Answer:
The nitrogenous bases guanine and adenine are A. purines.
Explanation:
Adenine and guanine are purines, whereas the other two bases in DNA (thymine and cytosine) are pyrimidines. The main difference between purines and pyrimidines is the number of rings that the base has: purines have two rings while pyrimidines only have one ring.
In addition, phosphate group and sugar group cannot be the answer to this question because these two elements in addition to a nitrogenous base makes up a nucleotide.
Hope this helps!
<h2>Region between 2 and 3</h2>
Explanation:
Muscles consists of two protein filaments:a thick filament which is made up of protein myosin whereas a thin filament is made up of protein actin
- During contraction,thin filaments slide past the thick filament resulting in shortening of sarcomere
- Myosin thick filaments grab on to the actin filaments by forming cross bridges
- The thick filaments pull the thin filaments past them making the sarcomere shorter
- The region between points 2 and 3 includes the area of overlap between thin and thick filaments
