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Midterm 3 - CH 16-24
Terms in this set (100)
is the incorrect hypothesis that characteristics in parents are averaged in offspring
True or False: In a human pedigree, females are represented by squares and males as circles; affected individuals as filled symbols and unaffected individuals as open symbols. Horizontal lines denote matings.
If Mendel based his data only on two traits, and the genes influencing those traits were linked and located close together on the same chromosome, which of his laws would he not have been able to resolve?
The Law of Independent Assortment
Hemophilia is a sex-linked recessive trait in humans. If a carrier female (heterozygous for the trait) mated with a normal male, what would be the expected outcome(s)?
None of the daughters would have hemophilia, and half of the sons would have hemophilia.
X-linked inheritance shows a pattern where:
a. Affected individuals are almost always male.
b. Affected males have unaffected sons.
c. A female whose father is affected can have affected sons.
d. None of the above.
e. All of the above.
True or False: In humans and other mammals the Y chromosome has a gene called STTY that results in male development.
the percentage of cases in which both members of a pair of twins show the trait when it is known that at least one member shows it
Small regulatory RNAs termed micro RNAs (miRNA) affect gene expression by
interfering with gene translation
Dosage compensation is:
b. the process by which expression of X-linked genes is equalized
c. involves the inactivation of one of the two X chromosomes in the females of some species
e. b and c only
True or False: At each successive stage in development, cells gain developmental potential as they become differentiated.
Proteins are considered "evolutionarily conserved" when
They are similar in sequence from one organism to the next
What is the total number of alleles in the population (when considering these two alleles)?
What is the frequency of allele 1?
only affect males, and affect all sons of an affected male.
What is the highest recombination frequency between two genes on the same chromosome?
Sometimes certain diseases affect all sons of an affected father, even when the mother is unaffected. What is the best explanation of this?
The disease-related gene is on the Y chromosome.
Considering an X-linked dominant trait, if an unaffected woman and an affected man decide to have children, then which of the following statements is true about the possibilities for their children?
Their daughters are expected to be heterozygous for the associated gene.
What is the recombination frequency between w and cv (from map below)?
A key difference between single-gene traits such as those Mendel studied and complex traits such as human height is that:
single-gene traits are generally uninfluenced by the environment, whereas complex traits have a significant environmental component.
A farmer in Kansas and a farmer in California each plant an acre of the same kind of corn. Because the environment differs for each field, how will this affect the height of their corn?
Both the average height of the corn and the variation in corn height within each field could differ between fields.
A cell that can give rise to a whole organism is called:
When considering speciation, in __________, mating occurs, but genetic incompatibilities prevent the development of a viable, fertile offspring.
Cells differentiate through:
Radioactive dating takes advantage of the fact that Carbon-14 decays to:
b. looks for patterns of relatedness.
c. compares anatomical or molecular features.
d. B and C
a. represent loss of many species in a short time
b. allow surviving species to proliferate
c. can be predicted from fossil records
d. all of the above
True or False: A single gene can yield different proteins.
True or False: Gene regulation is influenced by both genetic and environmental factors.
Hominins are defined as:
members of species in the lineage leading to humans.
What do King and Wilson think is driving the most significant evolution along the hominin lineage?
changes in gene regulation
Cultural evolution and biological evolution:
can sometimes affect each other
In genetics, two organisms are part of the same population if:
they are the same species and are in the same geographic area.
The methylation state of an individual CpG island:
can change over time in response to environmental cues, allowing genes to be turned on or off as needed.
A histone code is:
the pattern of chemical modification of an individual histone's tail.
In humans and other mammals, X-inactivation takes place:
early in development, with each new cell inheriting the same inactivated X chromosome as its parent cell.
Which process produces multiple proteins from the same primary transcript in the same cell?
MicroRNA (miRNA) regulates gene expression by:
inhibiting translation by binding to RNA transcripts.
Lysosomes are organelles normally associated with how enzymes normally break down proteins to help with protein recycling in the cell. A family of genetic disorders, called lysosomal storage disorders, has defects in this system. In some of these diseases, proteins that normally move to the lysosomes fail to be transported properly in the cell. As a result, lysosomes do not properly recycle proteins. Which of the following could produce this kind of disorder?
blockage of post-translational modification
You identify a mutation affecting the lactose operon and find the following:
lacZ is expressed whether lactose is present or not.
lacI is expressed normally.
lacO is deleted.
The early cell divisions of human development differ from other mitotic cell divisions in that:
cells do not grow in size; they subdivide the cytoplasm of the fertilized egg.
