Which of the following traits is not characteristic of flatworms?
a. hermaphrodites
b. bilaterally symmetrical
c. complete digestive tract with mouth and anus
d. acoelomate
c
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The figure shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?
A) Green and yellow wavelengths inhibit the absorption of red and blue wavelengths. B) Bright sunlight destroys photosynthetic pigments. C) Oxygen given off during photosynthesis interferes with the absorption of light. D) Other pigments absorb light in addition to chlorophyll a. E) Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.
Unicellular cyanobacteria are the most abundant phototrophs in the ocean and perform 80% of marine photosynthesis
Indicate whether the statement is true or false.
A ________ epidemic is characterized by a sharp rise to a peak then a rapid, but not as pronounced, decline in the number of individuals infected.
A. common-source B. sporadic C. herd D. propagated
Your text describes an experiment in which low-nutrient conditions select bacteria that would kill off other bacteria
When nutrients became plentiful again, these killer bacteria became less common because they had lower fitness in this environment, but they didn't become extinct. Why would some of the killer bacteria survive in the new environment? A) They're waiting for a future time when that trait may be useful again. B) They have changed the killer gene to a less costly one but can regenerate the killer gene when necessary. C) Competition must be low enough that the disadvantage of having the killer trait isn't great enough to cause extinction. D) The killer trait is a dominant trait, so it cannot be eliminated.