10 Questions Every High School Student Should Know the Answers To
1. What percentage of the earth is covered by water?
Answer: About 71 percent of the earth's surface is covered by water.
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.
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.
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.
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.
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.
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.
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 over treated with antibiotics.
9. How old are the oldest fossils on earth?
Answer: About 3.8 billion years; they're bacteria-like organisms.
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.