Biology basics: General Awareness & Current Affairs Notes for Jharkhand TET (Teacher Eligibility)

Biology Basics – Study Notes

(For Jharkhand TET – General Awareness & Current Affairs)

1️⃣ Simple Explanation

Biology is the science that studies life and living organisms. It explores how organisms grow, develop, reproduce, and interact with each other and their environment. The core of biology is the cell – the smallest unit of life – and the processes that keep cells alive, such as metabolism, homeostasis, reproduction, and evolution.

2️⃣ Key Points

Theme	Essential Facts
Cell Theory	1️⃣ All living things are made of cells. 2️⃣ Cells are the smallest units of life. 3️⃣ All cells arise from pre‑existing cells (mitosis & meiosis).
Cell Types	Prokaryotic (bacteria, archaea) – no nucleus. Eukaryotic (plants, animals, fungi, protists) – nucleus + membrane‑bound organelles.
Basic Cell Organelles	• Nucleus – genetic material. • Mitochondria – energy (ATP). • Chloroplasts – photosynthesis (plants). • Ribosomes – protein synthesis. • Endoplasmic reticulum – protein & lipid transport. • Golgi apparatus – packaging & shipping.
Genetics & Inheritance	• DNA – hereditary material. • Genes – DNA segments coding for traits. • Alleles – different versions of a gene. • Mendelian Laws – law of segregation & independent assortment.
Reproduction	• Asexual – single organism produces genetically identical offspring (binary fission, budding). • Sexual – fusion of gametes (meiosis → zygote → new organism).
Evolution	• Natural selection – traits favorable for survival increase in a population. • Speciation – new species from existing ones over time.
Ecology	• Biotic & abiotic factors – living & non‑living components. • Food chain & web – energy flow. • Ecosystems – communities + environment.
Plant Basics	• Photosynthesis – (6CO_2 + 6H_2O + light → C_6H_{12}O_6 + 6O_2). • Plant parts – roots, stems, leaves, flowers, seeds.
Animal Basics	• Classification – Kingdom: Animalia → Chordata → Mammalia/Amphibia/… • Body plans – bilateral symmetry, tissues, organ systems.
Human Physiology (Brief)	• Circulatory system – heart, blood vessels. • Respiratory system – lungs, diaphragm. • Digestive system – mouth, stomach, intestines. • Nervous & endocrine – brain, hormones.
Health & Hygiene	• Vaccination – immune protection. • Personal hygiene – handwashing, sanitation. • Nutrition – balanced diet, micronutrients.

3️⃣ Worked Example

Question:
A farmer notices that in one plot of wheat, 30% of the plants have white kernels, while in another plot, 70% of the plants have white kernels. Assuming the kernel color is a simple Mendelian trait (White = dominant allele W, Brown = recessive allele w) and both plots are bred from the same parental variety, what could explain the difference in percent of white kernels?

Solution:

Identify the trait:
- White (W) is dominant over Brown (w).
Possible genotypes producing white kernels (phenotype):
- WW (homozygous dominant) or Ww (heterozygous).
Assumption:
- The parental variety is heterozygous (Ww) common in many wheat cultivars.
Crossing two heterozygous parents (Ww × Ww):
- Punnett square → 1 WW : 2 Ww : 1 ww.
- Phenotype ratio → 3 white : 1 brown → 75 % white, 25 % brown.
Observations vs. theoretical ratio:
- Plot A: 30 % white → far below expected 75 %.
- Plot B: 70 % white → close to expected 75 % but slightly lower.
Possible explanations for Plot A:
- Selection bias – only white plants were counted.
- Seed contamination – some seeds might be homozygous recessive (ww) due to self‑pollination or accidental cross‑breeding.
- Environmental factors – stress can sometimes affect kernel color expression.
- Genetic drift – random loss of the dominant allele in a small population.
Conclusion:
The difference is likely due to seed mix variations or different breeding practices. Plot B’s 70 % white is near the expected Mendelian ratio, suggesting normal heterozygous breeding.

Take‑away: Understanding simple Mendelian genetics helps explain observable traits in crops and guides breeding decisions.

4️⃣ Quick Revision Summary

Topic	Quick Check
Cell Theory	All living things are cells; cells arise from pre‑existing cells.
Cell Types	Prokaryotic = no nucleus; Eukaryotic = nucleus + organelles.
DNA & Genes	DNA → genes → alleles → traits.
Mendelian Laws	Segregation (alleles separate); Independent assortment (genes on different chromosomes).
Reproduction	*Asexual = single parent;