NEET Biology — Practice Set 1

Cell biology, plant physiology, human physiology, genetics, and ecology, in NEET's four-option single-correct format — with the reasoning for the right answer and why each attractive wrong option is wrong.

How to use this: NEET allots roughly 60 seconds per Biology question and applies negative marking. The skill being tested is elimination, not derivation. Every solution below therefore explains the distractors, because that is where the marks actually move.

Cell Biology

1. Which of the following is not found in prokaryotic cells?

(a) Ribosomes (b) Cell membrane (c) Endoplasmic reticulum (d) Cell wall

Answer: (c)

Prokaryotes have no membrane-bound organelles. They do have ribosomes (70S), a cell membrane, and usually a cell wall.

Why the distractors attract: (a) tempts because ribosomes are often taught as "organelles" — but they are not membrane-bound, so prokaryotes have them. Holding the phrase membrane-bound in mind answers a whole family of NEET questions.

2. The powerhouse of the cell, containing its own DNA, is the:

(a) Mitochondrion (b) Golgi apparatus (c) Lysosome (d) Ribosome

Answer: (a)

Mitochondria contain circular DNA and 70S ribosomes — evidence for the endosymbiotic theory.

Extend this: chloroplasts also contain their own DNA. NEET frequently asks for "organelles with DNA" expecting both.

3. Which phase of mitosis is characterised by chromosomes aligning at the equatorial plate?

(a) Prophase (b) Metaphase (c) Anaphase (d) Telophase

Answer: (b)

Sequence mnemonic: Interphase → Prophase → Metaphase → Anaphase → Telophase (IPMAT). Metaphase = Middle.

Plant Physiology

4. The light-independent reactions of photosynthesis occur in the:

(a) Thylakoid membrane (b) Stroma (c) Grana (d) Outer membrane

Answer: (b)

• Light reactions → thylakoid membranes (grana) — they need light-harvesting pigments embedded in membrane
• Calvin cycle (light-independent) → stroma, the fluid matrix

Why (c) attracts: grana are stacks of thylakoids, so choosing it repeats the light-reaction answer. Keep the pairing thylakoid–light, stroma–dark memorised as a unit.

5. Which plant hormone promotes fruit ripening?

(a) Auxin (b) Gibberellin (c) Cytokinin (d) Ethylene

Answer: (d)

The hormone table NEET keeps returning to:

Memorise this table as a table. Several NEET questions each year are single lookups from it.

6. Transpiration pull is generated primarily by:

(a) Root pressure (b) Cohesion and adhesion of water molecules (c) Osmosis in root hairs (d) Active transport

Answer: (b)

Water lost from the leaf creates tension transmitted down a continuous column, held together by cohesion (water–water hydrogen bonding) and adhesion (water–xylem wall).

Why (a) is wrong: root pressure exists but is weak and cannot account for transport in tall trees — it is a supplementary mechanism, not the primary one. NEET tests exactly this distinction.

Human Physiology

7. Which blood vessel carries oxygenated blood away from the heart to the body?

(a) Pulmonary artery (b) Aorta (c) Vena cava (d) Pulmonary vein

Answer: (b)

The two exceptions worth memorising:
- The pulmonary artery carries deoxygenated blood (the only artery that does)
- The pulmonary vein carries oxygenated blood (the only vein that does)

Question (a) is the classic trap: candidates who reason "arteries carry oxygenated blood" pick it.

8. The enzyme that begins protein digestion in the stomach is:

(a) Trypsin (b) Pepsin (c) Amylase (d) Lipase

Answer: (b)

Pepsin, secreted as inactive pepsinogen, is activated by HCl at pH ~2. Trypsin works in the small intestine at alkaline pH — so (a) is right enzyme class, wrong location.

9. The functional unit of the kidney is the:

(a) Neuron (b) Nephron (c) Alveolus (d) Nephridium

Answer: (b)

Roughly one million per kidney. Distractor check: neuron (nerve cell) versus nephron (kidney) versus nephridium (invertebrate excretory organ) — NEET exploits the near-identical spellings under time pressure.

Genetics

10. In a monohybrid cross between two heterozygous tall plants (Tt × Tt), the phenotypic ratio is:

(a) 1 : 1 (b) 3 : 1 (c) 9 : 3 : 3 : 1 (d) 1 : 2 : 1

Answer: (b)

        T       t
   T   TT      Tt
   t   Tt      tt

Genotypic:  1 TT : 2 Tt : 1 tt  =  1 : 2 : 1
Phenotypic: 3 tall : 1 dwarf    =  3 : 1

The trap is (d) — the genotypic ratio. Read whether the question says phenotypic or genotypic; both appear as options precisely to punish skimming.

11. Colour blindness in humans is:

(a) Autosomal dominant (b) Autosomal recessive (c) X-linked recessive (d) Y-linked

Answer: (c)

Which is why it is far commoner in males — one X, so a single recessive allele expresses.

Same category: haemophilia is also X-linked recessive. Sickle-cell anaemia and thalassaemia are autosomal recessive.

Ecology and Evolution

12. The 10% law of energy transfer in a food chain was proposed by:

(a) Odum (b) Lindeman (c) Tansley (d) Darwin

Answer: (b)

Roughly 10% of energy passes to the next trophic level; the rest is lost mainly as heat in respiration. This limits food chains to about 4–5 levels.

13. Which of the following is a primary pollutant?

(a) Ozone at ground level (b) PAN (c) Sulphur dioxide (d) Photochemical smog

Answer: (c)

• Primary — emitted directly (SO₂, CO, NO, particulates)
• Secondary — formed by reaction in the atmosphere (ground-level ozone, PAN, photochemical smog)

Three of the four options here are secondary. Knowing the definition eliminates them all at once.

14. Darwin's theory of natural selection is based on:

(a) Use and disuse (b) Variation and survival of the fittest (c) Inheritance of acquired characters (d) Mutation

Answer: (b)

Options (a) and (c) are Lamarck's, offered as distractors in essentially every evolution question. Option (d) belongs to De Vries's mutation theory.

15. Assertion–Reason: A: Insulin lowers blood glucose. R: Insulin promotes glycogenesis in the liver.

(a) Both A and R are true, and R correctly explains A
(b) Both true, R does not explain A
(c) A true, R false
(d) A false, R true

Answer: (a)

Insulin promotes glucose uptake and its conversion to glycogen (glycogenesis), which is precisely how it lowers blood glucose — so R explains A.

Assertion–Reason technique: evaluate A alone, then R alone, and only then ask whether R is the mechanism of A. Judging the pair as a unit is the usual mistake, because two true statements need not be connected.

Scoring strategy under negative marking

1. +4 correct, −1 wrong, 0 unattempted. A pure guess among four has expected value $\frac{1}{4}(4) + \frac{3}{4}(-1) = +0.25$ — marginally positive, but not worth the time.
2. Eliminating one option makes guessing clearly worth it. Expected value rises to $+0.67$; with two eliminated, $+1.5$. So eliminate before you guess, and guess once you have eliminated.
3. Biology is 50% of the paper (360 of 720 marks). It is the most memorisation-responsive section and the highest-yield place to add marks.
4. NCERT is the source text. NEET Biology questions track NCERT lines closely — read it directly, not only through coaching notes.

Where to go next

• CBSE Class 12 Physics Practice Paper 1 — board preparation alongside NEET
• JEE Main Physics Practice Set 1 — if you are keeping the engineering route open
• CBSE Class 10 Mathematics Practice Paper 1 — foundations

Ask StudyAI for more NEET-format questions on any NCERT chapter, with the distractors explained.