Question

1. Garstang's hypothesis is based on the premise that:

1. jaws arose from branchial arches

2. spreading to new habitats required a free-swimming organism

3. sessile adults underwent secondary metamorphosis to become motile

2. Only living agnathan with a lateral line system:

1. Conodont
2. Lamprey
3. Hagfish
4. Calcichordate

Answer 1

Question

1. Garstang's hypothesis is based on the fact that chordates evolved from the larvae of another group of animal. The jaws that are present in chordates arise from branchial arches. Hence, option a is correct.

2. The only aganthan with a lateral line system is Lamprey. Hence, option b is correct.