AP Biology Unit 2

flaccid

(adj.) limp, not firm; lacking vigor or effectiveness

nucleolus

region of the nucleus where ribosomal RNA (rRNA) is synthesized and complexes with proteins to form ribosomal subunits

cilia

- usually much shorter and more numerous than flagella - cilia can be used in locomotion or, when held in place as part of a tissue layer, can move fluid over the surface of the tissue - example: the lining of the trachea moves mucus-trapped debris out of the lungs in this manner

hypotonic solution

- water will enter the cell faster than it leaves - fewer solutes in the water around the cell hence the movement of water into the cell where solutes are mor heavily concentrated - the cell will swell and may burst

four sweet potato cores were placed in solutions of varying concentrations and were found to neither gain nor lose mass in a sucrose solution of 0.42M. What is the molarity of the cores?

B) 0.42M the sweet potato cores would have the same molarity as the solution in which they are at osmotic equilibrium

which of the following are common traits of chloroplasts and mitochondria?

B) both have their own DNA a common feature of mitochondria and chloroplasts is they both have their own DNA and ribosomes. both are surrounded by a double membrane, mitochondria are found in both animal and plant cells while chloroplasts are found only in plant (and algae) cells

based on the figure, how might the rate of sucrose into the cell be increased?

B) decrease the extracellular pH decreasing the extracellular pH (for example, going from pH 7 to pH 6) would increase the H+ ion concentration, providing more H+ ions for cotransport as well as a steeper gradient into the cell

Large molecules are moved out of the cell by which of the following processes?

B) exocytosis large molecules are moved out of the cell by exocytosis. in exocytosis, vesicles that are to be exported from the cell (often coming from the golgi apparatus) fuse with the plasma membrane, and their contents are expelled into the extracellular matrix. vesicles are involved in exocytosis, but vesicles are a structure-not a process

look at the same figure but assume the membrane is not freely permeable to both glucose (C6H12O6) and sucrose (C12H22O11) but only to the smaller of the two sugars. using the same scenario, what results would you predict?

B) glucose will diffuse from side B to side A glucose is the smaller molecule. because its highest concentration is on side B, it will move to side A. the experimental conditions changed, but the outcome was the same

salivary glands produce a large quantity of enzymes that are transported out of the secretory cells. Which of the following organelles would be in abundance in these cells?

B) golgi apparatus centered on proteins for export, which would require an extensive golgi apparatus network

the endosymbiont theory is supported by all the following pieces of evidence except the fact that

B) mitochondria use ATP like prokaryotes because prokaryotes and eukaryotes use ATP, choice B does not provide evidence for the endosymbiotic hypothesis.

Americans spend up to $100 billion annually for bottled water (41 billion gallons). The only beverages with higher sales are carbonated soft drinks. Recent news stories have highlighted the fact that most bottled water comes from municipal water supplies (the same source as your tap water), although it may undergo an extra purification step called reverse osmosis. Imagine two tanks that are separated by a membrane that's permeable to water, but not to the dissolved minerals present in the water. Tank A contains tap water and Tank B contains the purified water. Under normal conditions, the purified water would cross the membrane to dilute the more concentrated tap water solution. In the reverse osmosis process, pressure is applied to the tap water tank to force the water molecules across the membrane into the pure water tank. After the reverse osmosis system has been operating for 30 minutes, the solution in tank A would

C) be hypertonic to tank B The solution in tank A started with more solutes; then, as the water is purified, its concentration of solutes increases through the process of reverse osmosis. tank A becomes increasingly hypertonic over the course of the purification treatment.

which two figures show a cell that is hypertonic to its environment

C) cells A and D in plant cells, the relatively inelastic cell wall exerts a back pressure on the cells, called turgor pressure. in cell D, the plant cell is immersed in a hypotonic solution, causing the cell to uptake water, thus creating the highest levels of turgor pressure. animal cell A lyses ("pops") because it has only a thin, flexible plasma membrane

prokaryotic and eukaryotic cells have all the following structures in common EXCEPT

C) linear chromosomes linear chromosomes are the only cell structure not found in both prokaryotes and eukaryotes. eukaryotic cells have a true nucleus, which has linear chromosomes surrounded by a double membrane called a nuclear envelope. the genetic material of prokaryotes is localized in a clump in one particular region of the cell without a nuclear envelope, with the main chromosome as a single molecule of circular DNA

membrane bound structures that contain hydrolytic enzymes and are found predominantly in animal cells

C) lysosomes lysosomes are characteristic of animal cells but not most plant cells. they are membrane-bound structures that contain hydrolytic enzymes, and they are responsible for the breakdown (lysis) of proteins, polysaccharides, fats, and nucleic acids. they function best at a low pH (around 5), so they pump hydrogen ions from the cytosol into their lumen to achieve acidic pH

white blood cells (WBCs) are more resistant to lysis than are red blood cells (RBCs). when looking at a sample of blood for WBCs, what could you do to reduce interference from RBCs?

