Answer:
Forest floor
Explanation:
Tropical rainforest is characterized by high rainfall that allows a diverse growth of plant species. The different species of plants and animals species that make up a rainforest are found in different layers. There are four layers or sections in the rainforest from top to bottom viz: emergent layer, canopy, understory and forest floor.
Since the layers are classified from top to bottom, each layer receives different amount of rainfall and sunlight. According to the question, the FOREST FLOOR receives the least amount of sunlight making it the darkest section of the rainforest. Due to the inhibited penetration of sunlight into this layer, it usually does not support any plant growth.
Mercury, due to it's low gravity it would not be able to hold a very strong atmosphere.
Answer:
The voltage-gated potassium channels associated with an action potential provide an example of what type of membrane transport?
A. Simple diffusion.
B.<u> Facilitated diffusion.
</u>
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.
<u>B. facilitated diffusion.
</u>
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 lowering the activation energy of a reaction.
