General science: the ideas behind the questions
Good science questions test understanding, not just vocabulary. Each question here includes an explanation of the idea behind the answer, so you can reason about similar problems you have not seen.
Biology in five facts
- Cells are the basic unit of life; the mitochondria produce most of a cell’s usable energy as ATP.
- DNA stores genetic information using four bases: adenine pairs with thymine, and cytosine pairs with guanine.
- Photosynthesis turns carbon dioxide and water into glucose and oxygen using light energy.
- Natural selection acts on variation within a population over many generations.
- The human body has about 37 trillion cells, according to widely cited estimates.
Chemistry essentials
Atoms are made of protons, neutrons and electrons. The periodic table currently lists 118 elements ordered by atomic number (the number of protons). Acids have a pH below 7, bases above 7, and pure water is neutral at about 7.
Physics you can use
- Light travels at about 299,792 kilometers per second in a vacuum.
- Newton’s second law: force equals mass times acceleration.
- Energy is conserved: it changes form but is not created or destroyed.
- Gravity on Earth’s surface accelerates objects at about 9.8 m/s².
Earth and space
The Sun is a star that holds more than 99% of the Solar System’s mass. Earth’s tilt of about 23.5 degrees causes the seasons, not its distance from the Sun. The atmosphere is roughly 78% nitrogen and 21% oxygen.
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Frequently asked questions
How many elements are on the periodic table?
There are 118 confirmed elements.
What causes the seasons?
The tilt of Earth’s axis, about 23.5 degrees, changes how directly sunlight hits each hemisphere through the year.
What is the powerhouse of the cell?
The mitochondrion, which makes most of the cell’s ATP through cellular respiration.
How can I get better at science quizzes?
Explain each answer in your own words and link it to a real-world example.
Curated Science Quizzes
General Science Trivia Master
Journey through physics, cell biology, chemistry, and atmospheric earth science questions.