1. Why is the rate of breathing faster after exercise?
During exercise, muscles need more energy, so more O₂ is required for aerobic respiration. The body
increases breathing rate to supply more O₂ and remove excess CO₂.
2. Why is the left ventricle thicker? The left ventricle
pumps oxygenated blood to the entire body (systemic circulation) against high pressure. Thicker walls
provide the force needed to push blood through long distances.
3. Why do plants need less energy than animals? Plants do
not move from place to place, have no nervous system, and large parts (like wood) are dead, requiring
minimal maintenance. Animals use a lot of energy for movement, maintaining body temperature, and brain
function.
4. Why do fish die when taken out of water? Fish extract
dissolved O₂ from water using gills. Gills cannot absorb O₂ directly from air. Out of water, gill filaments
collapse and cannot function, leading to suffocation.
5. Why are lungs designed with alveoli? Alveoli provide a
large surface area (~70-100 m²) for efficient gas exchange. Thin walls (one cell thick) and rich blood
supply allow rapid diffusion of O₂ and CO₂.
6. Aerobic vs Anaerobic Respiration:
Aerobic: Requires O₂, occurs in mitochondria, produces 38 ATP, end products are CO₂ + H₂O.
Anaerobic: No O₂ needed, occurs in cytoplasm, produces 2 ATP, end products are Lactic Acid or Ethanol + CO₂.
7. Xylem vs Phloem:
Xylem: Transports water and minerals, moves upward only, dead tissue, uses transpiration pull.
Phloem: Transports food (sucrose), moves bidirectional, living tissue, uses ATP for translocation.
8. Autotrophic vs Heterotrophic:
Autotrophs: Make their own food using CO₂, H₂O, and sunlight (e.g., plants).
Heterotrophs: Depend on other organisms for food (e.g., animals, fungi).
9. Heart Diagram Labels: Right Atrium (receives deoxygenated
blood from body via Vena Cava), Right Ventricle (pumps to lungs via Pulmonary Artery), Left Atrium (receives
oxygenated blood from lungs via Pulmonary Vein), Left Ventricle (pumps to body via Aorta), Septum (separates
left and right sides).
10. Nephron Diagram Labels: Bowman's Capsule (contains
glomerulus, filtration), Proximal Tubule (reabsorption of glucose, amino acids), Loop of Henle (water and
salt reabsorption), Distal Tubule (secretion of waste), Collecting Duct (collects urine).
11. Stomatal Apparatus: Guard cells (regulate opening),
Stomatal pore (allows gas exchange), Subsidiary cells (support guard cells). Stomata are usually open during
day (for photosynthesis) and closed at night.
