Biology 1001-Ch.5

What is one feature all receptor proteins must share? - Receptor proteins must anchor to the cytoskeleton inside the cell. - All receptor proteins must be glycoproteins modified in the golgi apparatus. - All receptor proteins must span the cell membrane, having a portion outside the cell and a portion inside. - Receptor proteins must be of the proper type in order for the immune system to ignore them, such as in an organ donation. - All receptor proteins must respond to the same chemical messages, allowing each cell to respond to the same signal.

All receptor proteins must span the cell membrane, having a portion outside the cell and a portion inside. If receptors were only attached to the surface, they couldn't send a signal further into the cell.

Cell A has no membrane proteins at all. Cell B has aquaporin membrane proteins. Both cells are placed in a hypertonic solution. What will happen? - Cell B swells faster than cell A. - Cell B remains the same and cell A shrivels. - Cell B swells and cell A remains the same. - Cell B shrivels faster than cell A. - Cell B shrivels and cell A remains the same. - Cell B shrivels more slowly than cell A.

Cell B shrivels faster than cell A. Both cells lose water, but cell B loses it faster due to the presence of aquaporins.

What causes a plant to wilt? - The cells lose turgor pressure. - The cells lose salt. - The cells die. - The cells run out of sugar.

The cells lose turgor pressure. Plant cells with too little water in them shrink away from the cell wall due to loss of turgor pressure.

How does the plasma membrane stop most substances from crossing it? - The phosphate heads form hydrogen bonds with one another and form a solid barrier to substances. - The interlocking lipid tails form a solid barrier to substances. - The non-polar phosphate heads form a barrier to polar substances. - The non-polar fatty acid tails form a barrier to polar substances.

The non-polar fatty acid tails form a barrier to polar substances. Ions and polar molecules cannot cross the non-polar interior of the membrane.

What do gap junctions, tight junctions, and desmosomes have in common with each other, but not with plasmodesmata? - They create waterproof attachments. - They connect the cytoplasm of adjacent cells. - They prevent movement of fluids and molecules in between cells. - They allow exchange between cells. - They are made of protein. - They anchor the cytoskeleton of one cell to another.

They are made of protein. Animal cells make greater use of proteins for structures than plant cells, so it makes sense that cellular these three animal cell junctions would be protein based.

Which direction is water most likely to move? - Water will move out of a hypotonic solution into a hypertonic solution. - Water will move from outside a cell towards the inside. - Water will move out of a hypertonic solution into a hypotonic solution. - Water will move from an isotonic solution to a hypotonic solution. - Water will move from a higher solute concentration towards a lower solute concentration.

Water will move out of a hypotonic solution into a hypertonic solution. Water is more likely to move from low solute concentration to high solute concentration.

When can a cell transport a molecule across the cell membrane without expending energy? - When the molecule is large. - When the molecule matches a channel in the cell. - When the molecule is ATP. - When the molecule is small and charged. - When the molecule matches a surface receptor. - When the molecule is more concentrated outside the cell.

When the molecule is more concentrated outside the cell. Osmosis Moving a molecule down a concentration gradient takes no energy.

Which of the following is most like a gap junction? - an intermediate filament - a desmosome - a plasma membrane - a nuclear envelope - a nuclear pore - a vesicle

a nuclear pore Gap junctions and nuclear pores are both channel proteins that cross between membranes.

The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of - active transport. - facilitated diffusion. - exocytosis. - passive transport. - diffusion.

active transport. The sodium-potassium pump moves ions across the plasma membrane against their concentration gradients. This requires energy and is an example of active transport.

Which of the following would be likely to raise the concentration of calcium ions in a cell? - blocking endocytosis - blocking aquaporins - blocking exocytosis - blocking pinocytosis - blocking surface receptors - blocking ATP binding sites

blocking ATP binding sites (Cells use active transport and ATP in order to maintain a low calcium ion concentration inside.)

The primary role of _____ is to bind animal cells together. - plasmodesmata - desmosomes - the cytoskeleton - gap (communicating) junctions - tight junctions

desmosomes The primary role of desmosomes (anchoring junctions) is to bind cells together.

