cell membrane review

Cell Membrane:

• The protective outer layer that controls what enters and leaves the cell.
  
• Stores information on DNA molecules / Directs and controls the activities of the cell.
  
• A folded membrane that moves materials around inside cells / Also acts as the site of manufacturing materials needed by the cell.
  
• The smallest organelle with a huge job / Makes proteins, which are the building blocks of the body.
  

What force between adjacent water molecules helps transpiration?

• Cohesion
• Adhesion

Capillary action is the result of adhesion. Which aspect of water is responsible for this?

• Nonpolar covalent bonds enable water to dissolve other substances.
• Polar covalent bonds join molecules of water to other substances.
• Hydrogen bonds form between water and another substance.
• Ionic bonds enable electrons to flow through water and into another substance.

Which of the following properties of water enables molecules to cling together as they move from the roots to the leaves of plants?

• Water expands as it freezes.
• Water is an excellent solvent.
• Water exhibits cohesive behavior.
• Water moderates temperature.

Large bodies of water do not quickly fluctuate, or change, in temperature. Why?

• Water is a solvent.
• Water has a high heat capacity.
• Water acts as a buffer.
• Water is non-polar.

Some insects can stand on the surface of calm water. Their feet push the surface of the water down slightly, but they do not break the surface. Why?

• The insects are light enough so 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 insect’s 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
  

Why does water move from the roots to the leaves of plants?

• Water is pushed by solutes.
• Capillary action pulls the water molecules like a chain.
• Water is pulled by gravity.
• Water’s cohesion causes it to “pull” towards the leaves.

The attraction that causes water and other liquids to form drops on thin films is called ________________. This is also water’s ability to be attraction to other water molecules.

• adhesion
• capillary action
• cohesion
• surface tension

Why does ice float?

• As water freezes, it expands and its density decreases.
• As water freezes, it takes up more hydrogen from the atmosphere, causing it to have a greater buoyancy.
• As water freezes, air becomes trapped between the hydrogen bonds of water molecules.
• As water freezes, it takes up more oxygen from the atmosphere, causing it to have a greater buoyancy.

Enzymes are considered to be 

• Lipids
• Carbohydrate
• Protein
• Nucleic Acid