In which case would facilitated diffusion be needed? A. With large polar molecules moving against the concentration gradient.
B. With large non polar molecules moving down the concentration gradient.
C. With very small polar particles moving against the concentration gradient.
D. With very small non polar particles moving down the concentration gradient.

The voltage-gated potassium channels associated with an action potential provide an example of what type of membrane transport?

A. Simple diffusion.

B. Facilitated diffusion.

C. Coupled transport.

D. Active transport.

You are studying the entry of a small molecule into red blood cells. You determine the rate of movement across the membrane under a variety of conditions and make the following observations:

i. The molecules can move across the membrane in either direction.

ii. The molecules always move down their concentration gradient.

iii. No energy source is required for the molecules to move across the membrane.

iv. As the difference in concentration across the membrane increases, the rate of transport reaches a maximum.

The mechanism used to get this molecule across the membrane is most likely:

A. simple diffusion.

B. facilitated diffusion.

C. active transport.

D. There is not enough information to determine a mechanism.

Carrier proteins - exist in two conformations, altered by high affinity binding of the transported molecule. Moves material in either direction, down concentration gradient (facilitated diffusion). EXAMPLE: GluT1 erythrocyte glucose transporter.

Channel proteins - primarily for ion transport. Form an aqueous pore through the lipid bilayer. May be gated. Moves material in either direction, down concentration gradient (facilitated diffusion). EXAMPLES: Voltage-gated sodium channel, erytrhocyte bicarbonate exchange protein.

This might be helpful... because I don't know anything about facilitated diffusion.

d concave shape of wave rock

explanation:

the concave shape of wave rock is a very good evidence that supports the evolution of earth due to chemical weathering. if we talk about structure of   wave rock, studies have estimated that it is around 2.7 billion years old. it also serves as the foundation of evidence that it was the place where australian continent began to form.

how the structure of wave rock was created?

studies suggest that structure of wave rock was created when the surrounded area was started to weather due to which deposition of material started on the part of land which now contains wave rock.

the structure of wave rock is considered to be one of the best-known landforms in australia. at the height of around 15 cm, there can be found flared slopes which formulate the margins of hyden rock. it is now assumed by geologists that wave rock was created by subsurface water-induced weathering and not by glaciers, waves or wind.

due to deposition of material over the period of long time, the wave rock became tougher and tougher due to weathering from surrounding terrain. this makes it a physical evidence that supports   the evolution of earth due to chemical weathering.

hope it !

b - the respond is innate and varies over time.

good luck!