Plant Structure
The mitochondria were known in the nineteenth century to be osmotically active on the basis of evidence that

mitochondria were derived from a symbiotic bacterium
the mitochondrial matrix is hypertonic to the cellular cytoplasm
mitochondria are surrounded by a semi permeable membrane
the mitochondrial matrix is hypotonic to the cellular cytoplasm

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Plant Structure
Which of the following experimental results does not support Mitchell's chemiosmosis theory?

Addition of dinitrophenol to isolated mitochondria was shown to inhibit electron transport, but had no effect on ATP synthesis
An artificial proton gradient across the inner mitochondrial membrane drives ATP synthesis in the absence of electron transport
Electron transport in isolated mitochondria was shown to result in acidification of the medium
Addition of dinitrophenol to isolated mitochondria during electron transport was shown to inhibit acidification of the medium

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Plant Structure
Which of the following observations is not used as evidence to support the concept of endosymbiotic origin of chloroplasts and mitochondria?

Both have their own ribosomes
Both have their own DNA
Both strongly resemble prokaryotes, especially in size
Both can live and function independently of the cell

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Plant Structure
Why do some redox reactions in cells result in the transfer of electrons from a reductant with a higher standard redox potential to an oxidant with a lower standard redox potential?

Electrons always go from reductants with high redox potentials to oxidants with low redox potentials
None of these
The rules governing oxidation and reduction apply only in vitro, and not in vivo
Redox potentials are defined under standard conditions, and cellular conditions are typically not standard conditions

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