B.
It allows some substances to pass through but blocks the passage of others.
True, try remembering that opposites attract! (north and north don't attract and south and south don't either, but north and south do!)
Biological molecules such as proteins and DNA reveal differences between humans and chimps that would have taken around 7 million years to accumulate.
<h3>What is DNA?</h3>
All known animals and viruses have genetic information in the form of deoxyribonucleic acid, a polymer consisting of two polynucleotide chains that coil around one another to form a double helix. Ribonucleic acid is a type of nucleic acid, as is DNA.
The two DNA strands are known as polynucleotides because they are constructed from simpler monomeric units called nucleotides.
The four nucleobases that contain nitrogen—cytosine (C), guanine (G), adenine (A), or thymine (T)—along with deoxyribose and a phosphate group—make up each nucleotide. The sugar of one nucleotide and the phosphate of the following make covalent bonds, creating what is known as the phospho-diester linkage, which results in an alternating sugar-phosphate backbone.
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All of these are necessary
