The sequence of a polypeptide is determined by the order of codons that specify the amino acids in the polypeptide. How many different sequences of codons can specify the polypeptide sequence methionine-histidine-alanine-leucine? (Chapter 16)
48
Which type of mutation causes a premature termination of protein synthesis? (Chapter 16)
Nonsense
An organism's phenotype is _____. (Chapter 14)
the traits exhibited by the organism
If a plant homozygous for round peas (RR) is crossed with a plant homozygous for wrinkled peas (rr), which of the following statements is true? (Chapter 14)
The F1 generation of this cross will produce some gametes that contain R and some that contain r, in equal proportions.
If the first five seeds (offspring) grown from a cross between two heterozygous pea plants with the genotype Rr are all round, what is the probability that the next offspring from these parents will be wrinkled? (Chapter 14)
25 percent
In Drosophila, the white-eyed gene (w) is on the X chromosome (w+ = red eyes; w = white eyes). The w+ allele is dominant over w. If a w+ homozygous female is crossed with a wY male, what is the phenotypic ratio of the F2 generation?
2:1:1
Which of the following statements about an X-linked dominant disease is true? (Chapter 14)
All female offspring from an unaffected female and an affected male would have the disease.
A woman who is a carrier of an autosomal recessive genetic disease marries a man with the disease. Their only child is a girl without the disease. In a pedigree, you would show the woman as ____. (Chapter 14)
a half-filled circle
If a cell has a diploid number of 50, how many chromosomes are present in the nucleus at the beginning of meiosis? How many chromosomes are present in each resulting nucleus at the end of meiosis? (Chapter 13)
Beginning: 50; end: 25
Which of the following statements best describes a phase that occurs in meiosis II? (Chapter 13)
Sister chromatids separate and begin moving to opposite sides of the cell.
What is the frequency of each phenotype in the F2 generation of a cross between two homozygous pea plants with the genotypes RR and rr? (Chapter 14)
Three round, one wrinkled
Which of the following statements about transcription in bacteria and eukaryotes is true? (Chapter 17)
Bacteria and eukaryotes rely on proteins that recognize specific DNA sequences in the promoter to initiate transcription.
According to the wobble hypothesis, _____. (Chapter 17)
more than one codon codes for an amino acid and they all have the same nucleotides in the first two positions
In the Meselson-Stahl experiment, cells were grown for one generation in growth medium containing a relatively heavy nitrogen isotope, then transferred to new medium containing a lighter nitrogen isotope. After one round of DNA replication, what was true of the DNA in the cells? (Chapter 15)
Half of the DNA strands contained only the light nitrogen isotope.
Examine the following DNA sequence: 5′ AATTGCGCTTAG 3′. Which of the strands below represents the complementary RNA strand that would be formed from this DNA strand? (Chapter 17)
3′ UUAACGCGAAUC 5′
A metabolic pathway synthesizes a product through a series of steps, with each step producing an intermediate compound. What conclusion should be drawn when a genetic mutation in the DNA results in the production of only the first few intermediates? (Chapter 16)
The gene that codes for the enzyme required to produce the next intermediate in the pathway is knocked out.
A researcher examines a cell undergoing meiosis and identifies the nuclei of two daughter cells. Which of the following best represents how the researcher would characterize the cell? (Chapter 13)
Two haploid cells in metaphase II
Which of the following statements is true about DNA replication in bacteria and eukaryotes? (Chapter 15)
Eukaryotes can have multiple points of origin for DNA synthesis on each individual chromosome.
Which of the following enzymes is correctly matched to its function? (Chapter 15)
DNA polymerase III— adds nucleotides to the lagging strand.
DNA mutations that alter the sequence can be corrected by excision repair. Which of the following statements is true of this system? (Chapter 15)
The system detects mutations because they produce an irregularity in the DNA molecule's shape.
Cancer can occur when DNA is damaged. Which of the following statements about the cause of damage to DNA molecules is true? (Chapter 15)
DNA molecules can be damaged in the absence of environmental toxins or radiation.
How many different amino acids would be found in a polypeptide made from translation of an RNA containing only cytosines (C) and adenines (A) in random order? (Chapter 16)
Six
What is the end result of meiosis and the subsequent fertilization of gametes? (Chapter 13)
An offspring with a chromosome complement unlike that of either parent
If an F1 plant with the genotype RrYy self-fertilizes, what is the phenotypic ratio of the F2 generation? Keep in mind that R is the dominant allele for seed shape (round), r is the recessive allele for seed shape (wrinkled), Y is the dominant allele for seed color (yellow), and y is the recessive allele for seed color (green). (Chapter 14)
Nine round, yellow: three round, green: three wrinkled, yellow: one wrinkled, green
If an organism is heterozygous for two linked traits, how many genotypes are possible in the gametes produced from a single germ-line cell if a single crossing over event occurred during meiosis I? (Chapter 14)
Four
In the Hershey-Chase experiment, bacterial cultures infected with a virus were agitated in a kitchen blender to _____. (Chapter 15)
separate viral protein coats from the bacterial cells in the culture
What change in the nature of the genetic code could be possible if, instead of two sets of base pairs (A-T, G-C), there were three sets of base pairs (A-T, G-C, X-Y)? (Chapter 16)
The extra base pair would make it possible to have codons two bases in length rather than three.
Why is it possible that a point mutation may have no effect on an individual's fitness? (Chapter 16)
The encoded protein may be unchanged due to the redundancy of the genetic code.
In snapdragon plants, T is the dominant allele for plant height (tall), t is the recessive allele for plant height (dwarf), RR flowers are red, rr flowers are white, and flower color exhibits incomplete dominance. A cross between Ttrr and TtRR results in what proportion of offspring with pink flowers on dwarf plants? (Chapter 14)
One-quarter
Some plants are triploid. If a plant has a haploid chromosome number of 42, how many chromosomes are present in its somatic cells? (Chapter 13)
126
An individual plant that exhibits self-fertilization can produce offspring different from itself primarily as a result of _____. (Chapter 13)
independent assortment and crossing over
How could you distinguish human mitotic cells from human meiotic cells? (Chapter 13)
By counting the number of daughter cells resulting from mitotic and meiotic division
The following DNA sequence occurs at a DNA origin of replication. Which of the sequences below would be most likely to bind to this sequence to initiate DNA replication in a cell? 3' AATTGCAGATTCA 5' (Chapter 15)
5' UUAACGUCUAA 3'
Which is the best description of the loops in a tRNA molecule? (Chapter 17)
Regions of the molecules that remain as single-stranded RNA due to the absence of complementary base pairs
Which of the following statements is a leading hypothesis to explain why many organisms reproduce sexually? (Chapter 13)
The offspring that result from sexual reproduction are genetically variable, and some of them can fight off diseases more easily than genetically identical offspring.
DNA synthesis is best characterized by which of the following statements? (Chapter 15)
New nucleotides are added in the 5' to 3' direction on both the lagging and leading strands.
If an individual is heterozygous for hair color (Hh) and eye color (Ee), which of the following statements is true? (Chapter 14)
The individual can make gametes that contain HE, He, hE, or he.
When a sperm and egg combine, the resulting embryo has _____. (Chapter 13)
half of the mother's genetic information and half of the father's
The lack of membrane-bound organelles in bacteria impacts transcription and translation in which way? (Chapter 17)
Transcription and translation can occur simultaneously.