GRE Biology Practice Tests

1. Stabilization of the unique coiled structure of an alpha helix in a protein is primarily attributed to
hydrogen bonding between the peptide backbone atoms
disulfide bridges between cysteine side chains
carbohydrate moieties attached to polar amino acids
an abundance of amino acids with electrically charged side chains
gpeptide linkages that covalently bond amino acids
2. A DNA strand with the sequence 5’ CGA TTG 3’ would be complementary to the sequence
5 GCU AAC 3
5 GCT AAC 3
5 CAA TCG 3
5 GTT AGC 3
5 CUU TCG 3
3. Which of the following best explains how mutations in DNA can result in the expression of a new phenotype?
Eukaryotes and prokaryotes have similar ribosomes
The gene is now read in the 3¢ to 5¢ direction
Nucleic acids are methylated
The polarity of tRNA becomes the opposite of that of DNA
A different polypeptide is produced
4. Which of the following techniques could be used to demonstrate protein binding to specific DNA sequences?
Western blot hybridization
Northern blot hybridization
Southern blot hybridization
Electrophoretic mobility shift assay
Polymerase chain reaction
5. In cloning experiments on the frog Xenopus laevis, nuclei were removed from intestinal cells of tadpoles and transplanted into zygotes whose nuclei had been removed. A small percent of these zygotes developed into normal frogs, suggesting that
intestinal cells can be transformed into all cell types
frogs do not have the same developmental constraints as other species
intestinal cell nuclei are highly specialized
the genomes of all somatic cells are equivalent
the zygotic nucleus cannot be successfully inactivated
6. In garden peas, the allele for tall plants (D) is completely dominant to the allele for dwarf plants (d) and the allele for violet flower color (W) is completely dominant to the allele for white flower color (w). In a cross between a tall violet plant, with the genotype DDWw, and a dwarf white plant, what phenotypic ratio of the progeny would be expected from this cross?
All tall violet
1 tall violet: 1 dwarf violet
1 tall violet: 1 tall white: 1 dwarf violet: 1 dwarf white
1 tall violet: 1 tall white
All dwarf white
7. Which of the following best explains why enzymes are effective in facilitating chemical reactions?
They raise the temperature of the reaction mixture, thereby speeding up the conversion of reactants to products.
They alter the equilibrium constant of a reaction (Keq) so that more reactant can be converted to product.
They increase the maximal rate of the chemical reaction (Vmax).
They lower the activation energy, thereby speeding up the conversion of reactants to products.
They donate energy to reactions, thereby allowing nonspontaneous reactions to proceed
8. Targeting of a newly synthesized protein is most likely to require two different signal peptides for which of the following destinations?
Plasma membrane
Lysosome
Cytosol
Chloroplast
Endoplasmic reticulum
9. Approximately what fraction of the human genome encodes proteins?
2%
25%
50%
90%
99%
10. Which of the following contain DNA sequences required for the segregation of chromosomes in mitosis and meiosis?
Telomeres
Centromeres
Nucleosomes
Spliceosomes
Ribosomes
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