Answer:
A.
Explanation:
All other options are simply situational, while cold periods are usually seasonal.
I think the answer is {b.false}
Infectious diseases are diseases that spread from one person to other either directly or indirectly. I think this is the answer.
The correct answer is B
The genetic codes language in all living organisms is the same. This is to say that the molecules of life namely DNA and RNA share the same make up in all living things .
There are five types of nucleotides in nature which are the building blocks of RNA and DNA and these are the same in all living organisms . These nucleotides are Adenine, Thymine, Guanine, Cytosine and Uracil.
According to base pairing rules, in all DNA molecules Adenine will always pair with Thymine while Guanine will always pair with Cytosine.
This rule is the same with RNA except that here Thymine is replaced with Uracil. Otherwise the base pairing rule applies in all living organisms, that is to say it is universal.
Answer:
Receptors are highly specific and only have high affinity for those ligands for whom they are specific.
Explanation:
Receptors are proteins that receive a stimulus or bind a ligand and mediate effects via receptor effector system.
Receptors are macromolecules that are highly specific.
The affinity between the ligand and the receptors is determind by the disassociation constant Kd.
The receptors produce maximun effect when an appropriate specific stimulus is present.
Different recptors types are present for different ligands.
For example, muscrinic receptors are specific for acetycholine and adrenergic receptors are specific for adrenaline/nor adrenaline.
It is important to know the specificity so that the body remains in a state of balance.
They are semi-permeable because they can diffuse and pass through the plasma membrane easily.
