Biology — Study Notes for SSC GD Constable

Overview

Biology questions in SSC GD Constable comprise roughly 5–8 marks from the General Science portion under General Knowledge. 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, making it highly scoring if you commit the core facts to memory. Expect direct factual questions rather than complex mechanisms.

Key Concepts

• **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.

• **Deficiency diseases result from lack of nutrients**: Vitamins and minerals are essential in small amounts. Lack of Vitamin A causes night blindness. Lack of Vitamin C causes scurvy. Lack of Vitamin D causes rickets. Iron deficiency causes anaemia. Iodine deficiency causes goitre.