Answer:
Argon
Explanation:
Argon is actually used to determine the age. It's called potassium-argon dating b/c when volcano erupts the rocks in it contain potassium. The potassium slowly decays and produces argon. Scientists measure how much argon is in a given volcanic rock and do math backwards to figure out how many potassium atoms were needed to produce the given amount of argon. We already know the rate at which potassium decays so then they put two and two together to find the age.
Here's a link with some cool info on it:
https://divediscover.whoi.edu/archives/hottopics/volcano.html
Based on the CDC guidelines a person with a CD4+ cell count between 200-400 is regarded as being in <u>the second stage</u> of the HIV infection.
Acquired Immunodeficiency Syndrome
Acquired immunodeficiency syndrome (AIDS) is a condition caused by HIV (human immunodeficiency virus). AIDS is a chronic disorder and can become life-threatening for the infected person. The HIV viruses reproduce inside the host and while doing so they destroy the CD4+ immune cells which reduce the person's ability to fight against other diseases.
CD4+ cell count and AIDS
According to the CDC (U.S. Centers for Disease Control and Prevention), HIV infection is categorized into different stages based on the number of CD4+ cells.
- Stage 1: - CD4+ cell count is more than 500 per microlitre. There are no symptoms or AIDS-related conditions.
- Stage 2: - CD4+ cell count is more than 500 per microlitre. There are no symptoms or AIDS-related conditions.
- Stage 3: - The CD4+ cell count falls below 200 and AIDS-related symptoms and conditions are present.
Learn more about HIV infection here:
brainly.com/question/13662165
#SPJ4
Answer:
Secretes a protective covering against UV damage
Explanation:
Keratinocytes is an important protective organelle that work with melanocytes to produce melanin in the skin to protect damages from the UV
Answer:
on-native species can become such a common part of an environment, culture, and even diet that little thought is given to their geographic origin. For example, soybeans, kiwi fruit, wheat, honey bees, and all livestock except the American bison and the turkey are non-native species to North America.
Explanation:
Answer:
Direct observation of evolutionary change: creation of drug-resistant bacteria.
Fossil record: discovery of transitional forms of animals, discovery of shells of extinct organisms
Homology: similarities in mammalian forelimbs, identical genetic code in fireflies and tobacco plants, vestigial pelvis in right whales
Biogeography: resemblance of endangered island species to neighboring mainland species,
