👉 CBSE Class 10 Science Question Paper 2026 Set 1
SECTION - A (Biology)
Q. No Correct Answer Explanation
1 (C) Uterus
Implantation of the fertilized egg (embryo) occurs in the lining of the uterus.
2 (D) Budding
Yeast reproduces asexually through the process of budding.
3 (C) Guard cells
Guard cells control the opening and closing of stomatal pores by changing shape.
4
(D)
This equation represents anaerobic respiration specifically in human muscle cells.
5 (B) DDT
DDT is a synthetic chemical that does not break down naturally in the environment.
6 (C) 44+XY
A human egg (22+X) fertilized by a Y-sperm (22+Y) results in a male zygote (44+XY).
7 (C) (i), (ii), (iii) and (iv)
All listed factors contribute to the excessive generation of waste.
8 (A)
Assertion & Reason are both true; muscles in the gut lining push food via peristalsis.
9 (A)
Assertion & Reason are both true; asexual reproduction creates clones with minor DNA errors.
Answer 10.
Part (A) Identification of Reflex Arc:
P: Receptor (Heat/Pain receptors in the skin)
Q: Sensory Neuron
R: Relay Neuron (located in the Spinal Cord)
S: Effector (Muscle in the arm)
OR
Part (B) Plant Hormones:
(i) Promote cell division: Cytokinins
(ii) Inhibition of growth: Abscisic acid
(iii) Detection of light: Auxins (which facilitate phototropism)
(iv) Wilting of leaves: Abscisic acid
Answer 11. Double Circulation in Human Heart
Double circulation involves the blood passing through the heart twice during one complete cycle through the body:
Pulmonary Circulation: Deoxygenated blood is pumped from the right ventricle to the lungs, where it gets oxygenated and returns to the left atrium.
Systemic Circulation: Oxygenated blood is pumped from the left ventricle to all body parts (except lungs) and returns as deoxygenated blood to the right atrium.
Answer 12. Leaf Structure and Photosynthesis
(i) P: Chloroplast; Role: It contains chlorophyll, which traps solar energy necessary for the process of photosynthesis.
(ii) Balanced Equation for Photosynthesis:
Answer 13.
(a) Plastic Bags:
Harmful Effect: They are non-biodegradable and cause soil/water pollution or choke animals.
Alternatives: Jute bags, paper bags, or cloth bags.
(b) Chemicals in Food Chain:
How they reach us: Chemicals in soil/water are absorbed by plants (paddy), which are then consumed by humans.
Phenomenon: Biological Magnification (Biomagnification).
Answer 14. Control and Coordination (Adrenaline)
(a) Gland: Adrenal Gland.
Hormone: Adrenaline.
(b) Body Responses:
Increased heart rate: To supply more oxygen to the muscles.
Increased breathing rate: Due to contractions of the diaphragm and rib muscles.
Answer 15.
(a) Bowman’s Capsule: A cup-shaped structure at the upper end of a nephron that collects the initial filtrate from the glomerulus.
(b) Filtration vs. Excretion: Most of the 180 L of filtrate is reabsorbed by the nephron tubules, leaving only 1-2 L as urine.
(c) Excretion: The biological process of removing harmful metabolic wastes from the body. It is necessary to prevent the toxic buildup of substances like urea.
OR
(c) Similarities (Lungs vs. Kidneys): Both are primary excretory organs and both possess a large surface area for exchange (alveoli in lungs, nephrons in kidneys).
Answer 16.
Part (A) Vegetative Propagation:
(i) Process: Vegetative Propagation.
(ii) Advantages: Plants can be grown faster than from seeds, and they are genetically identical to the parent.
(iii) Examples: Rose, Grapes, or Potato.
(iv) Regeneration Limitation: Complex organisms have specialized tissues and organs; they cannot regrow a whole body from a small piece because their cells are highly differentiated.
OR
Part (B) Post-Fertilization Changes:
(i) Structure Changes:
(a) Zygote: Develops into the Embryo.
(b) Ovule: Develops into the Seed.
(c) Ovary: Develops into the Fruit.
(d) Sepals: Usually wither and fall off.
(ii) Germination: The process by which a seed develops into a seedling under appropriate conditions of water, air, and temperature.
SECTION - B (Chemistry)
Q. No Correct Answer Explanation
17 (D) C4H8 and C5H12
C4H8 is an alkene (Butene), while C5H12 is an alkane (Pentane).
18 (D) Al2O3
Aluminum oxide is amphoteric; it reacts with both acids and bases.
19 (C) The amount of H2 gas evolved is less.
Acetic acid is a weak acid compared to sulfuric acid, so the reaction is slower.
20 (B) 2:1
Water (H2O) breaks into 2 parts Hydrogen and 1 part Oxygen by volume.
21 (D)
CH3COONa is formed from a weak acid and strong base, making it Basic.
22 (C) C3H8
Propane (C3H8) is a saturated hydrocarbon (alkane) and does not undergo addition.
23 (D) Magnesium and Aluminium
Both are above Hydrogen in the reactivity series and can displace it from HCl.
24 (A)
Assertion & Reason are both true; the reaction of quicklime and water is highly exothermic.
SECTION - C (Physics)
Q. No Correct Answer Explanation
30 (A) Converging lens
A reduced eyeball causes hypermetropia, which is corrected using a convex (converging) lens.
31 (A) 20 cm
The focus (f) is 25 cm. For a virtual image in a convex lens, the object must be within the focal length (u<25 cm).
32 (D)
Assertion is False, Reason is True. In a strong external field, the needle aligns with that field, not necessarily Earth's North-South.
Students can use this key to quickly check the 1-mark objective questions that appeared in today's paper.
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