<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.

Tears and mucous membrane are part of the General defense
system. The General defense system of the body consists of the skin, clotting,
sweat glands, lysozyme, mucous membranes, nasal hairs, cilia, hydrolic acids,
and the vagina. General defense systems have a vital role in giving barriers to
stop bacteria in entering our body which will make us sick.
11 and 12 seem to be right :) For 13, only organisms which are homozygotic for a certain gene (aa) express a recessive phenotype.
14. This dna exchange between the homologous chromosomes is called crossing-over.
15. geneticly linked or coupled, the phenomenon is known as genetic linkage
16. and 17. also seem all right :)
Layer that is 0.2 to 1.1 percent of Earth's total diameter is the thinnest layer of the Earth- Crust.
So, the correct answer is: oxygen and silicone. The crust consists of tectonic plates (in relative motion one from another) and has 5–70 km (~3–44 miles) in depth. The most abundant elements of this layer are: oxygen-46.6 percent by weight; silicon-27.7 percent; aluminum-8.1 percent; iron-5 percent.