The heartbeat has two specialised areas of muscle (the sa node and the av node) that control and synchronise the heartbeat. The rhythm of relaxation and concentration of the pacemaker sets the rythym of the heartbeat.
Answer:
D. toxins
Explanation:
<u>Toxins are not microorganisms</u>, in fact they are non-living substances/chemicals which can cause infection in our body. Toxins may be produced by microorganisms but they are themselves not microorganisms. Some of the examples of toxins produced by microorganisms are botulinum toxin A, tetanus toxin A, muscarine etc.
Other options can refer to potentially infectious type of microorganisms. Option A. talks about microbes, among microbes some are pathogenic. Option B. talks about pathogenic, as the name indicates will be infectious for sure.
Option C. talks about nonpathogenic, it may be non pathogenic at a time but later on it can be pathogenic. For example: some vaccines use inactivated microbes which are non pathogenic for generating antibodies in the body but later on in the human body when they get optimum conditions for growth they can turn pathogenic and start infecting our body.
atoms rearrange to form new substances. So basically when two substances are chemically bined together there is no going back.
Answer:
An inference is different from a prediction because a prediction is usually an educated guess (which is usually not correct) while an inference is a guess based on evidence that you have studied or read somewhere
Explanation:
A <u>tropical rainforest</u> is an example of an ecosystem with high primary productivity while a <u>desert</u> is an example of an ecosystem with low primary productivity.
