RRB Technician Grade III 2024, 2025 PYQs

Concept: Meristems are growing tissues found only in plants. Apical meristem lies at the tips of stems and roots and increases their length.

1. Plants grow throughout life only in regions having meristems.
2. Apical (tips), lateral/cambium (girth) and intercalary (base of leaves, internodes) are its types.
3. Animals, bacteria and viruses have no meristematic tissue.

Yaad rakhein: Apical → length; Lateral (cambium) → girth; Intercalary → near nodes.

Answer: (A) Plants

Concept: Meiosis is reduction division: it occurs in reproductive cells and forms gametes with half the number of chromosomes.

1. Parent cell: $2n$ chromosomes (human $2n=46$).
2. After meiosis, each gamete has $n$ (human $n=23$).
3. At fertilisation $n+n=2n$, so the number stays constant over generations. Mitosis/binary fission keep the number the same.

Yaad rakhein: Meiosis → half (gametes); Mitosis → same (growth and repair).

Answer: (D) meiosis

Concept: Most non-metals are solids or gases at room temperature; bromine is the only non-metal that is a liquid.

1. Fluorine and oxygen are gases.
2. Mercury is a liquid but it is a metal, not a non-metal.
3. Bromine (reddish-brown liquid) is the liquid non-metal.

Yaad rakhein: Liquid metal → mercury; liquid non-metal → bromine.

Answer: (D) Bromine

Concept: Nerve cells (neurons) have long extensions called axons to carry messages over long distances, making them the longest cells in the body.

1. An axon can be up to about 1 m long (spinal cord to toe).
2. The ovum is the largest cell (by size/volume), not the longest.
3. Blood and fat cells are small.

Yaad rakhein: Longest cell → neuron; largest cell → ovum; smallest cell → sperm.

Answer: (A) Nerve cell

Concept: Cambium is the lateral meristem; its dividing cells add new tissue on the sides, so the stem and root become thicker.

1. Apical meristem at tips → increases length.
2. Intercalary meristem near nodes → growth of internodes/leaves.
3. Cambium (lateral) → increases girth (secondary growth).

Yaad rakhein: Girth = cambium (lateral meristem).

Answer: (C) Cambium

Concept: Basic power formula: $P=VI$. Using Ohm's law $V=IR$, it can be rewritten in two more forms.

1. Put $V=IR$: $P=(IR)I=I^{2}R$.
2. Put $I=\frac{V}{R}$: $P=V\times \frac{V}{R}=\frac{V^2}{R}$.
3. $P=IR$ is actually Ohm's law for $V$, not power – wrong relation.

Trick: Check units: $IR$ gives volts, not watts – so $P=IR$ must be wrong.

Answer: (D) $P=IR$

Concept: Characteristics of particles of matter: very small, have spaces between them, are continuously moving, and attract each other.

1. Sugar dissolving in water without raising the level shows spaces between particles.
2. Diffusion and Brownian motion show constant motion.
3. A solid piece is hard to break → particles attract each other.
4. So 'no spaces between them' is NOT true.

Yaad rakhein: 4 properties: tiny, spaces, motion, attraction.

Answer: (B) They do not have spaces in between them.

Concept: For a spherical mirror $f=\frac{R}{2}$. By the New Cartesian sign convention, positive $R$ and $f$ (behind the mirror) belong to a convex mirror.

1. $f=\frac{R}{2}=\frac{+20}{2}=+10\text{cm}$
2. Positive focal length → focus lies behind the mirror.
3. Hence the mirror is convex.

Yaad rakhein: Sign of $f$: concave → negative, convex → positive.

Answer: (B) +10 cm, convex

Concept: Saturated hydrocarbons generally burn with a clean blue flame; unsaturated hydrocarbons give a yellow, sooty flame.

1. Ethane (${\mathrm{C}}_2{\mathrm{H}}_6$) – saturated (single bonds) → clean flame.
2. Ethylene/ethene (${\mathrm{C}}_2{\mathrm{H}}_4$) – double bond, unsaturated → sooty.
3. Ethyne (${\mathrm{C}}_2{\mathrm{H}}_2$) – triple bond, unsaturated → sooty.

Yaad rakhein: Ethylene and ethene are the same compound; '-ane' = saturated = clean flame.

Answer: (B) Ethane

Concept: In electrolytic refining, impure metal is the anode, a thin strip of pure metal is the cathode, and a soluble salt of the same metal is the electrolyte.

1. Anode: impure Cu; cathode: pure Cu.
2. Electrolyte: acidified copper sulphate, $\mathrm{C}\mathrm{u}\mathrm{S}{\mathrm{O}}_4$.
3. Cu dissolves from the anode and deposits on the cathode: $\mathrm{C}{\mathrm{u}}^{2+}+2{\mathrm{e}}^{-}\to \mathrm{C}\mathrm{u}$; impurities fall as anode mud.

Yaad rakhein: Electrolyte always contains ions of the metal being refined → copper needs a soluble copper salt.

