, Carbon monoxide, Nitrogen dioxide. [1 Mark]

Answer:
Odd term: Oxygen.
Category: Air pollutants.

Teacher's Note:
a) Oxygen is a life-supporting gas, while others are toxic air pollutants.
b) State both the odd term and the common category clearly.

(b) Pons, Epidermis, Xylem, Phloem. [1 Mark]

Answer:
Odd term: Pons.
Category: Plant tissues / Plant parts.

Teacher's Note:
a) Pons is a part of the human hindbrain.
b) Epidermis, xylem, and phloem are plant tissues.

(c) Tympanum, Pinna, Auditory canal, Malleus. [1 Mark]

Answer:
Odd term: Malleus.
Category: Parts of outer ear.

Teacher's Note:
a) Malleus is an ear ossicle located in the middle ear.
b) Pinna, auditory canal, and tympanum form the outer ear structures.

(d) Ureter, Urethra, Uterus, Renal Pelvis. [1 Mark]

Answer:
Odd term: Uterus.
Category: Parts of the urinary system.

Teacher's Note:
a) Uterus is a female reproductive organ.
b) Ureter, urethra, and renal pelvis are parts of the excretory system.

(e) Stomata, Lenticles, Cuticle, Root hair. [1 Mark]

Answer:
Odd term: Root hair.
Category: Structures through which transpiration takes place.

Teacher's Note:
a) Root hairs absorb water and minerals from the soil.
b) Stomata, lenticels, and cuticle are sites of transpiration in plants.

 

(iv) Rajeev, a 10 year old boy, went to an Ophthalmologist to get his eyes tested. He noticed a poster in the clinic with questions related to the parts of human eye. Help Rajeev answer the questions: [5 Marks]

(a) Which is the fluid that lubricates the eye? [1 Mark]

Answer: Tears (or aqueous humour / conjunctival fluid).

Teacher's Note:
a) Tears secreted by lacrimal glands lubricate the front of the eye.
b) Aqueous humour nourishes internal structures of the anterior chamber.

(b) Which cells help in colour vision? [1 Mark]

Answer: Cone cells.

Teacher's Note:
a) Cones are sensitive to bright light and colours.
b) Rods are sensitive to dim light (scotopic vision).

(c) Which nerve sends impulses from the eyeball to the brain? [1 Mark]

Answer: Optic nerve.

Teacher's Note:
a) The optic nerve transmits sensory impulses from the retina to the visual cortex of the brain.
b) The blind spot is where the optic nerve leaves the retina.

(d) Name the structure that gives colour to the eyes. [1 Mark]

Answer: Iris.

Teacher's Note:
a) The pigment in the iris determines eye color (brown, blue, green).
b) It also regulates the amount of light entering the pupil.

(e) Name the part that allows entry of light rays into the eye. [1 Mark]

Answer: Pupil.

Teacher's Note:
a) The pupil is the aperture in the center of the iris.
b) The cornea is the outermost transparent structure through which light first enters.

 

(v) Study the diagram given below and match the structure with its function:
Example: Scrotum - (f) [5 Marks]

[Figure: Diagram of human testis showing seminiferous tubules, epididymis, vas deferens, and efferent ducts.]

Structure	Functions
(a) Interstitial cells (Leydig cells)	(a) Secrete Testosterone
(b) Efferent Ducts	(b) Transports sperms to Epididymis
(c) Epididymis	(c) Stores sperms till maturation
(d) Vas deferens	(d) Transport sperms to urethra
(e) Seminiferous tubules	(e) Produce sperms

Answer:
(a) - (a)
(b) - (b)
(c) - (c)
(d) - (d)
(e) - (e)

Teacher's Note:
a) Match each male reproductive structure to its correct physiological role.
b) Interstitial cells secrete male sex hormone testosterone.

 

SECTION B (40 Marks)

(Attempt any four questions from this Section.)

 

Question 3

(i) Explain the term Menarche. [1 Mark]

Answer: It is the onset of menstruation in a young female around the age of 13 years.

Teacher's Note:
a) Menarche marks the beginning of reproductive life in human females.
b) It is controlled by gonadotropic hormones.

 

(ii) In what form is water lost during transpiration and guttation from plants? [2 Marks]

Answer:
1. Transpiration: Water is lost in the form of water vapour.
2. Guttation: Water is lost in the form of water droplets.

