Biology Unit 2 Questions

Which of these provides the cell with structural support?

D

Which of the following particles can pass through the ATP synthase channel?

Protons

True or false? Osmosis is a type of diffusion.

True (Osmosis is the diffusion of water across a selectively permeable membrane.)

Among humans, increased interest in food intake normally occurs _____

via chemical signals released when the stomach is empty Explanation: A shrunken, empty stomach releases ghrelin, a protein hormone that sharply increases appetite.

Triglycerides vary with respect to the number of

(b) C atoms in the tails. (c) double bonds in the tails. Explanation: Tail lengths of 16 to 22 are common. There may be from 0 to 6 double bonds.

The lipid bilayer of a cell membrane is selectively permeable. Name a substance or a class of substances, whether or noy it passes easily through the lipid bilayer, and whether that transport is passive or active.

- Ions do not pass easily, they require active transport - Oxygen easily passes through the lipid bilayer since it is a small nonpolar molecule

What is the main component of gastric juice?

- Water (Water is the primary component of many secretions, including gastric juice)

Endocytosis

- decreases the surface area of the plasma membrane -forms vesicles from inward folding of the plasma membrane

Describe the signifigance of cell surface area, cell volume, and the ratio of surface area to volume. Note that we will also see that the concept of surface area to volume will be important for larger structures such as organisms and some organs.

- larger organisms have more cells, not larger cells -metabolic needs get bigger as cell gets bigger -

What is true of channel transport proteins?

- provide a continuous path across the membrane - allows water molecules and small ions to flow quickly across the membrane

What is true of both channels and carriers?

- provide a hydrophillic path across the membrane -are integral membrane proteins - transport solutes down a concentration or electrochemical gradient Explanation: Carrier proteins and channels are both transport proteins involved in facilitated diffusion, the passive transport of solutes across a membrane down their concentration or electrochemical gradient. As integral membrane proteins, both carriers and channels protect polar or charged solutes from coming into contact with the hydrophobic interior of the lipid bilayer.

Which of the following statements correctly describe(s) the driving forces for diffusion of Na+ and K+ ions through their respective channels? Select all that apply.

- the diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane - the diffusion of k+ ions out of the cell is impeded by the electrical gradient across the plasma membrane - The electrochemical gradient is larger for Na+ than for K+ Explanation: The concentration gradient of Na+ ions across the membrane (higher Na+ concentration outside) facilitates the diffusion of Na+ into the cell. At the same time, the electrical gradient across the membrane (excess positive charge outside) drives Na+ into the cell. The concentration gradient of K+ ions across the membrane (higher K+ concentration inside) facilitates the diffusion of K+ out of the cell. However, the electrical gradient across the membrane (excess positive charge outside) impedes the diffusion of K+ out of the cell. The electrochemical gradient for an ion is the sum of the concentration (chemical) gradient and the electrical gradient (charge difference) across the membrane. For Na+ ions, diffusion through the Na+ channel is driven by both the concentration gradient and the electrical gradient. But for K+ ions, the electrical gradient opposes the concentration gradient. Therefore, the electrochemical gradient for Na+ is greater than the electrochemical gradient for K+.

What is true of carrier transport proteins?

- undergo a change in shape to transport solutes across the membrane -transport primarily small polar organic molecules

Name an organelle and briefly describe its function. How many membranes surround that organelle?

-Mitochondria, power house of cells and makes energy, it is surround by two membranes -

Exocytosis

-increases the surface area of the plasma membrane, requires fusion of vesicles -secretes large molecules out of the cell

Both exocytosis and endocytosis

-requires cellular energy -transported substances never physically cross the plasma membrane

What is the function of Structure E?

-stabilization of the phospholipids Cholesterol helps to stabilize the structure of the plasma membrane.

What is activation energy?

-the amount of energy needed for a chain reaction to start

How many electrons at a time are passed between the pigment molecules in the light-harvesting complexes?

0 explanation:The excited state energy of the electron passes between pigment molecules, not the electron itself.

Which statements are true for chloroplasts?

1. They are the sites of reactions that convert solar energy into chemical energy. 2. They have membranous sacs called thylakoids that are surrounded by a fluid called stroma. 3. They contain the green pigment chlorophyll. Explanation: The chloroplast and the chemical reactions associated with it are extremely important for all living things. The photosynthetic reactions are responsible for converting solar energy into chemical energy that is used not only by the cells in which photosynthesis occurs but also by other organisms. For example, all of the foods you eat can be traced back to a plant or other photosynthetic organism. Furthermore, the chloroplast and its reactions have had a profound influence on the constitution of Earth's atmosphere due to the fact that oxygen is a byproduct of photosynthesis.

