ACT Science Practice Test 63

PASSAGE V

Sea anemones look like plants, but they actually are predatory animals. They are invertebrates, which means that they do not have a skeleton. To protect themselves, they will attach to firm objects on the sea floor, such as rock or coral.

Sea anemones can alter their body shape according to changes in their environment. For example, when ocean currents are strong, the sea anemone will reduce its internal volume in order to decrease the surface area that is exposed to the current. Sea anemones are dependent on water flow for food and nutrients and also for assistance in eliminating waste.

Most anemones share a symbiotic relationship with marine algae called zooxanthellae. These are photosynthetic organisms whose waste products are a food source for the sea anemone. The sea anemone also enjoys a mutualistic relationship with the clown fish. This fish is immune to the stinging tentacles of the sea anemone, and it helps the anemone by actually cleaning the tentacles. The cleaning process yields food for the clown fish, while it remains protected from potential predators by the sea anemone's stinging tentacles.

Figure 1 shows a cross-section of portions of the internal anatomy of a sea anemone.

Figure 1

PASSAGE VI

Compost is the name given to a mixture of decaying leaves and other organic material. This mixture is often used as fertilizer. Several students designed experiments to test various types of soil, and various combinations of soil and compost on plant growth.

Experiment 1

The students dug a soil sample from an empty field next to the school. They put soil into 4 different clay pots, and mixed in various amounts of compost so that the volume of soil mixture was the same in each pot. They then planted the same number of radish seeds (4) in each pot. The soil/compost mixtures for each pot are shown in Table 1.

The clay pots were placed next to each other on a windowsill and watered at the same time each day. The students took care to ensure that the pots each received the same amount of sunlight and water each day. After 2 weeks, the students began recording the growth of the radish plants. They continued recording this data for two more weeks. The results are shown in Table 2.

Experiment 2

The students repeated Experiment 1, with the following changes; each pot contained a different soil type, and no compost was used. This experiment was begun at the same time as Experiment 1. The results of Experiment 2 are shown in Table 3.