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of - active transport. - endocytosis. - exocytosis. - diffusion. - passive transport.

endocytosis In endocytosis, the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.

Which membrane proteins increase the rate of chemical reactions? - reactive proteins - attachment proteins - chemical proteins - receptor proteins - enzymatic proteins

enzymatic proteins These are enzymes attached to the inner face of the plasma membrane.

_____ is the movement of intracellular vesicles to the plasma membrane, where they fuse with the membrane and release their contents into the surrounding fluid. This process occurs predominantly in secretory cells, such as mucus-producing cells or pancreatic cells, that secrete enzymes into the digestive tract. - facilitated diffusion - exocytosis - osmosis - phagocytosis - endocytosis

exocytosis A membranous vesicle is fusing with the plasma membrane and releasing its contents into the extracellular fluid.

A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of - exocytosis. - active transport. - diffusion. - endocytosis. - facilitated diffusion.

facilitated diffusion In facilitated diffusion, molecules use a transport protein to move across the plasma membrane. There is a net movement of molecules down the concentration gradient -- that is, there is a net movement of molecules from where they are more concentrated to where they are less concentrated.

Which type of transport requires assistance from membrane proteins, but no energy? - simple diffusion - exocytosis - active transport - facilitated diffusion - simple osmosis - endocytosis

facilitated diffusion This form of passive transport requires a transport protein, but since it only works if you can move the substance down a concentration gradient, it does not require energy.

What is the word for membrane proteins that have carbohydrates attached to them? - carbopeptide - proteinoglucose - carboprotein - glycoprotein - glucosoprotein - peptidoglycan

glycoprotein Glycoproteins are a protein with a carbohydrate group attached.

Endocytosis moves materials _____ a cell via _____. - out of ... diffusion - into ... a transport protein - into ... facilitated diffusion - into ... membranous vesicles - out of ... membranous vesicles

into ... membranous vesicles The prefix "endo-" means "inward."

Where can the phosphate portion of the phospholipids in a membrane be found? - on the surface facing outside, the surface facing inside, or in between the lipid bilayers - inside the membrane, isolated from water - in between the lipid bilayers - on the surface, facing the outside liquid or the cytoplasm inside - on the surface, facing the inside cytoplasm - on the surface, facing the outside liquid

on the surface, facing the outside liquid or the cytoplasm inside The phosphate head is hydrophilic, therefore it will either face the water outside the cell or the water inside the cell

What name is given to the process by which water crosses a selectively permeable membrane? - phagocytosis - passive transport - pinocytosis - osmosis - diffusion

osmosis Osmosis is the passive transport of water.

A cell has no membrane proteins at all. Which substance will diffuse across the membrane fastest? - Na+ - glucose - oxygen - H2O - Cl-

oxygen Dissolved oxygen gas is small enough to diffuse through the membrane unassisted.

In _____, or "cell eating," the cell engulfs debris, bacteria, or other sizable objects. Phagocytosis occurs in specialized cells called phagocytes, which include macrophages, neutrophils, and other white blood cells. Invagination produces a vacuole, which usually fuses with one or more lysosomes containing hydrolytic enzymes. Materials in the vacuole are broken down by these enzymes and degraded. - facilitated diffusion - exocytosis - receptor-mediated endocytosis - diffusion - phagocytosis

phagocytosis Phagocytosis involves the engulfing of large particles.

Some white blood cells in the human body are able to engulf bacteria and destroy them. What should this engulfing process be called? - receptor-mediated endocytosis - exocytosis - phagocytosis - pinocytosis - endocytosis - secretion

phagocytosis A large particle, like another cell, must always be brought in by phagocytosis.

Why can't cells the size of golf-balls exist? - A cell that large would be too hypertonic to prevent swelling. - A cell that large would not have enough energy inside it to run. - A cell that large would not have enough surface area to use in exchanging materials. - A cell that large would collapse under its own weight. - A cell that large wouldn't have enough volume to conduct chemical reactions.

A cell that large would not have enough surface area to use in exchanging materials. The larger the cell, the more nutrients it needs to pull in and the more waste in needs to expel. The volume outgrows the available surface area quickly.

