Q: During the winter, production of what amine involved in the sleep-wake cycle may be affected by less sunlight hours? Read this paragraph and choose the correct option from the provided answers: What does sunshine have to do with sleep (other than the sun shining in your eyes and waking you up)? For many people, sleeping problems have to do with an amine that the brain makes called melatonin. This compound affects the sleep-wake cycle and is affected by sunlight. During the winter, the daily cycle of melatonin production may be affected by less sunlight hours. If this cycle is changed, the person may have trouble sleeping. Melatonin supplements are available in pharmacies and health food stores and may be of help for those with sleeping problems. Choices: - serotonin - dopamine - folate - melatonin A:
melatonin

Q: Three-prong plugs, circuit breakers, and gfci outlets are safety features that recognize the danger of what? Read this paragraph and choose the correct option from the provided answers: Because electricity can be so dangerous, safety features are built into modern electric circuits and devices. They include three-prong plugs, circuit breakers, and GFCI outlets. You can read about these three safety features in the Figure below . You can learn more about electric safety features in the home by watching the video at this URL: http://www. dailymotion. com/video/x6fg5i_basics-of-your-home-s-electrical-sy_school . Choices: - heat - magnetism - gravity - electricity A:
electricity

Q: Q: Insects have a highly specialized type of respiratory system called what? Read this paragraph and choose the correct option from the provided answers: Tracheal Systems Insect respiration is independent of its circulatory system; therefore, the blood does not play a direct role in oxygen transport. Insects have a highly specialized type of respiratory system called the tracheal system, which consists of a network of small tubes that carries oxygen to the entire body. The tracheal system is the most direct and efficient respiratory system in active animals. The tubes in the tracheal system are made of a polymeric material called chitin. Insect bodies have openings, called spiracles, along the thorax and abdomen. These openings connect to the tubular network, allowing oxygen to pass into the body (Figure 39.6) and regulating the diffusion of CO2 and water vapor. Air enters and leaves the tracheal system through the spiracles. Some insects can ventilate the tracheal system with body movements. Choices: - nasal system - gland system - grunion system - tracheal system A:
A: tracheal system

Question: Q: The characteristic sound of a motorcycle buzzing by is an example of which effect? Read this paragraph and choose the correct option from the provided answers: 17.4 Doppler Effect and Sonic Booms The characteristic sound of a motorcycle buzzing by is an example of the Doppler effect. The high-pitch scream shifts dramatically to a lower-pitch roar as the motorcycle passes by a stationary observer. The closer the motorcycle brushes by, the more abrupt the shift. The faster the motorcycle moves, the greater the shift. We also hear this characteristic shift in frequency for passing race cars, airplanes, and trains. It is so familiar that it is used to imply motion and children often mimic it in play. The Doppler effect is an alteration in the observed frequency of a sound due to motion of either the source or the observer. Although less familiar, this effect is easily noticed for a stationary source and moving observer. For example, if you ride a train past a stationary warning bell, you will hear the bell's frequency shift from high to low as you pass by. The actual change in frequency due to relative motion of source and observer is called a Doppler shift. The Doppler effect and Doppler shift are named for the Austrian physicist and mathematician Christian Johann Doppler (18031853), who did experiments with both moving sources and moving observers. Doppler, for example, had musicians play on a moving open train car and also play standing next to the train tracks as a train passed by. Their music was observed both on and off the train, and changes in frequency were measured. What causes the Doppler shift? Figure 17.14, Figure 17.15, and Figure 17.16 compare sound waves emitted by stationary and moving sources in a stationary air mass. Each disturbance spreads out spherically from the point where the sound was emitted. If the source is stationary, then all of the spheres representing the air compressions in the sound wave centered on the same. Choices: - warp effect - coreolis effect - polar effect - doppler effect A:
Answer: doppler effect

*Question*
Q: What is a group of connected cells that have a similar function within an organism called? Read this paragraph and choose the correct option from the provided answers: A tissue is a group of connected cells that have a similar function within an organism. More complex organisms such as jellyfish, coral, and sea anemones have a tissue level of organization. For example, jellyfish have tissues that have separate protective, digestive, and sensory functions. Choices: - organ - nucleus - colony - tissue A:
**Answer**
tissue

Q: Acid rain may be caused by what? Read this paragraph and choose the correct option from the provided answers: Air pollution may also cause acid rain. This is rain that is more acidic (has a lower pH) than normal rain. Acids form in the atmosphere when nitrogen and sulfur oxides mix with water in air. Nitrogen and sulfur oxides come mainly from motor vehicle exhaust and coal burning. Choices: - hurricanes - water pollution - volcanos - air pollution A:
air pollution