AP Biology Practice Test: Unit 6 — Gene Expression & Regulation - High School Test Prep (2024)

Question 1

Question 1 Explanation:

The correct answer is (B). In RNA, thymine (nucleic acid present in DNA) is replaced with uracil.

Question 2

Question 2 Explanation:

The correct answer is (A). Each gene on a DNA molecule directs the synthesis of a messenger RNA (mRNA). The mRNA molecule directs the production of a polypeptide.

Question 3

Question 3 Explanation:

The correct answer is (D). Uracil is a RNA nucleotide.

Question 4

Question 4 Explanation:

The correct answer is (A). The two strands of DNA are complimentary, which allows one strand to serve as a template for ordering nucleotides into a new, complimentary strand.

Question 5

Question 5 Explanation:

The correct answer is (B). Since DNA is elongated in the 5' → 3' direction, only one strand can be elongated continuously. On the other strand, it must be replicated in segments since it can only be replicated in the 5' → 3', and this strand goes from 3' → 5'.

Question 6

Question 6 Explanation:

The correct answer is (A). Origins of replication contain specific sequences of nucleotides where DNA replication begins.

Question 7

Question 7 Explanation:

The correct answer is (B). DNA polymerase is responsible for adding nucleotides to a preexisting chain. DNA ligase joins together sugar-phosphate backbones of the Okazaki fragments into a continuous strand of DNA. Helicase unwinds parental double helix at replication forks. Topoisomerase breaks, swivels and rejoins DNA strands ahead of replication forks to relieve overwinding strain ahead of the replication forks.

Question 8

Question 8 Explanation:

The correct answer is (D). Specific base pairing, the double stranded structure and DNA’s antiparallel elongation are all important properties that contribute to DNA’s ability to replicate and repair.

Question 9

Question 9 Explanation:

The correct answer is (C). A promoter is a nucleotide sequence in DNA that is the binding site of RNA polymerase, positioning the RNA polymerase to begin transcription at the appropriate position.

Question 10

Question 10 Explanation:

The correct answer is (D). Pre-messenger RNA carries information from DNA by copying the genetic information through a process called transcription.

Question 11

Question 11 Explanation:

The correct answer is (B). Molecules of mRNA are processed through ribosomes and codons are translated into amino acids. tRNA molecules translate the codons on the mRNA molecules, and deliver amino acids to the growing polypeptide chain.

Question 12

Question 12 Explanation:

The correct answer is (A). Enzymes change the ends of the pre-mRNA molecule by adding a 5' cap to the 5' end. The 3' end is modified by adding a poly-A tail. Also, during this stage, introns (non-coding segments of a nucleic acid) are removed and the remaining mRNA exons are joined back together.

Question 13

Question 13 Explanation:

The correct answer is (C). Genetic information is transcribed onto a pre-mRNA molecule, then it is modified during RNA processing, and finally it is used to make polypeptides in translation.

Question 14

If a DNA template strand has the following sequence, what is the correct mRNA sequence?

DNA Template Strand Sequence: AAACCGAGT

Question 14 Explanation:

The correct answer is (C). mRNA’s pairs with DNA with the following base pairs: A – U and C – G.

Question 15

Questions 15–16

If a codon has the following sequence, what is the anticodon?

Codon: UCA

Question 15 Explanation:

The correct answer is (D). mRNA base’s complementary base pairs are A – U and C – G.

Question 16

If a DNA template strand’s DNA sequence is AAA, what amino acid will be formed?

Question 16 Explanation:

The correct answer is (B). A triplet code of AAA on a DNA strand is translated into the codon UUU. Using the chart, UUU codes for the amino acid Phe.

Question 17

Question 17 Explanation:

The correct answer is (C). Prions are misfolded versions of a protein which are infectious and cause brain diseases. Prion diseases occur when prion protein becomes abnormal and clump in the brain, When the prions accumulate in the brain it can cause memory impairment, personality changes, and difficulties with movement. Prion diseases are fatal.

Question 18

Question 18 Explanation:

The correct answer is (D). The brainstem includes the midbrain, pons and medulla oblongata. The cerebellum coordinates movement and balance. The cerebrum is the information processing center of mammals. The diencephalon includes the thalamus, hypothalamus, and epithalamus.

Question 19

Question 19 Explanation:

The correct answer is (D). The frontal lobe controls speech. The temporal lobe controls smell and hearing. The parietal lobe controls speech, taste, and reading. The occipital lobe controls vision.

