PSSA PSSA Science 2 — Questions and Answers
Question 1: Which of the following best describes a food chain?
- A cycle showing how water moves through an ecosystem
- A sequence showing how energy passes from one organism to another (Correct answer)
- A diagram of all organisms living in a habitat
- A chart showing population sizes over time
Correct answer: A sequence showing how energy passes from one organism to another
A food chain shows the sequence in which energy is transferred from one organism to another through feeding relationships.
Question 2: What is the difference between a mixture and a compound?
- A mixture has fixed ratios while a compound does not
- A compound is physically combined while a mixture is chemically bonded
- A mixture is physically combined and can be separated, while a compound is chemically bonded (Correct answer)
- There is no difference between mixtures and compounds
Correct answer: A mixture is physically combined and can be separated, while a compound is chemically bonded
A mixture is a physical combination of substances that can be separated, while a compound involves chemical bonding of elements in fixed ratios.
Question 3: Which layer of Earth's atmosphere contains the ozone layer?
- Troposphere
- Stratosphere (Correct answer)
- Mesosphere
- Thermosphere
Correct answer: Stratosphere
The ozone layer is located in the stratosphere, approximately 15 to 35 kilometers above Earth's surface.
Question 4: What process do plants use to make their own food?
- Respiration
- Fermentation
- Photosynthesis (Correct answer)
- Decomposition
Correct answer: Photosynthesis
Photosynthesis is the process by which plants convert light energy, water, and carbon dioxide into glucose and oxygen.
Question 5: Which of the following is NOT a renewable energy source?
- Solar energy
- Wind energy
- Natural gas (Correct answer)
- Hydropower
Correct answer: Natural gas
Natural gas is a fossil fuel, making it a nonrenewable energy source that cannot be replenished on a human timescale.
Question 6: What is Newton's Third Law of Motion?
- An object in motion stays in motion unless acted upon by an outside force
- Force equals mass times acceleration
- For every action there is an equal and opposite reaction (Correct answer)
- Objects with greater mass have greater inertia
Correct answer: For every action there is an equal and opposite reaction
Newton's Third Law states that for every action force, there is an equal and opposite reaction force.
PSSA PSSA Science 2
Which of the following best describes a food chain?