Life Processes in Living Organisms Part 2 — Maharashtra (SSC) Class 10 Science Solutions (Free)
Free step-by-step Maharashtra (SSC) Class 10 Science solutions for "Life Processes in Living Organisms Part 2" — important questions with detailed answers, download PDF for board exam preparation.
TL;DR: Free step-by-step Maharashtra (SSC) Class 10 Science solutions for "Life Processes in Living Organisms Part 2" — important questions with detailed ans…
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Q1: Describe the circulatory system: blood composition, heart structure, and blood flow pathways.
Blood: plasma (55%, water, proteins, nutrients), RBCs (oxygen), WBCs (immunity), platelets (clotting). Heart (four chambers: 2 atria, 2 ventricles): receives deoxygenated blood in right atrium, pumps to lungs via pulmonary artery; receives oxygenated blood in left atrium, pumps to body via aorta. Circulation: deoxygenated blood → right heart → lungs → left heart → body → right heart. Valves (tricuspid, bicuspid, semilunar) prevent backflow. Systolic: 120 mmHg, diastolic: 80 mmHg.
Q2: Explain double circulation in humans: pulmonary and systemic circulation.
Pulmonary circulation: right ventricle → pulmonary artery → lungs (CO2 release, O2 pickup) → pulmonary veins → left atrium. Systemic circulation: left ventricle → aorta → body tissues (O2 delivery, CO2 pickup) → vena cava → right atrium. Double circulation ensures constant oxygenation; each circuit is a complete loop through heart. Pressure high in systemic (delivers to all organs), moderate in pulmonary (delicate lungs). Fetal circulation has foramen ovale and ductus arteriosus bypass.
Q3: What is excretion? Describe kidney structure and the process of urine formation.
Excretion removes metabolic wastes (urea, uric acid, excess ions, water). Kidneys are bean-shaped; each has 1 million nephrons (functional units). Nephron: Bowman's capsule (filtration), proximal tubule (reabsorption), loop of Henle (countercurrent, reabsorbs water), distal tubule (fine-tuning), collecting duct. Three stages: ultrafiltration (small molecules forced into capsule), selective reabsorption (glucose, amino acids, water reabsorbed), secretion (H+, drugs into tubule lumen). Urine = 95%…
Q4: Explain the role of ADH and aldosterone in osmoregulation and water balance.
ADH (antidiuretic hormone) from pituitary: released when blood osmotic pressure high, increases water reabsorption in collecting duct via aquaporin channels, dilutes blood. Low ADH → dilute urine (high volume). Aldosterone from adrenal cortex: released when blood Na+ low, increases Na+ reabsorption in distal tubule and collecting duct, followed by water osmotically. Both hormones maintain blood osmotic balance and blood pressure. Deficiency of ADH causes diabetes insipidus (excessive thirst).
Q5: Describe the nervous system structure: CNS, PNS, and reflex arc mechanism.
Nervous system: CNS (brain, spinal cord) processes information; PNS (31 spinal nerves, 12 cranial nerves) connects CNS to body. Somatic nervous system (voluntary), autonomic (involuntary: sympathetic, parasympathetic). Reflex arc: stimulus → sensory neuron → spinal cord synapse → motor neuron → muscle response, bypassing brain. Example: touching hot surface, hand jerks back before brain registers pain. Ensures rapid protective response.
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