General Science — Biology — SSC CGL General Awareness
Biology in SSC is a set of fixed pairings: an organelle and its job, a vitamin and its deficiency disease, a disease and its cause. Learn the pairs — mitochondria ↔ powerhouse, vitamin C ↔ scurvy, malaria ↔ Plasmodium — and you have the chapter. This is factual recall, so the work is memorising the right lists in the groups SSC uses.
1. What SSC actually asks
Tier 1: 1–2 Q · Tier 2: 1–2 Q (within GA). Topics: cell structure and organelles, human body systems and organs, blood and the heart, vitamins/minerals and deficiency diseases, disease-causing organisms (bacteria/virus/protozoa), photosynthesis, and classification/genetics basics.
2. The cell and its organelles
- Cell — the basic structural and functional unit of life; Robert Hooke first observed cells (1665, in cork).
- Prokaryotic (bacteria — no true nucleus) vs eukaryotic (plants, animals — true nucleus).
- Mitochondria — the "powerhouse of the cell" (produces energy/ATP).
- Nucleus — control centre; holds DNA. Ribosomes — protein synthesis. Chloroplast — photosynthesis (in plant cells). Cell wall — only in plant cells.
3. Human body — systems and organs
- Heart: 4 chambers — 2 atria (upper), 2 ventricles (lower); pumps blood.
- Blood: RBCs carry oxygen (via haemoglobin); WBCs fight infection; platelets clot blood. Groups A, B, AB, O; O⁻ is the universal donor, AB⁺ the universal recipient.
- Largest gland: the liver (secretes bile). Largest organ: the skin.
- Pancreas secretes insulin (controls blood sugar). Kidneys filter blood (excretory system).
- Bones: an adult human has 206 bones.
4. Vitamins and deficiency diseases
| Vitamin / mineral | Deficiency disease |
|---|---|
| Vitamin A | Night blindness |
| Vitamin B₁ | Beriberi |
| Vitamin C | Scurvy |
| Vitamin D | Rickets ("sunshine vitamin") |
| Vitamin K | Poor blood clotting |
| Iron | Anaemia |
| Iodine | Goitre |
5. Diseases and their causes
- Bacteria: tuberculosis, cholera, typhoid, tetanus.
- Virus: common cold, influenza, dengue, polio, measles, AIDS, COVID-19.
- Protozoa: malaria — caused by Plasmodium, spread by the female Anopheles mosquito.
- Fungi: ringworm, athlete's foot.
- Dengue is spread by the Aedes mosquito; both malaria and dengue are mosquito-borne but by different mosquitoes.
6. Photosynthesis, classification and genetics
- Photosynthesis: in the presence of chlorophyll and sunlight, plants convert CO₂ + water → glucose + oxygen. It happens in the chloroplast.
- Binomial nomenclature (two-part scientific names) was given by Carolus Linnaeus.
- Genetics: Gregor Mendel is the "Father of Genetics". DNA carries heredity; humans have 46 chromosomes (23 pairs).
7. Solved PYQ-style examples
Q1. Which organelle is called the "powerhouse of the cell"? Solution. Mitochondria.
Q2. Deficiency of vitamin C causes: Solution. Scurvy.
Q3. Malaria is caused by: Solution. Plasmodium (a protozoan), spread by the female Anopheles mosquito.
Q4. The number of chambers in the human heart is: Solution. Four (two atria, two ventricles).
Q5. The largest gland in the human body is the: Solution. Liver.
Q6. An adult human body has how many bones? Solution. 206.
8. Exam protocol
- Memorise organelle ↔ function pairs (mitochondria = powerhouse, chloroplast = photosynthesis).
- Learn vitamin ↔ deficiency disease as a table — the most-tested biology block.
- Fix disease ↔ pathogen: malaria = Plasmodium (Anopheles), dengue = virus (Aedes).
- Body facts recur: 4 heart chambers, 206 bones, liver = largest gland, skin = largest organ.
- Genetics anchors: Mendel = father of genetics, 23 pairs of chromosomes.