The diameter of a typical eukaryotic cell is approximately ten times the diameter of a typical prokaryote. What is the ratio of the volume of typical eukaryotic:prokaryotic cells?

1000:1 Explanation: As the diameter of a cell increases, other dimensions also change. For two cells of approximately equivalent shape but different diameters, surface area increases as the square of diameter, and volume increases as the cube of diameter. Thus, if a eukaryotic cell is ten times the diameter of a prokaryote, its surface area will be one hundred (102) times that of the prokaryote and its volume will be one thousand (103) times that of the prokaryote.

How many fatty acids are in a phospholipid?

2

In glycolysis, how many ATP molecules are produced per glucose?

2

How many carbon atoms in a molecule of pyruvate (pyruvic acid)?

3

In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?

3

How many carbon atoms are in a molecule of glucose?

6

Which of these structures stores, modifies, and packages products?

A

Which molecule is less soluble in water--a fat or a phospholipid? Why?

A fat molecule is less soluble in water because it has three non-polar fatty acids and no polar or charged head like a phospholipid has. Explanation: The replacement of one of the fatty acids with a polar chemical group makes phospholipids more soluble in water than fats.

Which of the following statements is not true of most cellular redox reactions?

A hydrogen atom is transferred to the atom that loses an electron

Which of the following statements about equilibrium of chemical reactions is correct? The equilibrium point of a reaction represents the least stable configuration for that reaction. Reactions can only go in the direction toward equilibrium. The equilibrium point is where the system has the highest free energy Most reactions in a living cell are close to equilibrium. A reaction that is at equilibrium is not capable of doing any work.

A reaction that is at equilibrium is not capable of doing any work. Explanation: The ΔG for a reaction at equilibrium is zero, which means that there is no free energy available to do any work.

In cells, what is usually the immediate source of energy for an endergonic reaction?

ATP

Chloroplast membrane vesicles are equilibrated in a simple solution of pH 5‎ . The solution is then adjusted to pH 8‎ . Which of the following conclusions can be drawn from these experimental conditions?

ATP will not be produced because there is no ADP and inorganic phosphate in the solution. Explanation: This statement is true; although the proton gradient is present, ADP and inorganic phosphate are required to make ATP and were not added to the reaction.

What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?

Amphipathic nature Explanation: Detergents form micelles around the grease, which are then washed away because the polar head groups facing outward on the micelle are water-soluble.

Plant cells and animal cells share many of the same structures, but each type of cell also has unique structures. In this activity, you will indicate which cell structures are found only in plant cells, only in animal cells, or in both plant and animal cells. Plant cell only: Animal cell only: both:

Animal Cell only: Centriole Plant Cell only: Cellulose Cell Wall, Central Vacuole, Chloroplast Both: Plasma Membrane, Golgi apparatus, cytoskeleton, endoplasmatic reticulum, nucleus, mitochondrian Explanantion: Plant cells and animal cells have more in common than they have differences. Nevertheless, plant cells' unique structures play important roles. Photosynthesis occurs in plant cells' chloroplasts. The plant cell's central vacuole takes up most of the space within the cell and serves a variety of functions, including storage and hydrolysis of organic compounds. Plant cell walls, which are composed primarily of cellulose, protect the cells from damage and maintain their shape. Cellulose is the most abundant organic compound on the planet.

Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?

Anion and cation.

Select the correct statement describing cellular structure or function. a. Only plant cells contain chloroplasts, and only animal cells contain mitochondria. b. Plant and animal cells both carry out cellular respiration, producing ATP. c. Mitochondria and chloroplasts are part of the endomembrane system of the eukaryotic cell.

B. Explanation: All plant and animal cells carry out cellular respiration in mitochondria, producing ATP.

_____ is/are identical in structure to centrioles.

Basal bodies (Basal bodies and centrioles have identical structures.)

_____ is secreted by the _____ and acts to emulsify _____ in the _____.

Bile ... liver ... fats ... small intestine Explanation: Bile, produced by the liver and stored by the gall bladder, emulsifies fats in the small intestine. The smaller fat droplets present a greater surface area for the action of lipases.

Which of the following statements is TRUE with regard to this animation?

Both sodium and potassium ions are transported against their concentration gradients. Explanation: Both ions are transported from where their concentration is low to where their concentration is high, and the cell expends energy in the form of ATP to do it.

Choose the letter that indicates the organelle that contains most of a cell's DNA.

