The NDA (National Defence Academy) and CDS (Combined Defence Services) examinations are prestigious national-level exams conducted by the Union Public Service Commission (UPSC) to select candidates for the Indian Armed Forces — Army, Navy, and Air Force.
In the General Science section, Biology plays an important role, contributing a significant portion of multiple-choice questions (MCQs). A strong grasp of Human Physiology helps aspirants tackle conceptual and factual questions with confidence.
In this first Biology class, we will cover the Excretory System, Circulatory System, and Digestive System — three vital physiological systems that maintain balance and functionality in the human body.
Main Topics and Subtopics
1. Human Excretory System
- Overview: Role of kidneys and urinary system in removal of metabolic wastes.
- Subtopics:
- Structure and function of kidneys, nephrons, and urinary tract.
- Mechanism of urine formation: filtration, reabsorption, secretion.
- Regulation of excretion: role of ADH and osmoregulation.
- Common disorders: kidney stones, uremia, dialysis basics.
2. Human Circulatory System
- Overview: Transport system responsible for circulation of blood, nutrients, gases, and hormones.
- Subtopics:
- Structure and function of heart, arteries, veins, and capillaries.
- Double circulation and cardiac cycle.
- Blood components and their functions (RBCs, WBCs, platelets, plasma).
- Blood groups (ABO and Rh factor).
- Common cardiovascular disorders: hypertension, anemia, heart attack.
3. Human Digestive System
- Overview: System responsible for breakdown and absorption of food to supply energy.
- Subtopics:
- Structure and function of alimentary canal and digestive glands (salivary glands, liver, pancreas).
- Process of digestion in mouth, stomach, small and large intestine.
- Role of digestive enzymes and bile.
- Absorption and assimilation of nutrients.
- Common disorders: indigestion, ulcers, constipation.
MCQ Practice Focus
- Concept-based and factual questions from NCERT Biology (Class 11 & 12 basics).
- Diagram-based questions (especially heart, nephron, and digestive organs).
- Assertion-Reason and Match-the-following type questions for conceptual clarity.
Conclusion
A clear understanding of Human Physiology not only strengthens your Biology foundation but also enhances your overall performance in the General Science section of the NDA CDS 1 2026 Exam.
Mastering these systems will help you answer MCQs efficiently and build a scientific approach to understanding life processes — a key quality for future defence officers.