Question 20

Question 20 Explanation:

The correct answer is (B). The question describes symptoms of Parkinson’s Disease, a neurodegenerative disorder that comes about as a result of the loss of dopamine-producing neurons.

Question 21

Question 21 Explanation:

The correct answer is (D). The frontal and parietal areas of the brain are associated with speech and reading.

Question 22

In the fall of 1957, Hans Fromme was conducting research at the Frankfurt Zoological Institute in Germany. He noticed that several caged European robins were becoming restless and attempting to fly to the southwestern part of the cage. Fromme wondered how the birds knew which direction they were supposed to be migrating, since they were in a darkened room and could not see any landmarks, the sun or the stars.

Which type of sensory cell receptor is responsible for guiding the migration of the robins?

Question 22 Explanation:

The correct answer is (C). Electromagnetic receptors detect electromagnetic energy and assist animals as they migrate along the Earth’s magnetic field lines.

Question 23

Question 23 Explanation:

The correct answer is (A). Hormones are secreted into extracellular fluids by endocrine cells, and reach their target cells through the bloodstream.

Question 24

Question 24 Explanation:

The correct answer is (D). The endocrine system uses hormones released into the bloodstream that travel to all parts of the body. Hormones are slow acting and can affect various cells. The nervous system uses impulses to quickly send information along axon to a specific location. Both systems help maintain homeostasis.

Question 25

Question 25 Explanation:

The correct answer is (A). The thyroid gland stimulates and maintains metabolic processes and lowers blood calcium levels. The pancreas raises and lowers blood glucose levels. The adrenal glands raise blood glucose levels, increase metabolic activities, constrict certain blood vessels and promote reabsorption of sodium and excretion of potassium in the kidneys. The pineal gland is involved in biological rhythms.

Question 26

Chromosome structure can be altered by damages to the chromosome, or during an error in meiosis.

When a chromosomal fragment reattaches to the original chromosome in reverse order, it is called:

Question 26 Explanation:

The correct answer is (A). A deletion occurs when a chromosome fragment is lost. A duplication leads to the addition of one or copies of a preexisting DNA sequence to a chromosome. A translocation is the result of a chromosomal breakage during which the fragment of one chromosome joins a nonhom*ologous chromosome resulting in a rearrangement of DNA.

Question 27

Question 27 Explanation:

The correct answer is (A). Homeotic genes control the development of the overall organization of the body.

Question 28

Question 28 Explanation:

The correct answer is (A). Cells contain genes that inhibit cell division, called tumor-suppressor genes, which help to prevent uncontrolled cell growth, or cancer.

Question 29

Question 29 Explanation:

The correct answer is (A). Typically substitutions result in missense mutations, and the altered codon still codes for an amino acid. But if a point mutation changes a codon for an amino acid to a stop codon, it is called a nonsense mutation.

Question 30

Question 30 Explanation:

The correct answer is (D). If a nucleotide is inserted or deleted in a gene, it will change the reading frame of the genetic message. The triplet grouping of bases on the mRNA that is read during translation will be altered, along with every grouping after the insertion or deletion. The result is typically extensive missense.

Question 31

Question 31 Explanation:

The correct answer is (C). Reverse transcriptase catalyzes the formation of a strand of DNA from an RNA template.

Question 32

Questions 32–33

What important conclusion did Griffith reach after conducting his experiment?

Question 32 Explanation:

The correct answer is (D). Griffith was attempting to develop a vaccine against pneumonia when he discovered the process of transformation, which is a change in genotype and phenotype due to the assimilation of external DNA by a cell.

Question 33

Which group demonstrates that DNA is the agent of transformation?

Question 33 Explanation:

The correct answer is (D). Since it was found that the S cells were able to reproduce, the agent of transformation must be DNA.

Question 34

Question 34 Explanation:

The correct answer is (A). The lytic cycle is the type of phage reproductive cycle that results in the death of the host cell. The bacterium breaks open (lyses) and releases the phages that were produced within the cell.

Question 35

Question 35 Explanation:

The correct answer is (C). Transduction occurs when bacteriophages carry bacterial genes form one host cell to another. This usually results from an accident during the phage reproductive cycle. The virus that carries the DNA may not be able to reproduce because it lacks its own genetic information. The virus may be able to attach to another bacterial cell and inject the bacterial DNA into the next cell. If this DNA replaces the hom*ologous region of the recipient cell’s chromosomes by DNA recombination, then it has introduced genetic variation into the subsequent cell.