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1. 10 Science Questions Every High School Graduate
Should Know - Answers
By: Jason Lindsey
Cape Girardeau, MO - A team of leading scientists have come up with a 10 question science quiz you
should be able to pass with flying colors if you have a high school diploma.
With questions in hand science reporter Jason Lindsey put two Heartland schools to the test. In the end,
the students got most of the questions right. The one that stumped most, "Why do we put salt on
sidewalks when it snows?"
1. What percentage of the earth is covered by water?
Answer: About 71 percent of the earth's surface is covered by water.
--Submitted by Robert Gagosian, Woods Hole Oceanographic Institute
2. What sorts of signals does the brain use to communicate sensations, thoughts and actions?
Answer: The single cells in the brain communicate through electrical and chemical signals.
--Submitted by Torsten Weisel, Rockefeller Institute, New York
3. Did dinosaurs and humans ever exist at the same time?
Answer: No. Dinosaurs went extinct at the end of the Cretaceous period, 65 million years ago. Modern
humans did not appear until around 200,000 years ago.
--Submitted by Andrew C. Revkin, New York Times Science Reporter
4. What is Darwin's theory of the origin of species?
Answer: Darwin's theory of species origination says that natural selection chooses organisms that
possess variable and heritable traits and that are best suited for their environments.
--Submitted by Jonathan Weiner, 1995 Pulitzer Prize-Winning Author
5. Why does a year consist of 365 days and a day of 24 hours?
Answer: A year, 365 days, is the time it takes for the Earth to travel around the Sun. A day, 24 hours, is
the time it takes for the Earth to spin around once on its axis.
--Submitted by Leslie Sage, Nature Magazine
6. Why is the sky blue?
Answer: Solar radiation sunlight is scattered across the atmosphere by a process called diffused sky
radiation. The sky is blue because much more short-wave radiation--blue light--is scattered across the sky
than long-wave radiation--red light.
--Submitted by Roy Glauber, 2005 Nobel Prize Winner; Harvard University
7. What causes a rainbow?
Answer: Rainbows can be seen when there are water droplets in the air and the sun is shining. Sunlight,
which contains all colors, is refracted, or bent, off the droplets at different angles, splitting into its different
colors of red, orange, yellow, green, blue, indigo and violet.
--Submitted by Kim Kastens, Columbia University
8. What is it that makes diseases caused by viruses and bacteria hard to treat?
Answer: Influenza viruses and others continually change over time, usually by mutation. This change
enables the virus to evade the immune system of its host so that people are susceptible to influenza virus
infection throughout their lives. Bacteria mutate in the same way and can also become resistant if
overtreated with antibiotics.
--Submitted by Helle Gawrylewski, Johnson & Johnson

2. 9. How old are the oldest fossils on earth?
Answer: About 3.8 billion years; they're bacteria-like organisms.
--Submitted by Paul Nurse, 2001 Nobel Prize Winner; Rockefeller Institute
10. Why do we put salt on sidewalks when it snows?
Answer: Adding salt to snow or ice increases the number of molecules on the ground surface and makes
it harder for the water to freeze. Salt can lower freezing temperatures on sidewalks to 15 degrees from 32
degrees.