Organisms that derive their energy and carbon from organic molecules are called:
a. Photoautotrophs.
b. Chemoheterotrophs.
c. Photoheterotrophs.
d. Chemoautotrophs.
e. Chemolithotrophs.
The lac operon is repressed (prevents RNA synthesis) when:
a. The lac repressor binds to tryptophan and then binds to the lac promoter.
b. The lac repressor binds to tryptophan and then binds to the lac operator.
c. The lac repressor binds to lactose and then binds to the lac promoter.
d. The lac repressor binds to lactose and then no longer binds the lac operator.
e. The lac repressor binds to the lac operator in the absence of lactose.
Small regulatory RNAs that either inhibit translation of mRNAs or cause mRNA degradation are called:
a. tRNAs and rRNAs.
b. miRNAs and siRNAs.
c. gRNAs and pRNAs.
d. tRNAs and tmRNAs.
e. itRNAs and rdRNAs.
The structure of DNA has been likened to a spiral staircase or a spiral ladder. In this model, the steps (or rungs) of the ladder are:
a. Individual nitrogenous bases.
b. Alternating bases and sugars.
c. Alternating bases and phosphate groups.
d. Alternating sugars and phosphates.
e. Base pairs (pairs of bases held together by hydrogen bonds).
Which of the following explains how a single eukaryotic gene can encode more than one form of a protein?
a. Addition of a 5' cap.
b. Removal of a 5' cap.
c. Addition of a poly(A) tail.
d. Removal of a poly(A) tail.
e. Alternative splicing.
How many different kinds of gametes can an organism with the genotype Aa BB Cc produce, assuming that genes A, B, and C are unlinked?
a. 1.
b. 2.
c. 3.
d. 4.
e. 6.
The enzyme that causes the nuclear envelope to dissociate during mitosis is:
a. MAP kinase.
b. Cyclin-dependent kinase and cyclin.
c. Protein kinase A.
d. Protein kinase G.
e. Hexokinase.
Bacterial transposable elements:
a. Are pieces of DNA that can move from one place in a bacterial chromosome to another.
b. Are proteins that are integrated into the bacterial chromosome.
c. Are RNA molecules integrated into the bacterial chromosome.
d. Are the bacterial equivalent of centromeres.
e. Are the bacterial equivalent of telomeres.
All of the following are true of receptor kinases except:
a. Are found on the plasma membrane.
b. Are ion channels.
c. Dimerize when binding to their signaling molecule.
d. Are transmembrane proteins.
What is the most visibly obvious sign that a cell is in metaphase?
a. The mitochondria disintegrate.
b. The chromosomes are moving toward the opposite poles of the cell.
c. Chromatin decondenses.
d. The centromeres of the duplicated chromosomes are lined up in the middle of the cell.
e. The mitotic spindle disintegrates.