Mastering Biology Exam 2

The light microscope can magnify specimens by at most ______ times and can resolve details down to about the size of _______.

1,000: 0.2 µm

How many molecules of ATP are produced in 1) glycolysis; 2) the citric acid cycle; and 3) oxidative phosphorylation?

2: 2: 28

Each turn of the citric acid cycle yields which of the following molecules that will go on to donate their electrons to the electron transport chain?

3 molecules of NADH and 1 molecule of FADH2

An hour of walking at 3 mph consumes approximately _____ times as much energy as an hour of sitting and writing.

8

What is meant by the term "enzyme specificity"?

An enzyme catalyzes only one type of reaction.

Which of the following is an INCORRECT statement comparing lactic acid fermentation and alcohol fermentation?

Both reduce pyruvate to lactate.

Which of the following statements about brown fat is INCORRECT?

Brown fat produces more heat and more ATP than white fat.

Which of the following is the summary equation for cellular respiration?

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP + heat

The bubbles in dough that arise after yeast has been added are ______.

CO2, a product of alcohol fermentation

________ energy is the type of ________ energy used to power the work of the cell.

Chemical: potential

Which of the following is a CORRECT statement about aquaporins?

Each aquaporin molecule allows billions of molecules of water to cross the plasma membrane each second.

The pesticide malathion and some drugs used as anesthetics both block an enzyme that is critical for transmitting nerve impulses. Why don't patients die like insects when they undergo surgery?

Enzyme inhibition with malathion is irreversible but with anesthetics, reversible.

Imagine a U-shaped tube with a membrane at the bottom of the "U". The membrane is permeable to glucose, sucrose and water. You place a concentrated glucose solution on Side A and an equally concentrated sucrose solution on Side B. Describe the movement of each solute across the membrane during the first few hours.

Glucose will move into Side B down its concentration gradient, and sucrose will move into Side A down its concentration gradient.

_______ generates the ATP created in fermentation reactions.

Glycolysis

What is one way of reducing the effectiveness of a competitive enzyme inhibitor?

Increase the concentration of the substrate.

One model of the cell membrane is that it is a "fluid mosaic." What does this mean?

It consists of proteins suspended in a fluid phospholipid bilayer.

What is the role of oxygen in the electron transport chain?

Its high electronegativity makes it the final electron acceptor.

Jonah has consumed too much alcohol on a regular basis for many years. While celebrating his graduation from skydiving school, he cut his foot on a broken beer bottle and developed an infection. Over the next two weeks, several antibiotics proved ineffective and his infection grew worse. Why might this have happened?

Jonah's high levels of detoxifying enzymes made the antibiotics less effective.

Lysosomes contain digestive enzymes. Perioxosomes contain H2O2. Both the digestive enzymes and H2O2 can kill cells. How is it possible that cells can contain toxic substances without being damaged?

Membranes isolate substances into separate compartments.

Which of the following statements about NADH and NAD+ is correct?

NADH delivers electrons to the electron transport chain in oxidative phosphorylation and becomes oxidized to NAD+.

In what way, if any, does osmosis differ from simple diffusion?

Polar water molecules cluster with hydrophilic molecules, so only free water diffuses down its concentration gradient.

When you hear "Substance X is moved against its concentration gradient," what do you think of?

Substance X has moved from a region of lower to a region of higher concentration with the help of ATP.

What benefits do scientists think might result from increasing the amount of brown fat inpeople who are obese or who have type 2 diabetes?

Such people might benefit from a higher proportion of brown to white fat, which would reduce the amount of stored fat.

What is the consequence of this inhibition as Product X accumulates?

The concentration of Molecule B increases.

According to the endosymbiont theory, what benefit was gained when the ancestor of the eukaryotic cell incorporated a photosynthetic prokaryote?

The newcomer provided nourishment to its host.

Which of the following is a correct statement about the relationship between photosynthesis and cellular respiration?

The products of photosynthesis are the reactants of cellular respiration, and the products of cellular respiration are the reactants of photosynthesis.

Researchers used frog eggs to learn more about aquaporins. What characteristic of normal frog eggs was essential in these studies?

They are largely impermeable to water.

Which of the following statements about coenzymes is correct?

They are organic cofactors with enzymes in reactions.

Why do fats make such excellent cellular fuel?

They contain many hydrogen atoms.

In what sense are living cells more efficient than internal combustion engines?

They convert a greater proportion of fuel to useful energy.

