Frog legs and fish eggs: When scientists compare DNA, there are usually thousands upon thousands—or even millions—of nucleotide bases involved. A computer then scans the sequences and aligns them in a way that provides the best match. In some cases, the computer will add “blank” spaces to improve alignment. Such spaces represent nucleotides that were added or deleted as opposed to changed in one or more lineages. In this level, you’ll get the hang of analyzing DNA by looking at a tiny 4-base snippet. A dash (–) represents either a blank space added to improve alignment or a position that is not important for the analysis you’ve been asked to do. To make things easier, the information from the species compare tab is shown below. However, don’t forget to read the species tabs—they might help you.

Question

Frog legs and fish eggs: When scientists compare DNA, there are usually thousands upon thousands—or even millions—of nucleotide bases involved. A computer then scans the sequences and aligns them in a way that provides the best match. In some cases, the computer will add “blank” spaces to improve alignment. Such spaces represent nucleotides that were added or deleted as opposed to changed in one or more lineages. In this level, you’ll get the hang of analyzing DNA by looking at a tiny 4-base snippet. A dash (–) represents either a blank space added to improve alignment or a position that is not important for the analysis you’ve been asked to do. To make things easier, the information from the species compare tab is shown below. However, don’t forget to read the species tabs—they might help you.

On your phylogenetic tree, which two species are grouped together?
1 point
Cichlid and frog
Frog and coelacanth
Cichlid and coelacanth

Answer 1

Cichlid and frog

Answer 2

One fish, two fish, red fish, lungfish: For a long time, scientists thought that coelacanths were the closest living relatives to amphibians. Coelacanths have big fleshy fins and hinged jaws, two traits they share with fossils of ancestral amphibians. When they went to analyze the DNA, however, they got a surprise. Take a look at the data yourself and see what you come up with.

Scientists previously thought that frogs and coelacanth are most closely related due to physical characteristics. With DNA evidence, we now know that frogs are more closely related to which of the following?
1 point
Great white shark
Cichlid
Lungfish

Answer 3

To determine which two species are grouped together on the phylogenetic tree, we need to analyze the 4-base snippet and compare the DNA sequences. However, the given information does not provide the necessary details or the phylogenetic tree. It is not possible to determine the two species that are grouped together without specific data.