11. Evolutionarily
protochordates may be
intermediate animals between
invertebrates and vertebrates.
Imagine a scientist is testing
the hypothesis that
vertebrates evolved from
echinoderms. Having as
research object a newly found
protochordate species, what is
an example of a discovery that
would weaken the hypothesis?
What is an example of a
discovery that would
strengthen it?

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
Hypothesis to be : Vertebrates
evolved from . Testing
material: A found protochordate
species (.e., a vertebrate forerunner).

of weakening observation (
puts the new species
evolutionarily far echinoderms):
“The new is protostome”, as
to echinoderms, that
deuterostomes. This observation
the suspicion that
vertebrates is independent origin
from echinoderms.

of strengthening observation
( nears the new
species to echinoderms): “ new
species has radial
symmetry”, similar echinoderms. This
observation stronger the
hypothesis echinoderms and
vertebrates relatives.

(This item how science works,
with the placement
hypothesis and further
testing.)