Teacher's Note:
a) Transpiration occurs mainly through stomata as invisible vapour.
b) Guttation occurs through hydathodes at margins of leaves under high root pressure.

 

(iii) Ayush was in the final round of a carrom match. He was focussing intently on the strokes of the opponent player. [2 Marks]

[Figure: Two boys playing a game of carrom.]

(a) Which part of the brain helps Ayush to focus on the game?
(b) Name the part of the brain that co-ordinates his muscles while using the striker.

Answer:
(a) Cerebrum.
(b) Cerebellum.

Teacher's Note:
a) Cerebrum is the center of consciousness, intelligence, and voluntary concentration.
b) Cerebellum coordinates smooth muscular activities and balance.

 

(iv) State the permeability of cell membrane and cell wall. [2 Marks]

Answer:
1. Cell membrane: Semipermeable (or selectively permeable).
2. Cell wall: Freely permeable.

Teacher's Note:
a) The cell membrane allows selective movement of substances based on cell requirements.
b) The plant cell wall is made of cellulose and permits free passage of water and solutes.

 

(v) Draw a neat, labelled diagram of a cross section of an Artery and a Vein. [3 Marks]

Answer:
[Figure: Cross section comparing an Artery (thick muscular wall, narrow lumen) and a Vein (thin wall, wide lumen with valves).]
Labels: Connective tissue, Muscle and elastic fibres, Inner lining - Endothelium, Lumen.

Teacher's Note:
a) Arteries have thicker muscular and elastic walls to withstand high blood pressure.
b) Veins possess a wider lumen and valves to prevent backflow of blood.

 

Question 4

(i) What is Excretion? [1 Mark]

Answer: It is the removal of harmful nitrogenous waste products from the body.

Teacher's Note:
a) Excretion maintains chemical homeostasis in the body.
b) Principal nitrogenous wastes include urea, uric acid, and creatinine.

 

(ii) Differentiate between Diabetes mellitus and Diabetes insipidus with reference to the hormone involved. [2 Marks]

Answer:
1. Diabetes mellitus is caused by the hyposecretion of Insulin.
2. Diabetes insipidus is caused by the hyposecretion of Antidiuretic Hormone (ADH / Vasopressin).

Teacher's Note:
a) Diabetes mellitus leads to high blood sugar levels and excretion of glucose in urine.
b) Diabetes insipidus results in excessive excretion of dilute urine (polyuria).

 

(iii) Give the common name and the scientific name of the plant on which Gregor Mendel conducted his breeding experiments. [2 Marks]

Answer:
1. Common name: Garden pea.
2. Scientific name: Pisum sativum.

Teacher's Note:
a) Binomial nomenclature rules require underlining or italicising scientific names in print.
b) Ensure both genus (Pisum) and species (sativum) start with correct capitalization.

 

(iv) Name the tonicity of the solutions for a living cell to show Endosmosis and Exosmosis. [2 Marks]

Answer:
1. Endosmosis: Hypotonic solution.
2. Exosmosis: Hypertonic solution.

Teacher's Note:
a) In a hypotonic solution, water enters the cell due to lower solute concentration outside.
b) In a hypertonic solution, water leaves the cell due to higher solute concentration outside.

 

(v) Plant hormones are produced in extremely low concentrations in plants to regulate the physiological processes and tropic movements - [3 Marks]

[Figure: Sequence showing a healthy green plant turning senescent, yellow, and resulting in leaf fall.]

(a) Name one plant hormone responsible for the changes shown in the above picture.
(b) Identify a hormone that has an opposite effect to the one depicted in the picture.
(c) Give an example of a plant that shows Thigmotropism.

Answer:
(a) Abscisic acid (or Ethylene).
(b) Auxin (or Cytokinin / Gibberellin).
(c) Peas (or Grapes / Ivy / Passion flower).

Teacher's Note:
a) Abscisic acid promotes senescence, leaf yellowing, and abscission.
b) Thigmotropism is directional growth in response to touch, seen in tendril climbers.

 

Question 5

(i) What are non-biodegradable wastes? [1 Mark]

Answer: Materials that cannot be broken down by microorganisms and persist in the environment causing pollution.

Teacher's Note:
a) Examples include plastics, glass, and synthetic materials.
b) They accumulate in ecosystems and disrupt ecological balances.

