Okay, biology isn't exactly my strongest subject (it never has been), but I'm pretty sure the answer is nucleotides. DNA is made up of nucleotides. Each nucleotide contains a phosphate group, a sugar group, and a nitrogen base. There are four different nitrogen bases: adenine (A), thymine (T), guanine (G), and cytosine (C). A always pairs with T, and G always pairs with C.
        
             
        
        
        
Answer:
oceanography
Explanation:
This is because astronomy is the study of stars and celestial things. Biology is the study of life and organisms. Meteorology is the study of weather and atmospheric phenomena. Oceanography is the study of physical and biological properties of the sea.
 
        
             
        
        
        
Answer: The answer is D: to allow maximum exposure to light and to reduce shading of lower leaves. 
Explanation:
The arrangement of leaves on a Stem is known as Phyllotaxy. It is used to enable them obtain maximum exposure to sunlight.
Leaves are classified as either alternate, spiral or opposite. 
Leaves with alternate pattern arise at a different point (node) on the stem. This helps reduce shading of the lower leaves. 
 
        
             
        
        
        
I'm a bit confused about this question. But I will try my best to answer. :)
To prevent a certain virus, or increase someone's immunity towards a virus, doctors give patients a shot/vaccine. For example, people get a flu shot yearly to help prevent them from getting the flu. The shot contains a small portion of the flu itself. The flu remains dormant until the body decides to activate it or fight it off. This also helps the body become more immune to the virus/sickness and fight it off easier.
I hope this helps! :)