Ch 5 Bio

Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen . Oxygen will diffuse more quickly into cell ____ because _____.

.. the diffusion gradient there is steeper.

The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of

Active Transport The sodium-potassium pump moves ion across the plasma membrane against their concentration gradient. This requires energy and is an example of active transport.

Which of the following is an accurate comparison of active transport and facilitated diffusion?

Active transport moves salutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient.

Which of the following is a difference between active transport and facilitated diffusion?

Active transport requires the expenditure of cellular energy, and facilitated diffusion does not.

Green olives may be preserved in brine, which is a 20-30% salt solution. How does this method prevent contamination by microorganisms?

Bacteria can't survive in a hypertonic solution because they lose water.

Frequently, transplanted organs are rejected by the recipient's body. How is this reaction to plasma membranes?

Each person has a unique set of carbohydrate chains attached to his or her plasma membranes. When cells with unrecognized carbohydrate chains are placed in a person, his or her immune system attacks the foreign cells as though they were infectious agents.

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from it's mother's milk. These molecules probably enter the cells lining the baby's digestive tract via _____

Endocytosis

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of

Endocytosis In endocytosis, the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.

Which statement regarding enzyme function is true?

Excessive salt ions can cause an enzyme to denture. Few enzymes can tolorate extremely salty conditions, because the salt ions interfere with some of the chemical bonds that maintain protein structure.

What condition might result from an excess of aquaporin?

Fluid retention in pregnant women.

In a theoretical world where all things are possible, how could you increase the amount of energy that could be stored in a molecule of ATP?

Increase the negative charge of each phosphate group?

What drives osmosis?

The difference in water concentration across selectively permeable membrane. The driving force for osmosis is waters concentration gradient across a selectively permeable membrane. Differences in solute concentration across a membrane cream water concentration difference, but solute concentration differences do not directly drive osmosis.

What controls the direction of a molecule, such as oxygen, involved in passive transport?

The direction of the oxygen concentration gradient. The direction a material moves in passive transport is determined solely by the material's concentration gradient, with material diffusing from regions of higher concentration to regions of lower concentration.

A pharmaceutical company wishes to focus on an enzyme to develop new medications. What type of study would be of the greatest benefit?

Understanding the enzyme's structure would help pharmaceutical companies design molecules that fit to the binding site and alter activity.

In an oil based, non polar environment, phospholipids would arrange themeselves so that they

Would stay together but in reverse orientation, with their tails projecting outward.

A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of

facilitated diffusion. In facilitated diffusion, molecules use a transport protein to move across the plasma membrane. There is a net movement of molecules down the concentration gradient-- that is, there is a net movement of molecules from where they are more concentrated to where they are less concentrated.

In cellular respiration, most energy is released and transferred to ATP when ______.

high energy electrons "fall" to lower energy levels

In active transport,

molecules move across the plasma membrane against their concentration gradient. Molecules move against their concentration gradient in active transport.

Which of the following is highest in chemical energy?

one molecule of glucose

Kinetic energy is energy in motion. Potential energy is ______ energy.

stored

The hydrolysis of DNA into nucleotides constitutes an exedgonic reaction. Yet, DNA is quite stable. Why is this the case?

the activation energy required to initiate this reaction is seldom reached.

Succinylcholine is structurally almost identical to acetylcholine, but if combined with the enzyme that normally hydrolyze acetylcholine, the enzyme is no longer able to hydrolyze acetylcholine. This suggests that ________

succinylcholine must be a competitive inhibitor of acetylcholine. (competitive inhibition occurs when a molecule mimics the substrate.

Water crosses the plasma membrane

though facilitated diffusion or diffusion water can cross the plasma membrane though the process of facilitated diffusion. However, water molecules can also cross the lipid bilayer directly.

Energy is conserved. This means that in any system

total energy input equals total energy output.