ACT Success - Science - Practice #8

There are several passages in this test. Each passage is followed by several questions. After reading a passage, choose the best answer to each question. You may refer to the passages as often as necessary. You are NOT permitted to use a calculator on this test.

In an ecological study, scientists monitored the population dynamics between a predator species and its prey over a four-year period. The graph displays population sizes for the prey (in thousands) and predator (in thousands) populations as a function of time, with each species’ population represented by a separate line. The prey population (indicated by a dotted line) fluctuates significantly, showing large peaks followed by rapid declines. The predator population (indicated by an 'x' pattern) appears to follow the prey population, with increases and decreases in predator numbers occurring slightly after changes in the prey population. This pattern suggests a cyclical relationship between the two species, with the predator population changes lagging behind prey population shifts, likely due to the predator's dependence on the prey for food. Understanding these interactions can provide insight into how predator-prey relationships contribute to population stability in ecosystems.

Which of the following best explains why the predator population peaks shortly after the prey population peaks?

Based on the cyclical nature of the data, which of the following predictions about the predator-prey populations in Year 5 is most likely correct?

If a sudden disease caused a 50% decrease in the prey population during Year 2, which of the following changes would most likely occur in the predator population?

This study examines temperature and pressure variations across different atmospheric layers. The graph illustrates how temperature (solid line) and pressure (dashed line) change with altitude, represented by different atmospheric layers, including the troposphere, stratosphere, mesosphere, and thermosphere. Pressure (measured in psi) decreases consistently with altitude, while temperature shows complex patterns, rising and falling depending on the layer. For example, temperature decreases with altitude in the troposphere but rises again in the stratosphere, then drops in the mesosphere before increasing sharply in the thermosphere. These fluctuations are attributed to differences in atmospheric composition, solar radiation absorption, and density in each layer. Understanding these variations is essential for studying weather patterns, climate, and aircraft and spacecraft design.

Based on the data, which atmospheric layer is likely characterized by the greatest solar radiation absorption, given the sharp increase in temperature?

If a spacecraft were to re-enter Earth's atmosphere, in which atmospheric layer would it first encounter significantly increased pressure levels?

Which of the following statements is most consistent with the temperature trend observed in the stratosphere?

The RLC circuit experiment investigates the behavior of an electrical circuit containing a resistor (R), inductor (L), and capacitor (C) connected to an alternating power supply. The circuit allows current to flow either clockwise (positive current) or counterclockwise (negative current), depending on the phase of the alternating current. Figure 2 shows the changes in current (I, in amperes) and power supply voltage (VS, in volts) over a 20-millisecond interval. Figure 3 displays the voltage across each circuit component (resistor, inductor, and capacitor) during the same interval. The voltage and current oscillate due to the alternating current, with the voltages across the components peaking at different times. This delay is due to the circuit's inductive and capacitive reactance, which causes phase shifts in the voltage relative to the current. Understanding the behavior of RLC circuits is critical for designing systems that rely on alternating current, such as radio transmitters and signal filters.

In an RLC circuit, the voltage across which component is most likely to lag the power supply voltage due to inductive reactance?

According to the data in Figure 2, at approximately what time does the current in the circuit reach its maximum positive value?

If the frequency of the power supply were doubled, how would this most likely affect the oscillation period of the current and voltage in the circuit?

A chemist is studying how the concentration of a particular enzyme affects the rate of a chemical reaction. She finds that as the enzyme concentration increases from 0.1 to 1.0 mg/mL, the reaction rate also increases. However, when the enzyme concentration exceeds 1.0 mg/mL, the reaction rate begins to level off and does not increase significantly even at 2.0 mg/mL.

Which of the following best explains why the reaction rate levels off at higher enzyme concentrations?

Biologists are studying the effect of light intensity on photosynthesis in two plant species, Species X and Species Y. They find that Species X reaches its maximum photosynthetic rate at a light intensity of 500 lux, while Species Y continues to increase its rate of photosynthesis up to 1000 lux.

If both species were grown under a light intensity of 750 lux, what is the most likely outcome for the photosynthetic rates of Species X and Species Y?

A physicist is analyzing the rate at which heat is transferred through different metals. He discovers that metal X conducts heat twice as fast as metal Y, and metal Y conducts heat three times faster than metal Z. If the rate of heat transfer in metal Z is 5 J/s (joules per second), what is the rate of heat transfer in metal X?

What is the rate of heat transfer in metal X?