Answer:
Starting molecules not completely and quickly convert to its possible product because an activation energy barrier exist that must be overcome for conversion to product.
Explanation:
The activation energy of a chemical reaction is closely related to its rate. This is because molecules can only complete the reaction once they have reached the top of the activation energy barrier. The higher the barrier is, the fewer molecules that will have enough energy to make it over at any given moment.
Many reactions have such high activation energies that they basically don't proceed at all without an input of energy. For instance, the combustion of a fuel like propane releases energy, but the rate of reaction is effectively zero at room temperature. Once a spark has provided enough energy to get some molecules over the activation energy barrier, those molecules complete the reaction, releasing energy. The released energy helps other fuel molecules get over the energy barrier as well, leading to a chain reaction.
CO2 is a relatively small non-polar molecule that can easily fit through the phospholipids in the plasma membrane without getting repelled by the hydrophobic core of the bilayer. Hence CO2 diffuses across the membrane without the aid of any intrinsic proteins (simple diffusion).
Amino acids however are large molecules that cannot fit through phospholipids in the bilayer. Hence, amino acids are most likely to diffuse across the cell plasma membrane with the help of channel and carrier proteins via facilitated diffusion.
You'll be able to make contrast and compare by reading both of them.
Answer:
Scientists throughly understand what dark matter is and what it does
New data could cause scientist to change their hypotheses about dark matter
Explanation:
Answer: <u>Option 4; Oxygen gains electrons and hydrogen to form water.
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Respiration is a process where glucose is used and energy is released stored in this molecule. Oxygen is used during respiration as well and it gains the electrons and hydrogen to form water. And, gain of electrons is an oxidation reaction. So answer is option 4.
Since, oxygen is consumed during respiration, option 1 is incorrect.
Loss of electrons is reduction, so option 2 is also incorrect.
Glucose is used in respiration, thus option 3 is incorrect.
