The inside of the barrel-shaped LDL protein consists of hydrophobic amino acids, while its outside portions in contact with the blood fluid consist of hydrophilic amino acids.
LDL is a type of lipoprotein, i.e., it contains protein as well as lipid (cholesterol). The full form of LDL is Low Density Lipid. LDL is considered to be the bad cholesterol for the body. It can cause diseases of the heart like heart attack or stroke. 
Amino acids are the essential molecule that act as a monomer for the formation of proteins inside the body. They contain an amino group and  a carboxylic group attached to the same carbon atom. There are also a hydrogen atom and a variable R group attached to the carbon, also called the alpha carbon. 
To know more about LDL, here
brainly.com/question/28199215
#SPJ4
 
        
             
        
        
        
<span>At least 50% of the variation in the trait in the population is due to genetic differences.</span>
        
                    
             
        
        
        
Answer: humoral immune response 
The main antibody isotypes in the influenza-specific humoral immune response are IgA, IgM and IgG. Mucosal or secretory IgA antibodies are produced locally and transported along the mucus of the respiratory tract by transepithelial transport and can afford local protection from infection of airway epithelial cells.
        
             
        
        
        
The key function of classical conditioning is to allow an organism to <span>learn new species-typical behaviors.
Classical conditioning refers to when two or more different stimuli are joined in order for an organism to learn something it didn't know before. The more you repeat the conditioning, the faster the organism will learn. For example, Pavlov experimented with dogs - each time they were presented with food, they would also hear a bell. So each time dogs heard the bell, they knew that they would be getting food soon.
</span>
        
             
        
        
        
Answer:
cell membrane 
Explanation:
i took this class last year