C

Which of these equations best summarizes photosynthesis?A. C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + EnergyB. C6H12O6 + 6 O2 → 6 CO2 + 12 H2OC. 6 CO2 + 6 H2O → C6H12O6 + 6 O2D. 6 CO2 + 6 O2 → C6H12O6 + 6 H2OE. H2O → 2 H+ + 1/2 O2 + 2e-

C. 6 CO2 + 6 H2O → C6H12O6 + 6 O2

What is the basic role of CO2 in photosynthesis?

CO2 is fixed or incorporated into organic molecules.

The electrons derived from this oxidation reaction in the Calvin cycle are used to reduce

CO2 to G3P.

Choose the correct statement from the list below. a. Carbohydrate absorption occurs primarily in the large intestine. b. Carbohydrate digestion begins in the mouth with salivary amylase. c. Bile salts from the gall bladder are essential to the digestion of carbohydrates. d. Carbohydrates are fully digested after passage through the stomach .

Carbohydrate digestion begins in the mouth with salivary amylase. Explanation: Carbohydrate digestion begins with the action of salivary amylase in the mouth

Some solutes are able to pass directly through the lipid bilayer of a plasma membrane, whereas other solutes require a transport protein or other mechanism to cross between the inside and the outside of a cell. The fact that the plasma membrane is permeable to some solutes but not others is what is referred to as selective permeability. Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply.

Carbon Dioxide, Lipids, Water, and Oxygen Explanation: Some solutes pass readily through the lipid bilayer of a cell membrane, whereas others pass through much more slowly, or not at all. Small nonpolar (hydrophobic) molecules, such as dissolved gases (O2, CO2, N2) and small lipids, can pass directly through the membrane. They do so by interacting directly with the hydrophobic interior of the lipid bilayer. Very small polar molecules such as water and glycerol can pass directly through the membrane, but much more slowly than small nonpolar molecules. The mechanism that permits small polar molecules to cross the hydrophobic interior of the lipid bilayer is not completely understood, but it must involve the molecules squeezing between the hydrophobic tails of the lipids that make up the bilayer. Polar molecules such as glucose and sucrose have very limited permeability. Large molecules such as proteins cannot pass through the lipid bilayer. Ions and charged molecules of any size are essentially impermeable to the lipid bilayer because they are much more soluble in water than in the interior of the membrane.

Which molecules do not normally cross the nuclear membrane?

DNA Explanation: All processes involving DNA take place in the nucleus.

Which of these is the double membrane that encloses the nucleus?

E

All proteins are synthesized by ribosomes in the cell. Some ribosomes float freely in the cytosol, while others are bound to the surface of the endoplasmic reticulum. Most proteins made by free ribosomes function in the cytosol. Proteins made by bound ribosomes either function within the endomembrane system or pass through it and are secreted from the cell. Which of the following proteins are synthesized by bound ribosomes?

ER protein, insulin, lysomal enzyme Explanation: Most proteins that function in the cytosol (such as actin) or in the nucleus (such as DNA polymerase) are synthesized by free ribosomes. Proteins that function within the endomembrane system (such as lysosomal enzymes) or those that are destined for secretion from the cell (such as insulin) are synthesized by bound ribosomes. As a protein destined for the endomembrane system is being synthesized by a ribosome, the first amino acids in the growing polypeptide chain act as a signal sequence. That signal sequence ensures that the ribosome binds to the outer membrane of the ER and that the protein enters the ER lumen.

Which term describes the degree to which an element attracts electrons?

Electronegativity.

Why is it correct to say that the linear electron flow of the light reactions directly captures energy in NADPH but only indirectly captures energy in ATP?

Electrons are directly transferred to NADP+ to form NADPH, but electron flow is used to generate a proton gradient for ATP synthesis. Electrons are not directly transferred to ATP.

Which process is not required for an animal to obtain energy from food?

Excretion

Two fundamental types of cells are known to exist in nature: prokaryotic cells and eukaryotic cells (like the one shown in the Tour of an Animal Cell animation). Both prokaryotic and eukaryotic cells carry out all of the processes necessary for life, but they differ in some important ways. In this activity, you will identify which cell structures are found only in prokaryotic cells, only in eukaryotic cells, or in both types of cells. Drag each cell structure to the appropriate bin. Prokaryotic only: Eukaryotic only: Both:

Explanation: Only bacteria and archaea have prokaryotic cells, which lack a nucleus and other membrane-enclosed organelles. Prokaryotic cells are smaller and, at the level of the individual cell, are generally less versatile than eukaryotic cells, which compartmentalize many of their metabolic pathways into organelles. Nevertheless, prokaryotes are indispensable in every known ecosystem, and certain species are capable of surviving in some of the harshest and most nutrient-limiting environments on Earth.

True or false? Large proteins containing a nuclear localization signal (NLS) bind to the nuclear pore and enter the nucleus without any expenditure of energy.