 

(ii) Mention any two objectives of the Swachh Bharat Abhiyan. [2 Marks]

Answer:
1. To eliminate open defecation.
2. To clean streets, roads, and infrastructure of cities and towns.

Teacher's Note:
a) The national cleanliness campaign aims to improve sanitation and waste management.
b) Any two valid objectives from the government initiative are accepted.

 

(iii) Arrange the following food chain in a proper sequence: [2 Marks]

(a) Small fish, Penguin, Algae, Seal, Mosquito larvae
(b) Woodpecker, Caterpillar, Mountain lion, Fox, Cabbage

Answer:
(a) Algae -> Mosquito larvae -> Small fish -> Penguin -> Seal.
(b) Cabbage -> Caterpillar -> Woodpecker -> Fox -> Mountain lion.

Teacher's Note:
a) Food chains always begin with a producer (autotroph) followed by consumers.
b) Check trophic levels from primary producers to top carnivores.

 

(iv) Mention the number of cranial nerves and spinal nerves in a human being. [2 Marks]

Answer:
1. Cranial nerves: 12 pairs.
2. Spinal nerves: 31 pairs.

Teacher's Note:
a) Cranial nerves arise directly from the brain.
b) Spinal nerves originate from the spinal cord.

 

(v) Surya used a plant with variegated leaves for an experiment on photosynthesis. He tested a leaf with iodine after keeping the plant in sunlight for a few hours. [3 Marks]

[Figure: Potted plant with variegated leaves showing green and white patches.]

(a) Which parts of the leaf will turn blue black after the iodine test?
(b) What does this tell us about the role of chlorophyll in photosynthesis?
(c) Write the overall chemical equation for photosynthesis.

Answer:
(a) Green parts.
(b) Green parts contain chlorophyll which traps sunlight for photosynthesis.
(c) 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O
(Carbon dioxide) (Water) (Glucose) (Oxygen) (Water)

Teacher's Note:
a) Iodine turns blue-black in the presence of starch.
b) Ensure balanced chemical equations include necessary conditions like sunlight and chlorophyll.

 

Question 6

(i) State Mendel’s Law of Dominance. [1 Mark]

Answer: Out of a pair of contrasting characters present together, only one is able to express itself while the other remains suppressed.

Teacher's Note:
a) The allele that expresses itself is dominant, and the suppressed one is recessive.
b) This law explains phenotypic uniformity in the first filial generation (F1).

 

(ii) State the rate of transpiration when the air surrounding a plant has: [2 Marks]
(a) more atmospheric humidity.
(b) hot and dry air.

Answer:
(a) Less transpiration.
(b) More transpiration.

Teacher's Note:
a) High humidity decreases the diffusion gradient between leaf air spaces and external air.
b) Hot and dry air increases the rate of evaporation and transpiration.

 

(iii) Expand the following abbreviations: [2 Marks]
(a) ACTH
(b) ADH

Answer:
(a) Adrenocorticotropic hormone.
(b) Antidiuretic hormone.

Teacher's Note:
a) Spelling of medical and hormonal terms must be precise.
b) ACTH stimulates the adrenal cortex, while ADH regulates water reabsorption in kidneys.

 

(iv) Which part of the ear equalizes air pressure on either side of the ear drum? Where is this structure located? [2 Marks]

Answer:
1. Part: Eustachian tube.
2. Location: Connects the middle ear to the pharynx.

Teacher's Note:
a) Equalizing pressure prevents damage to the tympanic membrane.
b) Note both the structure name and location to secure full marks.

 

(v) Santosh loved his garden, especially his pea plants. One year, he noticed that all the pea plants he grew from one batch of seeds had round seeds. Curious, he took the seeds from one of those plants and grew a new generation. To his surprise, 75% of the new plants had round seeds, but 25% had wrinkled seeds. [3 Marks]

[Figure: Diagrams of round seeds and wrinkled seeds of pea plants.]

(a) What were the genotypes of the parent plants that Santosh originally planted?
(b) Which trait is dominant - round or wrinkled seeds?
(c) What is the genotypic ratio of the second generation (F2) plants?

Answer:
(a) Heterozygous dominant (Rr).
(b) Round.
(c) 1 : 2 : 1 (or RR : Rr : rr).

Teacher's Note:
a) A 3:1 phenotypic ratio in F2 indicates monohybrid cross between heterozygous parents.
b) Genotypic ratio in monohybrid cross is always 1 homozygous dominant : 2 heterozygous : 1 homozygous recessive.

