BIOL 111 - Homework Chapter 7 and 8

Which of the following would likely diffuse through the lipid bilayer of a plasma membrane most rapidly?

•   a steroid hormone

•   calcium ions

• glucose

•   sodium ions

When ATP hydrolysis releases ADP and some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?

•   It enters the nucleus to be incorporated in a nucleotide.

•   It may be used to form a phosphorylated intermediate.

•   It is secreted as waste.

•   It is secreted as waste.

Which of the following statements about anabolic pathways is true?

• Which of the following statements about anabolic pathways is true?

•   They are usually spontaneous chemical reactions.

•   They decrease the entropy of the organism and its environment.

•   They consume energy to build up polymers from monomers.

Winter wheat membranes remain fluid (don't solidify) when it is extremely cold. Beginning in autumn the plants acclimate for winter by

•   increasing the proportion of unsaturated phospholipids in the membrane

•   increasing the proportion of glycolipids in the membrane

•   decreasing the number of hydrophobic proteins in the membrane

•   decreasing the percentage of cholesterol molecules in the membrane

  decreasing the percentage of cholesterol molecules in the membrane

•   the energy contained in the organism is constant

•   the energy contained in the organism is constant

•   energy necessary for life must be obtained from the environment

•   as complexity grows, entropy decreases

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

•   Metabolism manages the increase of entropy in an organism.

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

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

•   Metabolism uses all of an organism's resources.

Which of the following statements about enzyme function is true?

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

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

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

•   Enzyme function is generally increased if the three-dimensional structure or conformation of an enzyme is altered.

Five dialysis bags, constructed of a type of membrane that is permeable to water and impermeable to sucrose, were filled with 5 different concentrations of sucrose solution and then placed in separate beakers each initially containing a 0.7 M sucrose solution. At 10-minute intervals, the bags were weighed, and the percent change in mass of each bag was graphed.

Which line in the graph represents the bag that contained a solution isotonic to the 0.7 M beaker solution at the beginning of the experiment?

• A

• B

• C

• D

Consider a phospholipid bilayer that has a specific permeability to glucose and contains equal amounts of unsaturated and saturated fatty acids.  In what way will membrane permeability to glucose change if the proportion of unsaturated fatty acids increases?

•   Permeability to glucose will stay the same

•   Permeability will decrease initially then increase as the bilayer fills with glucose.

•   Permeability to glucose will increase.

•   Permeability to glucose will decrease.

If, when placed in a solution, an animal cell bursts and a plant cell becomes turgid, the solution they were placed in is _____ compared to the cells.

•   hypotonic

•   hypertonic

•   both hypotonic and isotonic

• isotonic