HiSET Science Practice Test #2 3 — Questions and Answers
Question 1: What is the difference between a hypothesis and a theory in science?
- A hypothesis is proven fact; a theory is an educated guess
- A hypothesis is a testable prediction; a theory is a well-supported explanation backed by extensive evidence (Correct answer)
- A theory is less reliable than a hypothesis
- There is no difference — both terms mean the same thing
Correct answer: A hypothesis is a testable prediction; a theory is a well-supported explanation backed by extensive evidence
A hypothesis is a testable, falsifiable prediction made before an experiment. A scientific theory is a well-substantiated explanation supported by repeated testing and a large body of evidence — not a guess.
Question 2: Which force keeps planets in orbit around the sun?
- Electromagnetic force
- Strong nuclear force
- Gravity (Correct answer)
- Friction
Correct answer: Gravity
Gravity is the attractive force between masses. The sun's gravitational pull on the planets provides the centripetal force that keeps them in orbit rather than flying off in a straight line.
Question 3: Which part of the human nervous system is responsible for voluntary muscle movements?
- Autonomic nervous system
- Somatic nervous system (Correct answer)
- Parasympathetic nervous system
- Sympathetic nervous system
Correct answer: Somatic nervous system
The somatic nervous system controls voluntary actions — movements you consciously initiate, such as picking up an object or walking. The autonomic nervous system controls involuntary functions like heartbeat and digestion.
Question 4: In a chemical reaction, what is a catalyst?
- A substance that is consumed by the reaction
- A substance that speeds up a reaction without being permanently changed (Correct answer)
- A product formed during the reaction
- A reactant that slows down the reaction
Correct answer: A substance that speeds up a reaction without being permanently changed
A catalyst increases the rate of a chemical reaction by lowering the activation energy needed. It participates in the reaction but is regenerated at the end, so it is not permanently consumed.
Question 5: What is the primary driver of plate tectonics?
- The moon's gravitational pull on Earth's crust
- Earth's magnetic field
- Convection currents in the mantle (Correct answer)
- The rotation of Earth on its axis
Correct answer: Convection currents in the mantle
Convection currents in Earth's semi-fluid mantle are driven by heat from the core. This movement drags the tectonic plates that sit on top of the mantle, causing them to move apart, collide, or slide past each other.
Question 6: In DNA, which base pairs with adenine (A)?
- Guanine (G)
- Cytosine (C)
- Thymine (T) (Correct answer)
- Uracil (U)
Correct answer: Thymine (T)
In DNA, adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C). These are called complementary base pairs. (In RNA, uracil replaces thymine.)
HiSET Science Practice Test #2 3
What is the difference between a hypothesis and a theory in science?