Enzymes and properties of water 18.11 and 18.12 quiz

Enzymes are an example of

• lipids

• carbohydrates

• protein

• nucleic acid

What is a substance called if it speeds up a chemical reaction?

• reusable

• catalyst

• specific

• fragile

In the diagram, what is letter A?

• product

• enzyme-substrate complex

• substrate

• active site

An enzyme speeds up a reaction by

• raising the activation energy

• lowering the activation energy

• releasing energy

• absorbing energy.

What happens to an enzyme when it is denatured?

• Activation energy is lowered

• It becomes stronger

• It loses its shape

• Activation energy is raised

What word describes when water is attracted to other substances?

• cohesion
• adhesion
• capillary action
• surface tension

Which end of the water molecule has a slightly positive charge?

• the oxygen end
• the hydrogen end
• both ends are slightly positive
• neither end is positive

 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

Which statement explains why water molecules stick together?

• both sides are negative
• one side has a positive charge and the other side has a negative charge
• one side has a negative charge adn the other side has a neutral charge
• both sides are positive

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

• Water is pushed by solutes

• Water is pulled by gravity

• Capillary action pulls the water molecules like a chain

• Water's cohesion causes it to "pull" towards the leaves