<span>The ischemic penumbra can maintain metabolic demand with marginal blood flow from collateral circulation for a maximum of 50% before increasing in size. A penumbra is the area where the flow of blood at about 25 - 50% can maintain normal metabolic demands for 6 - 8 hours only. When it continues to increase, the human cells will die and other neurological activity will be suspended causing the person to die slowly.</span>
The answer is A: Mass extinction.
"Abrupt disappearance of many land and marine species" = extinction of many species.
Use renewable energy sources, like hydro or solar power. Or use more recyclable items.
Diptheria is a serious infection mainly caused by a specific type of bacteria. This diseases is associated to different symptoms.
<h3>What is the causing agent?</h3>
This disease is caused by Corynebacterium diphtheriae, which is a specific type of bacteria. Moreover, this bacteria produces toxins and this is the cause of the symptoms.
<h3>How is it transmitted?</h3>
This can be transmitted through saliva droplets from one infected person to a healthy person. Usually, symptoms appear within 5 days after getting the bacteria.
<h3>What are the symptoms?</h3>
Although this disease has many symptoms, the most important ones are sore throat and gray lining on the throat and nearby areas.
<h3>How to prevent it or treat it?</h3>
Antibiotics and antitoxins are often used, but the best is to prevent it through vaccination.
Learn more about diphtheria in: brainly.com/question/13061650
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Its the Eccentricity of the earth. (shape of Earth's Orbit around the sun, whether it is more circular or ovular.)