C) mix the blood in a hypotonic solution, which will cause the RBCs to lyse Cell A in the figure demonstrates what happens when red blood cells are placed in a hypotonic solution. with the RBCs destroyed, the WBCs will be easier to observe

use the information in question 17 to calculate the solute potential of the potato cores to the nearest hundredth. the temperature of the solutions is 25C

D) -10.40 bars the formula of solute potential is -iCRT. in this case the values are -(1)(0.42)(0.0831)(298) = -10.40 bars. sucrose does not ionize, which makes the value of i in the formula 1.

cells of the pancreas will incorporate radioactively labeled amino acids into proteins. this "tagging" of newly synthesized proteins enables a researcher to track their location. predict the most likely pathway of an enzyme secreted by pancreatic cells

D) ER --> golgi apparatus --> vesicles that fuse with the plasma membrane the radioactive tracking starts with the formation of the protein, which occurs on the ER. the protein then moves to the golgi and out of the cell via vesicles that will fuse with the membrane

bound ribosomes

attached to the outside of the endoplasmic reticulum and make proteins destined for export from the cell

osmosis

the diffusion of water across a selectively permeable membrane

exocytosis

vesicles from the cell's interior fuse with the cell membrane, expelling their contents

chromatin

- The complex of DNA and proteins that makes up eukaryotic chromosomes - When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope - as a cell gets ready for cell division, the diffused threads of chromatin condense into visible chromosomes

hypertonic solution

- a cell will lose water to its surroundings - more solutes in the water around the cell hence the movement of water to the higher (hyper) concentration of solutes - the cell loses water to the environment, shrivels, and may die

cholesterol

- a hydrophobic steroid primarily found imbedded in animal membranes where it helps membranes resist changes in fluidity when the temperature changes - at higher temperatures, cholesterol makes the membrane less fluid, while at cooler temperatures, cholesterol helps the membrane retain its fluidity

passive diffusion

- a substance travels from where it is more concentrated to where it is less concentrated/diffusing down its concentration gradient - hydrocarbons, carbon dioxide, and oxygen (O2) are hydrophobic substances that can pass easily across the cell membrane by passive diffusion - does not require work to be done and relies only on the thermal motion energy intrinsic to the molecule in question

surface-area-volume ratio

- becomes less favorable as a cell increases in size - the total volume grows proportionately more than the surface area resulting in a decrease in the surface area to volume ratio - because a cell acquires resources through the plasma membrane (diffusion), cell size is limited

microfilaments

- composed of the protein actin - much smaller than microtubules - microfilaments function in smaller-scale support - examples: amoeboid movement, cytoplasmic streaming, and contraction of muscle cells

nucleus

- contains most of the cell's DNA - within the nucleus, DNA is the template to make messenger RNA (mRNA), which contains the code to produce a protein - surrounded by a double membrane (nuclear envelope) that has pore structures that regulate what may enter or leave the nucleus

carbohydrates

- crucial in cell-cell recognition which is important in the sorting of cells into tissues in an animal embryo and is also the basis for rejection of foreign cells by the immune system - membrane carbohydrates are short, branched chains of fewer than 15 sugar units

sodium potassium pump

- example of active transport - the transmembrane protein pumps sodium out of the cell and potassium into the cell - necessary for proper nerve transmission and is a major energy consumer in the body

Plasma membrane

- forms the boundary for a cell - it is selectively permeable and permits the passage of selected materials into and out of the cell - made up of phospholipids, proteins, carbohydrates, and cholesterol that determine the functions of the membrane - primary component of cell walls is the carbohydrate cellulose - cell wall is perforated by plasmodesmata (channels that connect plant cells and allow communication and movement of materials between cells) - phospholipids and proteins held together by weak interactions that cause the membrane to be fluid

chloroplasts

- found in plants and algae - sites of photosynthesis (metabolic process that captures energy from the sun and converts it to chemical energy - bounded by two membranes and also contain membrane-bound compartments, the thylakoids - the fluid surrounding the thylakoids is the stroma, which contains chloroplast DNA and ribosomes

intermediate filaments

- important in maintaining the shape of the cell and fixing the position of certain organelles

