For which of the following can Koch's postulates be used to identify the organism causing the disease?
a. Streptococcus pyogenes, the organism that causes strep throat, which can be cultured on blood agar in the laboratory
b. Treponema pallidum, the causative agent of syphilis, which cannot be grown in the laboratory
c. HIV (human immunodeficiency virus), the agent causing AIDS, a disease of the human immune system
d. Allergies
Ans: a. Streptococcus pyogenes, the organism that causes strep throat, which can be cultured on blood agar in the laboratory
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Bones, joints, and muscles form part of which organ system(s)?
a. skeletal b. muscular c. integumentary d. both skeletal and muscular
In this figure, the authors of the study looked for a correlation between which two variables?
A. being extinct and nasal cross-section
B. mass and endothermy
C. being extinct and mass
D. mass and nasal cross-section
E. presence of a turbinate and nasal cross-section
A biologist has been studying two populations of trout in Montana for the last 25 years, when the two populations were established from one common population. In the southern population, the fish now have a slightly different mouth shape
But the northern population hasn't changed from the original type. The new shape works well in catching the type of prey common in the habitat of the southern population. Which is the best explanation for the gene differences in the two populations? A) The mutation only appeared in the southern population after it was exposed to the new prey. B) The gene that produces the variation is probably still present in a small percentage of the northern population, but since there's no advantage to having it, individuals with the variation aren't selected. C) The gene that produces the variation used to be present in a few individuals, but since it wasn't advantageous, individuals with that variation died out. D) The gene that produces the variation used to be common in both populations, but since it wasn't advantageous in the northern population, the variation died out.
Which pigment(s) do red algae contain?
a. chlorophyll a b. chlorophyll a and chlorophyll b c. chlorophyll a, chlorophyll b, and phycoerythrin d. chlorophyll a, phycocyanin, and phycoerythrin