AP BIO MID TERM TEST 4
Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?
As a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth.
Which of the following is a statement of the first law of thermodynamics?
Energy cannot be created or destroyed
Which of the following statements regarding enzymes is true?
Enzymes increase the rate of a reaction by lowering the activation energy barrier
Which of the following is true of enzymes?
Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
Which of the following statements is a logical consequence of the second law of thermodynamics?
Every chemical reaction must increase the total entropy of the universe
Which of the following statements is correct about diffusion?
It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.
Which of the following is true of metabolism in its entirety in all organisms?
Metabolism consists of all the energy transformation reactions in an organism.
Three lab groups carried out an experiment to identify the correct molarities for five solutions. Each unknown contained one of the following sucrose concentrations: 0.0 M, 0.2 M, 0.4 M, 0.6 M, 0.8 M, and 1.0 M. Each data entry represents the average of 3 sample replications of 1 cm3 sweet potato cubes expressed as percent change in mass after an overnight (24 hr) soak in the unknown solutions. From the data given, which statement most accurately describes what is occurring in response to a particular unknown solution. Unknown Percent change in mass (%) Percent change in mass (%) Percent change in mass (%) Group 1 Group 2 Group 3 A 6.6 7.8 7.5 B 3.1 3.7 2.9 C -2.7 -3.5 - 2.5 D 0.7 0.5 1.1 E -11.6 -12.3 -12.6 F -5.2 -6.2 -4.9
Osmosis of water molecules from unknown solution A likely caused the increase in mass observed.
Suppose that the cell shown in this figure is secreting insulin, a protein hormone, via exocytosis. Which statement most accurately describes why this mechanism of transport is ideal for insulin secretion?
Proteins are large molecules that cannot be transported efficiently across the membrane via transport proteins
In a biological reaction, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, a substance that resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate molecules to those of malonic acid reduces the inhibitory effect if malonic acid. Select the correct identification of the molecules described in the reaction.
Succinate is the substrate, and fumarate is the product in the reaction.
Biological systems use free energy based on empirical data that all organisms require a constant energy input. The first law of thermodynamics states that energy can be neither created nor destroyed. For living organisms, which of the following statements is an important consequence of this first law?
The organism must ultimately obtain all the necessary energy for life from its environment.
Which of the following is true for all exergonic reactions?
The reaction proceeds with a net release of free energy.
Which of the following is true of integral membrane proteins?
They are usually transmembrane proteins.
According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
They can move laterally along the plane of the membrane.
Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater?
Water will leave the cells, causing them to shrivel and collapse.
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's
activation energy.
In order for a protein to be an integral membrane protein it would have to be
amphipathic, with at least one hydrophobic region
How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?
by changing the shape of the enzyme's active site
Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
catabolism
Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
competitive inhibition
The presence of cholesterol in the plasma membranes of some animals
enables the membrane to stay fluid more easily when cell temperature drops.
A chemical reaction that has a positive ΔG is best described as
endergonic
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as
feedback inhibition.
What is the voltage across a membrane called?
membrane potential
Which of these are not embedded in the hydrophobic portion of the lipid bilayer?
peripheral proteins
Which of the following types of molecules are the major structural components of the cell membrane?
phospholipids and proteins
The difference between pinocytosis and receptor-mediated endocytosis is that
pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity
What kinds of molecules pass through a cell membrane most easily?
small and hydrophobic
Celery stalks that are immersed in fresh water for several hours become stiff and hard. Similar stalks left in a 0.15 M salt solution become limp and soft. From this we can deduce that
the fresh water is hypotonic and the salt solution is hypertonic to the cells of the celery stalks.
Which of the following statements is true about enzyme-catalyzed reactions?
the reaction is faster than the same reaction in the absence of the enzyme
The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is
to mediate cell-to-cell recognition.