facilitated diffusion

- ions and polar molecules cannot pass easily across the membrane - the process by which ions and hydrophilic substances diffuse across the cell membrane with the help of transport proteins - transport proteins are specific (like enzymes) for the substances they transport: - they provide a hydrophilic channel through which the molecules in question can pass - they bind loosely to the molecules in question and carry them through the membrane

rough ER

- its associated ribosomes on the surface make the structure appear rough under the microscope - ribosomes associated with the ER synthesize proteins that are generally secreted by the cell - as the proteins are produced by the ER-bound ribosomes, the polypeptide chains travel across the ER membrane and into the cisternal space - within the cisternal space, the proteins reach conformation and are packaged into transport vesicles, which bud off the ER and move toward the Golgi apparatus - the formation of proteins inside the ER membranes requires a specific cellular chemistry that is an example of the powerful benefits of cellular compartmentalization

vacuoles

- large vesicles that perform a variety of functions in different kinds of cells - ex. food vacuoles such as those formed by phagocytosis in protists

microtubules

- made of the protein tubulin, are the largest of the cytoskeleton fibers - microtubules shape and support the cell and also serve as tracks along which organelles equipped with motor molecules can move - microtubules separate chromosomes during mitosis and meiosis (forming the spindle) and are the structural components of cilia and flagella (found primarily in animal cells)

endoplasmic reticulum

- makes up more than half the total membrane structure in many cells - network of membranes and sacs whose internal area is called the cisternal space

lysosomes

- membrane-bound sacs of hydrolytic enzymes that can digest large molecules including proteins, polysaccharides, fats, and nucleic acids - have digestive enzymes that break down macromolecules to organic monomers that are released into the cytosol and thus recycled by the cell - digestive or hydrolytic enzymes work best in the acidic environment found in lysosomes - if a lysosome breaks open or leaks, the enzymes are not very active in the neutral pH of the cell

fluid mosaic model

- model that describes the arrangement and movement of the molecules that make up a cell membrane - proteins embedded in or associated with the phospholipid bilayer

cell wall

- protects the plant and helps maintain its shape while also providing a barrier for some substances to enter the plant cell - it is found outside the plasma membrane

ribosomes

- protein factories and are common to all cells, both prokaryotic and eukaryotic - composed of rRNA and protein and are sites of protein synthesis in the cell - each ribosome consists of a large and a small subunit

golgi apparatus

- proteins from the transport vesicles of the ER are received, sorted, folded, chemically modified as needed and then shipped

phospholipids

- provide a hydrophobic barrier in the membrane that separates the cell from its liquid environment - the hydrophilic phosphate portions of the phospholipids are oriented toward the aqueous inside and outside environments of cells - hydrophobic fatty acid tails face each other in a double layer (bilayer) in the interior - hydrophilic molecules cannot easily enter the cell, but hydrophobic molecules can enter much more easily

mitochondria

- sites of cellular respiration, the metabolic process that uses oxygen to generate ATP by extracting energy from sugars, fats, and other fuels - bounded by an outer and inner membrane - inner membrane is highly folded/folds are called cristae and increase surface area, enhancing the productivity of cellular respiration - the inner compartment, the mitochondrial matrix, is fluid filled and cellular respiration occurs here - the mitochondrial matrix contains mitochondrial DNA and ribosomes

proteins

- some are completely embedded in the membrane, including some that span the membrane completely

nonpolar molecules

- such as hydrocarbons, carbon dioxide, and oxygen are hydrophobic and can dissolve in the hydrophobic interior of the phospholipid bilayer and cross the membrane easily

membrane potential

- the inside of the cell is negatively charged compared with the outside - the difference in electric charge across a membrane is expressed in voltage - because the inside of the cell is negatively charged, positively charge ions on the outside, such as sodium, is attracted to the negative charges inside the cell - two forces drive the diffusion of ions across a membrane chemical force: ion's concentration gradient voltage gradient: attracts positively charged ions and repels negatively charged ions

flagella

- usually long and few in number - many unicellular eukaryotic organisms are propelled through the water by flagella, as are the sperm of animals, algae, and some plants

aquaporins

A transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane

Which figure depicts an animal cell placed in a solution hypotonic to the cell?

A) Cell A water moves in a hypotonic to hypertonic direction. cells A, B, and C are all animal cells (red blood cells) and lack a cell wall. cell D is a plant cell with a cell wall. Cell A is in a hypotonic solution, cell B is in an isotonic solution, and cell C is in a hypertonic solution. in A, the solution is hypotonic to the hypertonic cell

which of the following processes could result in the net movement of a substance into a cell if the substance is more concentrated in the cell than in the surroundings?