False Explanation: Cytoplasmic proteins called importins bind to large proteins containing an NLS and mediate their transport across the nuclear membrane through an active transport (energy-requiring) process.

True or false? One advantage of having a tube-like digestive tract is that digestion of all compounds can take place simultaneously down the tract.

False Explanation: One advantage of having a tube-like digestive tract is that digestive processes with different requirements (for example, an acidic or basic environment) can be separated within the tract.

True or false? The chemiosmotic hypothesis states that the synthesis of ATP generates a proton gradient that leads to electron flow through an electron transport chain.

False Explanation: The chemiosmotic hypothesis states that the flow of electrons through an electron transport chain generates a proton gradient that leads to the synthesis of ATP.

True or false? The region of ATP synthase that catalyzes the production of ATP from ADP and inorganic phosphate spans the chloroplast membrane.

False Explanation: The region of ATP synthase that catalyzes ATP production protrudes out of, but does not span, the chloroplast membrane; the region that spans the membrane is an ion channel through which protons can pass.

True or False? The liver is a component of the alimentary canal.

False. The alimentary canal is the tube through which food passes, beginning at the mouth and ending at the anus. The liver is an accessory organ of digestion and not part of the actual canal through which food passes.

Choose the correct statement from the list below. a. Fat digestion begins in the stomach with the activation of trypsinogen to trypsin. b. Fats are fully digested after passage through the mouth and stomach. c. Bile salts from the pancreas are essential to the digestion of fats d. Free fatty acid absorption occurs in the small intestine.

Free fatty acid absorption occurs in the small intestine. Explanation: Fat digestion is not complete until pancreatic lipases finalize fat digestion in the small intestine.

During osmosis, water diffuses across a selectively permeable membrane from the region of higher ___concentration and lower ___ concentration to the side with lower ____concentration and higher ____concentration

Free water;solute x2, free water

Select the correct molecule that is the main product of the Calvin cycle.

G3P

_____ aid in the coordination of the activities of adjacent animal cells.

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

In the light reactions, light energy is used to oxidize - to -

H2O to O2

Which substance is transported by ETC carrier molecules across the inner mitochondrial membrane?

Hydrogen ions (H+)

Gaseous hydrogen burns in the presence of oxygen to form water:2H2 + O2 → 2H2 O + energyWhich molecule is oxidized and what kind of bond is formed?

Hydrogen, polar.

In many animal cells, the uptake of glucose into the cell occurs by a cotransport mechanism, in which glucose is cotransported with Na+ ions. Complete the diagram below using the following steps. Use targets of Group 1 to indicate the relative concentration of glucose inside and outside the cell. Use targets of Group 2 to indicate the direction that Na+ ions and glucose move through the cotransporter. Use targets of Group 3 to complete the sentences on the right, indicating how Na+ ions and glucose move through the cotransporter relative to their electrochemical and concentration gradients.

In cotransport, the energy required to move one solute against its concentration or electrochemical gradient is provided by an ion moving into the cell down its electrochemical gradient. The ion that moves into the cell down its gradient is usually the same ion that is pumped out of the cell by an active transport pump: for example, Na+ in animal cells using the sodium-potassium pump, or H+ in plants and prokaryotes using the proton pump. In the case of the glucose-sodium cotransporter in animals, Na+ moves back into the cell down its electrochemical gradient, providing the energy for glucose to move into the cell against its concentration gradient. The energy for glucose transport into the cell is supplied indirectly by the sodium-potassium pump's hydrolysis of ATP, and directly by the Na+ electrochemical gradient created by the pump.

Where is ATP synthase and photosystem 1 found?

Internal membrane of mitochondrion and/or chloroplast

What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?

Ionic.

Which of the following statments about diffusion is true? a. It is very rapid over long distances. b. It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration c. It requires an expenditure of energy by the cell. d. It is an active process in which molecules move from a region of lower concentration to a region of higher concentration.

It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

What is the fate of the phosphate group that is removed when ATP is converted to ADP?

It is acquired by a reactant in an endergonic reaction.

What structure is the site for electron transport?

Mitochondrial inner membrane

What molecules that carry hydrogen and high energy electrons are also produced during glycolysis?

NADH

What two molecules carrying hydrogens and high energy electrons are formed during the citric acid cycle (CAC)?

NADH and FADH2

The electrons derived from this oxidation reaction in the light reactions are used to reduce -- to ---

NADP+ to NADPH

After 3-PGA is phosphorylated, it is reduced by

NADPH NADPH supplies the electrons that reduce the phosphorylated 3-PGA.

