Chapter 8 Test

Which of the following is true of metabolism in its entirety in all organisms?

• Metabolism depends on a constant supply of matter from food.

• Metabolism uses all of an organism's resources

• Metabolism consists of all the energy transformation reactions in an organism

• Metabolism manages the increase of entropy in an organism.

Which of the following is an example of potential rather than kinetic energy?

• water rushing over Niagara Falls

• light flashes emitted by a firefly

• a molecule of glucose

• a crawling beetle foraging for food

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

• catabolism

• metabolism

• anabolism

• dehydration

Anabolic pathways ___

• are usually highly spontaneous chemical reactions

• consume energy to build up polymers from monomers

• release energy as they degrade polymers to monomers

• consume energy to decrease the entropy of the organism and its environment

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ____ is to ____.

• exergonic; spontaneous

• exergonic; endergonic

• free energy; entropy

• work; energy

Why is ATP an important molecule in metabolism?

• its hydrolysis provides an input of free energy for exergonic reactions

• it provides energy coupling between exergonic and endergonic reactions

• its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, release free energy.

• its terminal phosphate bond has higher energy than the other two phosphate bonds.

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

• it is used to power yet more cellular work

• it is used to store energy as more ATP

• it is used to generate ADP from nucleotide precursors

• it is lost to the environment

A number of systems for pumping ions across membranes are powered by ATP. Such ATP powered pumps are often called ATPases, although they do not often hydrolyze ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP powered calcium pumps. For example, muscle cells transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a resting muscle cell's cytosol has a free calcium ion concentration of 10^-7 while the concentration in the SR is 10^-2, then how is the ATPase acting?

• ATPase activity must be powering an inflow of calcium from outside of the cell into the SR

• ATPase activity must be transferring Phosphate groups to the SR to enable this to occur

• ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient

• ATPase activity must be opening a channel for the calcium ions to diffuse back into the SR along the concentration gradient

Which of the following is the most correct interpretation of the figure?

• Energy from catabolism can be used directly for performing cellular work

• ADP + P are a set of molecules that store energy for catabolism

• ATP is a molecule that acts an an intermediary to store energy for cellular work

• P acts as a shuttle molecule to move energy from ATP to ADP

Which of the following is true of enzymes?

• Enzyme function is increased if the 3-D structure or conformation of an enzyme is altered

• Enzyme function is independent of physical and chemical environmental factors such as pH and temperature

• Enzymes increase the rate of chemical reaction by lowering activation energy barriers

• Enzymes increase the rate of chemical reaction by providing activation energy to the substrate