The external hydrophilic environment attracts polar hydrophilic phosphate head groups to the exterior, while allowing non-polar hydrophobic fatty acids to remain shielded in the interior of what becomes the phospholipid bilayer.

A hydrocarbon is made up of a carbon and two hydrogen atoms attached to it.

By process of elimination, lipids and fats cannot be the correct answer-they are synonymous (lipids are also known as fats). Carbohydrates, eg sugars and starches are composed only of carbon, hydrogen, and oxygen. Nucleic acids contribute to DNA and RNA structure and function. The correct answer is proteins, made of long chains of amino acids-amino acids are sometimes called the "building blocks" of proteins. 

Examples of nucleic acids include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Because DNA is not an answer choice, we know that the correct answer in this problem must be RNA. Cellulose is a carbohydrate, asparagine is an amino acid, and carbon is an element. 

Uracil is a base utilized in RNA synthesis, whereas adenine, cytosine, guanine, and thymine are utilized in DNA synthesis.

By definition, a missense mutation will still code for an amino acid, but not the desired amino acid. Silent mutations will have a different base pair, but due to the redundancy of genetic code, it will still code for the desired mutation. Nonsense mutations code for an amino acid that leads to a stop codon, which terminates the translation of mRNA into protein. Insertions and deletions result in a shifted reading frame and typically are detrimental.

The question specifies that this is DNA replication. U (uracil) is found only in RNA and T (thymine) is found only in DNA.  In DNA, A (adenine) pairs with T (thymine) and G (guanine) pairs with C (cytosine) so the complementary strand will have "A" where the original has "T," "G" where the original has "C," "C" where the original has "G" and "T" where the original has "A."  

DNA strands run antiparallel, so the 3' end on the new strand will go opposite the 5' end on the original and vice versa. In this case, that means the complementary strand will run from 5' to 3' to read 5' - TAGCTTCACG - 3'. This sequence is shown in bold below:

5' - TAGCTTCACG - 3'

3' - ATCGAAGTGC - 5'

The nuclear envelope separates transcription from translation in a eukaryotic cell. Translation cannot occur until transcription is finished, which is the opposite of what occurs in a prokaryotic cell. In eukaryotic cells, transcription occurs in the nucleus where mRNA will be produced. Once mRNA is produced, it will exit the nucleus through pores and then proceed to be translated into protein in the cytoplasm.

With a repressible system, the operon is on, meaning the repressor is inactive. Repressible operons are the opposite of inducible operons, which are always off until their repressor is inactivated.

With an inducible system, the operon is off, meaning its repressor is active, or actively repressing the system from turning on. Inducible operons are opposite to a repressible operon, which is always on until it is repressed.