natural selection
A key point in Darwin’s explanation of evolution by natural selection is that
a. the biological structures most likely inherited are those that have become better suited to the environment through constant use.
b. mutations that occur are those that will help future generations fit into their environments.
c. slight variations among individuals significantly affect the chance that a given individual will survive in its environment and be able to reproduce.
d. genes change in order to help organisms cope with problems encountered within their environments.
e. extinction is nature’s way of weeding out undeserving organisms.
c. slight variations among individuals significantly affect the chance that a given individual will survive in its environment and be able to reproduce.
A woman has six sons. The chance that her next child will be a daughter is
a.1.
b.0.
c.1/2.
d.1/6.
e.5/6.
c. 1/2
The description "antiparallel" regarding the strands that make up DNA means that
a.The twisting nature of DNA creates nonparallel strands.
b.The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
c.Base pairings create unequal spacing between the two DNA strands.
d.One strand is positively charged and the other is negatively charged.
e. One strand contains only purines and the other contains only pyrimidines.
b.The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
What is the effect of a nonsense mutation in a gene?a.It changes an amino acid in the encoded protein.
b.It has no effect on the amino acid sequence of the encoded protein.
c.It introduces a premature stop codon into the mRNA.
d.It alters the reading frame of the mRNA.
e.It prevents introns from being excised.
c.It introduces a premature stop codon into the mRNA.
Evolutionary biologists support the position that all species present today, along with species that lived in the past, are descended from
a. A single ancestral species.
b. Thousands of different species.
c. One ancestral species per kingdom.
d. Two or three ancestral species per kingdom.
a. A single ancestral species.
A mutation occurs in one of your lung cells. Which of the following is TRUE?
a. You have evolved to be better adapted to your environment.
b. You will soon die because most mutations are lethal.
c. You will be sterile and no longer be able to have children.
d. The human species will have evolved because this mutation will be passed on to your children.
e. This mutation does not affect human evolution because it will not be passed on to your offspring.
e. This mutation does not affect human evolution because it will not be passed on to your offspring.
Of the following, which is the most current description of a gene? a.
a unit of heredity that causes formation of a phenotypic characteristic
b.a DNA subunit that codes for a single complete protein
c.a DNA sequence that is expressed to form a functional product: either RNA or polypeptide
d.a DNA—RNA sequence combination that results in an enzymatic product
e.a discrete unit of hereditary information that consists of a sequence of amino acids
c.a DNA sequence that is expressed to form a functional product: either RNA or polypeptide
Which of the following removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?a.Helicase
b.DNA polymerase III
c.Ligase
d.DNA polymerase I
e.primase
d.DNA polymerase I
What is a ribozyme?
a.an enzyme that uses RNA as a substrate
b.an RNA with enzymatic activity
c.an enzyme that catalyzes the association between the large and small ribosomal subunits
d.an enzyme that synthesizes RNA as part of the transcription process
e.an enzyme that synthesizes RNA primers during DNA replication
b.an RNA with enzymatic activity
The same basic internal organs (kidneys, stomach, heart, lungs) are found in frogs, birds, snakes. and rodents. This is primarily an example of ________. a.structural homology.
b.developmental homology.
c.genetic correlation.
d.inheritance of acquired characteristics.
a.structural homology
A 1:2:1 phenotypic ratio in the F2 generation of a monohybrid cross is a sign of
a.complete dominance.
b.multiple alleles.
c.incomplete dominance.
d.polygenic inheritance.
e.pleiotropy.
c.incomplete dominance.
15.What is the function of topoisomerase?
a.relieving strain in the DNA ahead of the replication fork
b.elongation of new DNA at a replication fork by addition of nucleotides to the existing chain
c.the addition of methyl groups to bases of DNA
d.unwinding of the double helix
e.stabilizing single-stranded DNA at the replication fork
a.relieving strain in the DNA ahead of the replication fork
Which point mutation would be most likely to have a catastrophic effect on the functioning of a protein?
a.a base substitution
b.a base deletion near the start of a gene
c.a base deletion near the end of the coding sequence, but not in the terminator codon
d.deletion of three bases near the start of the coding sequence, but not in the initiator codon
e.a base insertion near the end of the coding sequence, but not in the terminator codon
b.a base deletion near the start of a gene
What keeps organisms from becoming perfectly adapted to their environment?
a. Environments change, so different alleles (or traits) become more fit.
b. Mutations introduce new variation into a population, some may affect traits to be more advantageous than previous traits.
c. Genetic drift causes random changes in allele frequencies.
d. All of the above processes; organisms never become perfectly adapted to their environment. e. None of the above; some organisms do become perfectly adapted.
d. All of the above processes; organisms never become perfectly adapted to their environment.
30.Which of the following must exist in a population before natural selection can act upon that population?
a.Genetic variation among individuals
b.Variation among individuals caused by environmental factors
c.Sexual reproduction
d.B and C only
e.A, B, and C
a.Genetic variation among individuals
Which of the following statements is true?
a. The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.
b. The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%.
c. of the traits that Mendel studied seed colour, pod shape, flower colour, and others are due to genes linked on the same chromosome.
d. Linked genes are found on different chromosomes.
e. Crossing over occurs during prophase II of meiosis.
a. The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.
19.What are the coding segments of a stretch of eukaryotic DNA called?
a.Introns
b.Exons
c.Codons
d.Replicons
e.Transposons
b.Exons
An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. Which of the following hypotheses describes the most likely result?
a.tRNA will not form a cloverleaf.
b.The nearby stem end will pair improperly.
c.The amino acid methionine will not bind.
d.The anticodon will not bind with the mRNA codon.
e.The aminoacyl synthetase will not be formed.
c.The amino acid methionine will not bind.
Evolutionary theory predicts that species are related, not independent. Four of the following examples provide support for this prediction, but one is irrelevant. Which one of these examples does not support the claim that species are related?
a.Many dinosaurs and other organisms went extinct following a huge asteroid impact at the end of the Cretaceous.
b.The endostyle of lancelets (invertebrate chordates) and the thyroid gland of vertebrates develop similarly, and both produce iodinated proteins.
c.All prokaryotes and eukaryotes use DNA to carry their genetic information.
d.Ground squirrel species found on the north and south sides of the Grand Canyon are very similar to each other.
e.Before synthetic insulin was available, diabetics used injections of purified pig insulin to manage their disease.
a.Many dinosaurs and other organisms went extinct following a huge asteroid impact at the end of the Cretaceous.