Life Processes-1 Nutrition, Transportation and Excretion — Important Questions

Oxygen

Step 1: Photosynthesis equation is 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6H₂O + 6O₂. Step 2: Plants use carbon dioxide and water as raw materials. Step 3: Through light reactions, water molecules are split to release oxygen. Step 4: The oxygen produced is not needed by the plant for photosynthesis. Step 5: This oxygen is released into atmosphere through stomata as a beneficial by-product. Carbon dioxide is consumed, not released; nitrogen and hydrogen are not directly involved in photosynthesis.

Diaphragm

Step 1: Diaphragm is a dome-shaped muscular sheet located below the lungs. Step 2: It separates thoracic (chest) cavity from abdominal cavity. Step 3: During inhalation, diaphragm contracts and flattens, increasing chest cavity volume. Step 4: During exhalation, diaphragm relaxes and becomes dome-shaped, decreasing chest cavity volume. Step 5: This movement creates pressure changes that help air flow in and out of lungs. Ribs also help in breathing but don't separate cavities; lungs are organs for gas exchange; trachea is the windpipe.

Salivary amylase

Step 1: Saliva is produced by salivary glands and contains the enzyme salivary amylase. Step 2: Starch is a complex carbohydrate made of many glucose units joined together. Step 3: Salivary amylase breaks the bonds between glucose units in starch. Step 4: This converts starch into simpler sugars like maltose. Step 5: You can taste this sweetness when you chew bread for a long time. Pepsin digests proteins in stomach, trypsin digests proteins in small intestine, and lipase breaks down fats.

Four

Step 1: Human heart is divided into four chambers. Step 2: The upper two chambers are called atria (right atrium and left atrium). Step 3: The lower two chambers are called ventricles (right ventricle and left ventricle). Step 4: Right side chambers handle deoxygenated blood, left side chambers handle oxygenated blood. Step 5: This four-chambered structure prevents mixing of oxygenated and deoxygenated blood, making circulation more efficient. Fish have 2 chambers, amphibians have 3, but mammals like humans have 4 chambers.