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FREE BIOLOGY AND STUDY GAMES ABOUT EXAM 4-
BIOLOGY
Actual Qs and Ans Expert-Verified Explanation
This Exam contains:
-Guarantee passing score -116 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation Question 1: Which of the following processes helps bacterial cells protect their own DNA from restriction enzymes (endonucleases)?
Answer:
Adding methyl groups to adenines and cytosines Question 2: How does extracellular glucose inhibit transcription of the lac operon?
Answer:
by reducing the levels of intracellular cAMP Question 3: .For a repressible operon to be transcribed, which of the following conditions must occur?
Answer:
RNA polymerase must bind to the promoter, and the repressor must be inactive.
Question 4: How do steroid hormones produce their effects in cells?
Answer:
By binding to intracellular receptors and promoting transcription of specific genes
Question 5: Which of the following statements is accurate with regard to a phylogeny, as represented by a phylogenetic tree?
Answer:
Descendant groups (branches) from the same node likely share many derived characters.Question 6: In positive control of several sugar metabolism-related operons, the cAMP receptor protein (CRP) binds to DNA to stimulate transcription. Which of the following environmental conditions causes an increase in CRP activity in stimulating transcription?
Answer:
a decrease in glucose and an increase in cAMP Question 7: .Which of the following functions are characteristic of general transcription factors in eukaryotes?
Answer:
They bind to other proteins or to the TATA box.Question 8: Which of the following processes correctly describes alternative RNA splicing?
Answer:
It can allow the production of proteins of different sizes and functions from a single mRNA.Question 9: How are bacteria able to change their patterns of protein synthesis so quickly in response to environmental changes?
Answer:
mRNAs that are produced are short-lived and degraded within a few minutes of being synthesized.Question 10: Which of the following methods would be most successful in attempting to introduce a particular piece of DNA into an animal cell?
Answer:
electroporation followed by recombination Question 11: Refer to the metabolic pathway illustrated. If A, B, and C are all required for growth, a strain that is mutant for the geneencoding enzyme A would be able to grow on medium supplemented with which nutrient(s)?
Answer:
nutrients A and B
Question 12: Organisms share many conserved core processes and features, including transcription and translation, using a uniform genetic code. Select the appropriate condition to determine if the plasmid has entered the
- coli bacterial cell.
Answer:
Nutrient broth to which ampicillin has been added.Question 13: Using the figure above, identify a 5? ? 3? sequence of nucleotides in the DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys.
Answer:
5-CTTCGGGAA-3
Question 14: Which of the following molecules is a protein produced by a regulatory gene?
Answer:
repressor Question 15: Given a population that contains genetic variation, what is the correct sequence of the following events under the influence of natural selection?
Answer:
- -> 4 -> 1 -> 3
Question 16: Describes the difference between the leading and the lagging strands of DNA during DNA replication.
Answer:
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.
Question 17: The genetic code is redundant. What is meant by this statement?
Answer:
More than one codon can specify the addition of the same amino acid Question 18: How many distinct species, both living and extinct, are depicted in this tree?
Answer:
six
Question 19: When taken up by a cell, which of the following molecules binds to a repressor so that the repressor no longer binds to the operator
Answer:
Inducer Question 20: Suppose that a researcher is successful at producing induced pluripotent stem cells (iPS) for replacement of pancreatic insulin-producing cells for people with type 1 diabetes.Which of the following could still pose problems for this individual?
Answer:
All 3 of them Question 21: Under what conditions does the trp repressor block transcription of the trp operon?
Answer:
when the repressor binds to tryptophan Question 22: Codons are three-base sequences in mRNA that specify the addition of a single amino acid to the growing protein chain during translation. How do eukaryotic codons and prokaryotic codons compare?
Answer:
Codons are a nearly universal language among all organisms.Question 23: Which statement illustrates the connection between natural selection and overreproduction of a population?
Answer:
Individuals with inherited traits that promote survival tend to have more surviving offspring.Question 24: It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that
________.
Answer:
island forms and mainland forms descended from common ancestors.Question 25: Rank the following one-base point mutations with respect to their likelihood of affecting the structure of the corresponding polypeptide (from most likely to least likely).
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