More Than Half a Century Ago, Two Cell Biologists Published

question 75

Multiple Choice

More than half a century ago, two cell biologists published details of their research involving isolated membrane vesicles from chloroplasts. Normally, the fluid inside these vesicles is near neutral. In an experiment, these membrane vesicles were soaked in an acidic solution (pH 4) until the inside of the vesicle also became pH 4. Based on the details provided in this scenario, by what mechanism could hydrogen ions have crossed the vesicle membrane, and what do you think happened at the molecular level?

• A)Facilitated diffusion; hydrogen ions moved into the vesicle through a channel.
• B)Osmosis; water moved from inside the vesicle to outside.
• C)Simple diffusion; hydrogen ions moved into the vesicle through a channel.
• D)Active transport; hydrogen ions moved out of the vesicle with the help of ATP.
• E)Pinocytosis; water moved from outside the vesicle to inside.

---

Definitions:

Toy Dog

A term used to describe small dog breeds that are often kept as companions or pets, characterized by their compact size and playful nature.

Stimulus Generalization

A process in learning where a response to a specific stimulus becomes associated with similar stimuli.

Generalization Gradient

The spread or diffusion of a response to stimuli that are similar but not identical to the conditioned stimulus.

Stimulus Discrimination

The ability to differentiate between similar stimuli when only one of them is consistently associated with a particular response.