SSC GD · Bite-size lessons

Biology

About 7 min · General Knowledge and General Awareness · English

Time worked out from the lesson's 508 words at 150 words a minute, plus a minute for each question.

These questions test fundamental understanding of life processes, human anatomy, plant structure, and disease awareness at the matriculation level. Unlike medical entrance exams, SSC GD focuses on practical, everyday biology—recognising organs and their functions, identifying deficiency diseases, understanding basic cell structure, and knowing how plants make food. Mastery here requires memorising key facts about the human body systems (digestive, respiratory, circulatory, nervous), plant parts and their roles, cell organelles, and common diseases with their causative agents and symptoms. This topic overlaps significantly with health awareness and general science literacy.

Key ideas

• Cell as the basic unit: All living organisms are made of one or more cells. The cell is the smallest structural and functional unit of life. Unicellular organisms (amoeba, bacteria) consist of a single cell; multicellular organisms (humans, plants) have millions of specialised cells.
• Cell organelles and their roles: Nucleus controls cell activities and contains genetic material (DNA). Mitochondria generate energy (ATP) and are called the powerhouse of the cell. Chloroplasts (in plant cells only) perform photosynthesis. Ribosomes synthesise proteins. Cell membrane regulates entry and exit of substances.
• Plant nutrition and photosynthesis: Green plants prepare their own food using sunlight, carbon dioxide, water, and chlorophyll in a process called photosynthesis. The equation: Carbon dioxide + Water + Sunlight → Glucose + Oxygen. Stomata (tiny pores on leaves) regulate gas exchange.
• Human body systems work in coordination: The digestive system breaks down food into nutrients. The respiratory system exchanges oxygen and carbon dioxide. The circulatory system transports blood, nutrients, and oxygen. The nervous system transmits signals and coordinates responses. The excretory system removes waste products.
• Disease classification: Communicable diseases spread from person to person (malaria, tuberculosis, COVID-19) via air, water, vectors, or contact. Non-communicable diseases do not spread (diabetes, cancer, hypertension) and result from lifestyle, genetics, or deficiencies.

Watch out for

• Confusing arteries and veins: Students often think arteries carry oxygenated blood and veins carry deoxygenated blood in all cases. Correction: Arteries carry blood away from the heart; veins carry blood to the heart.
• Mixing up disease agents: Saying malaria is caused by mosquitoes themselves. Correction: Malaria is caused by Plasmodium (a protozoan parasite); the female Anopheles mosquito is the vector (carrier), not the pathogen.
• Thinking all vitamins prevent the same disease: Assuming any vitamin deficiency causes anaemia. Correction: Anaemia is primarily due to iron deficiency (and sometimes Vitamin B₁₂ or folic acid), not all vitamins. Each vitamin has specific deficiency diseases.

Quick reference

• Cell → Nucleus (control centre), mitochondria (energy), chloroplast (plants, photosynthesis).
• Photosynthesis → CO₂ + H₂O + Sunlight → Glucose + O₂ (in chloroplasts).
• Heart → 4 chambers: 2 atria, 2 ventricles; left side oxygenated, right side deoxygenated.
• Blood groups → A, B, AB (universal recipient), O (universal donor); Rh +/−.
• Vitamins → A (night blindness), C (scurvy), D (rickets), B₁ (beriberi).

Check yourself: 3 questions

This lesson is cut from the topic's note, not rewritten. Fact-checked on 18 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.

Read the full noteFlashcards for this topic