ACT Science Practice Test 116

Directions: Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passages as often as necessary.

You are NOT permitted to use a calculator on this test.


Echinoderms are defined as any of a variety of invertebrate marine animals characterized by a hard, spiny covering or skin. They have attracted much attention due to their extensive fossil record, ecological importance, and bizarre body forms. Most echinoderms are extinct, but many living representatives still exist. All living echinoderms have an internal skeleton and a central cavity, but the outward appearance can vary significantly. For example, starfish and brittle stars have arms that extend from a central disk; sea lilies have a central stalk, or stem, and resemble flowers; sea cucumbers are wormlike and tend to burrow.

The ways in which echinoderms move and feed are as diverse as their body forms. Table 1 lists certain echinoderms and their methods of locomotion (movement) and feeding.

Table 2 includes examples of echinoderm habitats around the world.

1. The echinoderm shown below is most likely a:

F. sea lily.
G. starfish.
H. sea cucumber.
J. brittle star.

2. According to Table 1 and Table 2, crinoids can be found feeding on plankton:

A. near the shore.
B. in deep ocean trenches.
C. in offshore mud and ooze.
D. on the deep-sea floor.

3. Based on the data provided in the passage, sea cucumbers most likely burrow in order to:

F. locate food.
G. avoid worms.
H. move offshore.
J. shed their spines.

4. Suppose scientists discover a new echinoderm that uses its tube feet to move across the deep-sea floor as it hunts for prey. This newly discovered echinoderm can most likely be classified as a(n):

A. crinoid.
B. asteroid.
C. ophiunoid.
D. holothurian.

5. A student hypothesized that large populations of sea cucumbers could greatly alter the physical and chemical composition of the sea floor. Is this hypothesis supported by the data in the passage?

F. Yes; sea cucumbers often prey upon commercially important organisms, such as oysters.
G. Yes; sea cucumbers feed by swallowing sediment, extracting organic matter, and ejecting the remainder.
H. No; sea cucumbers cannot burrow into the sediment, so will not affect the composition of the sea floor.
J. No; sea cucumbers do not have a viable method of locomotion.