The body of the human embryo develops from the ____ of the blastocyst.
inner cell mass
Which of the following lists cell types in order from those capable of differentiating into the greatest number of different specialized cells to those capable of differentiating into the least number of different specialized cells?
totipotent, pluripotent, multipotent
Which of the following correctly matches a cell or group of cells with its ability to differentiate into different specialized cells?
fertilized egg: multipotent
Gene regulation during development is _____, which means that _____.
hierarchical; genes expressed at each stage control the expression of genes that act later
are expressed by the mother and affect offspring phenotype.
In almost all organisms that have been studied, the genes in Hox clusters:
are arranged on chromosomes in the same order as their products function along the anterior-posterior segments of the embryo.
In mammals, Hox genes:
direct development of structures that become parts of the hindbrain, spinal cord, and vertebral column.
Evolutionarily conserved molecules:
are similar in sequence among distantly related organisms, were likely present in their most recent common ancestor, and have likely changed very little because they serve a vital function.
As a transcription factor, Pax6:
activates some target genes and represses others.
Signal transduction is the process by which:
an extracellular molecule activates a membrane protein, which in turn activates molecules inside the cell.
The muscle cells and nerve cells in a mouse look very different and serve very different functions in the mouse's body. These differences are because the muscle cells and nerve cells in the mouse ___________.
express different genes
A mutation occurs that causes a defect in the development of skeletal muscle. Which of the following kinds of cells are affected?
From an evolutionary perspective, germ-line mutations are more significant than somatic mutations. This is because:
somatic mutations affect only one or a few cells and only germ-line mutations will appear in an individual's descendants.
Human ABO blood groups are determined by a single gene with 3 alleles: A, B, and O. In a sample of 300 individuals, 100 are blood type A and genotype AA, 100 are blood type B and genotype BO, and 100 are blood type O and genotype OO. What are the allele frequencies?
33.3% A, 16.6% B, 50% O
In New Mexico, large expanses of black lava create patches of unique habitat. If, in every generation, selection favors the darkest colored pocket mice in those habitats because they are best hidden from predators, this would be an example of:
The only evolutionary process that leads to adaptive change is:
In regions where malaria is prevalent, the S allele is beneficial because:
It causes red blood cells to distort, which makes them less hospitable to Plasmodium, the parasite that causes malaria.
What does it mean to say that an allele is "fixed" in the population?
It is an indication of no genetic variation at that locus in the population.
You have two populations of flowering plants. In these populations floral color is controlled by one gene. The red allele (R) is dominant to the white allele (r). In population one, 75% of the flowers are red, in population two 25% of the flowers are white. Assuming H-W, which population has a greater frequency of the R allele?
Neither, they both have the same frequency.
You have spent time working with a population of beetles. Males range in size from 2-6 cm in length. You realize that the females only mate with males that measure less than 3 cm long. If you measured allele frequencies at a single locus that contributes to overall length, would you expect this population to be in H-W equilibrium from one generation to the next?
33. You have a small population of beetles. One day a large rainstorm causes flooding and wipes out 87% of the population. The remaining individuals have much lower genetic variation than the original population. Which of the following would explain the lack of H-W equilibrium seen after the flood?
A population of charmingly charismatic rodents, population A, lives on a small island. The population consists of 100,000 individuals.
Are all individuals of A genetically identical?
You are shown a DNA sequence chosen at random from the total pool of 200 sequences; can you tell which population, A1 or A2, it comes from?
A drawback of the biological species concept is that it cannot be applied to:
extinct and asexual organisms.
A bacteriologist is studying two asexually reproducing strains of E. coli. The two require different amounts of trace minerals for survival; on these grounds, the bacteriologist determines that they are separate species. In making his determination, he is using which species concept?
ecological species concept
Several species of fireflies are active on the same summer nights in the same fields. Males and females recognize one another by their distinctive flashing patterns. This is an example of what kind of reproductive isolation?
pre-zygotic, behavioral isolation
Horses and donkeys can interbreed, but their offspring (mules) are infertile. This is an example of what kind of reproductive isolating mechanism?
Different species of fruit flies occupy each of the islands in the Hawaiian island chain, a group of volcanic islands that formed one after the other. One hypothesis for how the different fruit fly species formed is that, after each new island was formed, fruit flies from existing islands colonized it and subsequently diverged. If this hypothesis is correct, it would be an example of:
allopatric speciation by dispersal.
Gus and Ida are 2 polar bears (Ursus maritimus) that live at the Central Park Zoo in New York City. They are 1st generation zoo polar bears. They have lived at the zoo since 1985 and are reproductively isolated from all other polar bears. Are they a different species based on the biological species concept?
The Zoo decides to keep all of Gus and Ida's descendants under zoo conditions for the next 30,000 years. They breed only with each other. You visit the zoo in 30,000 years and see their offspring. Do you expect their offspring, which are alive in 30,000 years, to be identical in genotype and phenotype to Gus and Ida? Keep in mind, polar bears start reproducing when they are between 5 and 10 years old, and adult females give birth to 2 cubs every 2-3 years.
