Biology Basics – CUET PG (General Awareness & Current Affairs)
Why it matters
Biology is the science that explains life. In a competitive exam like CUET PG, a solid grasp of the fundamentals helps you answer questions on current medical breakthroughs, environmental policies, and science policy debates.
1. Simple Explanation
| Concept | What it is | Why it matters |
|---|---|---|
| Cell | The smallest unit of life. | All living organisms are made of cells. |
| DNA | Genetic material that stores information. | Determines traits; basis of genetics & biotechnology. |
| Ages of Life | Evolution, ecology, human physiology. | Links biology to societal issues (climate change, health). |
2. Key Points
2.1 Cell Biology
| Feature | Human Cell | Plant Cell |
|---|---|---|
| Nucleus | Contains DNA | Contains DNA |
| Cell Wall | No | Yes (cellulose) |
| Chloroplasts | No | Yes (photosynthesis) |
| Mitochondria | Energy production | Energy production |
| Size | ~10 µm | 10–50 µm |
- Cell Division
- Mitosis → growth, repair.
- Meiosis → gametes, genetic diversity.
2.2 Genetics
- DNA Structure – double helix, nucleotides (A, T, C, G).
- Genes & Alleles – units of inheritance.
- Mendelian Laws
- Law of Segregation – alleles separate during meiosis.
- Law of Independent Assortment – genes on different chromosomes assort independently.
- Modern Genetics
- CRISPR‑Cas9 – gene editing.
- Human Genome Project – sequenced entire human DNA.
2.3 Evolution & Natural Selection
- Darwin’s Theory – survival of the fittest.
- Speciation – new species arise via reproductive isolation.
- Evidence – fossil record, comparative anatomy, molecular biology.
2.4 Human Physiology (selected systems)
| System | Main Organs | Key Function |
|---|---|---|
| Circulatory | Heart, blood vessels | Transport O₂, nutrients |
| Respiratory | Lungs, trachea | Gas exchange |
| Nervous | Brain, spinal cord | Control & coordination |
| Digestive | Stomach, intestines | Nutrient absorption |
| Immune | White blood cells, lymph nodes | Defense against pathogens |
- Homeostasis – body’s self‑regulation (temperature, pH, glucose).
2.5 Ecology & Environment
- Ecosystem – community + environment.
- Food Chain / Web – energy flow.
- Biodiversity – variety of life; crucial for ecosystem resilience.
- Human Impact – deforestation, pollution, climate change.
2.6 Biotechnology & Current Affairs
| Topic | Recent Example | Relevance to CUET |
|---|---|---|
| COVID‑19 mRNA vaccines | Pfizer‑BioNTech, Moderna | Illustrates RNA technology. |
| CRISPR gene drives | Sterilizing mosquitoes | Ethical and policy debates. |
| Microbiome research | Gut‑brain axis | New frontiers in medicine. |
| Bio‑inspired materials | Spider silk polymers | Industrial applications. |
3. Worked Example – Mendelian Cross
Problem
A pea plant heterozygous for flower color (Tt) is crossed with a homozygous recessive plant (tt). Predict the genotypic and phenotypic ratios.
Solution
| Parent | Genotype | Gametes |
|---|---|---|
| Plant 1 | Tt | T or t |
| Plant 2 | tt | t |
Punnett Square
| T | t | |
|---|---|---|
| t | Tt | tt |
| t | Tt | tt |
- Genotypic ratio: 1 : 2 : 1 (Tt : Tt : tt) → simplifies to 1 : 2 : 1 (heterozygous : heterozygous : homozygous recessive).
- Phenotypic ratio: 1 : 1 (purple flowers : white flowers).
Take‑away: Dominant allele (T) masks recessive (t).
4. Quick Revision Summary
| Topic | Core Idea | Quick Mnemonic |
|---|---|---|
| Cell | Unit of life; nucleus houses DNA | Cells Need DNA |
| DNA | Double helix; A‑T, C‑G | Always Twist, Check Games |
| Mitosis vs Meiosis | Growth vs gametes | Mitosis = Maintenance, Meiosis = Mating |
| Mendel | Segregation & Independent Assortment | Segregate → Intermix |
| Evolution | Natural selection | Survival Fitness |
| Physiology | Systems maintain homeostasis | Home Operates Systematically |
| Ecology | Ecosystem, biodiversity | Everything Bears Ecosystem |
| Biotechnology |