Patients with cystic fibrosis have a variety of symptoms, including congestion in the lungs from a thick mucous, liver blockage by thickened bile, and excessively salty sweat. Based on these symptoms, what would you guess to be the cause of cystic fibrosis? - Failure of aquaporins causes water imbalances. This causes problems with diffusion of salt. - Failure of receptor-mediated endocytosis results in more sugar in the extracellular fluid, making it and all secretions hypertonic. - Failure of exocytosis prevents mucous, bile, and sweat from being secreted from cells. - Failure of tight junctions allows water to leak into the lungs, liver, and sweat glands. - Failure of an ion transporter causes salt imbalances. This causes problems with osmosis.

Failure of an ion transporter causes salt imbalances. This causes problems with osmosis. In patients with cystic fibrosis, a chloride ion transporter is faulty. Imbalances in sodium and chloride cause water to leave mucous and liver secretions, making them thick. As chloride accumulates outside of the skin sodium is transported out, making the sweat very salty.

_____ aid in the coordination of the activities of adjacent animal cells. - Tight junctions - Gap (communicating) junctions - Keratin fibers - Desmosomes - Plasmodesmata

Gap (communicating) junctions Gap junctions allow for the passage of material between cells, thus facilitating communication between these cells.

How does a freshwater Paramecium counteract osmosis? - It pumps salt out of a contractile vacuole, drawing excess water in to be squeezed out of the cell. - It pumps water out of the cell by facilitated diffusion. - It pumps salt into a contractile vacuole, drawing excess water in to be squeezed out of the cell. - It pumps salt out of a contractile vacuole, drawing more water into the cell for storage. - It pumps salt into a contractile vacuole, drawing more water into the cell for storage.

It pumps salt into a contractile vacuole, drawing excess water in to be squeezed out of the cell. Pumping salt into the contractile vacuole causes water to flow into it and be pumped out of the cell when the vacuole squeezes.

Vibrio cholerae causes severe diarrhea in its victims. How might it cause this to occur? - It tricks the cells of the intestines into absorbing water. - It tricks the cells of the intestines into hardening their desmosomes. - It tricks the cells of the intestines into secreting ions. - It tricks the cells of the intestines into secreting water. - It tricks the cells of the intestines into absorbing ions. - It tricks the cells of the intestines into releasing their desmosomes.

It tricks the cells of the intestines into secreting ions. Water follows the ions into the intestines by osmosis, causing a watery bowel

Cells are rarely large enough to be visible due to restrictions of area/volume. How then can neuron cells reach lengths of up to several feet? - Neurons store extra nutrients to minimize exchange with the extracellular fluid. - Neurons have extra transport proteins to carry out the work. - Neurons have more surface area than spherical cells because they are long and thin. - Neurons have less volume than most cells. - Neurons are not growing, so don't need to exchange materials. - Neurons do not need as much surface area as other cells.

Neurons have more surface area than spherical cells because they are long and thin. A long, thin cell still has plenty of surface area for materials exchange.

If the cytoplasmic fluid of cells in a houseplant were to become very salty, what would happen inside those cells? - The vacuoles would stay the same and the cells would maintain turgor pressure. - The vacuoles would shrivel, but the cells would maintain turgor pressure. - The vacuoles would swell and the cells would have an increase in turgor pressure. - The vacuoles would shrivel and the cells would lose turgor pressure. - The vacuoles would shrivel, but the cells have an increase in turgor pressure.

The vacuoles would shrivel, but the cells would maintain turgor pressure. The cells would not lose turgor pressure, even though the vacuoles would lose water to the cytoplasmic fluid.

What do channel proteins, aquaporins, and carrier proteins have in common? - They all transport molecules up the concentration gradient. - They all perform facilitated diffusion. - They all perform active transport. - They all perform in osmosis. - They all require ATP to function.

They all perform facilitated diffusion. No energy is expended when these membrane proteins allow their target molecules through.

Which of these is hydrophobic like the interior of the plasma membrane? - glucose - lipid soluble molecule - water - Hydrogen Ion - Glucose and Hydrogen Ion

lipid soluble molecule Hydrogen ions are charged and hydrophilic, not hydrophobic.

