Which scenario best describes a double-blind study?
a. The investigator and the subjects wear blindfolds.
b. No one knows what is in the experimental or control group
c. The subjects do not know if they are in the experimental or control group.
d. Neither the investigator or the subjects know if they are in the experimental or control group.
e. The investigator does not know if subjects are in the experimental or control group.
d
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Which of the following is true regarding sympatric speciation?
A. Sympatric speciation requires physical separation of two populations. B. Sympatric speciation requires a selective disadvantage of hybrids (e.g., medium-billed birds) of two diverging populations.
Auxin moves between cells through a process called polar transport. Auxin molecules move from one cell to the next through PIN proteins. However, their movement is unidirectional. What accounts for this unidirectional movement?
A. PIN proteins are only found on the basal side of the cell. B. PIN proteins are only found on the apical side of the cell. C. Auxin diffuses down its concentration gradient. The concentration of auxin molecules decreases as you move down the stem away from the apical meristem. D. Auxin moves independently of its concentration gradient because the presence of the PIN protein provides a channel that auxin can "leak" through to get into adjacent cells. E. Auxin in the unprotonated form can move between cells by going into adjacent spaces occupied by plant cell walls. The movement of auxin is lateral, not unidirectional.
What quality of the traits that Mendel chose to study allowed him to establish the basic laws of inheritance?
A. The genes for most of the traits were linked. B. The genes for all of the traits had more than two alleles each. C. The alleles that he studied were either dominant or recessive. D. The epistatic genes for the traits he studied were homozygous recessive. E. The traits he studied were never controlled by two or more genes.
Phospholipids assemble spontaneously into bilayers driven by the attraction of their "tail" portions to each other and of their "head" portions to each other. The tail regions are:
A) hydrophilic. B) hydrophobic. C) molecularly charged. D) adhesive. E) cohesive.