Self-study
Sponges attach to the ocean floor, continually filtering seawater for food and ejecting water they have just filtered to avoid reingesting it. ███████ ███ ███████████ ███████ ███ █████ ████████ █████ ███████ ██████████ ████ ███████████ █████ ████████ ███ ████ ███ ███████ ██ ████████████ █████ ███████ ███████ ██ █████ ██████ ████████ █████ ███████ ██████ ████ ██ ██████ █████████ █████ ██████ ████████ █████ ████████ █████ ████ ██ █████ █████████ ██ ██████ ████ ██████████ ██████ ███ ████ ████████ ███████
Summary
Sea sponges live on the ocean floor and feed by filtering water. Two sponge types (tubular sponges and vase-shaped sponges) can filter feed without help from the current, so they do well in quiet waters. They also can’t live in stronger currents, because they would be dislodged from the ocean floor. Finally, both tubular and vase-shaped sponges were widespread in the late Jurassic period.
Strongly Supported Conclusions
These facts strongly support the conclusion that the late Jurassic period had many areas of ocean floor with slow currents, thus allowing tubular and vase-shaped sponges to be widespread. They also support the conclusion that areas with slow currents can still have enough fresh water moving through for sponges to find food.
19.
The statements above, if true, ████ ████████ ███████ █████ ███ ██ ███ █████████ ███████
a
Few tubular or ███████████ ███████ █████ ██████ ███ ████ ████████ ███████
Like (B), this is not supported. The only period covered by the stimulus is the late Jurassic: we don’t know what conditions were like for sponges, or how many sponges were around, either before or after.
b
Tubular and vase-shaped ███████ ████ ████ ██████ ██████ ███ ████ ████████ ██████ ████ ██ ██████████ ██████████ █████
Like (A), this is not supported. Because the facts only apply to the late Jurassic period, we can’t draw any conclusions about other periods, either before or after.
c
During the late ████████ ██████ █████ ████ ████ █████ ██ ███ █████ █████ █████ ████████ ████ █████
This is strongly supported. The facts tell us that tubular and vase-shaped sponges can only live on the ocean floor where the current is weak. So, for them to be widespread during the late Jurassic period, there had to be widespread areas of the ocean floor with weak currents.
d
All sponges that ███ ███████ ███████ ███ ███████████ ███████ █████ ██ ███ █████ █████ █████ █████ ███ █████████ ██████ █████████
This is not supported. The author only discusses tubular and vase-shaped sponges; we learn nothing about other kinds of sponges. We don’t even know if there are other sponges, let alone what environmental conditions they prefer.
e
No types of ██████ ████ ██ █████ █████████ █████ ███████ ██ ███ ████████ ██ █████ █████ ████ ██ ███ █████ ███ ████ ████████ ██ █████ ████████
This is not supported. The stimulus doesn’t directly discuss sponge colonies, and we also cannot infer this from what we do know. We just don’t have enough detail about sponges’ filter feeding to know whether a sponge in a colony could still access enough food to flourish.