In active transport, - molecules move across the plasma membrane against their concentration gradient. - no energy input is required from the cell. - the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. - a vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell. - molecules move across the plasma membrane by crossing the lipid bilayer directly, rather than by using a transport protein.

molecules move across the plasma membrane against their concentration gradient. Molecules move against their concentration gradient in active transport.

A white blood cell engulfing a bacterium is an example of _____. - receptor-mediated endocytosis - facilitated diffusion - phagocytosis - exocytosis - pinocytosis

phagocytosis Phagocytosis occurs when a cell engulfs a large particle.

Thermus aquaticus is a species of archaebacteria that grows in steaming hot springs. What would you expect to find in the plasma membrane of this species? - phospholipids with saturated fatty acid tails - more membrane proteins - outer coating of protective proteins - thicker than normal cell wall - phospholipids with less polar heads

phospholipids with saturated fatty acid tails The saturated fatty acids would keep the membrane from melting apart at high temperatures.

Which of these allows hormones to pass from one plant cell to another? - vacuoles - plasmodesmata - desmosomes - tight junctions - gap junctions - channel proteins

plasmodesmata Plasmodesmata play a crucial role in transporting materials and signaling molecules intercellularly in higher plants. Plasmodesmata connect the cytoplasm of two plant cells, allowing substances to pass from one cell to another.

What simple property causes molecules to diffuse from high concentration towards a lower concentration? - random motion of molecules - gravitation down a gradient - attraction to the solvent - concentration of like molecules - repulsion by other solutes - repulsion of like molecules

random motion of molecules osmosis Molecules randomly moving causes them to spread out, balancing out concentration gradients.

Unlike phagocytosis and pinocytosis, ______ is very specific. It is triggered when membrane receptors bind to specific external molecules, such as protein-cholesterol complexes or proteins bound to iron. Membrane vesicles pinch off, and the external protein and its cargo are brought into the cell. - facilitated diffusion - exocytosis - receptor-mediated endocytosis - diffusion - phagocytosis

receptor-mediated endocytosis A receptor protein is involved in this process.

Which method of transport can a cell use to bring in molecules without allowing them to pass through the plasma membrane? - active transport - facilitated diffusion - receptor-mediated endocytosis - osmosis

receptor-mediated endocytosis The end-result of this process pulls the membrane itself into a vesicle. The molecule never passes through the membrane.

Which of the following scenarios is most similar to desmosomes? - short straws connecting two cups - a hammock woven from nylon rope - staples holding together two pieces of paper - stitching in a seam - glue holding together plastic toy parts - a tire with a slow leak

staples holding together two pieces of paper Desmosomes are a strong attachment between two cells.

Water crosses the plasma membrane - using a process that requires energy from the cell. - against its concentration gradient. - through active transport. - through cotransport. - through facilitated diffusion or diffusion.

through facilitated diffusion or diffusion. Water can cross the plasma membrane through the process of facilitated diffusion. However, water molecules can also cross the lipid bilayer directly.

Which type of connection would you expect to find between cells of the blood vessels? - desmosomes - plasmodesmata - tight junctions - gap junctions

tight junctions These are found anywhere in the body that a waterproof layer is needed. They perform three vital functions: They hold cells together. They prevent the passage of molecules and ions through the space between cells. So materials must actually enter the cells (by diffusion or active transport) in order to pass through the tissue. This pathway provides control over what substances are allowed through. Tight junctions play a role in maintaining the blood-brain barrier.

Which of these cell junctions form a barrier to the passage of materials? - gap (communicating) junctions - keratin fibers - tight junctions - plasmodesmata - desmosomes (anchoring junctions)

tight junctions Tight junctions form a barrier that prevents fluids from moving between cells.

Which of these would you add to a membrane to make it easier for membrane proteins to move about? - hydrophilic membrane proteins - hydrophobic membrane proteins - cholesterol - unsaturated phospholipids - hydrophilic cellulose - saturated phospholipids

unsaturated phospholipids Phospholipids are the "fluid" part of the fluid mosaic model and unsaturated phospholipids are the most fluid.

As a cell gets larger, which measurement of the cell increases the fastest? - area/volume - radius - surface area - volume

volume Volume grows as a cube of the radius and is the fastest growing number as size increases.