I remember the secondary structure by visualizing it. Understand that primary structure is just the order of the amino acids. The tertiary structure is the 3dimensional configuration of the whole protein molecule with multiple interactions guiding its fold (disulfide bonds, ionic interactions, hydrogen bonds, van der walls). Secondary structure is a step towards the conformation of the protein where it is made up of either alpha-helices or beta-pleated sheets. The alpha helices look like a spiraling staircase while the beta-pleated sheets look like a repetition of long loops. These two structures hold itself by hydrogen bonds.
        
             
        
        
        
They are well at surviving because of their thick white coat. The white fur helps them blend in with the snow and ice. The polar bear also has a layer of fat under their skin so they can survive harsh temperatures. 
        
             
        
        
        
Answer:
Option B and E and D
Explanation:
Technological advancement has led to growth of industries and manufacturing units and hence the net production of goods. This has led to the use of natural resources and release of pollution of all forms. Environmental research leads to intrusion into niche habitats and hence causes its destruction.
Option B, D and E are correct
 
        
             
        
        
        
It’s false, sickle cell anemia is about erythrocytes