Which of the following processes must be present before ATP can be generated in oxidative phosphorylation?

a higher concentration of H+ within the mitochondrial intermembrane space than within the mitochondrial matrix

Walking at 3 mph burns about 245 kcal/hour. A slice of pizza contains about 474 kcal. How far would you have to walk to burn off the calories in that slice of pizza?

about 6 miles

A plant cell placed into an isotonic solution _______. An animal cell placed into an isotonic solution _______.

becomes flaccid: neither swells nor shrivels

What effect do inherited lysosomal storage diseases have on cells?

buildup of undigested material because key lysosomal enzymes are absent

Which choice has its items arranged in descending order of size (i.e., from largest to smallest)?

chicken egg, Paramecium, animal cell, mitochondrion, viruses, lipids

What comes to mind when you hear the term "9 + 2"?

cilia and flagella

Before refrigeration, meat was preserved by adding ________. What effect did this have on any contaminating bacteria or fungi?

concentrated salt solutions: plasmolysis

Which of the following lists includes only components that provide structural support, allow movement, or enable communication between cells? Keep in mind that this is a functional, not purely structural, classification.

cytoskeleton, plant cell wall, plasma membrane

At which stage of cellular respiration is the first molecule of CO2 released?

during the oxidation of pyruvate to acetyl CoA

Building a molecule of ATP is an ________process. Hydrolyzing a molecule of ATP is an _______ process. This cycle is an example of _________.

endergonic: exergonic: energy coupling

Photosynthesis is an _______ process. Energy from ______ allows the production of products with ________.

endergonic: the sun: higher potential energy than the reactants

At what stage of active transport is ATP needed?

for the transport protein to change its shape

Ions flow through _______ between cells of heart muscle. How does this help the heart do its job?

gap junctions: coordinate contraction

Which out of the listed choices is the earliest metabolic pathway to have developed in living things?

glycolysis

What is the correct order of the stages of cellular respiration?

glycolysis, citric acid cycle, oxidative phosphorylation with chemiosmosis

Where do the chemical reactions of cellular respiration take place in plants?

in the matrix of the mitochondrion

Oxidative phosphorylation occurs in the ______ and produces _____.

inner mitochondrial membrane: ATP

The maximum size of a cell is limited by which of the following?

its need for enough surface area for exchange with its environment

A differential interferencecontrast microscope uses __________ to examine a specimen. Which type of microscope would one use to examine the internal structure of a nucleolus?

light: transmission electron microscope

Enzymes ______ the activation energy of a reaction. The energy change between products and reactants is _______ for a reaction that is catalyzed versus one that is not.

lower: the same

Which of the following are present in animal cells but not in plant cells?

lysosomes and centrosomes

Consider a free ribosome. What enters this organelle, and what comes out of it, in the process of protein synthesis?

messenger RNA (mRNA) enters: a polypeptide comes out

Which of the following lists the smallest of the cell's cytoskeletal elements, and what is the function of these elements?

microfilaments: muscle contraction

Which of the following organelles is present in a prokaryotic cell, but not a eukaryotic cell?

nucleoid

Ribosomal RNA is produced in the ________ according to instructions from the cell's _________. Subunits are then formed from ribosomal RNA and ______ imported from the cytoplasm.

nucleolus: DNA: proteins

Which of the following prevents the cells of a freshwater fish from becoming hypotonic and bursting?

osmoregulation

The two-carbon compound that enters the citric acid cycle joins with which of the following molecules before it begins its turn around the cycle?

oxaloacetate, a 4-carbon molecule

Both a living cell and an automobile convert fuel and ______ to the waste products ___________. In the process, ______ is produced, which represents the entropy of the reaction.

oxygen: CO2 and water: heat

All of the following originate from the endomembrane system EXCEPT _______.

perioxisomes

The cell wall of plants consists of which substances?

polysaccharides and proteins

Which of the following functions is performed by the Golgi apparatus?

processing proteins for secretion and for use within the cell

What is the function of the sodium-potassium pump in nerve cells?

pump Na+ out of the cell and K+ into the cell

Which method of transport uses coated pits?

receptor-mediated endocytosis

Endergonic reactions _______ energy and result in products that have _____ potential energy than the reactants.

require: higher

The endomembrane system is in a constant state of renewal. Which organelle manufactures new membrane for this system?

rough endoplasmic reticulum

Which of the following organelles is responsible for folding proteins and adding the short sugar chains that make them glycoproteins?

rough endoplasmic reticulum

A cell that produces proteins for export contains large quantities of _______, while a muscle cell contains abundant _______.

rough endoplasmic reticulum: microfilaments

Which is the most inclusive and correct list of substances that use facilitated diffusion to cross cell membranes?

sugars, amino acids, ions, water

In addition to providing fuel in the form of ATP, the intermediates of cellular respiration also provide ______.

the building blocks of proteins, fats, and carbohydrates

Several genetic disorders of mitochondria have now been identified. If such a defect resulted in a less active electron transport chain, what would you predict might occur? (Note: think of this in terms of basic mechanisms: genetic disorders rarely affect just one process.)

the concentration of ADP within the mitochondrial matrix would increase

Which of the following events takes place in the cell's cytosol?

the formation of ATP by substrate phosphorylation

Which of the following is (are) the hydrophilic regions of the cell membrane?

the regions nearest to the external and internal environments

Which of the following is the best description of substrate-level phosphorylation in glycolysis?

the transfer of a phosphate group from a substrate molecule to ADP

Glycolysis is a series of reactions that can be divided into two phases: an "energy investment" and an "energy payoff" phase. Which of the following is produced at the end of the "energy investment" phase in the metabolism of one molecule of glucose?

two molecules of glyceraldehyde-3-phosphate (G3P), a 3-carbon sugar

Which of the following can perform these functions in plants: digestion, water circulation, pigmentation, and food storage?

vacuole