The Calvin cycle oxidizes the light-reactions product --- to ----

NADPH to NADP+

A critical feature of the plasma membrane is that it is selectively permeable. This allows the plasma membrane to regulate transport across cellular boundaries--a function essential to any cell's existence. How does phospholipid structure prevent certain molecules from crossing the plasma membrane freely?

Nonpolar molecules: hydrophobic, can cross easily, no transport protein required Polar and Ions: hydrophilic, have difficulty crossing the hydrophobic part, transport protein required to cross efficiently

What atom accepts protons (H+) and electrons (e-) at the end of ETC?

O

What molecule is formed when the final electron acceptor accepts protons (H+) and electrons (e-) at the end of the mitochondrial ETC?

O2

Which of the following would likely diffuse through the lipid bilayer of a plasma membrane most rapidly? a. O2 b. sucrose c. an amino acid d. Na+

O2

If the Calvin cycle slows down, what will happen to the rate of O2 production in PS II, and why?

O2 production will slow down because less NADP+ will be regenerated in the Calvin cycle. Explanation NADP+ is required as an electron acceptor during linear electron flow of the light reactions. Therefore, if less NADP+ is available because of a slowdown in the Calvin cycle, electron flow in the light reactions will slow down, and less O2 will be produced.

Nucleoplasmin is a nuclear protein. This protein was divided into two segments and linked to the same large cytoplasmic protein, generating two fusion proteins. After injecting these fusion proteins into a cell, one of the proteins was found in the nucleus and the other in the cytoplasm. Which of the following conclusions can be drawn from these results?

Only one of the two fusion proteins possesses a nuclear localization signal. Explanation: The nuclear localization signal is only present in the fusion protein that enters the nucleus.

All molecules have energy that causes thermal motion. One result of thermal motion is diffusion: the tendency of substances to spread out evenly in the available space. Although the motion of each individual molecule is random, there can be directional motion of an entire population of molecules. Consider a chamber containing two different types of dye molecules, purple and orange. The chamber is divided into two compartments (A and B) by a membrane that is permeable to both types of dye. Initially (left image), the concentration of the orange dye is greater on side A, and the concentration of the purple dye is greater on side B. With time, the dye molecules diffuse to a final, equilibrium state (right image) where they are evenly distributed throughout the chamber.

Orange dye moves independently of purple dye. - always Concentration gradient exist that drive diffusion of both dyes- only before equilibrium is reached There is a net movement of orange dye from side A to side B- only before equilibrium is reached Purple dye moves only from side B to side A- Never There is no net movement of purple dye- only at equilibrium Explanation: Each dye molecule and the water molecules that surround it are in constant motion due to their thermal energy. Any individual molecule's motion is random because of the frequent collisions among all of the molecules. If a concentration gradient exists for a population of molecules, the motion of the individual molecules in that population will result in a net (directional) movement from higher to lower concentration. For example, in the initial condition, there is a concentration gradient for the orange dye. As a result, the orange dye molecules diffuse down the concentration gradient, with net movement from side A to side B. Once diffusion has eliminated the concentration gradient and equilibrium is reached, net movement stops, but the random motion of each molecule continues (as indicated by the red arrows in the image below).

What name is given to the process by which water crosses a selectively permeable membrane?

Osmosis

Defend the statement that osmosis is a special case of passive transport across a membrane.

Osmosis is a special case of passive transport because it specifically requires aquaporins to diffuse h2O specifically

Which of the following statements is true of the bonds in a water molecule?

Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.

A small protein (molecular weight = 25,000 daltons) is injected into a cell and observed in the nucleus a short time later. What type of transport has taken place?

Passive Transport Explanation: A 25,000-dalton protein is small enough to diffuse through nuclear pores without any expenditure of energy.

What type of protein NADP+ reductase?

Periperal protein

Which term describes ATP production resulting from the capture of light energy by chlorophyll?

Photophosphorylation Explanation: The excitation of chlorophyll by light energy initiates a chain of events that leads to ATP production.

Which process produces oxygen?

Photosynthesis

Why do animal cells lyse burst when placed in a hypotonic solution while plant cells do not?

Plant cells walls prevents this expansion

Choose the correct statement from the list below. a. Proteins that are consumed in the diet are absorbed as individual amino acids following digestion. b. Protein digestion begins in the small intestine with the activation of trypsinogen to trypsin c. Mechanical digestion of proteins is more important than chemical digestion. d. The stomach has a high pH which allows for the activation of digestive enzymes.

Proteins that are consumed in the diet are absorbed as individual amino acids following digestion.

According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis?

Proton gradient Explanation: A proton gradient across chloroplast and mitochondrial membranes drives ATP synthesis by the enzyme ATP synthase.

_____ has a longer wavelength than _____.

Red ... green Red has a longer wavelength than green.

