Top 25 Biology Facts You Must Revise Before NEET 2026

Why NCERT Biology Facts Matter?

Biology is largely NCERT-based and fact-driven, which makes it the easiest scoring section in NEET for aspirants. Majorly, the questions are directly picked or slightly modified from NCERT lines, especially in topics like Human Physiology, Genetics, Ecology, and Reproduction.

Learning precise factual statements helps in:

• Quick recall during the exam

• Avoiding common traps and statement-based errors in questions

• Saving time in assertion-reason and match-the-following questions

Top 25 Biology Facts for NEET 2026 Revision: Last-Minute Hacks

These Top 25 Biology facts for NEET 2026 are selected from high-weightage NCERT topics and frequently asked concepts. Revising these key points will help improve recall, accuracy, and performance in the exam.

Fact 1: The A-band retains its length during muscle contraction.
A band corresponds to thick myosin filaments, which do not shorten. It remains constant while actin slides inward.

Fact 2: The embryo sac is 8-nucleate and 7-celled at maturity.
It has 3 antipodals, 2 synergids, 1 egg cell and 1 central cell. The central cell contains 2 polar nuclei but counts as one cell.

Fact 3: Ex-situ conservation includes conservation of organisms outside their natural habitats.
Examples include zoos, botanical gardens and seed banks. In-situ conservation occurs in natural habitats like national parks.

Fact 4: Innate immunity is non-specific and present at birth.
It includes barriers like skin, mucus and phagocytic cells. It does not show memory or antigen specificity.

Fact 5: All vertebrates are chordates, but not all chordates are vertebrates.
Chordates include both vertebrates and non-vertebrates like Amphioxus. Vertebrates possess a vertebral column.

Fact 6: Cilia and flagella have a 9+2 arrangement of microtubules.
They consist of 9 peripheral doublets and 2 central singlets. Centriole and basal body have a 9+0 arrangement.

Fact 7: The reaction centre in PS II is P680, and in PS I is P700.
P680 absorbs light at 680 nm and splits water. P700 absorbs at 700 nm and forms NADPH.

Fact 8: Oxytocin and vasopressin are synthesised in the hypothalamus and released from the posterior pituitary.
They are produced by hypothalamic neurons. The posterior pituitary only stores and releases them.

Fact 9: RNA interference takes place in all eukaryotic organisms as a method of cellular defence.
It silences specific mRNA using complementary RNA molecules. It protects against viruses and transposons.

Fact 10: Menarche is the beginning of menstruation at puberty.
It marks the onset of the reproductive phase in females. It usually occurs around 12–13 years of age.

Fact 11: DNA replication is semi-conservative.
Each daughter's DNA has one parental and one new strand. This was proved by Meselson and Stahl.

Fact 12: Viruses contain either RNA or DNA.
They never contain both types of nucleic acids together. Plant viruses are usually RNA, and bacteriophages are DNA.

Fact 13: The resting membrane is more permeable to $K^+$ than to $Na^+$.
This is due to more potassium leak channels being present. It helps maintain resting membrane potential.

Fact 14: An epiphyte growing on a tree shows commensalism.
The epiphyte gets support and better access to light. The host tree is neither harmed nor benefited.

Fact 15: DNA replication occurs in the S-phase of interphase.
DNA content doubles, but chromosome number remains unchanged. This prepares the cell for division.

Fact 16: In C4 plants, mesophyll chloroplasts are granal while bundle sheath chloroplasts are agranal.
Mesophyll cells perform initial $CO_2$ fixation. Bundle sheath cells carry out the Calvin cycle.

Fact 17: Insulin cannot be administered orally as it is degraded by digestive enzymes.
Being a protein, it is broken down in the gut. Hence, it is given through injections.

Fact 18: Male frogs possess vocal sacs and copulatory pads on the forelimbs.
Vocal sacs help in producing mating calls. Nuptial pads help in holding the female during amplexus.

Fact 19: In bryophytes, the dominant phase is the gametophyte, whereas in pteridophytes it is the sporophyte.
Bryophytes have a haploid dominant stage. Pteridophytes have a diploid vascular plant body.

Fact 20: Vital capacity is equal to inspiratory reserve volume plus expiratory reserve volume plus tidal volume.
It is the maximum air expelled after a deep breath. Residual volume is not included in it.

Fact 21: The lac operon is an inducible operon.
It is activated in the presence of lactose. Allolactose inactivates the repressor to allow transcription.

Fact 22: Thalassemia is a quantitative defect in haemoglobin synthesis, whereas sickle-cell anaemia is a qualitative defect.
Thalassemia reduces the amount of haemoglobin formed. Sickle cell alters haemoglobin structure.

Fact 23: The secondary oocyte is released at ovulation and is arrested at metaphase II.
The primary oocyte completes meiosis I before ovulation. Meiosis II completes only after fertilisation.

Fact 24: Fermentation regenerates $NAD^+$ to allow glycolysis to continue.

It maintains redox balance under anaerobic conditions. No extra ATP is produced beyond glycolysis.

Fact 25: Mesosomes are extensions of the plasma membrane in prokaryotes.
They help in respiration and DNA replication. They are absent in eukaryotic cells.

