Exam 3

Biological evolution is best defined as

c. the change in genetic characteristics of populations over generations. FEEDBACK: The idea of genetic change over generations, or time, is key to understanding biological evolution.

According to this evolutionary tree, when did the human lineage branch away from the lineage leading to gorillas?

d. 7-8 mya FEEDBACK: The branch leading to humans branched away from the gorillas roughly 7-8 million years ago.

Which of the following is NOT a correct statement regarding the evolutionary process?

d. Allele frequencies in an individual change over time. FEEDBACK: Allele frequencies change in a population rather than in an individual. Individuals do not evolve, populations do.

Cultivation of corn over thousands of years has resulted in a modern corncob that looks very different from the tiny ancestral cob. Does this support the concept of evolution?

Yes; artificial selection demonstrates that evolution can occur, even though the driving force was humans rather than natural selection.

Refer to the information on the genetic code. Use this information to determine how many amino acids are coded for by the mRNA sequence AUGCGCAGUCGGUAG.

a. 4 FEEDBACK: The first four sets of triplet bases code for the amino acids methionine (start codon), arginine, serine, and arginine, respectively. The last codon is a termination (stop) signal. Thus, the polypeptide coded for by this segment of mRNA will have a total of four amino acids

Compare and contrast the genetic code in plants and humans.

a. The genetic code is identical for both plants and humans FEEDBACK: The genetic code is universal; this means it is the same for almost all organisms. In all organisms that use the genetic code, a given codon codes for the same amino acid.

Examine the figure shown. Which of the following statements is supported by the figure?

a. There was a greater number of animal families living on Earth just before the Cretaceous extinction event than at any previous time on Earth. FEEDBACK: The bar width represents the number of living families. The band width is widest at the end of the Cretaceous and is almost as wide now. This indicates the greatest number of families. None of the other statements can be supported by the evidence presented in the figure.

Both human and bird embryos have gill slits. This indicates that

a. birds and mammals have a common ancestor. FEEDBACK: Similarity in embryo development is part of the evidence used to identify evolutionary relationships between organisms. Similar embryonic structure implies common descent from an ancestor that also had that structure.

A cat paw and a bat wing are examples of

a. homologues structures FEEDBACK: Homologous structures originated from a common ancestor but diverged over time. Cats and bats are both mammals with similarities in limb structure, though their limbs have diverged.

To use the information contained in a gene to produce a functioning protein

a. information must be transcribed into mRNA and then translated into amino acids. FEEDBACK: Protein synthesis is a two-step process involving transcription in the cell nucleus followed by translation in the cytoplasm. All the other choices are either factually inaccurate or, if accurate, need not necessarily take place for protein synthesis to occur. Amino acids produced from the mRNA transcript are linked to create functioning proteins.

The line of descent between two species with an evolutionary relationship is often referred to as a(n)

a. lineage FEEDBACK: Scientists trace lineages to determine how closely related organisms are. This reveals much about the evolutionary relationships between organisms.

The node on an evolutionary tree represents

a. the most recent common ancestor shared by the two lineages branching out from it. FEEDBACK: The node marks the split of one lineage into two separate lineages and represents the most recent common ancestor of those two lineages. Organisms in the two separate lineages emerging from the node may share some characteristics with each other and/or the species at the node, but they will be distinctly different species.

The synthesis of RNA molecules from a DNA template is known as

a. transcription FEEDBACK: This is the definition of transcription, which is the first step in gene expression. Translation is the second step, and involves the creation of proteins from RNA transcripts.

When researchers found a fossilized jawbone from a late (about 43,000-45,000 years ago) Italian Neanderthal, they noted that the shape of the jawbone suggested the individual had an intermediate chin instead of no chin like most Neanderthals. This would provide evidence supporting which of the following hypotheses?

a.Modern Homosapiens and Homoneanderthalensis successfully bred with each other while both were present in central Africa. b.Homohabilis and Homoneanderthalensis successfully bred with each other while both were present in central Africa. c.Modern Homosapiens and Homoneanderthalensis successfully bred with each other while both were present on the Italian peninsula of Europe. d.Homohabilis and Homoneanderthalensis successfully bred with each other while both were present on the Italian peninsula of Europe

Which of the lettered arrows in the diagram of translation indicates an amino acid?

b. C FEEDBACK: This image depicts a tRNA (B) coming in to bind to the mRNA strand. The tRNA has an anticodon (A) that is complementary to the codon (D) on mRNA. The tRNA also carries an amino acid (C).

The four eukaryotic kingdoms include

b. Fungi, Animalia, Protista, Plantae. FEEDBACK: Bacteria and Arachaea contain prokaryotic organisms. Protista, Plantae, Fungi, and Animalia are the four kingdoms of Eukarya that evolved after the prokaryotes.

This evolutionary tree of hominins shows that

b. The Homo lineage split off from the Australopithecus lineage. FEEDBACK: The node at the very base of the tree shows where the Australopithecus and Homo lineages split from each other. The tree is not linear, but contains several branches.

