1.
All of the following are correct about transport except
Correct Answer
B. Exocytosis moves solid material into the cell
Explanation
exocytosis moves materials out of the cell
2.
Which is incorrect about the "mosaic" portion of the membrane?
Correct Answer
C. PeripHeral proteins are embedded in the membrane and other molecules attach to them
Explanation
peripheral proteins are on the edge-integral proteins are embedded
3.
Choose the correct statement about membrane saturation:
Correct Answer
A. Saturated pHospHolipids tails fit close together, inhibiting movement
Explanation
Saturated phospholipids have straight tails with no double bonds, which allows them to pack closely together in the membrane. This close packing inhibits movement and makes the membrane less fluid. Unsaturated phospholipids, on the other hand, have kinked tails due to double bonds, which prevents them from packing tightly together and increases membrane fluidity. Proteins, however, do not directly affect membrane saturation.
4.
Having both polar and nonpolar areas makes a molecule
Correct Answer
D. AmpHipathic
Explanation
A molecule that has both polar and nonpolar areas is considered amphipathic. This means that it has regions that are attracted to water (polar) and regions that repel water (nonpolar). These opposing characteristics allow the molecule to interact with both polar and nonpolar substances. In biological systems, amphipathic molecules play important roles, such as forming cell membranes, where the polar regions face the watery environment while the nonpolar regions are shielded from it. This property of being amphipathic allows the molecule to have diverse interactions and functions in different environments.
5.
These scientists proposed that the cell membrane was a "sandwich" model:
Correct Answer
B. Davson and Danielli
Explanation
Davson and Danielli proposed the "sandwich" model of the cell membrane. According to their model, the cell membrane consists of a phospholipid bilayer with protein layers on both sides. The phospholipid bilayer acts as a barrier, while the protein layers provide structural support and regulate the movement of substances in and out of the cell. This model was widely accepted for many years until further research revealed that the cell membrane is more fluid and dynamic than originally thought.
6.
Which is not a factor affecting permeability?
Correct Answer
C. Color
Explanation
Permeability refers to the ability of a substance to allow the passage of another substance through it. Factors that affect permeability include size, temperature, and concentration. Color, on the other hand, does not affect permeability as it is a visual characteristic and does not influence the ability of a substance to allow the passage of another substance.
7.
If a cell is placed into a hypertonic solution, what will happen to it?
Correct Answer
B. Shrink
Explanation
When a cell is placed into a hypertonic solution, the concentration of solutes outside the cell is higher than inside the cell. As a result, water molecules move out of the cell through osmosis, causing the cell to shrink. This is because water moves from an area of lower solute concentration (inside the cell) to an area of higher solute concentration (outside the cell) in an attempt to equalize the solute concentration on both sides of the cell membrane.
8.
Receptor mediated endocytosis is different than most types of transport we discussed because it involves
Correct Answer
A. Coated pits
Explanation
Receptor-mediated endocytosis is a unique form of transport as it involves the formation of coated pits. These coated pits are specialized regions on the cell membrane that contain clathrin, a protein that forms a lattice-like structure. Receptor molecules on the cell surface bind to specific ligands, such as hormones or growth factors. This binding triggers the formation of coated pits, which then invaginate and pinch off to form coated vesicles. These vesicles contain the receptor-ligand complexes and are internalized into the cell. This process allows for selective uptake of specific molecules into the cell, making it different from other types of transport mechanisms like pinocytosis or facilitator molecules.
9.
Reactions in which the products have less energy than the reactants are called
Correct Answer
B. Exergonic
Explanation
Exergonic reactions are those in which the products have less energy than the reactants. In these reactions, energy is released and the overall reaction is spontaneous. This means that the reaction can occur without the input of additional energy. Endothermic reactions, on the other hand, require an input of energy to proceed. Isogonic is not a term used to describe reactions.
10.
Catalysts
Correct Answer
A. Lower the activation energy needed to start a reaction
Explanation
Catalysts are substances that lower the activation energy needed to start a reaction. Activation energy is the energy required to break the bonds of the reactant molecules and initiate the reaction. By lowering this energy barrier, catalysts increase the rate of reaction by allowing more reactant molecules to have sufficient energy to overcome the activation energy. This means that reactions can occur more easily and quickly in the presence of a catalyst.
