In 1932, researchers Emerson and Arnold showed that the rate of photosynthesis saturated at a lower light intensity than expected for the number of individual chlorophyll molecules. From this observation they determined
A. that pigments were clustered in photosystems and they were measuring saturation of pigments in reaction centers.
B. that high light intensities destroyed most pigment molecules.
C. that they had overestimated the number of chlorophyll molecules present in their test organism.
D. that plants must be able to fix carbon before their pigments can absorb light.
Answer: A
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Which theory states that eukaryotic organelles originated as prokaryotes that survived ingestion by a host cell and
ultimately evolved mutualistic relationships with the host cell? a. endosymbiont theory b. heterosymbiont theory c. obligative symbiotic theory d. facultative symbiotic theory e. autotrophic symbiotic theory
The nonporous, flexible central region of a tracheid wall pit in conifers is called
a. resin duct b. torus c. end wall d. sorus e. xylet
Respond to the following statements with reference to the five trophic categories listed below.
A. B. A herbivore is this. C. A bear eating blueberries is functioning as this. D. A Venus flytrap devouring an insect to obtain nitrogen functions as this. E. A bear feeding on an adult salmon (which eats other fish, squid, and shrimp) is functioning as this. F. Most fungi function as this.
The ________ is responsible for deep-seated emotions, including sex, hunger, thirst, pain, anger, and pleasure.
A. hypothalamus B. cerebellum C. limbic system D. pituitary gland