Which of the following anatomical changes was an especially important contributor to the development of full bipedalism in hominins?

c. restructuring of the pelvis accompanied by a change in the angle of knee joints that support body weight

If your mitochondrial DNA was sequenced and compared to the sequence of mitochondrial DNA isolated from your mother's maternal grandmother (the mother of your mother's mother) would you expect to see a significant match to yours and why?

b. Yes, there would be a significant match because I inherited my mitochondrial DNA from my mother who inherited it from her mother who inherited it from her mother. FEEDBACK: All mitochondrial DNA is inherited through the mother and her maternal lineage; therefore, it does not change significantly through generations as it is not combined with paternal DNA.

The universal use of DNA as hereditary material is one of the strongest pieces of evidence for evolution because it suggests that

b. all living things evolved from a common ancestor. FEEDBACK: All living things use DNA as their genetic material, which is evidence that DNA was passed on from a single common ancestor during the evolution of life on Earth.

Pangaea is

b. an ancient, giant continent

Archaic Homo sapiens originated about 300,000-400,000 years ago and had features intermediate between those of ___________ and anatomically modern Homo sapiens.

b. homo erectus FEEDBACK: Homo erectus is a likely ancestor to Homo sapiens, so archaic H. sapiens would have had characteristics that resembled those of both species

A population experiencing a genetic bottleneck would have which of the following characteristics?

b. small population size FEEDBACK: A genetic bottleneck involves a large reduction in population size, which can lead to genetic drift.

The genetic mutations that occur in organisms are

b. the raw material of evolution FEEDBACK: Mutations are common events that are critical to evolution because they are the ultimate source of new alleles. They are not directed nor are they predictable.

Which of the following is a feature of hominins that helps to distinguish them from other apes?

b. upright posture

Which modern group of people does not carry any trace of Neanderthal DNA in their genome?

c. Africans FEEDBACK: Svante Pääbo's studies showed that all modern ethnic groups, except Africans, have between 1 to 4 percent of their genomes made up of Neanderthal DNA.

Examine the figure shown. The most recent mass extinction event occurred at the end of which geologic period?

c. Cretaceous FEEDBACK: Compared to the dates of the other mass extinctions, the Cretaceous extinction that occurred at 65 mya is the most recent (the ones occurring at the ends of the Triassic, Permian, Devonian, and Ordivician happened at 200 mya, 250 mya, 360 mya, and 445 mya, respectively).

When natural selection is operating, which of the following is likely to occur?

c. Individuals within a population may have greater survival than others. FEEDBACK: One of the keys to natural selection is the enhanced survival and reproduction of individuals with particular inheritable characteristics that can be passed on to subsequent generations.

Which of the following is an advantage of bipedalism in hominins?

c. The hands are free to carry food, tools, and weapons.

Sexual selection in a population

c. can lead to physical differences between the males and females of a species FEEDBACK: Sexual selection occurs when a characteristic or set of characteristics makes individuals better at finding mates. When one sex prefers certain traits in a mate, this can result in the evolution of sexual dimorphism, or a large difference in the appearance of males and females of the same species. However, some of the characteristics that allow for better mating potential may actually be detrimental to survival.

Single-base substitutions are not always a problem because the

c. do not cause a genetic "frameshift" FEEDBACK: A mutation to a DNA sequence that substitutes one base for another because only one codon is affected. The remaining codons downstream of the mutation are unaffected, so a frameshift does not occur.

According to the tree shown, which of these groups shares the most recent common ancestor?

c. green algae and plants FEEDBACK: The green algae and plants branch off of the same node. All of the other combinations are connected by nodes that are two to three or more ancestors/nodes back. Therefore, green algae and plants are more closely related to each other than are the members of the other groupings listed.

The image shown compares the genetic sequence of a particular gene in a human, chicken, mouse, and chimpanzee. These data demonstrate that

c. more closely related organisms share more DNA similarities. FEEDBACK: Organisms that are more closely related will have more similar DNA sequences because they share a more recent common ancestor.

Genes code for which of these biological molecules?

c. proteins FEEDBACK: Genes are segments of DNA that code for proteins. Proteins can be used to build other biological structures like tissues and antibodies, and they participate in a wide range of biological processes.

A triplet base sequence on the template strand of DNA reads ATT. What will be the corresponding mRNA codon, tRNA anticodon, and amino acid coded for by this DNA?

d. UAA; AUU; no amino acid (= stop codon FEEDBACK: The complementary base-pairing rules of DNA-to-RNA and RNA-to-RNA give the codon and anticodon. Recall also that there is no thymine in RNA; uracil and adenine are complementary bases for RNA. Stop codons signal the end of translation; they do not code for an amino acid.

Both humans and whales evolved from a common ancestor. Although our forelimbs are quite different, they are made of the same bones. This is an example of a(n)

d. homologous structure

Nuclear or genomic DNA is passed down from ___________ to all their offspring.

d. mothers and fathers FEEDBACK: Half of an animal's genomic DNA comes from its mother and half comes from its father.

What does the following analogy demonstrate?

d. only organisms with the purple trait survive FEEDBACK: This analogy demonstrates that the environment (the strainer) will cause the yellow organisms to die; the purple organisms survive and reproduce.

Artificial selection occurs when humans

d. select which organisms will breed. FEEDBACK: Artificial selection, also known as selective breeding, is when humans (rather than nature) determine which organisms will breed.

In natural selection, the traits of individuals become more common when

d. they produce more offspring FEEDBACK: In natural selection, those who successfully breed the most often produce a greater number of offspring that inherit their traits, so those traits become more common.