A) active transport because the substance is being moved against the concentration gradient energy is required. requiring energy to move a substance against its concentration gradient is characteristic of active transport

an ATP-powered pump that transports a specific solute can indirectly drive the active transport of another solute in a mechanism called cotransport, as illustrated in the figure. the cotransporter protein can use the diffusion of H+ ions down their electrochemical gradient into the cell to drive the uptake of sucrose into the cell by what process are H+ ions being moved from the cytoplasm to the extracellular fluid in this figure?

A) active transport notice that the H+ ions in the diagram are moving against their concentration gradient. movement of solutes against their concentration gradient requires energy and is therefore active transport

small, nonpolar, hydrophobic molecules

A) easily pass through a membrane's lipid bilayer because membranes are hydrophobic, hydrophobic molecules can easily pass across the membrane (hydrophilic dissolves hydrophilic; hydrophobic dissolves hydrophobic)

which of the following is not found in all of the following cell types: bacterial , prokaryotic, and eukaryotic

A) mitochondria all cell types contain ribosomes, plasma membrane, and RNA (and DNA). only eukaryotic cells contain mitochondria, which are membrane-bound organelles

organelles present in large numbers in cells with high energy demands, such as muscle cells

A) mitochondria cellular respiration takes place in the mitochondria, forming ATP, the cell's energy currency. mitochondria are bound by double membranes, and the proteins involved in ATP production are embedded in the inner membranes of the mitochondria

using the same figure and assumption as for question 6 , what effect will the movement of the sugar have on the water level in the tubes?

A) the water level will go up on side A as glucose moves into side A, the total amount of solute on that side increases, becoming hypertonic, causing water to follow

an organelle with a receiving (cis) and shipping (trans) face, which acts as the packaging and secreting center of the cell

B) golgi apparatus the golgi apparatus is the organelle that has cis and trans face, and it acts as the packaging and secreting center of the cell. it consists of a series of flattened sacs of membranes called cisternae

If you shut the system off and pressure was no longer applied to Tank A, you would expect

B) the water to reverse flow from tank B to tank A tank A, with the tap water, is hypertonic to the purified water. because water flows from hypotonic to hypertonic, water would would move from tank B to tank A

gaucher disease is the most common of lipid storage diseases in humans. it is caused by a deficiency of an enzyme necessary for lipid metabolism. this leads to a collection of fatty material in organs of the body including the spleen, liver, kidneys, lungs, brain, and bone marrow. identify the statement below that best explains how internal membranes and the organelles of cells would be involved in gaucher disease

C) the lysosomes lack sufficient amounts of enzymes necessary for the metabolism of lipids the key statement in the stem of the question is "this leads to a collection of fatty material in organs of the body" lysosomes are the organelles responsible for the breakdown of lipids. a problem with lipid metabolism indicates a lysosome problem

Both the volume and the surface area for three different cells were measured. These values are listed in the following table: Volume Surface Area Cell 1 9.3 µm3 26.5 µm2 Cell 2 12.2 µm3 37.1 µm2 Cell 3 17.6 µm3 40.6 µm2 Using data from the table above, select the best explanation for why that cell will be able to eliminate waste most efficiently?

D) cell 2 because it has the highest surface area to volume ratio that facilitates the exchange of materials between a cell and its environment the surface area to volume ratios are as follows: cell A is 2.85, B is 3.04, and C is 2.31. the higher the surface area to volume ratio the greater the area of the plasma membrane is to the unit volume of the cell. this means the cell has more area to move materials into and out of the cell (eliminate waste in the question) per unit volume of the cell

the fluid mosaic model describes the plasma membrane as consisting of

D) diverse proteins embedded in a phospholipid bilayer the fluid mosaic model is a reference to a membrane with a mosaic of various proteins embedded or attached to a double layer of phospholipids

The diagram shows two different solutions of glucose and sucrose in a U-tube containing a semipermeable membrane. the membrane is permeable to both glucose and sucrose which of the following is a reasonable hypothesis describing what will happen next?

D) glucose will diffuse from side B to side A substances will move down their concentration gradient until their concentration is equal on both sides of the membrane. the concentration of glucose on side B is 2.0M, whereas the concentration of glucose on side A is 1.0M; therefore, glucose will move from side B to side A. solutes move down their own concentration gradients, not the combined gradients as answer A would indicate

which of the following is most likely to impose a limit on cell size?

