Biology Exam 4: DNA structure and function, Genes and Proteins, Gene Expression, Evolution and Origin of Species, Evolution of Populations

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Which of the following are NOT the four requirements for evolution by natural selection in a given population?
O A. Individuals in a population vary in their traits.
O B. Some variations are heritable.
O C. Not all individual survive and reproduce. Some survive and reproduce better than others.
O D. Certain traits lead to greater reproductive success than others.
O E. All individuals in a population reproduce equally.
Which of the following is the best restatement of Darwin's phrase "descent with modification'?
O A. Species change over time, and those extant today descended from other, preexisting species.
B. Previously existing species that did not modify offspring for new environment went extinct.
C. Ancestral species are more primitive/less complex than descendant species alive today.
O D. Natural selection is survival of the fittest.
There are different types of muscle tissues in the human body. In smooth muscles and skeletal muscles, these muscle
cells have the same sequence of the tropomyosin gene, but mRNA found in the cytoplasm is different. Which of the
following is the most likely cause of the production of the tissue specific tropomyosin mRNAs?
O A. Tropomyosin gene is probably very large and contains multiple introns and exons which are alternatively spliced to produce cell-type specific
mRNA.
O B. The transcription of the tropomyosin gene starts at the same place in all cell types. However, the transcription stops early in the smooth muscle
cells, producing a shorter mRNA than what is found in the skeletal muscle cells.
• C. Tropomyosin gene is a part of an operon which produces multiple cell-type specific mRNAs.
In the trp operon, under what conditions does the trp repressor affect the transcription?
O A. When the trp repressor binds to the tryptophan, transcription is blocked.
O B. When the trp repressor binds to the tryptophan, transcription is activated.
O C. When the trp repressor is not bound to tryptophan, transcription is blocked.
O D. When the trp repressor is not bound to the operator, transcription is blocked.
Which of the following statements best describes the structure of a double-helical DNA molecule?
A. a deoxyribonucleoside triphosphate with an adenine, thymine, gluanine, or cytosine base attached to it
B. antiparallel ribose-phosphate backbones with adenine, thymine, guanine, or cytosine attached to each ribose and projecting toward the outside of the helix
C. antiparallel ribose-phosphate backbones with adenine, thymine, guanine, or cytosine attached to each ribose and projecting toward the inside of the helix
D. parallel ribose-phosphate backbones with adenine, uracil, guanine, or cytosine attached to each ribose and projecting toward the inside of the helix
Semiconservative DNA replication involves
A. the separation of strands of DNA, and the synthesis of a new complementary strand on each old strand.
B. the outward rotation of nitrogenous bases in a double helix, and the generation of completely new double-stranded DNA copy.
C. the separation and cutting of template strands; these sections are then copied and recombined to make the new DNA strands.
D. synthesis of an RNA copy of the DNA, and the generation of a new DNA strand using the RNA as a template.
Which of the following statements correctly describes the difference between the leading and the lagging strands of DNA during DNA replication? A. The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. B. The leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. C. The lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. D. The leading strand requires an RNA primer, whereas the lagging strand does not.A. The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.Which of the following statements regarding the TATA box is NOT correct. A. The TATA box is a key element of the promoter of most eukaryotic genes. B. Basal transcription factors bind to the TATA box and recruit RNA polymerase to the promoter. C. The sequence of the TATA box is conserved among eukaryotes. D. The TATA box is essential for RNA splicing.D. The TATA box is essential for RNA splicing.You survey a wild population of Mendel's garden peas and find that 36 percent have the homozygous recessive white-flowered phenotype. The population shows Hardy-Weinberg proportions, and there are only two alleles for this trait in the population: the dominant purple allele (A) and the recessive white allele (a). What are the frequencies of the two alleles? A. The frequency of A is .64 and the frequency of a is .36. B. The frequency of A is .8 and the frequency of a is .2. C. The frequency of A is .4 and the frequency of a is .6. D. The frequency of A is .75 and the frequency of a is .25.B. The frequency of A is .8 and the frequency of a is .2.After the volcanic explosion of Mount St.Helens, prairie lupine seeds recolonized the ash plain around the mountain. Populations of lupine emerged in various location in the ash plain initially differed greatly in their appearance (e.g. shape of flowers and size of leaves etc) from each other. These differences were most likely due to A. the founder effect B. natural selection C. gene flow D. genetic bottleneckD. genetic bottleneckgenetic bottleneckan extreme example of genetic drift that happens when the size of a population is severely reduced. Events like natural disasters (earthquakes, floods, fires) can decimate a population, killing most individuals and leaving behind a small, random assortment of survivors.gene flowmovement of genes into or out of a population. Such movement may be due to migration of individual organisms that reproduce in their new populations, or to the movement of gametes (e.g., as a consequence of pollen transfer among plants)founder effect"The establishment of a new population by a few original founders (in an extreme case, by a single fertilized female) which carry only a small fraction of the total genetic variation of the parental population." A population may be descended from a small number of ancestral individuals for two reasons: • A small number of individuals may colonize a place previously uninhabited by their species. The 250 people making up the human population on the island of Tristan da Cunha, are mostly descended from one Scottish family who arrived in 1817. • An established population may fluctuate in size: the founder effect occurs when the population passes through a 'bottleneck' in which only a few individuals survive, and later expands again under more favorable conditions.natural selectionA process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.