_____ are the sites of protein synthesis.

Ribosomes Ribosomes are the site of protein synthesis.

Carbon fixation involves the addition of carbon dioxide to

RuBP

Which molecule is regenerated in the regeneration phase of the Calvin cycle? Without regeneration of this molecule, the Calvin cycle would stop.

RuBP Explanation: The regeneration of RuBP ensures that the Calvin cycle can proceed indefinitely, since RuBP fixes carbon dioxide into an organic molecule that is used to produce sugar.

Which structure is not part of the alimentary canal?

Salivary Glands Explanation: The salivary glands are not part of the alimentary canal but contribute digestive enzymes to break down food in the mouth.

How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?

Six carbon dioxide molecules are required to produce two G3P molecules, which can be combined to make one glucose molecule.

Which of these can RAPIDLY pass directly through the phospholipids of the plasma membrane, without the help of a transport protein?

Small, nonpolar, lipid-soluble molecules can pass rapidly through the phospholipids of the plasma membrane. Ions, such as hydrogen ions, and hydrophilic molecules, such as water and glucose, cannot rapidly pass directly through the phospholipids of the membrane. To move rapidly through the membrane, they must pass through membrane transport proteins.

Membranes are mosaics: they are composed of many different kinds of molecules including phospholipids and proteins. The proteins in a cell membrane contribute to the membrane's permeability. Name a substance or a class of substances that is transported across a cell membrane by a membrane protein, and whether that transport is passive or active.

Sodium and potassium through active

Where is rubisco?

Stroma (chloroplast)

Which of the following molecules is the primary product of photosystem I?

The NADPH produced by photosystem I is used to supply energy for the production of sugars during photosynthesis.

Select the most accurate statement describing the basic function of the light reactions of photosynthesis.

The basic function of the light reactions of photosynthesis is the conversion of solar energy to chemical energy.

Which statement is correct? a. A solution of distilled water is hypotonic b. A solution of seawater is hypertonic c. The contents of red blood cells are hyperosmotic to distilled water

The contents of a red blood cell are hyperosmotic to distilled water Explanation: The red blood cell has a greater solute concentration than distilled water, which means that its contents are hypertonic to distilled water.

When a pigment molecule in a light-harvesting complex absorbs a photon of light, what happens to its excited-state electron?

The electron falls back to its ground state, while passing its excited-state energy to an electron in a nearby pigment molecule.

Which of the following statements about the combustion of glucose with oxygen to form water and carbon dioxide (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O) is correct?

The entropy of the products is greater than the entropy of the reactants. Explanation: A large molecule (glucose) has been converted into several smaller molecules (water and carbon dioxide); thus, the products have more disorder (greater entropy) than the reactants.

If the pores in the selectively permeable membrane became larger, but still not large enough to let the sugar pass through, what would happen during osmosis in the U-shaped tube compared to what is shown in the figure?

The final water levels would be the same as shown in the figure, but the solutions would reach near equal concentrations faster. Explanation: The relative concentrations of solutes and free water on either side of the membrane determines the amount of osmosis, but the size of the pores determines how fast osmosis occurs.

Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?

The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions. Explanation: Light energy drives the formation of ATP and NADPH during the light-dependent reactions; these energy molecules are then used during the light-independent reactions to form sugars.

What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?

The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars.

Which of the following statements about the nuclear envelope is false?

The nuclear envelope is continuous with the Golgi apparatus. Explanation: This statement is false; the nuclear envelope is continuous with the endoplasmic reticulum.

Identify the correct statement about differences between rough and smooth endoplasmic reticulum (ER).

The outer surface of smooth ER lacks ribosomes, whereas the outer surface of rough ER has ribosomes.

How do phospholipids interact with water molecules?

The polar heads interact with water; the nonpolar tails do not.

Cell membranes have distinct inside and outside faces. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature?

The two sides of a cell membrane face different environments and carry out different functions. Explanation:

If more sugar were added to the solution on the left side of the tube, what would happen to the water level on the right side of the tube?

The water level would go down

What is the biological significance of the light-independent reactions of photosynthesis?

They convert carbon dioxide to sugar.

Plants are photoautotrophs. What does this mean?

They use light energy to drive the synthesis of organic molecules from inorganic materials.

In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules?

To make the proteins easy to see

Imagine that a patient has mitochondria with "leaky" inner membranes. "Leaky" in this case means that small ions can pass through the membrane. The patient feels tired all the time and has trouble moving around. What best describes the molecular mechanism underlying this mitochondrial disease?

Transmembrane voltage (Vmito) across the inner mitochondrial membrane would be diminished

True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.

