Exam 5: The Working Cell

A group of single-cell organisms collected from the ocean was brought into the lab for examination. The lab assistant was concerned that the water had become full of toxic waste products and so added clean water to the culture. All of the organisms died, and when she looked at them under the microscope, all she could see were bits and pieces of them scattered throughout the water. What likely happened?

Which of the following processes can move a solute against its concentration gradient?

Lipase is an enzyme released by the pancreas that digests fats in the small intestine; however, lipase is also found in bacteria. Researchers examined lipase function in two species of bacteria, species X and species Y. Data regarding the activity of lipase as a function of temperature are shown below for the lipase from bacteria X (white circles) and the lipase from bacteria Y (black circles). Use this information to answer the following three questions. Lipase activity as a function of temperature. -What is true regarding the function of lipase?

When an enzyme catalyzes a reaction

In the reaction A → B + C + heat

Water movement is important in urine formation in the kidneys. Urine is formed when the blood is filtered by the kidneys into kidney tubules. Three figures are presented here that relate to how the kidney tubules respond to the administration of the hormone vasopressin. The direction that water flows in these figures is from the kidney tubules back into the blood. Figure A. Changes in permeability of tubules in the kidney in response to the hormone vasopressin (AVP), which aids in osmoregulation. Figure B. Density of aquaporins in kidney tubule cells before, during, and after administration of vasopressin. Figure C. Permeability of tissues to water before, during, and after administration of vasopressin. -Using the data from the graphs and what you know about membranes and metabolic pathways, predict which of the following is the likely reason why actions of aquaporins in a membrane can change so rapidly.

Which of the following direct energy transfers is impossible in living systems?

All cells are enclosed by a plasma membrane that is similar in ________ and ________.

Relaying a message from a membrane receptor to a molecule that performs a specific function within a cell occurs when

Living systems

Anything that prevents ATP formation will most likely

How does inhibition of an enzyme-catalyzed reaction by a competitive inhibitor differ from inhibition by a noncompetitive inhibitor?

Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment

Which of the following statements regarding enzyme function is false?

Which of the following statements about ATP is true?

Suppose that while the reverse osmosis system is running tank B becomes contaminated with salt water such that it ends up with a higher salt concentration than tank A. What would happen if the reverse osmosis system was turned off?

The cholesterol associated with animal cell membranes

An energy barrier

Which of the following processes is endergonic?

Most of the functions of a cell membrane, including transport and enzymatic function, are performed by