Science : Ch 06 – Life Processes

The process of digestion begins in the mouth. The mouth contains a digestive enzyme, salivary amylase. This enzyme breaks the starch molecules in the food, into maltose. The absence of amylase in the saliva thus afects the breakdown of starch into simpler sugar molecules.

A nephron is a fltering unit present in kidney. It has diferent parts like Bowman’s capsule, glomerulus and tubular region (Renal tubule). Glucose, amino acids and salts are selectively reabsorbed in tubular region.

Pseudopodia are developed in amoeba. Amoeba engulfs its food particles by forming pseudopodia around it. The food particle gets surrounded by encircling pseudopodia’s tips.

Rice water contains starch, hence when iodine solution is added to rice water it turns blue-black.

The lime water turns milky on passing carbon dioxide gas into it due to formation of insoluble calcium carbonate. When the exhaled air rich in carbon dioxide is blown from mouth into test tube, it reacts with lime water (calcium hydroxide) to produce calcium carbonate and water

Digestion of food starts in mouth by salivary amylase. From here it enters into the stomach via oesophagus The simpler substances formed by chemical digestion are then absorbed by small intestinal villi.

During inhalation, the ribs move out and the diaphragm fattens. As a result, the surface area for gaseous exchange increases. The site for gaseous exchange in the lungs are alveoli._x000D_During inhalation, ribs move inward and diaphragm is raised_x000D_In the alveoli, exchange of gases takes place i.e. oxygen form alveolar air difuses into blood and carbon dioxide from blood into alveolar air._x000D_Haemoglobin has greater aǝinity f or carbon dioxide than oxygen_x000D_Alveoli increases surface area for exchange of gase

The anterior vena cava collects deoxygenated blood from the head, chest, and arms and enters the right atrium while the inferior vena cava collects blood from the lower body regions_x000D__x000D_Left atrium receives oxygenated blood from diferent parts of body while right atrium receives deoxygenated blood from lungs_x000D_Left ventricle pumps oxygenated blood to diferent body parts while right ventricle pumps deoxygenated blood to lungs_x000D_Left atrium transfers oxygenated blood to right ventricle which sends it to diferent body parts_x000D_Right atrium receives deoxygenated blood from diferent parts of the body while left ventricle pumps oxygenated blood to diferent parts of the body

The examples and the relation of animal group and heart are as Fishes have two chambered heart and exhibit single circulation while three chambered heart of amphibian and reptiles and four chambered heart of birds and mammals exhibit double circulation.

The oxygen during photosynthesis comes from split water.

Steps of photosynthesis are as follows: (i) Absorption of light energy by chlorophyll. (ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. (iii) Reduction of carbon dioxide to carbohydrates.