Mastering biology chapter 4,5 and 6

The cellular process of synthesizing large molecules from smaller ones is defined as

anabolism

The fluid mosaic model of membrane structure suggests that membranes

are composed of protein molecules embedded in a fluid bilayer of phospholipids.

The mechanism by which testosterone alters cell function is by

binding to a receptor protein that enters the nucleus and activates specific genes.

Which of the following are among the most common second messengers?

calcium ion and cAMP

The cellular process of breaking down large molecules into smaller ones is defined as

catabolism

A noncompetitive inhibitor decreases the rate of an enzymatic reaction by

changing the shape of the enzyme active site.

Proteins that allow the diffusion of ions across membranes in the direction of their concentration gradients are most likely

channel proteins

Zinc, an essential trace element for most organisms, is required in the active site of the enzyme carboxypeptidase in order for the enzyme to function properly. The zinc most likely functions as a(n)

cofactor necessary for enzyme activity.

Which temperature and pH profile curves on the graphs in the figure were most likely generated from analysis of an enzyme from a human stomach, where conditions are strongly acidic?

curves 1 and 4- low temp and acidic

Which curves on the graphs in the figure may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot spring at temperatures of 70∘∘C or higher?

curves 3 and 5- high temp and basic

Motor proteins provide for molecular transport of materials in cells by interacting with what type(s) of cellular structures?

cytoskeletal

Which of the following reactions tend to require an input of energy?

dehydration

The movement of the hydrophobic gas nitrous oxide (N2O) (laughing gas) into a cell is an example of

diffusion through the lipid bilayer

A chemical reaction that has a positive ΔG is best described as

endergonic

Which of the following molecules or structures may be found in eukaryotic cells but not in bacteria?

endoplasmic reticulum

The evolution of eukaryotic cells most likely involved

endosymbiosis of an oxygen-using bacterium in a larger host cell−−the endosymbiont evolved into mitochondria.

The mechanism by which the end product of a metabolic pathway inhibits an enzyme that catalyzes an earlier step in the pathway is most precisely described as

feedback inhibition

Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells?

gap junctions

Which of the following is a substance that acts at a long distance from the site at which it is secreted?

hormone

Enzymes are described as catalysts, which means that they __________.

increase the rate of a reaction without being consumed by the reaction

Cell fractionation is commonly used in biological research to

isolate organelles to examine their biological functions

Which of the following is a characteristic feature of a carrier protein in a plasma membrane?

it exhibits a specificity for a particular type of molecule

Water can move quickly through the plasma membrane of some cells because

it moves through aquaporin channel proteins

The sodium-potassium pump generates the following concentration gradients across the plasma membrane:

low [Na+] and high [K+] inside the cell and high [Na+] and low [K+] outside.

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in

lysosomes

Which of the following is a correct match between a cytoskeletal element and its function?

microtubules and chromosome movement

Movement of vesicles within the cell depends on what cellular structures?

microtubules and motor proteins

Which of the following functions is NOT associated with the cytoskeleton in eukaryotic cells?

movement of RNA molecules from the nucleus to the cytoplasm

Which of the following membrane activities requires energy from ATP hydrolysis?

movement of sodium ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid

In an animal cell, DNA may be found in which of the following organelles?

only in the nucleus and mitochondria

Which of the following molecules are localized on the exterior of a phospholipid bilayer?

phosphate groups

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 is highly selective.

mitochondria are found in

plant and animal cells

The total volume of plant cells is often significantly greater than the total volume in animal cells. The most reasonable explanation for this observation is that

plant cells contain a large vacuole that occupies much of the volume of the cell.

A cell with an abundance of free ribosomes is most likely carrying out which of the following processes?

producing primarily cytoplasmic proteins

Some key innovations in the evolution of eukaryotic cells from a prokaryotic ancestor are membrane-bound organelles. Which of the following organelles or features is a common structure shared by both eukaryotic cells and their prokaryotic ancestors?

ribosomes

Extracellular matrix proteins are produced by ribosomes in which part of a eukaryotic cell?

rough ER

What kinds of molecules pass through a cell membrane most easily?

small hydrophobic

The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and therefore abundant in liver cells?

smooth ER

Which organelle or structure is primarily involved in the synthesis of oils, phospholipids, and steroids?

smooth endoplasmic reticulum

Which of the following types of signaling is represented in the figure?

synaptic

Energy is observed in two basic forms: potential and kinetic. Which of the following correctly matches these forms with a source of energy?

the covalent bonds of a sugar molecule: potential energy

The primary function of G proteins in signal transduction is

transmitting the signal from an activated receptor to the next protein in the pathway.

Which of the following molecules is required to build cilia or flagella?

tubulin

Which of the following clues would tell you if a cell is prokaryotic or eukaryotic?

whether or not the cell is partitioned by internal membranes

Which of the following statements best describes the critical role that ATP plays in cellular metabolism?

ATP serves as an energy shuttle in the cell, coupling exergonic and endergonic reactions.

Which component in the figure is a glycolipid?

B

In the figure, a peripheral membrane protein is represented by

D

Which of the following statements is true of enzymes?

Enzymes generally increase the rate of chemical reactions by lowering activation energy barriers.

Which of the following statements regarding enzymes is true?

Enzymes increase the rate of a reaction by lowering the activation energy barrier.

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?

Estrogen binds to specific receptors inside many kinds of cells, each of which has different responses to its binding.

When chemical, transport, or mechanical work is performed by an organism, what happens to the heat that is generated?

It is released to the environment.

Why might a severe fever result in death if it is not brought under control?

It may alter the tertiary and quaternary structures of cellular enzymes

Which one of the following statements about the endomembrane system is correct?

Proteins that will be secreted from the cell are likely to be found in closed spaces bounded by membranes of the endomembrane system.

Which of the following statements best describes the induced fit model of enzyme activity?

The binding of substrate changes the conformation of the active site to bind substrate more tightly.

The binding of a compound to an enzyme is observed to slow down or stop the rate of the reaction catalyzed by the enzyme. Increasing the substrate concentration reduces the inhibitory effects of this compound. Which of the following could account for this observation?

The compound is a competitive inhibitor.

Which of the following statements about ATP (adenosine triphosphate) is correct?

The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways.

Immediately after a membrane receptor protein binds to its ligand, which of the following processes occurs?

The membrane receptor protein undergoes a conformational change.

Which statement correctly describes the nuclear envelope of a eukaryotic cell?

The nuclear envelope is continuous with the endoplasmic reticulum.

Which of the following is an example of an anabolic pathway?

a set of reactions that combine monomers into larger, more energy-rich polymers