True

True or false? The light-dependent reactions of photosynthesis use water and produce oxygen.

True Explanation: The water molecules are split to replenish electrons in photosystem II, leaving behind protons, which are used to generate a proton gradient for the formation of ATP, and oxygen, which is released as a by-product.

True or false? Osmosis is a type of diffusion

True Explanation: Osmosis is the diffusion of water across a selectively permeable membrane.

What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium?

Water molecules move between the two solutions, but there is no net movement of water across the membrane. Explanation: Water molecules are constantly in motion and will continually move across the membrane. However, becuase the solutions are in equilibrium, there is not net movement across the membrane.

Dr. Haxton told one of his students, "To move in the bloodstream, fats need the help of phospholipids." What would a good student say?

Yes. Nonpolar molecules aren't compatible with water.

If you have a solution of 0.4 M NaCI is it a hypertonic, isotonic, or hypotonic solution?

a solution, having no comparing sample, cannot be hypertonic isotonic or hyptotonic, they are means of comparision, not qualitative descriptions

Which of these is exhibiting kinetic energy? a rock on a mountain ledge the high-energy phosphate bonds of a molecule of ATP an archer with a flexed bow a person sitting on a couch while watching TV a space station orbiting Earth

a space station orbiting earth Explanation: energy cannot be created or destroyed but can be converted from one form to another

Which statements about the fluid mosaic structure of a membrane are correct? Select the three correct statements. a. Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane. b. The kinky tails of some proteins help keep the membrane fluid by preventing the component molecules from packing solidly together. c. The diverse proteins found in and attached to membranes perform many important functions. d. Membranes include a mosaic, or mix, of carbohydrates embedded in a phospholipid bilayer. e. The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center.

a. Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane. c. The diverse proteins found in and attached to membranes perform many important functions. e. The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center Explanation: Membranes consist of diverse proteins suspended in and attached to a phospholipid bilayer. Kinks in the unsaturated fatty acid tails of some phospholipids keep the membrane fluid, and a mosaic of proteins perform a variety of functions.

In this study, scientists investigated the interactions between actin filaments (microfilaments) and myosin motor proteins. Why is it important to understand the interaction of these components of the cytoskeleton?

a. The organization of actin filaments into higher-ordered structures helps determine cell shape. b. The interactions of myosin with actin filaments enable white blood cells to migrate toward pathogens in the body. c. The interactions of myosin with actin filaments contribute to cytoplasmic streaming in plant cells. Explanation: Actin microfilaments (studied in this paper), microtubules, and intermediate filaments make up the cytoskeleton. Each of the three elements performs different functions that contribute to maintenance of cell shape and movement. The ability of different cell types in multicellular organisms to perform different functions is determined, in part, by the ability of those cells to assume different shapes. In addition, cell movement underlies many fundamental cell processes, including cell locomotion, cell division, and muscle contraction.

Which of the following statements about the conditions shown in the U-shaped tube are true? a. Water is tightly clustered around the hydrophilic solute molecules on both sides of the membrane. b. Solutes can pass through the selectively permeable membrane from right to left, but free water cannot. c. There is more solute in the left arm of the tube than in the right arm of the tube. d. There is less free water in the right arm of the tube than in the left arm of the tube.

a. Water is tightly clustered around the hydrophilic solute molecules on both sides of the membrane. d. There is less free water in the right arm of the tube than in the left arm of the tube.Explanation: Water molecules will cluster around hydrophilic solute molecules (shown as green dots), leaving less water "free" in the solution. There is more solute in the right arm of the tube, so there is less free water on that side.

Which of the following is least likely to be important in holding the components of a biological membrane together? a. covalent interactions between the phospholipid and protein components of the membrane b. hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane c. hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane d. hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane e. polar interactions among the phospholipid head groups on the same surface of the membrane

a. covalent interactions between the phospholipid and protein components of the membrane Explanation: This is not an important interaction because there are rarely covalent bonds between the phospholipids and integral membrane proteins.

Motor proteins are responsible for moving vesicles and organelles within the cell. Motor proteins move along protein "tracks." In the example shown in the Visualizing figure, what are those tracks made of?

actin

A substrate binds to an enzyme at the ____, where the reaction occurs.

active site

When digested, proteins are broken down into

amino acids

What are some biological processes that depend on the actin cytoskeleton?

amoeboid movement wound healing metastasis Explanation: All cellular movements involve elements of the cytoskeleton. Understanding how the cytoskeleton functions at the molecular level is crucial to understanding many basic biological processes. Ninety percent of cancer deaths are due to tumor cells migrating through the body and forming new tumors in other locations, a process called metastasis. Understanding how the cytoskeleton functions in tumor cells, and developing drugs to prevent tumor cells from migrating, is crucial to reducing mortality from cancer.

