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

1 answer:

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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It is called the seed coat

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Reproductive isolation is the separation of species populations on the basis of behavior, geography or time. According to the given information statement ii, i.e., one population breeds in late spring and one in late summer and statement iv, i.e., singing by male of first population than other ones shows evidence that two populations are likely experiencing reproductive isolation and genetic exchange.

<h3>What is genetic exchange?</h3>

New genotype of species are formed through the process of genetic exchange.

Reproductive isolation for example, is in changes of bird song from different species of finch. Females of one species of finch are unable to recognize the bird song of males. This is a barrier that is pre-zygotic.

Another includes one population breeds in late spring and one in late summer and singing by male of first population than other.

Thus, the correct statements are ii and iv so the correct option will be D.

For more details regarding reproductive isolation, visit:

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n airports, the control tower functions in directing air traffic and keeping all flights running smoothly like a command center.

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1 . base of brain : A. pituitary

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Explanation:

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The thyroid gland is a butterfly-shaped gland and is located just inferior to the larynx in the neck. The right and left lateral lobes of this gland are present on either side of the trachea. The pancreas is usually connected to the duodenum of the small intestine by two ducts. This arrangement releases the pancreatic juice into the small intestine.

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