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4 years ago

What were the two driving forces that drove the evolution in the variation of skin color

Biology

1 answer:

yarga [219]4 years ago

8 0

Answer:

The correct answer is: geography and UV radiation.

Explanation:

Skin variation occurred thanks to evolution, and was driven as a consequence of the geographical location of different populations of humans.

The humans that lived in hot and sunny places, closer to the equator, where much more exposed to the sun's ultraviolet radiation. In order to survive the amount of UV lights that they were exposed to, new humans in those regions were being born with a darker skin tone, which was rich in melanin (a brown pigment that protects us from the sun radiation).

Contrary to these humans that lived in the tropical areas, the humans that populated the areas that were closer to the poles, developed much lighter skin as a result of lower amounts of melanin in their skin. Since sun exposure in the poles is very limited, humans needed to receive as much as they could for the production of Vitamin D, and thus, their skins got lighter and less protected.

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Which of the following is a biotic factor that could reduce a population of frogs

Feliz [49]

Biotic mean alive, so we can cut off the first 2 easily. Aquatic birds eat frogs, so that one is safe for now. A decrease in something parasitic usually helps the population, so D is out too. The only one left is C.

4 0

3 years ago

What is a tumor? *

Helen [10]

Answer:

i think it is.. a mass of cancer cells

Explanation:

3 0

3 years ago

Cells from advanced malignant tumors often have very abnormal chromosomes as well as an abnormal number of chromosomes. What mig

patriot [66]

Answer:

Option- D: Is the best choice to choose from the given options.

Now, let us explain the term Cell cycle in a more comprehensive way.

As the cell cycle is controlled at three checkpoints.

The integrity of the DNA is assessed at the G₁ checkpoint.

Proper chromosome duplication is assessed at the G₂ checkpoint.
Attachment of each kinetochore to a spindle fiber is assessed at the M checkpoint.

Explanation:

The cell cycle is controlled by three internal checkpoints that evaluate the condition of the genetic information.

The G₁ Checkpoint:This stage determines whether all conditions are favorable for cell division to proceed. The cell can halt the cycle and attempt to remedy the problematic condition, or the cell can advance into G₀ (inactive) phase and await further signals when conditions improve.
The G₂ Checkpoint: The most important role of the G₂ checkpoint is to ensure that all of the chromosomes have been accurately replicated without mistakes or damage.
The M Checkpoint:It occurs near the end of the meta-phase stage of mitosis. it determines whether all the sister chromatids are correctly attached to the spindle micro-tubules

5 0

3 years ago

Explain how super-antigens, such as toxic shock syndrome toxin produced by staphylococcus aureus, often lead to the development

GaryK [48]

Toxic shock syndrome toxin is a super-antigen produced by Staphylococcus aureus bacteria .it causes toxic shock syndrome by stimulating the release of large amount of interleukin-1, interleukin-2 and tumor necrosis factor .

Interleukin-1:

It is a group of 11 cytokines that plays a central role in the regulation of immune and inflammatory responses to infections .

Interleukin-2:

It is a type of cytokine signaling molecule in the immune system .interleukin-2 is apart of the body's natural response to microbial infection and in discriminating self and non self foreign.

tumor necrosis factor :

Tumor necrosis factor is protein superfamily of type 2 transmembrane protein containing tnf homology domain and trimers .these proteins are expressed predominantly by immune cells and they regulate diverse cell functions ,including immune response and inflammation ,but also proliferation, differentiation and embryogenesis.

Staphylococcus aureus:

Staphylococcus aureus is a gram positive pathogen cable of producing a variety of bacterial exotoxin known as super antigens .

Toxic shock syndrome :

Toxic shock syndrome is an acute disease mediated by the production of super-antigenic toxin .it is rare , life threatening complication of certain type of bacterial infections. often it results from toxins produced by staphylococcus aureus bacteria but the condition may also be caused by toxins produced by group a streptococcus bacteria.

Toxic shock syndrome can affect anyone ,including men , older woman, children and postmenopausal women.risk factors of toxic shock syndrome includes skin wounds ,surgery ,and use of tampons and devices such as menstrual cups contraceptive devices ,etc.

Symptoms of toxic shock syndrome toxin:

A sudden high fever,low blood pressure ,vomiting or diarrhea ,rash resembling sunburn ,muscle aches ,redness of eyes ,mouth and throat ,headache and seizures.

Conclusion:

If you have these symptoms of toxic shock syndrome then immediately call your doctor or consult a doctor and take precautions.

Learn more about toxic shock syndrome toxin here:

brainly.com/question/3866751

#SPJ4

7 0

2 years ago

Please help, thank you!

koban [17]

Answer:

regulates which materials enter and leave the cell

4 0

3 years ago