Across
- 3. A large group of organisms ranging from meters-long seaweeds to single-celled microorganisms. Most algae are photosynthetic, meaning that they use light and carbon dioxide to make sugar and oxygen.
- 5. A physical condition in which part of the body becomes reddened, swollen, hot and/or painful
- 7. The body’s natural defense system. It is used to protect against infections or toxic substances, such as pollutants.
- 9. Radiation with waves shorter than violet light, but not as short or energetic as X-rays.
- 12. The envelope of gases that surrounds a planet.
- 13. Energy that moves from one place to another as electromagnetic waves or as moving particles. Radiation may be heat, light or electricity.
- 15. A scientist who studies the branch of biology that examines how organisms interact with each other and their environment.
Down
- 1. The natural community of plants, animals and microorganisms that evolved to live together in a particular place with a particular climate. Examples include tropical reefs, rainforests, alpine meadows and polar tundra.
- 2. Tiny floating animals (known as zooplankton) in the water that feed on single-celled plants and plantlike organisms (called phytoplankton) that also float in the water.
- 4. A colorless, odorless gas. Burning fossil fuels such as coal, oil or natural gas produces large amounts of carbon dioxide, which traps heat in Earth’s atmosphere. Plants, as well as plantlike phytoplankton (including algae), absorb carbon dioxide during photosynthesis.
- 6. A doctor who diagnoses, treats and studies allergies in people.
- 8. Any of various gases that trap heat in the atmosphere. Carbon dioxide is the leading greenhouse gas in Earth’s atmosphere.
- 10. A layer in Earth’s stratosphere at an altitude of about 10 km (6.2 miles) containing a high concentration of ozone, which absorbs most of the ultraviolet radiation reaching Earth from the sun.
- 11. A condition that causes difficulty in breathing, often triggered by an allergy.
- 14. A damaging immune response by the body to a substance like air pollution or pollen.