Describe why increasing depth in lakes leads to succession of microbes that have different modes of respiration. How are electron receptors other than oxygen involved?
What will be an ideal response?
Oxygen is the favored electron acceptor because it provides the greatest energy gain, when paired with any particular electron donor. But in many lakes, especially ones where there is not a lot of mixing, oxygen becomes less and less available at depth. Many bacteria have no problem with this and simply switch their electron acceptors to use molecules other than oxygen (like NO2-). Others specialize on the zone that best favor their growth. The lower in the lake, the less of a difference in E zero there is between reactants (electron acceptors) and their products, so there is less energy gained with these alternate electron acceptors.
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The global pattern of air circulation begins at
a. the equator. b. 30 degrees north latitude. c. 30 degrees south latitude. d. 60 degrees north latitude. e. 60 degrees south latitude
New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and find it difficult to continue exercising
These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise. Which of the statements below is the best explanation of why athletes would need to monitor lactate levels? A) During aerobic respiration, muscle cells cannot produce enough lactate to fuel muscle cell contractions and muscles begin to cramp, thus athletic performance suffers. B) During anaerobic respiration, lactate levels increase when muscles cells need more energy, however muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration. C) During aerobic respiration, muscles cells produce too much lactate which causes a rise in the pH of the muscle cells, thus athletes must consume increased amounts of sports drinks, high in electrolytes, to buffer the pH. D) During anaerobic respiration, muscle cells receive too little oxygen and begin to convert lactate to pyruvate (pyruvic acid), thus athletes experience cramping and fatigue.
The largest biome on Earth is the
A. desert. B. tundra. C. temperate deciduous forest. D. taiga. E. ocean (marine aquatic).
A lipid-soluble cofactor that can diffuse freely in the membrane of the electron transport chain and carry electrons across the membrane is ________.
A) ubiquinone (Q) B) Fe-S C) cytochrome c D) FADH2