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Scrat [10]
3 years ago
9

What index provides evidence of when different types of life evolved on Earth?

Biology
1 answer:
aev [14]3 years ago
4 0

There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms.

There are problems with each of these methods. The fossil record is like a movie with most of the frames cut out. Because it is so incomplete, it can be difficult to establish exactly when particular evolutionary changes happened.

Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. Confounding factors rack up for species that are very distantly related, making the earlier dates more uncertain.

These difficulties mean that the dates in the timeline should be taken as approximate. As a general rule, they become more uncertain the further back along the geological timescale we look. Dates that are very uncertain are marked with a question mark.

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A scientist claimed that hemophilia is caused by a functional deficiency in Factor VIII. The evidence in the passage that would
LekaFEV [45]

Answer:

C-able to relieve haemophilia

Explanation:

Factor  V111 is a blood clotting factor;produced in the liver and body endothelial cells. It is usually  exist as inactive form  beacuse it is  binded to glycoprotein (glycogen +protein) called  Von Willebrand factor when released into the blood stream.

If absent in the gene of certain individuals due to mutations, it result in a sex-linked conndtion called haemophilia, where blood failed to clot  when blood vessels are damaged leading to profuse bleeding/ hemorrhage.

Ideally in a normal individuals  the inactive from of factor VIII are continuously circulated in inactive forms in the blood stream, until a damaged blood vessels occurs. At the injured site they  are converted to active from called  coagulating factor VIIIa,,by separation  from Willebrand factor, react with coagulating factor IX to initiate clotting. The factor VIII is a co- factor for  factor IX, and together with calcium ion,phospholipids converts t to factor IXa,

The latter converts prothrombin to thrombin. The thrombin convert fibrinogen to fibrin, which form a stable fibrin clot at the injured site to arrest bleeding.<u> </u><u>The cascade of events is lacking individual without factor VIII. Therefore  bleeding occurs. </u>

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Consequently, symptoms of hemophilia can be relieved  by a functional factor VIII, because it will  prevent the deficiency in factor VIII in the affected individuals by acting as co-factors for the conversion of factor IX to IXa, to initiate clotting.

3 0
2 years ago
Which of the following best explains why cells remove waste?
andriy [413]

Answer:

D

Explanation:

To maintain homeostasis. If they did not remove wastes, there would be a buildup of wastes inside the cell, which is not maintains homeostasis.

Hope this helped!

7 0
2 years ago
Please help me ! I have a testtt
gregori [183]

Answer:

The answer is C I Hope's this helps with Your test

5 0
3 years ago
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Humans have 23 pairs of chromosomes. in a karyotype, the two chromosomes of each pair are lined up together and sorted from 1 to
lapo4ka [179]
Umm give me a few min i give u the answer
6 0
3 years ago
Sex-linked genetically inherited traits —
topjm [15]

Answer:

it b

Explanation:

both

4 0
2 years ago
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