No, because mutation would occur occasionally and there are selective pressures that exist in artificial as well as natural environments.
Say Gus and Ida were released back into the wild in 2011, in an area that has a population of polar bears. You observe them for many years and they only breed with each other. Does this prove that they are members of a different species than the wild polar bears?
You begin an experiment with 2 populations of E. coli that are each composed of 100 cells. The cells are all genetically identical (i.e., they are clones). You grow them up in flasks on a lab bench under identical conditions with unlimited resources. After 10,000 generations, you analyze the genome of each population. Do you expect the genomes of each population to be identical after 10,000 generations?
No, because mutation and natural selection (once genetic variation is present) were factors in this experiment.
In a phylogenetic tree, a node or branching point represents:
the common ancestor from which the descendent species diverged.
The diagram below depicts three phylogenetic trees. Which of the three show the same sister group relationships among groups A, B, and C?
1 and 2 are equivalent
A taxon that does not include the last common ancestor of all its members is a _____ group.
Characters that are similar because of descent from a common ancestor are _____; characters that are similar due to convergent evolution are _____.
With the advent of tools to incorporate molecular data, phylogenetic analysis can be used to:
a. reconstruct the evolutionary history of a group of organisms over millions of years.
b. track the spread of a pathogen, such as a fungus or virus, from place to place.
c. identify the origin of invasive pest species.
d. track shipments of endangered species or their products (such as elephant ivory or bushmeat).
e. All of the answer options are correct.
The probability that an ancient species will be represented in the fossil record is a function of:
the properties of the organisms themselves and the environments in which they live.
The Burgess Shale preserves a remarkable fossil record of:
marine life during initial diversification of animals in the Cambrian Period 505 million years ago.
During the end-Permian mass extinction:
a. oxygen levels in the deep oceans dropped.
b. global warming occurred as a result of volcanic eruptions.
c. oceans were acidified as a result of volcanic eruptions.
d. oxygen levels in the deep oceans dropped and oceans were acidified as a result of volcanic eruptions.
e. All of the answer options are correct.
The phylogeny below represents a hypothesis for the evolutionary relationships among major groups of plants. If it is correct, in what order should we predict to find the fossils of these groups, in order from oldest to youngest?
moss group, ferns, daisy
What is a disadvantage of using fossils to reconstruct phylogenetic history?
The probability of fossilization varies among species.
Which organism is most likely to be fossilized?
Why is the fossil record not a complete catalogue of biological history?
Not all organisms fossilize with equal probability.
57. Recent discoveries of fossils that surprisingly retain some coloration are the result of the preservation of:
cellular melanosomes that produced pigments
In what kind of environment are fossils most likely to form?
shallow lake bed
In what types of rocks are fossils most likely to be found?
What types of data can be used to construct phylogenies such as the one above?
molecular data, fossil evidence and anatomical, physiological and developmental studies of extant species
After you have found a new species of ape, you spend 10 years in the field seeking a fossil of its ancestor. You fail. This lack of fossil data:
is expected, because the fossil record is incomplete
One reason we see relatively little genetic variation among human regional populations is that:
humans migrated out of Africa so recently that we haven't had enough time for regional variation to accumulate.
Statistical analysis of genetic variation within and among human populations―including those we identify as different races―reveals:
more genetic variation within groups than we see between groups.
Which of the following is NOT a piece of genetic evidence that supports the "out of Africa" hypothesis for the origin of humans.
mtDNA alleles among samples from Africa are more similar than mtDNA alleles among samples from Europe.
All of the following statements are evidence that evolution of the FoxP2 gene may have contributed to the evolution of language in humans EXCEPT:
Studies of Neanderthal DNA have shown that Neanderthals possessed the modern human version of FoxP2.
What is the definition of neoteny?
retention of juvenile characteristics in an adult
How does the level of genetic variation in humans typically compare to other species?
lower than other species
Where did Homo sapiens evolve?
Gibbons and orangutans are from Asia. Gorillas and chimpanzees are from Africa. How was Charles Darwin able to predict that humans evolved in Africa?
He understood that humans and gorillas are more closely related than humans and orangutans based on anatomical criteria.
Which human populations have the highest levels of genetic variation?
Skin color is an example of a human trait influenced by natural selection. What factor(s) has/have directly shaped variation in skin color?
intensity of sunlight
Why do we think that male Neanderthals mated with non-African ancestral Homo sapiens?
Because Neanderthal nuclear DNA sequences are present in the human gene pool, and Neanderthal mtDNA sequences are not.
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