Most Important Biology Diagram For NEET UG 2026 to Score 650+

Most Important Biology Diagram For NEET UG 2026: Diagrams play a decisive role in NEET UG Biology, as a significant number of questions are either directly based on diagrams or become easier when concepts are visualized clearly. To strengthen daily revision and boost diagram-based accuracy, we have decided to publish 3 important NEET UG Biology diagrams every day as part of a focused revision series.

These carefully selected diagrams are frequently asked in the exam and are designed to help aspirants revise faster, retain concepts longer, and avoid common labeling mistakes. Regular practice of these high-yield diagrams will sharpen visual memory and play a crucial role in pushing your Biology score and overall NEET UG rank.

1. DNA Double Helix

The DNA Double Helix model was proposed by Watson and Crick (1953) based on X-ray diffraction data by Rosalind Franklin. This structure explains replication, transcription, heredity, and genetic continuity, making it a core NEET UG topic.

Points to Remember:

1. DNA consists of two polynucleotide strands
2. Strands are antiparallel (5′ → 3′ & 3′ → 5′)
3. Backbone is made of alternating sugar and phosphate
4. Bases are attached to sugar via N-glycosidic bond
5. Base pairing rule:
   • A = T (2 H-bonds)
   • G ≡ C (3 H-bonds)
6. Helix is right-handed
7. One turn = 10 base pairs
8. Pitch of helix = 3.4 nm
9. Distance between two base pairs = 0.34 nm

NEET Memory Tips:

1. “AT = 2, GC = 3” → Hydrogen bonds
2. “Pure DNA is Right-handed”
3. Antiparallel = Opposite direction strands
4. Sugar-Phosphate = Outside & Bases = Inside

Practice MCQs From the Diagram

Q.1. The hydrogen bond present between Adenine and Thymine is:

A. One
B. Two
C. Three
D. Four

Q.2. Which component forms the backbone of DNA?

A. Nitrogenous bases
B. Hydrogen bonds
C. Sugar and phosphate
D. Ribose sugar

Q.3. DNA strands are said to be antiparallel because:

A. Bases face opposite directions
B. Sugar-phosphate chains run in opposite directions
C. Hydrogen bonds are opposite
D. Helix turns in opposite direction

Q.4. Which base pair has three hydrogen bonds?

A. A-T
B. A-G
C. G-C
D. T-C

Q.5. Distance between two consecutive base pairs in DNA is:

A. 0.34 nm
B. 3.4 nm
C. 10 nm
D. 34 nm

Answers:

Ans.1. B
Ans.2. C
Ans.3. B
Ans.4. C
Ans.5. A

2. Structure of Bacteriophage

A bacteriophage is a virus that infects a bacterium. Bacteriophages were first discovered in 1915 by William Twort, and in 1917 by Felix d’Herelle realized that they had the potential to kill bacteria.

Points to Remember:

Part	Description
Head (Capsid)	Protein coat, icosahedral in shape
Genetic Material	Double-stranded DNA
Collar	Connects head to tail
Tail Tube & Sheath	Hollow tube for injecting DNA
Base Plate (bottom ring above the tail fibers)	Helps in attachment to bacteria
Tail Fibers	Recognize and bind to host cell

NEET Memory Tips:

1. Bacteriophage = Virus that infects bacteria
2. Shape looks like space shuttle / lunar lander
3. DNA virus (not RNA)
4. Tail fibers = attachment
5. Tail tube = injection

Read Also: NCERT Diagrams for NEET UG 2026: The Most Underrated NEET Scoring Tool

Practice MCQs from Structure of Bacteriophage

Q1. The genetic material present in a bacteriophage is:

A. ssRNA
B. dsRNA
C. dsDNA
D. ssDNA

Q2. Which part of bacteriophage helps in attachment to the host?

A. Head
B. Collar
C. Tail fibers
D. Capsomere

Q3. Shape of bacteriophage head is:

A. Helical
B. Cuboidal
C. Icosahedral
D. Spherical

Q4. Bacteriophage infects:

A. Plants
B. Animals
C. Bacteria
D. Fungi

Answers:

Ans.1. C.
Ans.2. C.
Ans.3. C.
Ans.4. C.

3. Structure Of Nephron

The nephron is the structural and functional unit of the kidney. Each human kidney contains about 1-1.5 million nephrons, and each nephron is specially designed to filter blood and form urine.

Points to Remember

Part	Function
Glomerulus	Ultrafiltration of blood
Bowman’s Capsule	Collects filtrate
PCT	Maximum reabsorption
Loop of Henle	Concentrates urine
DCT	Selective secretion
Collecting Duct	Final urine formation

Memory Tips:

1. PCT = maximum reabsorption (65-70%)
2. Glomerulus = filtration only
3. Loop of Henle = water & NaCl balance
4. Blood flow:
   • Afferent arteriole → Glomerulus → Efferent arteriole

MCQs from Nephron Diagram

Q1. The process of ultrafiltration occurs in:

A. PCT
B. DCT
C. Loop of Henle
D. Glomerulus

Q2. Maximum reabsorption of glucose occurs in:

A. DCT
B. Loop of Henle
C. PCT
D. Collecting duct

Q3. Which part of nephron helps in concentration of urine?

A. Bowman’s capsule
B. Loop of Henle
C. PCT
D. Glomerulus

Q4. The filtrate formed in Bowman’s capsule is similar to:

A. Blood
B. Plasma with proteins
C. Plasma without proteins
D. Urine

Answers:

Ans.1. D
Ans.2. C
Ans.3. B
Ans.4. C

An accurate understanding of NCERT diagrams helps in quick identification, eliminates confusion in options, and reduces silly mistakes. Many NEET toppers attribute their high Biology scores to consistent diagram practice, as it strengthens conceptual clarity and improves recall under exam pressure. Mastering important diagrams is not optional: it is a high-scoring strategy for aspirants aiming for 650+ marks in NEET UG.

All The Best!

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Read Also: What NEET UG 2026 Aspirants Must Learn From Last Year’s Paper Analysis