The main difference between active and passive transport is that active transport requires [blank_start]ATP[blank_end] and passive transport uses [blank_start]kinetic[blank_end] [blank_start]energy[blank_end].
Which of the following substances cross the plasma membrane by passive transport? Check all that apply.
Diffusion is a form of [blank_start]passive[blank_end] transport, requiring no [blank_start]ATP[blank_end]. It involves the movement of molecules from an area of [blank_start]high[blank_end] concentration, across a [blank_start]partially permeable[blank_end] membrane, to an area of [blank_start]low[blank_end] concentration. In other words, [blank_start]down[blank_end] the [blank_start]concentration gradient[blank_end]. The rate of diffusion depends on factors such as [blank_start]size[blank_end] of molecule, [blank_start]steepness[blank_end] of concentration gradient, [blank_start]temperature[blank_end], surface area, and diffusion [blank_start]distance[blank_end].
When transport requires no ATP, involves movement down a concentration gradient, and requires the aid of a transmembrane protein which changes conformation, this is a form of passive transport.
Osmosis is another word for diffusion.
Instead of talking about "water concentration", we normally refer to "[blank_start]water[blank_end] [blank_start]potential[blank_end]", which is the [blank_start]tendency[blank_end] of water molecules to [blank_start]diffuse[blank_end] from one [blank_start]region[blank_end] to another. Pure water has a water potential of (in digits) [blank_start]0[blank_end].
Water moves in and out of cells by [blank_start]osmosis[blank_end]. A plant cell with lots of water in it is [blank_start]turgid[blank_end], while [blank_start]cytolysis[blank_end] can be caused by too much water inside an animal cell. [blank_start]Plasmolysis[blank_end] occurs in plant cells when there is a [blank_start]low[blank_end] water potential in the cell and the cell membrane is [blank_start]drawn inwards[blank_end]. [blank_start]Crenation[blank_end] describes the shrinking of an animal cell with [blank_start]low[blank_end] internal water potential.
Which of the following statements are TRUE about active transport? Check all that apply.
Requires energy in the form of ATP.
Substance moves down concentration gradient.
Requires carrier proteins.
Heavily relied on my neurones to maintain resting cell potential.
Often used with inorganic ions.
Which of the following molecules are transport by bulk transport?
Exocytosis and endocytosis
Phagocytosis describes a process where a cell [blank_start]ingests[blank_end] a foreign particle, usually one that is quite [blank_start]large[blank_end]. First, the cell changes shape and [blank_start]engulfs[blank_end] the foreign particle. Then, parts of the cell surface membrane at the extremes [blank_start]fuse together[blank_end] and form a [blank_start]vesicle[blank_end] around the foreign particle. Cells capable of this process are [blank_start]phagocytic[blank_end]. This is [blank_start]an active[blank_end] process.
white blood cells
red blood cells
Why is ATP needed for active transport and bulk transport? Check all that apply.