D) ratio of surface area to volume the rate of movement of materials into and out of cells is determined by the surface area to volume ratio

the skin is the body's largest organ. It's made up of many different types of cells. oils, produced by the sebaceous glands, prevent the skin from drying and splitting. the protein melanin, produced by melanocytes in the epidermis, protects the skin from the harmful effects of ultraviolet radiation. sweat released through ducts to the skin surface, helps to cool the body. the types of cells that produce these compounds have different numbers of specific organelles, depending on their function. based on their function, you would expect melanocytes in the skin to have a higher than usual number of

D) ribosomes melanin is identified as a protein for export. with that information, you would expect an increase in ribosomes

An organelle that is characterized by extensive, folded membranes and is abundant in cells that detoxify poisons, such as liver cells

D) smooth endoplasmic reticulum the smooth er proliferates in cells that detoxify poisons

which of the following uses passive transport without the help of proteins to move materials across the plasma membrane

D) the movement of carbon dioxide across the plasma membrane carbon dioxide can passively diffuse through the cell membrane unaided by proteins

free ribosomes

Float in the cytosol; produce proteins used within the cell

In an experiment, researchers provided a radiolabeled amino acid to living plant cells. After one hour, the researchers determined the amount of the radiolabeled amino acid that was in each of several subcellular compartments. The results of the experiment are represented in the table. Which of the following conclusions about the radiolabeled amino acid is best supported by the results of the experiment?

It was mostly incorporated into proteins that regulate and manage metabolic reactions.

Eukaryotic cells

Larger, complex, with nucleus, membrane bound organelles, DNA tightly wrapped around histone proteins in chromosomes, cellulose in plant cell walls. - a membrane-enclosed nucleus contains the cell's linear chromosomes - many membrane-bound organelles are found in the cytoplasm - bigger than prokaryotes

Prokaryotic cells

Small, simple, no nucleus, no membrane-bound organelles, single loop of DNA (nucleosome), no cellulose, cytoplasm, cell membrane, cell wall (made of carbs), sometimes have cilia or flagella (movement). found in the domains bacteria and archaea - the single circular chromosome is found in a region called the nucleoid, but there is no nuclear membrane and therefore no true nucleus - no membrane-bound organelles are found in the cytosol (there are ribosomes, but they are not membrane bound) - smaller than eukaryotes

A group of mutations, known as MT-ND1, have been identified in mitochondrial DNA. These mutations are associated with a number of debilitating diseases stemming from the production of nonfunctional proteins in the mitochondria. Which of the following cellular deficiencies would most likely be related to these MT-ND1 mutations?

The cell is unable to complete reactions related to electron transport and ATP production.

bulk transport

The process by which large particles and macromolecules are transported through plasma membranes. Inc. exocytosis and endocytosis

A certain type of specialized cell contains an unusually large amount of rough endoplasmic reticulum (ER). Which of the following functions is this cell type most likely specialized to perform?

The production and secretion of proteins

peripheral proteins

The proteins of a membrane that are not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane. - ex. G protein, which can move along the membrane when a ligand binds a G protein-coupled receptor

A scientist is studying the various prokaryotic and eukaryotic species found floating in a sample of water taken from a marine ecosystem. Which cellular component will be found in the widest range of organisms in the sample?

The ribosome, since all organisms need to synthesize proteins.

cotransport

a single ATP powered pump that transports one solute can indirectly drive the active transport of several other solutes in this mechanism as the solute that has been actively transported diffuses back passively through a transport protein its movement can be coupled with the active transport of another substance against its concentration gradient

Plasmodesmata

channels through cell walls that connect the cytoplasms of adjacent plant cells and allow communication and movement of materials between cells

smooth ER

has several functions including synthesis of lipids and detoxification of drugs and poisons

transport proteins

move materials across the hydrophobic interior of the phospholipid bilayer or as molecular receptors to bind to signaling molecules (ligands)

cytoskeleton

network of protein fibers that run throughout the cytoplasm where it is responsible for support, motility, and regulation in some biochemical activities

isotonic solution

no net movement of water across the plasma membrane water crosses the membrane at the same rate in both directions

plasmolysed

plant cell where the contents have shrunk due to loss of water by osmosis and the plasma membrane has separated from the cell wall

endosymbiotic theory

proposes that mitochondria and chloroplasts share a similar origin - the organelles descended from prokaryotic cells once engulfed by ancestors of eukaryotic cells EVIDENCE - both organelles have a double membrane structure - both organelles have their own ribosomes and circular DNA molecules - both organelles reproduce independently within the cell

active transport

substances are moved against their concentration gradient - from the region where they are less concentrated to the region where they are more concentrated - requires energy in the form of ATP

turgid

swollen

endocytosis

the cell forms new vesicles from the plasma membrane (reverse of exocytosis)/ allows the cell to take in macromolecules - example: engulfing foreign particles by white blood cells or amoebas

electrochemical gradient

the combination of forces acting on an ion