1. Autotrophic vs Heterotrophic Nutrition
2. Respiration Pathways
Glucose breakdown starts in the cytoplasm (forming pyruvate) and branches out into three vital exam pathways:
- Absence of Oxygen (Yeast fermentation): Yields Ethanol + $CO_2$ + 2 ATP molecules.
- Lack of Oxygen (Human muscle cells during heavy workouts): Yields Lactic Acid + 2 ATP. Accumulation of lactic acid causes localized muscle cramps.
- Presence of Oxygen (Mitochondria): Yields $CO_2$ + $H_2O$ + 38 ATP (High energy yield).
3. Transportation in Humans (Double Circulation)
Blood travels through the human heart twice during each complete body cycle:
- Pulmonary Circulation: Deoxygenated blood goes from heart to lungs for oxygenation and returns.
- Systemic Circulation: Oxygenated blood is pumped from heart to body organs and returns deoxygenated. This separation prevents matching or mixing, maximizing systemic oxygen delivery.
4. Excretion Mechanism
The basic functional filtration unit of human kidneys is called a Nephron. It filters nitrogenous wastes (like urea or uric acid) out of the bloodstream to form urine.
CBSE Board Exam Classic Diagram Prompt
The Role of Villi: The inner lining of the small intestine features millions of tiny, finger-like projections called villi. Villi vastly increase the overall surface area available for rapid food absorption. They are richly packed with blood vessels to carry absorbed food to every cell in the body.