As the fire truck approached Mary, the pitch of the siren got higher. Once the fire truck passed and moved away, the siren's pitch got lower. This change in pitch is because of a change in the sound wave's

• concussion. 
• amplitude. 
• reflection.
• frequency. 

If the distance represented by the letter A were increased, how would it change the way the sound was heard?

• The sound would be higher. 
• The sound would be lower. 
• The sound would be softer. 
• The sound would be louder. 

When comparing the two waves that are shown, how would Wave A (green wave) differ than Wave B (black wave)?

• Wave A and B have the same amplitude, but wave B (black) has a lower pitch.
• Wave A and B have the same amplitude, but Wave A has a lower pitch. 
• Wave A and B have the same pitch, but Wave A is a softer sound. 
• Wave A and B have the same pitch, but Wave B is a softer sound. 

When a sound is louder what measurement gets bigger?

• Frequency 
• Amplitude 
• Wavelength 
• Crest

If distance C on the diagram increased, what would happen to the pitch? 

• The pitch would be louder. 
• The pitch would be softer. 
• The pitch would be higher. 
• The pitch would be lower. 

What are the main functions of the excretory system?

• deliver oxygen to the body

• remove water and waste from the body

• deliver nutrients to the body

• remove disease from the body

Which organ(s) remove waste gases?

• Bladder and kidneys

• Lungs

• Large intestine

The job of your kidneys is to

• Create feces

• Take carbon dioxide out of your blood

• Put oxygen into your blood

• filter the blood, sending waste to bladder

Main organs and their functions?

• The ureter,the kidneys,the bladder,the prostrate and the Uretha
• The kidneys and the urethera
• The ureter,the kidneys,the bladder and the prostrate
• Living things

Which organs help to remove waste from the body?

• Lungs, stomach, bladder, and kidneys

• Lungs, heart, bones, and bladder

• Lungs, large intestine, bladder and kidneys

• Lungs, esophagus, bladder and kidneys