Answer: (D) $CuS{O}_4$

Concept: Around a straight current-carrying wire, magnetic field lines are concentric circles centred on the wire.

1. These circles lie in a plane perpendicular to the wire.
2. So the field is perpendicular to the wire at every point (tangent to the circle).
3. Direction (clockwise/anticlockwise) is given by the right-hand thumb rule.

Trick: Right-hand thumb rule: thumb along current, curled fingers show the field direction.

Answer: (C) Perpendicular to the plane of the wire

Concept: Ethanol (${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{O}\mathrm{H}$) is a good solvent and is present in medicines such as tincture iodine, cough syrups and many tonics.

1. Ethanol dissolves the medicinal ingredients and acts as a preservative.
2. Methanol is poisonous – can cause blindness or death.
3. Ethanoic acid is not an alcohol (it is a carboxylic acid).

Yaad rakhein: Ethanol → medicines, drinks, sanitizers; methanol → poisonous, used to denature ethanol.

Answer: (A) Ethanol

Concept: Law of conservation of energy: energy can neither be created nor destroyed; it only changes from one form to another, so the total energy remains constant.

1. (A), (B), (D) are direct statements of this law – true.
2. (C) says total energy before and after transformation is not constant.
3. That contradicts the law, so (C) is NOT true.

Yaad rakhein: Free fall: PE decreases, KE increases, but PE + KE stays constant.

Answer: (C) The total energy before and after the transformation is not constant.

Concept: Spirogyra is a simple multicellular filamentous alga. When mature, its filament breaks into small pieces and each piece grows into a new individual.

1. This method of asexual reproduction is called fragmentation.
2. It works because each cell can divide and form a full filament.
3. Budding → Hydra/yeast; binary fission → Amoeba; vegetative propagation → plants like Bryophyllum.

Yaad rakhein: Spirogyra → fragmentation; Planaria → regeneration; Hydra → budding; Amoeba → binary fission.

Answer: (C) Fragmentation

Concept: Ovaries secrete the hormones oestrogen and progesterone, which control female secondary sexual characters and the menstrual cycle.

1. Oestrogen develops female sex organs and characters.
2. Oestrogen and progesterone regulate the menstrual cycle and maintain the uterus lining.
3. Growth of organs → growth hormone (pituitary); metabolism → thyroxine (thyroid).

Yaad rakhein: Ovary → oestrogen (menstrual cycle); testis → testosterone; thyroid → metabolism.

Answer: (B) Menstrual cycle

Concept: Carbon has 4 valence electrons (configuration 2, 4), so it always forms four bonds – its valency is 4 in every compound.

1. Ethene: ${\mathrm{H}}_2\mathrm{C}=\mathrm{C}{\mathrm{H}}_2$.
2. Each carbon: one double bond to the other C (2 bonds) + two C–H bonds (2 bonds).
3. Total bonds per carbon $=2+2=4$.

Yaad rakhein: Carbon is tetravalent in methane, ethene, ethyne alike – count bonds, a double bond counts as 2, a triple as 3.

Answer: (C) Four

Concept: In vegetative propagation, new plants arise from roots, stems or leaves instead of seeds. Bryophyllum leaves bear buds in the notches of their margin.

1. These buds develop into small plantlets on the leaf.
2. When the leaf falls on moist soil, each plantlet grows into a new plant.
3. Pistil, petal and stamen are flower parts used in sexual reproduction.

Yaad rakhein: Bryophyllum → leaf-margin buds; potato → eyes on stem tuber; ginger → rhizome.

Answer: (D) buds produced in the notches along the leaf margin

Concept: Muscle cells contain special contractile proteins; their contraction and relaxation pull on bones or organ walls and cause movement.

1. Muscle cells shorten (contract) and lengthen (relax).
2. This changes the shape of muscles, moving the attached body part.
3. Bones only act as levers; nerve cells send signals; cartilage gives smooth joint surfaces.

Yaad rakhein: Contraction/relaxation → muscle; message transmission → nerve; support → bone/cartilage.

Answer: (B) Muscle cells

Concept: Energy stored in a body due to change in its shape or position is potential energy. Stretching a spring changes its shape, so work done is stored as elastic potential energy.

1. Work is done against the spring's restoring force while stretching.
2. This work is stored in the stretched spring.
3. On release, it changes to kinetic energy.

Yaad rakhein: Stretched spring, wound watch spring, bent bow, stretched rubber band → potential energy.

Answer: (B) potential energy

Concept: Biodegradable substances are broken down by microorganisms such as bacteria and fungi into simpler, harmless substances.

1. Dead plants are decomposed by microbes and return nutrients to the soil – biodegradable.
2. Glass, plastic bags and electric wire (plastic insulation, metal) are not decomposed by microbes – non-biodegradable.
3. Hence the dead plant is the answer.

Yaad rakhein: Natural organic matter (vegetable peels, paper, cotton, dead plants/animals) → biodegradable.

Answer: (A) Dead plant