Sunday, April 16, 2006

Test your science knowledge

Why is the sky blue? Facts you should know

Take their quiz and see how you do.

1. What percentage of the earth is covered by water?

ROBERT GAGOSIAN, WOODS HOLE OCEANOGRAPHIC INSTITUTE

2. What sorts of signals does the brain use to communicate sensations, thoughts and actions?

TORSTEN WEISEL, ROCKEFELLER INSTITUTE, NEW YORK

3. Did dinosaurs and humans ever exist at the same time?

ANDREW C. REVKIN, NEW YORK TIMES SCIENCE REPORTER

4. What is Darwin's theory of the origin of species?

JONATHAN WEINER, 1995 PULITZER PRIZE-WINNING AUTHOR

5. Why does a year consist of 365 days, and a day of 24 hours?

LESLIE SAGE, NATURE MAGAZINE

6. Why is the sky blue?

ROY GLAUBER, 2005 NOBEL PRIZE WINNER; HARVARD UNIVERSITY

7. What causes a rainbow?

KIM KASTENS, COLUMBIA UNIVERSITY

8. What is it that makes diseases caused by viruses and bacteria hard to treat?

HELLE GAWRYLEWSKI, JOHNSON & JOHNSON (AND THE AUTHOR'S MOTHER)

9. How old are the oldest fossils on earth?

PAUL NURSE, 2001 NOBEL PRIZE WINNER; ROCKEFELLER INSTITUTE

10. Why do we put salt on sidewalks when it snows?

ARTHUR KNUDSEN, BRIDGETON, N.J., SCHOOLS

Extra credit: What makes the seasons change?

If this quiz wasn't as easy as you thought it would be, you're not alone. According to a recent National Science Board survey, 90 percent of Americans are interested in science, but only 15 percent consider themselves well-informed. In high schools, only 60 percent of students complete a general biology class, while only 40 percent complete a general chemistry class and a scant 27 percent complete a physics class, according to the National Center for Education Statistics.

Even if you did learn basic science in school, these questions might be tough to answer, according to O. Roger Anderson, professor of science education at Teachers College at Columbia University.

"People are so deeply involved in their family lives and professions," Anderson said. "How are they supposed to remember this stuff?"

Answers:

1. About 71 percent of the earth's surface is covered by water.

2. The single cells in the brain communicate through electrical and chemical signals.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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, yellow, blue, etc.

8. 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.

9. About 3.8 billion years; they're bacteria-like organisms.

10. 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.

Extra credit: Seasons occur because the earth is tilted at an angle of 23.5 degrees. At certain times of year the top half of the earth leans to the sun and therefore gets more sun and has summer. When that same half of the earth leans away from the sun it gets less light and has winter.

via startribune.com