The researchers who observed that magnetite was produced by bacterial cultures from the deep subsurface carried out a follow-up experiment. These biologists treated some of the cultures with a drug that poisons the enzymes involved in electron transport chains. In cultures where the drug was present, no more magnetite was produced. Does this result support or undermine their hypothesis that the bacteria in the cultures perform cellular respiration? Explain your reasoning.

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Hi everyone. Let's look at our next question. The hypothesis that bacterial cultures from the deep surface produce magnetite and perform cellular respiration is supported by the evidence that so as we kind of call from our content video about this. When we're looking at we're looking for evidence that these bacterial cultures produce magnetite as a result of their performance of cellular respiration. So when we look at our answer choices, choices A and B. Are sort of opposing here. Choice A says bacteria treated with drugs that inhibit enzymes of the electron transport chain failed to produce magnetite. Choice B says bacteria treated with drugs that inhibit enzymes, the electron transport chain produced more magnetite. Then we have a choice C. Which is bacteria that produce magnetite, use iron and photosynthesis. And then Choice D. Says all of the above. Well, Choice C. We can rule out right away. We're talking about cellular respiration, not photosynthesis. And certainly if we're talking about bacterial cultures from the deep surfaces, we're not going to be talking about photosynthesis because there's no light source there. Um So Choice C. Is not going to be our answer as a result. Choice D. Is also not going to be our answer because that's all of the above. So again, we're looking for evidence that they produce magnetite and perform cellular respiration well, if we treat it with drugs that inhibit enzymes of the electron transport chain well, without functional electron transport chain, they cannot perform cellular respiration. So we'd expect to see if they are doing both. Those things that inhibiting those enzymes which would equal ah stopping cellular respiration. So inhibiting enzymes of the electron transport chain would equal stopping respiration. If they do both things, we should see no magnetite being produced. So that is choice A bacteria treated with drugs that inhibit enzymes. The electron transport chain failed to produce magnetite. That would be evidence that would support the idea that these cultures produce magnetite and perform cellular respiration. Choice B has it backwards. Um saying that inhibiting the electron transport chain would produce more magnetite. So that would not be evidence in support. That would be evidence against uh this hypothesis here. So again, the hypothesis that they produce magnetite informs cellular respiration is supported by the evidence and its choice A. When they're treated with drugs that inhibit enzymes that the electron transport chain, they failed to produce magnetite. See you in the next video.

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Key Concepts

Cellular Respiration

Electron Transport Chain (ETC)

Magnetite Production