I could REALLY use some help with these AP Biology questions!

I'm doing test corrections for my AP Biology class, and I know what the correct answers for the questions are, but I don't know why they are correct. If you could please explain why they are correct, I would really appreciate it!

1. Which of the following mechanisms is (are) used to coordinately control the expression of multiple, related genes in eukaryotic cells?

A. Organization of the the genes into clusters, with local chromatin structures influencing the expression of all genes at once.
B. Each of the genes sharing a common control element, allowing a single activator to turn on their transcription at once, regardless of their location in the genome.
C. Organizing the genes into large operons, allowing them to be transcribed as a single unit.
D. A and B only
E. A, B, and C

Correct answer: D


2. The most prominent component of the DNA in eukaryotic genomes is

A. Operons
B. randomly repeating DNA
C. Gene regulatory sequences
D. Transposable elements and related sequences
E. Alu elements

Correct answer: D



3. In vertabrates, programmed cell death is essential for all of the following except

A. Normal development of the nervous system
B. Normal operation of the immune system
C. Normal morphogenesis of human feet
D. Normal removal of damaged cells
E. Normal triggering of the signal transduction pathways

Correct answer: E

4. Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

A. Viruses contain either DNA or RNA.
B. Viruses are enclosed in protein capsids rather than plasma membranes.
C. Viruses can reproduce only inside host cells.
D. Viruses can infect both prokaryotic and eukaryotic cells.
E. Viral genomes are usually more similar to the genome of the host cell than to the genomes of viruses that infect other cell types.

Correct answer: E

1) The first two are true, C is only true in bacteria which are not Eukaryotes.
2) This is just a rather boring fact I'm afraid.
3) As the nervous system develops various cells die as they guide nerve cells, and some nerve cells die as they fail to make correct synapses etc. Apoptosis is used in the immune system when selecting high affinity T and B cells among other things. In morphogenesis of the hands and feet they are initially webbed but the cells between die. Damaged cells are programmed to die. However, cell signal transduction pathways are activated in every living cell and therefore they can't require cell death. It's worth bearing in mind, though, that some signal transduction pathways are used by certain cells to result in apoptosis.
4) More of a tricky one that seems pretty ambiguous. If viruses evolved in other ways I'd still expect E to be true. However, you can look at it another way - B is quite obviously wrong, that doesn't suggest anything about their origins. D also. E does suggest that viruses use host nucleic acid, A's a maybe and C seems pretty strong to me Ask your teacher about that one.