What is the effect of a nonsense mutation in a gene?
A. It introduces a premature stop codon into the mRNA.
B. It alters the reading frame of the mRNA.
C. It has no effect on the amino acid sequence of the encoded protein.
D. It prevents introns from being excised.
E. It changes an amino acid in the encoded protein.
Ans: A. It introduces a premature stop codon into the mRNA.
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Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures?
A) mitochondria and chloroplasts B) membrane proteins of the inner nuclear envelope C) free ribosomes and ribosomes attached to the ER D) components of the cytoskeleton E) cellulose fibers in the cell wall
The small molecule intermediate phosphoenol-pyruvate (PEP) is unusual due to which chemical
characteristic?
a. supplies a high energy phosphate to phosphorylate ADP b. provides high energy electrons to make ATP c. its ability to carry out redox reactions d. regulates the activity of phosphofructokinase e. donates an electron to NAD+ and FAD
Species richness refers specifically to
a. the numbers of individuals of each species present. b. the ability of larger animals to enrich themselves by successfully preying on smaller ones. c. the number of different species in the habitat. d. the feeding levels at which the animals are located. e. none of these.
What prevents a plant cell from bursting in a hypotonic solution?
a. plasma membrane b. transport proteins which help pump the excess water out of the cell c. cell wall d. a plant cell will not burst in a hypotonic solution because water is moving out of the cell