11.
When a molecule fits into a spot on the enzyme that changes the shape of the active site of the enzyme, it is referred to as
Correct Answer
B. A noncompetitive inhibitor
Explanation
When a molecule fits into a spot on the enzyme and changes the shape of the active site, it is referred to as a noncompetitive inhibitor. In this case, the inhibitor does not compete with the substrate for the active site but instead binds to a different site on the enzyme, causing a conformational change that makes the active site less effective in catalyzing the reaction. This type of inhibition is not reversible by increasing the substrate concentration.
12.
No ATP is made in
Correct Answer
B. Transition reaction
Explanation
The transition reaction is the process that occurs between glycolysis and the Kreb's cycle. During this reaction, pyruvate, which is the end product of glycolysis, is converted into acetyl-CoA. No ATP is directly produced during the transition reaction. However, the acetyl-CoA that is formed enters the Kreb's cycle, where ATP is eventually generated through oxidative phosphorylation. Therefore, the correct answer is transition reaction.
13.
No NADH is made in
Correct Answer
D. ETC
Explanation
NADH is not made in the Electron Transport Chain (ETC). NADH is produced in the previous steps of cellular respiration, such as glycolysis, the transition reaction, and the Kreb's cycle. In glycolysis, NADH is generated when glucose is broken down into pyruvate. In the transition reaction, pyruvate is converted into Acetyl-CoA, producing NADH in the process. The Kreb's cycle further generates NADH through the oxidation of Acetyl-CoA. However, in the ETC, NADH is oxidized and donates its electrons to the electron carriers in the chain, creating a proton gradient for ATP synthesis but not producing any NADH.
14.
The purpose of oxygen in cellular respiration is
Correct Answer
C. To be reduced by electrons into water
Explanation
Oxygen is used in cellular respiration to be reduced by electrons into water. During cellular respiration, glucose is broken down in the presence of oxygen to produce energy in the form of ATP. Oxygen acts as the final electron acceptor in the electron transport chain, accepting electrons from the electron carriers NADH and FADH2. This process generates a proton gradient, which is used to produce ATP. Ultimately, oxygen combines with hydrogen ions to form water, completing the electron transport chain and allowing for the efficient production of ATP.
15.
When is carbon dioxide produced?
Correct Answer
B. Transition reaction and Kreb's cycle
Explanation
During the process of cellular respiration, carbon dioxide is produced in the transition reaction and Kreb's cycle. In the transition reaction, pyruvate molecules are converted into acetyl CoA, releasing carbon dioxide as a byproduct. Acetyl CoA then enters the Kreb's cycle, where it undergoes a series of reactions that result in the release of more carbon dioxide. The carbon dioxide produced in these two stages is eventually expelled from the cell as a waste product.
16.
Which of these molecules do not move the electrons in the ETC?
Correct Answer
A. Acetyl coA
Explanation
Acetyl coA does not move the electrons in the Electron Transport Chain (ETC). The ETC is responsible for transferring electrons from molecules in the form of NADH and FADH2 to generate ATP. Acetyl coA is not directly involved in this process. It is formed during the breakdown of glucose and fatty acids and enters the citric acid cycle to produce NADH and FADH2, which then donate their electrons to the ETC. However, acetyl coA itself does not participate in electron transfer within the ETC.
17.
Where does the ETC take place?
Correct Answer
A. Cristae
Explanation
The ETC (Electron Transport Chain) takes place in the cristae. Cristae are the folds in the inner membrane of the mitochondria, which provide a large surface area for the ETC to occur. This is where the majority of ATP (Adenosine Triphosphate) is produced through oxidative phosphorylation, which is the final step in cellular respiration. The cristae's structure allows for efficient electron transfer and the generation of a proton gradient, which is essential for ATP synthesis.
18.
Each FADH2 produces ___ ATP.
Correct Answer
A. 2
Explanation
FADH2 is a molecule that carries high-energy electrons to the electron transport chain in cellular respiration. Each FADH2 molecule produces 2 ATP molecules through oxidative phosphorylation in the mitochondria. This is because FADH2 donates its electrons to Complex II of the electron transport chain, which results in the pumping of fewer protons across the inner mitochondrial membrane compared to NADH. As a result, the energy generated from the electron transfer is used to produce 2 ATP molecules.