AP Biology : AP Biology

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #1 : Central Dogma

If a DNA sequence is mutated from AGCTAA to AGCCTAA, what kind of mutation has occurred?

Possible Answers:

Point mutation

Deletion

Insertion

Substitution

Correct answer:

Insertion

Explanation:

An insertion mutation is a mutation due to an additional nucleotide base pair being added to a DNA sequence. In this case, a cytosine nucleotide has been inserted.

Example Question #1 : Central Dogma

If a DNA sequence is mutated from AGCTAA to AGCAAA, what type of mutation has occurred?

Possible Answers:

Frameshift

Insertion

Substitution

Deletion

Correct answer:

Substitution

Explanation:

A substitution mutation occurs when a base pair is exchanged for a different base pair. In this case, a thymine nucleotide has been substituted for an adenine nucleotide.

Example Question #1 : Central Dogma

If a DNA sequence experiences an insertion mutation, what consequence may this have on the DNA sequence?

Possible Answers:

Cause a frameshift mutation

Cause a deletion

Prevent RNA polymerase from binding

Cause a point mutation

Correct answer:

Cause a frameshift mutation

Explanation:

An insertion mutation that occurs where an amount of nucleotides that is not a multiple of three is added to a DNA sequence will shift the reading frame.

Example Question #2 : Central Dogma

If a DNA sequence is mutated from TCCGGA to TCGGA, what type of mutation has occurred?

Possible Answers:

Deletion

Point

Substitution

Insertion

Correct answer:

Deletion

Explanation:

A deletion mutation occurs when a base pair is removed from the DNA sequence. In this case, a cytosine nucleotide has been deleted.

Example Question #1 : Understand Steps Of Transcription

Histones are most closely linked to which of the following processes?

Possible Answers:

Chromosome formation

Synthesis of ATP in the nucleolus

Eukaryotic cell division

Crossing over of genetic information

Correct answer:

Chromosome formation

Explanation:

Histones are the packaging proteins on which long DNA molecules are coiled before mitosis. In this respect they are involved in cell division, but they are most closely linked to chromosome condensation. During interphase DNA is mostly packaged as euchromatin. Euchromatin is loosely packed and is capable of being transcribed, making it essential for protein synthesis and cell growth during the G1 and G2 phases. During mitosis the DNA condenses into tightly-packed heterochromatin in the form of chromosomes, which allow for cell division. The difference in packaging between euchromatin and heterochromatin comes from histone proteins. During chromosome formation, DNA becomes tightly wound around the histones to create the chromosome structure.

Example Question #2 : Central Dogma

Which of the following proteins is essential for transcription?

Possible Answers:

Primase

DNA polymerase

Trypsin

RNA polymerase

Correct answer:

RNA polymerase

Explanation:

RNA polymerase is the protein that synthesizes an RNA complement to a gene. RNA polymerase binds the template DNA strand and recruits ribonucleotides to build a strand of heteronuclear RNA (htRNA). The htRNA then undergoes modification to become mature mRNA before exiting the nucleus into the cytosol for translation.

DNA polymerase and primase are essential for the replication of DNA. DNA polymerase recruits nucleotides to synthesize the daughter strand of DNA, and primase creates small RNA primers to recruit DNA polymerase to the replication fork. Trypsin is a protease that is not involved in transcription; it helps to digest proteins in the small intestine.

Example Question #3 : Central Dogma

A researcher discovers a highly bizarre eukaryotic species whose mature mRNA do not contain poly-A tails. Which of the following proteins might this species also lack?

Possible Answers:

eIF2

eEF1

eIF4E

PABP

Correct answer:

PABP

Explanation:

PABP (poly-A-binding protein) binds to the poly-A tail in the 3' UTR of eukaryotic mRNA. It is likely that this species would not have a PABP homolog because it does not have a poly-A tail.

eIF4E binds to the 5' cap. eIF2 is responsible for bringing the first tRNA to the initiation complex. eEF1 is an elongation factor that helps bring tRNAs to the ribosome. 

Example Question #4 : Central Dogma

What is the central dogma of molecular biology?

Possible Answers:

RNA, DNA, Protein

Protien, DNA, RNA

DNA, Protein, RNA

DNA, RNA, Protein

RNA, Protein, DNA

Correct answer:

DNA, RNA, Protein

Explanation:

Proteins are coded for by RNA, which is coded for by DNA. The central dogma of molecular biology is the general sequence for the flow of information in coding for a protein. An mRNA strand is created using the DNA strand as a template. This new strand of mRNA then leaves the nucleus and is used as a template for 3-pronged tRNA molecules carrying amino acids to create a chain, which will eventually create a protein.

The central dogma of molecular biology is the general sequence of DNA to RNA to protein.

Example Question #1 : Understand Steps Of Transcription

The TATA box is bound by which of the following proteins?

Possible Answers:

RNA polymerase II

DNA polymerase I

DNA polymerase III

RNA polymerase I

Transcription factors

Correct answer:

Transcription factors

Explanation:

Transcription factors bind to the TATA box (found only in eukaryotes and archaea). The TATA box is a promoter region of a gene on the DNA. If the transcription factor that binds it is an activator, then it will interact with RNA polymerase II to form a transcription initiation complex and begin transcription of mRNA. DNA polymerases I and III are involved in DNA replication, and do not interact with the TATA box. RNA polymerase I is responsible for transcribing rRNA genes in the nucleolus.

Example Question #1 : Understand Steps Of Transcription

Which of the following are purines?

Possible Answers:

Cytosine and guanine

Adenine and guanine

Cytosine only

Guanine only 

Adenine only

Correct answer:

Adenine and guanine

Explanation:

To help remember which bases are purines and which are pyrimidines, there are two acronyms. Pure As Gold. Adenine and guanine are purines because of their structure. Also, pyrimidines, like pyramids, are "sharp". Sharp things CUT (cytosine, uracil and thymine).

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