(Q).
Q: What element is an essential part of many molecules needed by living organisms? Read this paragraph and choose the correct option from the provided answers: Nitrogen is an essential part of many molecules needed by living organisms. Choices: - helium - silicon - hydrogen - nitrogen A:
(A).
nitrogen

(Q).
Q: What layer high in the atmosphere protects living things from most of the sun's harmful uv rays? Read this paragraph and choose the correct option from the provided answers: Earth's atmosphere is vital to life. The atmosphere provides the oxygen and carbon dioxide living things need for photosynthesis and respiration. Living things also need the ozone layer high in the atmosphere. Upper level ozone protects them from most of the Sun's harmful UV rays. Choices: - Mesosphere - troposphere - stratosphere - ozone layer A:
(A).
ozone layer

(Q).
Q: What are waves that pass a fixed point in a given amount of time called? Read this paragraph and choose the correct option from the provided answers: The number of waves that pass a fixed point in a given amount of time is wave frequency . Wave frequency can be measured by counting the number of crests (high points) of waves that pass the fixed point in 1 second or some other time period. The higher the number is, the greater the frequency of the waves. The SI unit for wave frequency is the hertz (Hz) , where 1 hertz equals 1 wave passing a fixed point in 1 second. The Figure below shows high-frequency and low-frequency transverse waves. You can simulate transverse waves with different frequencies at these URLs: http://phet. colorado. edu/en/simulation/wave-on-a-string and http://zonalandeducation. com/mstm/physics/waves/partsOfAWave/waveParts. htm. Choices: - tendency frequency - combination frequency - radio frequency - wave frequency A:
(A).
wave frequency