 

Question 7

(i) Explain the term Natality. [1 Mark]

Answer: It is the number of live births per 1000 people of population per year.

Teacher's Note:
a) Natality is a key factor increasing population growth rate.
b) It is also referred to as the birth rate.

 

(ii) Distinguish between Sympathetic system and Parasympathetic system on the basis of heartbeat. [2 Marks]

Answer:
1. Sympathetic system: Increases the heartbeat.
2. Parasympathetic system: Decreases and normalizes the heartbeat.

Teacher's Note:
a) These two systems form the autonomic nervous system with antagonistic actions.
b) Sympathetic prepares the body for action, while parasympathetic restores resting state.

 

(iii) Meena covered a potted plant as shown below with a transparent plastic bag. She observed water droplets inside the bag after a few hours when kept in sunlight. [2 Marks]

[Figure: Potted plant enclosed in a sealed transparent polythene bag showing water droplets condensed inside.]

(a) Name the process that resulted in the formation of water droplets inside the bag.
(b) Define the process mentioned above.

Answer:
(a) Transpiration.
(b) It is the loss of water as water vapour from the aerial parts of a plant.

Teacher's Note:
a) Transpiration creates a suction pull for water ascent in plants.
b) Enclosing a potted plant in polythene is a standard demonstration experiment.

 

(iv) Mention the regions of the kidney where we can find glomerulus and Henle’s loop. [2 Marks]

Answer:
1. Glomerulus: Renal cortex.
2. Henle's loop: Renal medulla.

Teacher's Note:
a) Nephrons span across both the cortex and medulla regions of the kidney.
b) Renal corpuscles (Bowman's capsule and glomerulus) are located in the cortex.

 

(v) Draw a neat, labelled diagram to show the internal structure of a root hair. [3 Marks]

Answer:
[Figure: Diagram of a root hair cell showing epidermal cell, cell wall, cytoplasm, large vacuole, cell membrane, nucleus, fully grown root hair, and newly growing root hairs.]

Teacher's Note:
a) Root hairs are single-celled extensions of epidermal cells that increase surface area for water absorption.
b) Label key cellular components clearly: cell wall, cell membrane, vacuole, and nucleus.

 

Question 8

(i) How does the ozone layer depletion affect life on earth? [1 Mark]

Answer: Causes skin cancer, cataract, reduced crop yields, and harms marine life.

Teacher's Note:
a) Ozone depletion allows harmful ultraviolet (UV) radiations to reach the earth's surface.
b) Mentioning any key harmful effect is sufficient for the mark.

 

(ii) Mention two body features of Australopithecus. [2 Marks]

Answer:
1. Chin absent.
2. Prognathus (projecting) face with projecting eyebrow ridges.

Teacher's Note:
a) Australopithecus represents an early hominid ancestor.
b) Note anatomical features distinguishing them from modern humans.

 

(iii) Identical twins are always of the same gender. Explain why. [2 Marks]

Answer: Because they develop from a single fertilised egg (zygote) which splits into two embryos.

Teacher's Note:
a) Identical (monozygotic) twins share the exact same genetic and sex chromosome makeup.
b) Fraternal twins develop from two separate eggs and can be of different genders.

 

(iv) We should not insert sharp objects into the ear to removes ear wax. Give a suitable reason. [2 Marks]

Answer: It may rupture the ear drum (tympanic membrane) leading to deafness.

Teacher's Note:
a) The eardrum is a delicate membrane sensitive to physical injury.
b) Ear wax is naturally produced and cleared by the body.

 

(v) In a school experiment, a few students grow plants in pots placed horizontally as shown below. After a few days, the students observed that the roots bent downward, and the shoots curved upward. [3 Marks]

[Figure: Potted plant placed horizontally showing roots bending downwards and shoots curving upwards.]

(a) Name the tropic movement seen in shoots.
(b) Why do roots always grow downwards?
(c) Which phytohormone regulates the above tropic movements?

Answer:
(a) Phototropism.
(b) Because roots are positively geotropic and hydrotropic.
(c) Auxins.

Teacher's Note:
a) Unequal distribution of auxin causes differential growth rates in plant organs.
b) Shoots grow towards light (negative geotropism), while roots grow towards gravity and water.