<h2><u>Answer</u> : </h2>
Proteins are basic nutrients comprising biomolecules, which are made up of long chains of Amino acids.
They have various functions in our body :
- they make up our hair, nails, bones etc
- they helps in recovery of damaged tissues (therefore known as body - building food)
- the structure and functions of protein depends on base sequence of nucleotides in the DNA coding for that specific protein.

Explanation:
1. Most autotrophs use a process called photosynthesis to make their food.
2. Carbon Dioxide and water are the raw material for photosynthesis.
3. This is a trick question because nitrogen is part of oxygen, so the answer is definitely oxygen.
Hope this helps! :)
Explanation:
For any enthalpy change in a chemical reaction, (exothermic/endothermic), the activation energy must be reached so as to break the strong chemical bonds between the reactant molecules.
Answer:
Frog forelimbs are typically short as the hind limbs are the principal limb pair generating propulsion.