Unit 2 review: Chemistry of life (Biochem)

What two elements make up water?

• Helium and oxygen

• Hydrogen and oxygen

• Helium and carbon

• Oxygen and carbon

What word describes when water is attracted to other substances?

• Cohesion

• Adhesion

• Capillary action

• Surface tension

A molecule with electrically charged areas is called a _______________.

• Magnet

• Polar molecule

• Solution

• Electrical molecule

The substance in which a solute is dissolved

• Sands

• Solvent

• Alloy

• Negative particles

Water is a universal solvent because it...

• It can be found anywhere

• It freezes when it gets cold

• Floats when frozen

• Dissolves most substances

Water droplets take a spherical shape (as pictured) because of ____________

• Adhesion

• Cohesion

• Capillary action

• Solubility

As you add drops of water to the surface of a coin, each drop sticks to the other water droplet because of ________________, and sticks to the penny because of ______________.

• Adhesion, cohesion

• Cohesion, adhesion

• Capillary action, specific heat

• Specific heat, capillary action

Which statement best describes an effect of the low density of frozen water in a lake?

• When water freezes, it contracts, decreasing the water level in a lake.

• Water in a lake freezes from the bottom up, killing most aquatic organisms. 

• When water in a lake freezes, it floats, providing insulation for organisms below.

•  Water removes thermal energy from the land around a lake, causing the lake to freeze.

Tags

NGSS.MS-LS2-3

NGSS.MS-PS1-4

 Small insects can walk across the surface of calm water. Their feet push the surface of the water down slightly, somewhat like a person walking across a trampoline, but they do not break the surface. What is the best explanation for why this happens?

• The insects are light enough so that they do not break the hydrogen bonds holding the water molecules together

• The insects actually use their wings to hover slightly above the water's surface and they only skim it with their feet

• The insects' feet are non-polar, so they are repelled by the polar water molecules and are pushed away from the water's surface

• The insects are small enough to see the individual water molecules, so they are able to step carefully from one molecule to the next

Tags

NGSS.MS-PS2-5

The element _______is found in all of the organic compounds.

• Iron

• Nitrogen

• Carbon

• Oxygen

Tags

NGSS.HS-LS1-6