Answer:
Proteins, carbohydrates, nucleic acids, and lipids are the four major classes of biological macromolecules.
 Macromolecules are made up of single units known as monomers that are joined by covalent bonds to form larger polymers.
Explanation:
 
        
             
        
        
        
Answer:
Igneous rocks and Metamorphic rocks determine the age of the earth.
 
        
             
        
        
        
Answer:
(a) The grains which are termed as millets are Amaranth, Barnyard, buckwheat, kodu, sorghum, bajra, Kangani, and Ragi.
(b) The following are the advantages of millet due to which they are given more preference than wheat and rice:
1. Millet's are free of gluten, a protein digestion of which is very difficult by the body.
2. When we compare the protein content of rice, wheat and millet, it is found that millet has high protein content.
3. In all aspects of components of nutrients called as carbohydrates, proteins, fats, minerals and vitamins, millet is in prime position and is also easy to digest. 
 
        
             
        
        
        
The only joint-less bone in the human body is the hyoid.
        
             
        
        
        
Answer:
in an animal cell, the center
Explanation: