Ch 5 questions

All eukaryotic cells have __________, which convert energy stored in sugar to ATP.

mitochondria

Most of the cell's ATP is synthesized in the - nucleus - ribosomes - chloroplast - Golgi complex - mitochondria

mitochondria

In what manner do molecules such as proteins and RNA enter into or exit from the nucleus? - movement through pores in the nuclear envelope - osmosis through the lipid bilayers of the nuclear envelope - diffusion through the lipid bilayers of the nuclear envelope - breakdown of the nuclear envelope

movement through pores in the nuclear envelope Correct. Large pores made of proteins provide channels through which large molecules and even larger particles can enter into or exit from the nucleus.

Which of the following organelle(s) is (are) found in animal cells, but not in plant cells? - cell wall - central vacuole - cytoskeleton - chloroplasts - mitochondria - none of the above

none of the above

The __________ surrounds the nucleus in eukaryotic cells.

nuclear envelope

The DNA in a eukaryotic cell is contained within the __________.

nucleus

Which organelle contains a eukaryotic cell's chromosomes? - nucleus - Golgi complex - mitochondria - chloroplast - ribosomes

nucleus

Choose the substance that will diffuse most rapidly across the plasma membrane. - amino acid - sodium ion - glucose - oxygen

oxygen Oxygen is small and nonpolar and readily diffuses through the lipid bilayer.

Recognition proteins function to __________. - regulate the movement of ions across the cell membrane - bind hormones and alter the intracellular physiology of a cell - permit the cells of the immune system to distinguish between pathogens such as bacteria and cells of your own body - catalyze a chemical reaction

permit the cells of the immune system to distinguish between pathogens such as bacteria and cells of your own body Recognition proteins function to distinguish "self" from foreign cells.

Two types of connections between cells, called "gap junctions" and "plasmodesmata," are specialized to __________. - prevent the movement of molecules between cells that are tightly joined along ribbons of cell membrane - tightly hold one cell against another at focal points, almost like a spot weld of Superglue - permit the passage of substances (e.g., ions) between cells through small passageways that directly link the cytoplasm of one cell to the cytoplasm of another cell - allow for active transport of substances into the cell

permit the passage of substances (e.g., ions) between cells through small passageways that directly link the cytoplasm of one cell to the cytoplasm of another cell Substances can pass from one cell directly to the other through these intercellular bridges of cytoplasm that are continuous between cells.

Many metabolic poisons work by inhibiting ATP production. Which type of transport would be most affected? - osmosis - facilitated diffusion - active transport - simple diffusion

active transport Active transport requires cellular energy in the form of ATP.

The concentration of sodium ions is lower in the cytoplasm of a heart muscle cell than it is in the extracellular fluid. By what mechanism does the cell maintain this difference? - active transport - osmosis - facilitated diffusion - endocytosis

active transport Sodium ions must be constantly pumped out of the cell in order to maintain the concentration gradient.

The outermost boundary of an animal cell is the - cell wall - cytoplasm - nucleus - cytoskeleton - plasma membrane

plasma membrane

The function of the endoplasmic reticulum is to __________. - provide a barrier between the cytoplasm and extracellular fluid - synthesize lipids and proteins - modify and repackage newly synthesized lipids and proteins - serve as a recycling and digestive center for the cell

synthesize lipids and proteins Correct. The endoplasmic reticulum is capable of synthesizing lipid and protein components of a cell or organelle membrane.

In which of the following does one find ribosomes? - chloroplasts - mitochondria - animal cells - bacterial cells - plant cells - all of the above

- chloroplasts - mitochondria - animal cells - bacterial cells - plant cells

Which of the following would NOT have originated by endosymbiosis? - chloroplasts - mitochondria - flagella - lysosomes - The first two answers are correct.

- chloroplasts - mitochondria Correct. Biologists believe that mitochondria and chloroplasts both evolved from prokaryotic bacteria that became part of ancestral eukaryotic cells.

Which of the following structures are found in all cells? Select the best answer. - cell wall - plasma membrane - nucleus - cytoplasm - ribosomes - b, d, and e

- cytoplasm - ribosomes - plasma membrane

The endoplasmic reticulum is needed for __________. - detoxification - synthesis of lipids - synthesis of certain proteins - hormone synthesis - all of the above - none of the above

- detoxification - synthesis of lipids - synthesis of certain proteins - hormone synthesis

Which of the following generalizations can you make about the cytoskeleton? - They provide a type of cellular armor on the outside of cells that serve a protective function. - A variety of cytoskeletal elements are integral in the performance of numerous essential cellular functions. - The name implies a fixed structure like the bones of a vertebrate or 2 x 4 boards in the wall of a building. - all of the above

A variety of cytoskeletal elements are integral in the performance of numerous essential cellular functions.

What is the difference between active transport and passive transport? - Passive transport involves the movement of substances directly through the lipid portion of a membrane. Active transport requires an input of energy, whereas passive transport does not. - Active transport requires energy and is unable to move substances against their concentration gradient. Passive transport does not require energy and can move substances against their concentration gradient. - Active transport requires energy and can move substances against their concentration gradient. Passive transport does not require energy and can move substances only down their concentration gradient. - Passive transport involves the movement of substances through proteins embedded in the membrane. Active transport does not require the help of membrane proteins.

Active transport requires energy and can move substances against their concentration gradient. Passive transport does not require energy and can move substances only down their concentration gradient. Active transport requires energy and can move substances against their concentration gradient. Passive transport does not require energy and can move substances only down their concentration gradient.

Which organelle sorts, chemically modifies, and packages newly synthesized protein? - chloroplast - ribosomes - nucleus - Golgi complex - mitochondria

Golgi complex

Which of the following is NOT consistent with the cell theory? - Embryos are a result of mitotic division of a single fertilized egg. - A human is composed of trillions of cells. - Bacteria will multiply in food left out overnight on the counter. - Bacteria are the smallest living organisms. - Mitochondria and chloroplasts have their own DNA, and can reproduce.

Mitochondria and chloroplasts have their own DNA, and can reproduce.

A chloride ion is in a cell that has no channel proteins in its membrane. Will the chloride be able to get out of the cell? - Yes, the chloride ion has a concentration gradient from inside to outside, so it can diffuse out of the cell. - No, there is no channel through which to diffuse. - No, the chloride ion can only follow a concentration gradient to get into the cell. - No, there is no energy to move chloride across the membrane.

No, there is no channel through which to diffuse. A charged ion or molecule cannot diffuse down its concentration gradient without a channel to pass it through the hydrophobic portion of the membrane.

Which of the following is an INCORRECT statement concerning the general characteristics of prokaryotic cells? - Prokaryotic cells contain multiple molecules of DNA. - Prokaryotic cells contain cytoplasm. - Prokaryotic cells do not contain a nucleus. - Prokaryotic cells are enclosed by a cell wall. - Prokaryotic cells contain a nucleoid.

Prokaryotic cells contain multiple molecules of DNA. Correct. Prokaryotic cells have one DNA molecule, unlike eukaryotic cells, which contain multiple DNA molecules (one per chromosome).

A researcher has discovered an unusual organism deep in the crust of Earth. She wants to know whether it is prokaryotic or eukaryotic. Imagine that she has rapid tests to determine whether the following molecules are present: DNA, RNA, and the proteins that form microtubules. Which test would you advise her to use and why? [Hint] - Test for DNA, because only eukaryotes have a nucleus. - Test for microtubule proteins, because only eukaryotes have microtubules. - Test for RNA, because only eukaryotes have ribosomes.

Test for microtubule proteins, because only eukaryotes have microtubules. Correct. A distinguishing feature of eukaryotic cells is the presence of microtubules, which are made of microtubule proteins (called tubulin).

Imagine that you are studying cell structure in various organisms in your biology lab. Your instructor gives you a microscope slide showing two types of cells that have been suspended in pure water. One type of cell swells up until it bursts. The other cell maintains its shape throughout the experiment. Suggest an explanation for these observations. Assume that both cells were alive at the start of the experiment and that the concentration of water inside both types of cells is similar - The cell that burst lacked gap junctions, so water that entered the cell via osmosis could not leak back out through the junctions. - The cell that burst lacked a plasma membrane for regulating osmosis. - The cell that remained intact had plasmodesmata that allowed the excess water to leak out, thus balancing the tendency of water to enter the cell via osmosis. - The cell that remained intact had a contractile vacuole for pumping out the excess water that entered the cell via osmosis.

The cell that remained intact had a contractile vacuole for pumping out the excess water that entered the cell via osmosis.

Suppose a Paramecium, a freshwater protist, was placed in salt water. What would occur (assume the salt water is hypertonic to the Paramecium)? - The cell would swell up and burst. - The contractile vacuole would need to expel water more frequently. - The contractile vacuole would shrink. - All of the above are correct.

The contractile vacuole would shrink.

Lysosomes contain very powerful digestive enzymes that can break down proteins, carbohydrates, and other molecules. Why don't these enzymes digest the cell itself? - The enzymes will digest only foreign material. - The enzymes are inactive until secreted from the cell. - The enzymes are separated from the cytoplasm by the lysosomal membrane.

The enzymes are separated from the cytoplasm by the lysosomal membrane. Correct. The membrane segregates the enzymes so they do not harm the cell.

Imagine that you are late for a date and you reach your friend's door out of breath because you just ran the last three blocks from the bus stop. In a lame effort to impress and to try to make your date forget that you are half an hour late, you describe what oxygen is used for in your cells. Which of the following is correct? - The lysosomes in my muscle cells need this extra oxygen to digest sugars and provide me with energy for running. - The mitochondria in my muscle cells need the extra oxygen to produce sugars that, in turn, provide the energy I need to run. - The mitochondria in my muscle cells need this extra oxygen to break down sugars and produce the energy I need to run. The cellular enzymes in my leg muscles need this extra oxygen to repair the damage that occurs to my muscle cells as I run.

The mitochondria in my muscle cells need this extra oxygen to break down sugars and produce the energy I need to run. Correct. Mitochondria capture chemical energy gained by breaking down sugars and use that energy to produce ATP. The ATP can then provide energy for cellular processes such as muscle contraction.

If there is a high concentration of oxygen on one side of a biological membrane, what will happen? - The oxygen will stay on the one side because it cannot cross the membrane. - The oxygen will diffuse across the membrane until the concentration of oxygen on each side is the same. - The oxygen will be actively transported across the membrane. - Oxygen will be carried across the membrane by a protein.

The oxygen will diffuse across the membrane until the concentration of oxygen on each side is the same. This will happen only while there is a concentration gradient.

Which of the following characteristics of mitochondria are true? - They are able to directly convert solar energy into high-energy sugar molecules. - They release oxygen during the process of aerobic metabolism. - All metabolic conversion of high-energy molecules (e.g., glucose) to ATP occurs within the mitochondria. - They are able to take energy from food molecules and store it in high-energy bonds of ATP.

They are able to take energy from food molecules and store it in high-energy bonds of ATP. Correct. This is done utilizing a series of enzymes within the intermembrane compartment.

A cell is placed in a hypotonic solution. What will happen? - Water will move out of the cell. - Water will move into the cell. - There will be no net movement of water. - It is impossible to predict the movement of water.

Water will move into the cell. The concentration of water is higher outside the cell, and the water follows a concentration gradient.

Facilitated diffusion requires __________. - a membrane transport protein - a concentration gradient - energy - a membrane transport protein and a concentration gradient

a membrane transport protein and a concentration gradient Facilitated diffusion requires a membrane transport protein and a concentration gradient.

A hormone circulating in the bloodstream would most likely bind to __________. - a recognition protein - a receptor protein - a channel protein - protein filaments in the cytoplasm

a receptor protein Receptor proteins trigger cellular responses when specific molecules, such as hormones, bind to them.

The cell theory states that __________. - all living things are composed of cells - all cells contain cytoplasm - cells are generally small to allow for diffusion - all cells arise from organic molecules such as DNA - cells are either prokaryotes or eukarotes

all living things are composed of cells

Diffusion is the movement of molecules from __________. - an area of higher concentration of that type of molecule to an area of lower concentration - an area of lower concentration of that type of molecule to an area of higher concentration - outside the cell to inside the cell - inside the cell to outside the cell

an area of higher concentration of that type of molecule to an area of lower concentration Diffusion moves molecules from an area of high concentration to an area of low concentration.

Due to a high percentage of unsaturated fatty acids in their membrane, certain microorganisms _____. - are able to withstand high temperatures because their membranes are firmer - are able to withstand low temperatures because their membranes do not solidify as rapidly - are able to carry out sodium ion transport more efficiently than most organisms - are more rapidly recognized and destroyed by cells of the immune system

are able to withstand low temperatures because their membranes do not solidify as rapidly The double bonds in unsaturated fatty acids increase the fluidity of the membrane.

The smallest type of cell are mycoplasmas, which have a diameter between 0.1 micrometer and 1.0 micrometer. Mycoplasmas most likely are __________. - fungi - bacteria - viruses - plant cells - animal cells

bacteria Mycoplasmas are bacteria.

Which of the following processes does a cell use to take up molecules against their concentration gradient? - simple diffusion - facilitated diffusion - active transport - endocytosis - both active transport and endocytosis

both active transport and endocytosis Both active transport and endocytosis are used to move molecules across membranes against their concentration gradients.

If the nucleus is the control center of the cell, how is information encoded and shipped to the cytoplasm? - by nuclear pores - by chromosomes - by RNA - by the nucleolus

by RNA Correct. Genetic directions from DNA are transcribed as RNA which is moved through the nuclear pores to the cytoplasm, where it is used for the translation of proteins.

Both __________ are slender extensions of the cell membrane that move the cell through fluid or move fluid past the cell.

cilia flagella

Which of the following associations is not correct? - gap junctions-allow communication between animal cells - plasmodesmata-allow communication between plant cells - desmosomes-allow inflexible attachments among cells - tight junctions-create watertight junctions between cells

desmosomes-allow inflexible attachments among cells Desmosomes allow for flexible attachments among cells.

Which of the following transport processes require(s) energy? - facilitated diffusion - osmosis - endocytosis - facilitated diffusion and osmosis - facilitated diffusion, osmosis, and endocytosis

endocytosis Endocytosis is an energy-requiring process.

The __________ forms membrane enclosed channels within the cell.

endoplasmic reticulum

Prokaryotic cells do not contain __________. - cell walls - endoplasmic reticulum - DNA - ribosomes - cytoplasm

endoplasmic reticulum Prokaryotic cells do not contain internal membranes.

Which of the following correctly lists organelles that are part of the internal membrane system of eukaryotic cells? - endoplasmic reticulum, Golgi apparatus, and cell wall - endoplasmic reticulum and mitochondria - Golgi apparatus and nucleus - endoplasmic reticulum, Golgi apparatus, and lysosomes

endoplasmic reticulum, Golgi apparatus, and lysosomes Correct. These organelles are part of the internal membrane system.

During endocytosis, the contents of the endocytic vesicle ________. - enter the cell - exit the cell - enter or exit the cell, always moving down a concentration gradient - become part of the plasma membrane

enter the cell Cells can take up certain molecules by the process of endocytosis.

Why are living cells limited to remaining microscopic in size? - cells produce a limited number of enzymes - the energy needs of giant cells would outstrip available supply from the environment - exchanges of substances at the membrane surface would take too long to diffuse throughout the interior of the cell - both a and b

exchanges of substances at the membrane surface would take too long to diffuse throughout the interior of the cell Correct. The net diffusion rate of substances in an aqueous environment (i.e., the cytoplasm of a cell) is so slow that the diffusion distances must be very small (on the order of a few micrometers) or cells would be unable to distribute nutrients within a cell, or remove wastes that are produced.

Which of the following lists the correct order in which newly synthesized proteins are delivered to the plasma membrane? - from the endoplasmic reticulum to lysosomes to the Golgi apparatus to the plasma membrane - from the Golgi apparatus to the endoplasmic reticulum to the plasma membrane - from the endoplasmic reticulum to the Golgi apparatus to lysosomes to the plasma membrane - from the endoplasmic reticulum to the Golgi apparatus to the plasma membrane - from the endoplasmic reticulum to the plasma membrane

from the endoplasmic reticulum to the Golgi apparatus to the plasma membrane

When placed in a certain sucrose solution, the volume of a cell decreases; therefore, the sucrose solution is _____ to the cell contents. - isotonic - hypertonic - hypotonic

hypertonic Cell shrinking is due to a net movement of water out of the cell from an area of high water concentration to an area of low water concentration.

Plasmids are located __________. - in the nucleolus - continuous with the nuclear envelope - in the nucleus - in the cytoplasm

in the cytoplasm

Membrane fluidity within a phospholipid bilayer is based upon __________. - interactions among nonpolar (hydrophobic) lipid tails - hydrophilic interactions among polar phospholipid heads - the presence of transport proteins in the lipid bilayer - the presence of water in the lipid bilayer

interactions among nonpolar (hydrophobic) lipid tails Phospholipid tails are hydrophobic and face the interior of the membrane. Individual phospholipid molecules are not bonded to one another.

The plasma membrane of the cell __________. - is permeable to water - is impermeable to water - is permeable to all charged molecules - is permeable to all large molecules

is permeable to water Water can freely cross the plasma membrane.

The point at which a substance is evenly dispersed within a fluid __________. - is referred to as dynamic equilibrium - occurs when random movements of the substance cease - happens when net diffusion is zero - is referred to as dynamic equilibrium and happens when net diffusion is zero

is referred to as dynamic equilibrium and happens when net diffusion is zero These are both principles of diffusion.

Membrane-enclosed digestive organelles that contain enzymes are called - mitochondria - Golgi complex - smooth endoplasmic reticulum - cilia - lysosomes

lysosomes

Prokaryotic cells __________. - are large cells, typically greater than 10 mm in diameter - include numerous membrane-enclosed structures known as organelles - possess a single strand of DNA, but no definable membrane-enclosed nucleus - all of the above

possess a single strand of DNA, but no definable membrane-enclosed nucleus Correct. Prokaryotic DNA is organized into a region known as a nucleoid.

Chromosomes consist of __________. - RNA - proteins and DNA - DNA - proteins - proteins and RNA

proteins and DNA Correct. Chromosomes consist of a single DNA double helix wound around proteins.

Which type of cell would you expect to burst when placed in a hypotonic solution? - plant cell - Paramecium (a type of protist) - bacteria - red blood cell

red blood cell A red blood cell lacks a mechanism to deal with the influx of water in a hypotonic environment so it will burst.

The __________ carry out the process of protein synthesis.

ribosomes

A series of membrane-enclosed channels studded with ribosomes are called - rough endoplasmic reticulum - smooth endoplasmic reticulum - mitochondria - lysosomes - Golgi complex

rough endoplasmic reticulum

Each substance needs a different type of transport to get into a cell. Pick the answer choices that accurately match the type of transport needed to convey each of the following substances into a cell. oxygen, water, sodium ions, potassium ions, bacteria (Note that sodium ions are more concentrated outside cells than inside; potassium ions are more concentrated inside cells than outside.) - simple diffusion, osmosis, facilitated diffusion, active transport, exocytosis - osmosis, simple diffusion, facilitated diffusion, active transport, endocytosis - passive transport, osmosis, simple diffusion, facilitated diffusion, active transport - simple diffusion, osmosis, facilitated diffusion, active transport, endocytosis - endocytosis, active transport, active transport, facilitated diffusion, exocytosis

simple diffusion, osmosis, facilitated diffusion, active transport, endocytosis This answer correctly matches the type of transport with the substance being moved.

Which of the following types of molecules must pass through membranes via the pores formed by membrane proteins? - gases such as carbon dioxide and oxygen - water - large particles such as bacteria - small charged ions such as Na+ and Ca++

small charged ions such as Na+ and Ca++ Ions alone are small, but because they are surrounded by a shell of water, they are too large to pass between the lipid tails of the bilayer and must move through pores in the membrane formed by proteins.

Substances are able to cross the lipid bilayer of a cell at different rates that are unique for each substance. Which of the following characteristics would favor the simple diffusion of a substance across a cell membrane? - low lipid solubility - small molecule size - small concentration gradients - the number of membrane transport proteins for the substance

small molecule size The smaller the molecule, the more likely it will be able to pass across the lipid bilayer via simple diffusion.

Which organelle would you expect to be in abundance in the liver of a drug addict? - ribosome - rough endoplasmic reticulum - nucleolus - smooth endoplasmic reticulum - Golgi complex

smooth endoplasmic reticulum

Sorting and modification of proteins is an important function of __________. - the Golgi complex - mitochondria - chloroplasts - lysosomes - the plasma membrane

the Golgi complex Correct. The Golgi complex receives protein cargo from the endoplasmic reticulum and then modifies it and sorts it into vesicles that are targeted to different destinations, including the plasma membrane and lysosomes.

In osmosis, water diffuses from the side of the membrane with a higher concentration of water to the side with a lower concentration of water. What determines the concentration of water in a solution? - the volume of the solution - the amount of molecules other than water dissolved in the solution - the size of the container - the temperature of the water

the amount of molecules other than water dissolved in the solution Water is less concentrated in solutions in which many other molecules are dissolved than in solutions with few other dissolved molecules.

The fluid mosaic model describes membranes as fluid because __________. - the phospholipids of membranes are constantly moving from one layer to the other layer - the membrane is composed mainly of water - the phospholipid molecules are bonded to one another, allowing them to move - the phospholipids move from place to place around the motionless membrane proteins - the phospholipids and proteins move from place to place within the bilayer

the phospholipids and proteins move from place to place within the bilayer The adjacent phospholipids are not chemically bonded to one another, so both the phospholipids and the molecules embedded in the membrane are free to "float" around relative to one another, unless they are anchored to cytoskeletal elements below the membrane.

When a drop of food coloring is placed in a glass of water, the spreading out of the molecules of food dye is caused by __________. - the concentration of the molecules of dye - the molecules trying to move to a lower concentration - structure - the random movement of molecules - osmosis

the random movement of molecules Molecules of dye are randomly moving; collisions between dye molecules are more frequent when the molecules are in high concentrations.

In certain types of genetic engineering, DNA is injected into the nucleus of a recipient animal cell. What is the fewest number of membranes that must be pierced by the microscopic needle in order to inject the DNA? (Note that the needles used are not small enough to pass through a nuclear pore.) - one - two - three

three

Which cell junctions function to make the connections between cells leakproof? - desmosomes - tight junctions - gap junctions - plasmodesmata

tight junctions These are the types of junctions found in tissues such as the bladder, where the tissue must be waterproof.