Questions

Allows for expansion or contraction of the trachea. Hence, so large masses of food can pass through the esophagus during swallowing.

An atom is the smallest particle of a substance. Chemical substances are divided into two major groups. They are

1. Pure Substances (and)

2. Mixtures.

There are two types of pure substances that are Elements and Compounds.

Elements : An element is a substance that is made up of only one kind of atoms and cannot be broken down into simpler substances by chemical means. Metals and Non- metals come under elements.

Examples of elements are Iron, Silver, Gold, Mercury etc.

Compounds : A Compound is a substance that is formed when two or more elements combine chemically.

Examples of compounds are Water, Carbon dioxide, methane, vinegar etc.

Mixtures : A Mixture is formed when two or more substances mixed together but not chemically combined.

Example: Air.

Urea is a by product of amino acid catabolism, Which occurs in the liver. The nitrogen in the  amino acid becomes converted to ammonia and this is further converted by the liver into urea

HIV is a virus that damages the immune system. HIV is a lifelong condition, and without treatment, a person with HIV can develop AIDS.

Canyon

The first wholly artificial gene was synthesized by Har Gobind Khorana.

The law of conservation of energy is a law of science which states that energy can neither be created nor destroyed - only converted from one form of energy to another.

In 1842, Julius Robert Mayer discovered the Law of Conservation of Energy.