Why do organisms take up oxygen and release carbondioxide?

Name the process of respiration which does not involves intake of oxygen (O_2) and release of carbon dioxide (CO_2) .

Why do halogens not found in free state.

True or false Micro -organism which use oxygen for respiration are known as anaerobes.

How do organisms meet their energy requirement?

Why our organs like the heart, blood vessels and intestines are enclosed in body?

When some unstable atoms break up, they release tremendous amount of ………..energy

Why do insects need moulting?

Why do animals need to maintain homeostasis?