Which phenomenon shows that light travels in a straight line?

What causes a bulb to glow?

Which organ circulates blood in the human body?

Through which medium can sound travel?

What are the basic needs of living things?

Which gas do trees release?

Which gas do plants take in?

What is the boiling point of water?

What is needed for the growth of living things?

Which gas is present most in the air?

What is the path through which electricity flows called?

What is the melting point of ice?

Which part of the plant carries water upward?

Which material does not conduct electricity?

Where does digestion begin?

What type of star is the Sun?

Which is the largest planet in the solar system?

What is the main function of lungs?

What are the three states of water?

What is the process by which plants prepare their food?

Which organ helps us hear?

What is the natural satellite of Earth?

Bones are part of which system?

Why does the Moon shine?

How long does Earth take to revolve around the Sun?