Life Processes Test - 8

Digestion of food starts as soon as we put food in our mouth. The mouth cavity contains teeth, tongue and salivary glands. The teeth cut the food into small pieces, chew and grind it. The teeth help in physical digestion. The salivary glands help in chemical digestion by secreting enzymes.

The salivary glands present in mouth secrete salivary amylase enzyme which digests the starch present in food into sugar. Digestion of starch or carbohydrate starts in mouth itself. Therefore, amylase is the first enzyme that helps in the process of digestion.

In woody stems of plants or trees have lenticels for the exchange of respiratory gases.

Lizard has three-chambered heart. Except crocodilians all the reptiles have three-chambered heart. Crocodiles have four-chambered heart. Pigeons have four-chambered heart. Fish have two-chambered heart. Lion have four-chambered heart.

Birds and mammals have four chambered heart i.e. 2 atria and 2 ventricles. Three-chambered consists of 2 atria and 1 ventricle and two-chambered heart consists of 1 atria and 1 ventricle.

After wound or cut in a body it starts to bleed. But within few seconds or minutes blood cells start to clump together and clot, preventing the further blood loss. These clots are created by a type of blood cell called platelet.

Plants have two tissues that help in transportation. Xylem transports water and solutes from the roots to the leaves while phloem transports food from the leaves to the rest of the plant.

The expansion of an artery each time the blood is forced into it is called pulse. The pulse rate of an adult person while resting is 70 to 72 per minute.

From the above quiz we have seen various life processes that take place in an organism.

• Photosynthesis is the process by which plants use the energy from sunlight to produce glucose from carbon dioxide and water.

• The following events occur during this process:

1. Absorption of light energy by chlorophyll.

2. Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.

3. Reduction of carbon dioxide to carbohydrates.

• Enzymes are known as biocatalysts because they act as catalysts.

• They remain unmodified or unchanged when they increase the rate of the chemical reaction.

• They help or aid in the reaction process but themselves are not affected by the reaction.