Biology MCQ Unit 4

A researcher claims that spinach leaves capture the most energy from light waves in the range of 500nm to 600nm. To test the claim, the researcher will place spinach leaves in separate chambers and expose the leaves to different wavelengths of For each chamber, the researcher will measure the amount of oxygen gas (O2) that is produced in one hour. Which of the following graphs best represents data from the experiment that will support the researcher's claim?

Graph that looks like a mountain. Is at its peak between 500 and 600.

The O2 released during photosynthesis comes from

H2O

Glycolysis is a definite sequence of ten reactions involving ten intermediate compounds. The intermediates provide entry points to glycolysis. Which of the following best describes where glycolysis occurs?

In the cytoplasm of both prokaryotic and eukaryotic cells

The data shown above was collected from a flask containing yeast in a sucrose solution. A sample was removed from the flask every minute for a total of 25 minutes and assayed for the sucrose concentration present as well as the concentration of other organic substances. The assay at the minute 20 reading indicated the presence of ethanol. Which of the following best explains these results?

Initially, the population was small enough to produce enough ATP through aerobic respiration. As the population grew, the oxygen was used up and the cells converted to fermentation producing ethanol.

The diagram below shows a reaction that occurs in glycolysis. Which statement best explains what is happening in this reaction?

Is not "The phosphate group is oxidized by donating hydrogen ions to NAD+ to form NADH." Try another one

Aminolevulinate dehydratase (ALAD) is an enzyme that relies on zinc as a coenzyme. A zinc ion binds to the ALAD active site, where it forms favorable interactions with the side chains of three amino Researchers have found that substituting a lead ion for a zinc ion in the ALAD active site causes inhibition of ALAD. Which of the following statements best helps explain how the lead ion causes inhibition of ALAD?

It changes the three-dimensional structure of the active site so that ALAD is no longer compatible with its substrate.

Which of the following statements about NAD is true?

It is a key electron carrier in redox reactions.

Which of the following is produced by the light reactions of photosynthesis and consumed by the Calvin cycle?

NADPH and ATP

Animals inhale air containing oxygen and exhale air with less oxygen and more carbon dioxide. Most of the carbon dioxide comes from

NOT hydrocarbons and the air.

Which of the following statements about photosynthesis is false?

Photosynthesis is the reverse of cellular respiration.

temperature on enzyme function. The student's plan is presented in Table Table 1. An experiment to investigate the influence of temperature on enzyme function Which test tubes are controls in the experiment?

Test tubes 1, 3, 5, and 7

Acetylcholinesterase (AChE) is a protein that catalyzes the conversion of acetylcholine to acetate and choline. When the concentration of AChE in an aqueous solution is held constant, the rate of the reaction catalyzed by AChE increases with increasing concentrations of substrate. At low concentrations of acetylcholine, a small increase in the substrate concentration results in a large increase in the reaction rate. At high concentrations of acetylcholine, however, a large increase in the substrate concentration results in only a small increase in the reaction rate. Which of the following statements correctly explains the observed effect of the acetylcholine concentration on the rate of the enzyme-catalyzed reaction?

The active site of AChE is specific for acetylcholine, and only one substrate molecule can occupy the active site at the time.

How do enzymes speed the conversion of a substrate into a product?

The enzyme binds to the substrate, inducing a slight conformational change in both the enzyme and the substrate that releases the product from the enzyme

The diagram below shows a partial model of photosystem II (PS II) and photosystem I (PS I) in the light-dependent reactions of photosynthesis.

The excited electrons are replaced when an enzyme splits a water molecule into two electrons, an oxygen atom, and two hydrogen ions.

Which graph depicts an enzyme that has reached a maximum rate of reaction?

The graph that flattens at the top and doesn't go down

The diagram below shows the concentration of hydrogen ions within the thylakoid space of a chloroplast. Which of the following describes the presence of the ions in the thylakoid space?

The ions are released from water molecules and are pumped into the thylakoid space as excited electrons move through the electron transport chain.

Which of the following is an important difference between light-dependent and light-independent reactions of photosynthesis?

The light-dependent reactions produce ATPand NADPH; the light-independent reactions use stored energy in ATP and NADPH.

All of the following are true regarding the molecule shown above EXCEPT

The molecule is used for long term storage of energy captured by autotrophs.

Brown fat is a type of fat tissue found in hibernating mammals. Inside the mitochondria of these fat tissue cells, these mammals have an uncoupling protein embedded in the inner mitochondrial membrane. This uncoupling protein allows hydrogen ions to leak from the intermembrane space back into the mitochondrial matrix. Figure 1 shows details of the processes in the inner mitochondrial membrane. Which of the following statements provides reasoning that supports the claim that brown fatty tissue keeps an animal warm

The uncoupling protein in this tissue reduces the proton gradient across the membrane and thus produces heat to warm the animal without ATP production

Oxidation and reduction

always occur together.

The rate at which an enzyme catalyzes a reaction is influenced by several chemical and physical factors-including temperature. At temperatures above that indicated by the red line, which would you expect to happen?

enzymes lose their shape and can be denatured

The overall function of the Calvin cycle is

making sugar

When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by

splitting of water

Which of the following is NOT a product of the light reactions of photosynthesis?

sugar

Carbon dioxide is utilized in photosynthesis during

the Calvin cycle.

Competitive inhibitors can prevent an enzyme from catalyzing a chemical reaction by binding to which of the following?

the enzyme's active site

Letter C in the diagram above results in the production of which of the following?

6 NADH, 2 FADH2, 2 ATP

Which letter represents the process where a molecule of glucose is split into two molecules of pyruvate?

A

Which of the following describes a metabolic consequence of a shortage of oxygen in muscle cells?

A buildup of lactic acid in the muscle tissue due to fermentation

Based on the model, which of the following statements best explains an enzyme's specificity for a particular substrate molecule?

A molecule with negative charges interacts with positively charged side chains in the enzyme's active site.

Because enzymes are proteins, they are sensitive to denaturing conditions that disrupt protein structure. Which of the following is NOT an example of a denaturing condition?

All of the above are examples of denaturing conditions.

Refer to the diagram below. Which of the following was proved by experiments tracing isotopes of oxygen through the process of photosynthesis?

All the oxygen gas produced during photosynthesis comes from water.

Which letter represents the process by which a molecule of pyruvate is oxidized into Acetyl-CoA?

B

How do competitive and noncompetitive enzyme inhibitors differ?

Competitive inhibitors bind to the active site, whereas noncompetitive inhibitors change the shape of the active site.

Which letter represents the process of oxidative phosphorylation (electron transport and chemiosmosis)?

D

The figures can best assist in answering which of the following questions?

Do electron transport chains create a gradient so that ATP synthase can generate ATP molecules?

The diagram below shows energy changes in a specific chemical reaction with and without the addition of an enzyme to the reaction.

Does the addition of an enzyme reduce the activation energy required for a reaction?

Which of the following directly produces the most ATP per mole of glucose during aerobic cellular respiration?

Electron transport chain and chemiosmosis

Which of the following processes occurs when oxygen is not available?

Fermentation

Which metabolic process is common to both aerobic cellular respiration and alcoholic fermentation?

Glycolysis