Biology Basics – UGC NET JRF (General Awareness & Current Affairs)
Goal: Provide a concise, self‑contained refresher that covers the core concepts you’ll encounter in the biology section of the UGC‑NET JRF exam.
Format:
- Simple explanation – clear, jargon‑free descriptions.
- Key points – bullet‑style facts, definitions, and equations.
- Worked example – step‑by‑step illustration of a common problem.
- Quick revision summary – one‑page cheat sheet you can glance at the night before.
1. Simple Explanation
Biology is the study of living organisms and their interactions with each other and the environment. At the most basic level, all life is built from cells—the smallest units that can carry out life processes. Inside each cell, a complex, coordinated system of molecules (DNA, RNA, proteins, lipids, carbohydrates) drives growth, reproduction, and adaptation.
Key themes for the exam:
| Theme | What it means |
|---|---|
| Cell Biology | Structure and function of cell organelles, membrane transport, cell cycle, apoptosis. |
| Molecular Biology | DNA replication, transcription, translation, gene regulation, mutations. |
| Biochemistry | Metabolic pathways, enzyme kinetics, co‑enzymes, thermodynamics. |
| Genetics | Mendelian inheritance, population genetics, molecular genetics. |
| Evolution & Taxonomy | Natural selection, speciation, phylogenetics, classification systems. |
| Physiology | Organ systems, homeostasis, hormone regulation. |
2. Key Points
2.1 Cell Biology
| Concept | Definition | Key Facts |
|---|---|---|
| Prokaryotic vs Eukaryotic | Presence/absence of membrane‑bound nucleus | Prokaryotes: 1–5 µm, no nucleus, circular DNA. Eukaryotes: >10 µm, linear DNA, organelles. |
| Plasma Membrane | Phospholipid bilayer with embedded proteins | Fluid mosaic model; selective permeability; transport: passive (diffusion), active (ATPases). |
| Organelle Functions | • Nucleus – DNA & transcription • Mitochondria – ATP via oxidative phosphorylation • Chloroplast – photosynthesis (plants, algae) • ER/Golgi – protein modification & trafficking • Lysosome – degradation |
|
| Cell Cycle | G₁ → S → G₂ → M (mitosis) → G₁ | Checkpoints: G₁/S, G₂/M; Cyclins & CDKs regulate transitions. |
| Apoptosis | Programmed cell death | Caspases, DNA fragmentation, “eat me” signals for macrophages. |
2.2 Molecular Biology
| Process | Key Steps | Important Molecules |
|---|---|---|
| DNA Replication | Initiation (origin), unwinding (helicase), synthesis (DNA polymerase), proofreading | Primer (RNA), ligase, Okazaki fragments |
| Transcription | Initiation → elongation → termination | RNA polymerase, promoter, terminator, mRNA |
| Translation | Initiation (ribosome, tRNA), elongation (peptide bond), termination | Ribosome, tRNA, aminoacyl‑tRNA synthetase, mRNA |
| Gene Regulation | Transcription factors, enhancers, repressors, epigenetics (DNA methylation, histone modification) | DNA methyltransferase, DNMT, HDAC |
2.3 Biochemistry
| Concept | Equation / Key Points |
|---|---|
| Enzyme Kinetics | Michaelis–Menten: (v = \frac{V_{\max}[S]}{K_m + [S]}) |
| Thermodynamics | ΔG = ΔH – TΔS; ΔG < 0 → spontaneous |
| Metabolic Pathways | Glycolysis, TCA cycle, oxidative phosphorylation, photosynthetic Calvin cycle |
| Cofactors / Coenzymes | NAD⁺/NADH, FAD/FADH₂, ATP, CoA, flavins |
2.4 Genetics
| Topic | Key Points |
|---|---|
| Mendelian Laws | Law of Segregation, Law of Independent Assortment |
| Genotype vs Phenotype | Genotype = genetic makeup; phenotype = observable traits |
| Hardy–Weinberg Equilibrium | (p^2 + 2pq + q^2 = 1) (for a locus with alleles A and a) |
| Mutation Types | Point mutations (missense, nonsense), insertions, deletions, chromosomal rearrangements |
| Population Genetics | Gene flow, genetic drift, selection coefficients |
2.5 Evolution & Taxonomy
| Concept | Highlights |
|---|---|
| Natural Selection | Survival of the fittest, adaptive traits |
| Speciation | Allopatric, sympatric, parapatric |
| Phylogenetics | Cladograms, molecular clocks |
| Classification | Kingdom → Phylum → Class → Order → Family → Genus → Species; binomial nomenclature |
2.6 Physiology
| System | Core Functions |
|---|---|
| Circulatory | Transport of O₂, CO₂, nutrients, hormones |
| Respiratory | Gas exchange, alveolar ventilation |
| Digestive | Enzymatic digestion, absorption |
| Endocrine | Hormone synthesis & secretion; feedback loops |
| Nervous | Signal integration, neurotransmission |
3. Worked Example
Question (typical UGC‑NET style):
A population of a diploid organism has a single gene with two alleles: A (dominant) and a (recessive). In a sample of 200 individuals, 120 are homozygous dominant (AA), 60 are heterozygous (Aa), and 20 are homozygous recessive (aa).
(a) Determine allele frequencies (p for A, q for a).