NEET 2026 High-Weightage Biology Facts Chapters

For NEET 2026 Biology preparation, focus on high‑yield NCERT chapters to secure higher marks. Key units include Human Physiology, Genetics & Evolution, Ecology & Environment, Plant Physiology & Diversity, and Reproduction. These dominate the Biology section. To prepare effectively, practice the top 100 biology questions to score 330+ marks.

How to Revise Biology Facts Effectively for NEET 2026

Revising Biology facts for NEET 2026 requires precision and smart strategies. Most questions are directly NCERT‑based biology MCQs. Unlike Physics and Chemistry, Biology need quick recall of factual statements rather than lengthy calculations. Here’s how NEET 2026 aspirants can revise effectively:

• Use NCERT line‑by‑line revision: Underline key facts and tables.

• Create flashcards: One fact per card for active recall.

• Practice assertion‑reason PYQs: It strengthens accuracy in statement‑based questions.

• Revise NCERT important biology diagrams: Many questions are diagram‑based.

• Attempt timed biology MCQ practice: It improves speed and exam confidence.

• Maintain an error log notebook: Track mistakes and revisit them regularly to avoid repetition.

• Do last‑minute NEET 2026 preparation: Memorise the Top 25 Biology facts before exam day.

NEET PYQs Frequently Asked Questions based on Biology Facts

NEET Biology is largely based on NCERT facts, with many questions asked directly from lines, diagrams, and tables. Practising NEET PYQs based on Biology facts helps improve recall and accuracy. It also strengthens confidence for NEET 2026.

Q1. (Assertion–Reason)

Assertion A: During muscle contraction, the A band retains its length.
Reason R: Thick myosin filaments do not change in length during contraction.

(1) Both A and R are true and R is the correct explanation of A
(2) Both A and R are true but R is not the correct explanation of A
(3) A is true but R is false
(4) A is false but R is true

Correct Answer: (1)
Explanation: A band corresponds to length of myosin filaments which do not change, hence A band remains constant.

Q2. (Statement-Based)

Statement I: A typical angiosperm embryo sac at maturity is 8-nucleate and 7-celled.
Statement II: The egg apparatus consists of one egg cell and two synergids.

(1) Both Statement I and II are correct
(2) Both Statement I and II are incorrect
(3) Statement I is correct but Statement II is incorrect
(4) Statement I is incorrect but Statement II is correct

Correct Answer: (1)
Explanation: Embryo sac is 8-nucleate, 7-celled and egg apparatus includes 1 egg + 2 synergids.

Q3. (Match the Column)

Match List I with List II:

(1) A-II, B-I, C-III, D-IV
(2) A-I, B-II, C-IV, D-III
(3) A-III, B-IV, C-II, D-I
(4) A-II, B-IV, C-I, D-III

Correct Answer: (1)
Explanation: Ex-situ includes botanical gardens and seed banks; in-situ includes national parks and sacred groves.

Q4. (Assertion–Reason)

Assertion A: Innate immunity is present at birth and is non-specific.
Reason R: Cell-mediated and humoral immunity are types of innate immunity.

(1) Both A and R are true and R is the correct explanation of A
(2) Both A and R are true but R is not the correct explanation of A
(3) A is true but R is false
(4) A is false but R is true

Correct Answer: (3)
Explanation: Innate immunity is non-specific and present at birth, but cell-mediated and humoral immunity are types of acquired immunity.

Q5. (Statement-Based)

Statement I: All vertebrates are chordates.
Statement II: All chordates are vertebrates.

(1) Both Statement I and II are correct
(2) Both Statement I and II are incorrect
(3) Statement I is correct but Statement II is incorrect
(4) Statement I is incorrect but Statement II is correct

Correct Answer: (3)
Explanation: Vertebrates are a subset of chordates, but all chordates are not vertebrates.

Q6. (Match the Column)

Match List I with List II:

(1) A-I, B-II, C-III, D-IV
(2) A-II, B-I, C-IV, D-III
(3) A-III, B-IV, C-I, D-II
(4) A-I, B-III, C-II, D-IV

Correct Answer: (1)
Explanation: Cilia and flagella have $9+2$ arrangement; centriole and basal body have $9+0$ arrangement.

Q7. (Assertion–Reason)

Assertion A: Photosystem II absorbs light at 680 nm and is involved in the photolysis of water.
Reason R: Photosystem I absorbs light at 700 nm and produces NADPH.

(1) Both A and R are true and R is the correct explanation of A
(2) Both A and R are true but R is not the correct explanation of A
(3) A is true but R is false
(4) A is false but R is true

Correct Answer: (2)
Explanation: Both statements are correct but R does not explain A; they describe different photosystems.

Q8. (Statement-Based)

Statement I: Oxytocin and vasopressin are released from the posterior pituitary.
Statement II: Both oxytocin and vasopressin are synthesised in the hypothalamus.

(1) Both Statement I and II are correct
(2) Both Statement I and II are incorrect
(3) Statement I is correct but Statement II is incorrect
(4) Statement I is incorrect but Statement II is correct

Correct Answer: (1)

Explanation: These hormones are synthesised in the hypothalamus and stored/released from the posterior pituitary.