DNA Evidence in Classification Flashcards

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What is DNA in living organisms?

DNA is a chemical found in cells. It carries genetic information for the organism.

Why is DNA useful as evidence for classifying organisms?

Because all living things have DNA. Its base sequence can be compared to show how similar they are.

How do scientists compare DNA from two different species?

They find the order of bases in the DNA from each species. They then compare the two base sequences.

What does it show if two species have very similar DNA sequences?

It shows they are closely related. They share a recent common ancestor.

What does it show if two species have very different DNA sequences?

It shows they are only distantly related. Their common ancestor lived a long time ago.

Why can DNA evidence be more reliable than appearance when classifying organisms?

Because appearance can be misleading. Different species can look similar, but their DNA can still be very different.

How has DNA evidence changed some existing classification groups?

DNA evidence has shown that some organisms in the same group are not close relatives. Scientists have moved these organisms into new or different groups.

What is meant by a common ancestor in DNA-based classification?

A common ancestor is an older species that later species evolved from. Shared DNA between species is evidence for this.

What are the basic steps in using DNA to help classify an unknown organism?

Scientists take cells from the organism and extract the DNA. They read its base sequence and compare it with DNA from known species to decide how to classify it.