Which of the following molecules dramatically increases the rate of diffusion of water across cell membranes?

aquaporins

A function of cholesterol that does not harm health is it role as..

as a component of animal cell membranes

Lyosomes

autophagy and macromolecule digestion

Which of these is NOT a lipid? a. phospholipid b. RNA c. cholesterol d. wax e. steroids

b. RNA Explanation: Its a nucleic acid

To survive, all animals must _____.

balance consumption of food with use and storage of nutrients Explanation: Energy input as food is required for growth, survival, and reproduction in all animals.

Why does water not pass through the bilayer as easily?

because of its polar nature, but some do pass because of its small nature -Aquaporens, proteins that allow us to excrete more water and also allows us to take water back up again

When digested, fats are broken down into

both glycerol and fatty acids

Animals obtain the energy they need for growth by

breaking down organic molecules. When enzymes in an animal's body break down complex organic molecules, some of those molecules' stored potential energy is captured; the rest is dissipated as heat that is lost to the environment. Often, the captured energy is stored in the form of ATP and is then used in synthesizing cell components, including macromolecules.

Which of the following statements is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures? a. Unsaturated fatty acids are more nonpolar than saturated fatty acids. b. The double bonds block interaction among the hydrophilic head groups of the lipids. c. The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. d. Unsaturated fatty acids have a higher cholesterol content, which prevents adjacent lipids from packing tightly.

c. The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.

An enzyme is considered a ___ because it speeds up chemical reactions without being used up.

catalyst

What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?

cell wall

In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?

cellular respiration

In what way do the membranes of a eukaryotic cell vary?

certain proteins are unique to each membrane

The _____ is composed of DNA and protein.

chromatin Chromatin is composed of DNA and protein.

A ____-, such as a vitamin, binds to an enzyme and plays a role in catalysis.

cofactor

When properly aligned, the enzyme and substrate form an enzyme-substrate (ES)

complex

What do DNA, proteins, and fats have in common?

contain carbonyl groups

Saturated fats ________ a. contain more hydrogen than unsaturated fats that consist of the same number of carbon atoms b. are generally liquid at room temperature c. are more common in plants than in animal d. shave multiple double bonds in the carbon chains of their fatty acids

contain more hydrogen than unsaturated fats that consist of the same number of carbon atoms

Where does gylcolysis occur?

cytoplasm

Where is phosphofructokinase and ribosome found?

cytoplasm

In C4 and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells.

cytoplasm Explanation: In C4 and CAM plants carbon dioxide fixation occurs in the cytoplasm.

Which of the following particles could diffuse easily through a cell membrane? a. Sodium ion (Na+) b. Hydrogen ion (H+) c. Glucose d. Oxygen (O2)

d. Oxygen (O2) Explanation: Small nonpolar molecules such as oxygen can diffuse across cell membranes.

An enzyme is -- when it loses its native conformation and its biological activity.

denatured

The primary role of _____ is to bind animal cells together.

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

Which of the following statements concerning unsaturated fats is true? a. They are more common in animals than in plants. b. They have fewer fatty acid molecules per fat molecule. c. They generally solidify at room temperature. d. They contain more hydrogen than do saturated fats having the same number of carbon atoms. e. They have double bonds in the carbon chains of their fatty acids.

e. They have double bonds in the carbon chains of their fatty acids.

Which of these is rich in unsaturated fats? a. a fat that is solid at room temperature b. beef fat c. lard d. butter e. olive oil

e. olive oil

Why are 3 molecules of CO2 shown in the diagram?

each molecules of pyruvate has 3 carbons

The reaction ADP + P --> ATP is a(n) _____ reaction.

endergonic

Which of these reactions requires a net input of energy from its surroundings?

endergonic

This graph illustrates a(n) _____ reaction.

endergonic The products contain more potential energy than the reactants.

What is the correct label for "A"?

energy of activation The energy of activation must be overcome in order for a reaction to proceed.

A(n) _____ reaction occurs spontaneously.

exergonic

The energy for an endergonic reaction comes from a(n) _____ reaction.

exergonic

The following reaction A --> B + C + heat is an _____ reaction

exergonic Explanation: Energy has been released.

Select the INCORRECT association. a. enzyme-protein b. exergonic-uphill c. kinetic energy-motion d. potential energy-positional energy d. exergonic-spontaneous

exergonic ... uphill

Which of the following are surface appendages that allow a bacterium to stick to a surface?

fimbriae

What type of protein is rubisco?

free protein

Your small intestine can absorb ____ without its being further digested.

fructose Explanation: Fructose is a monosaccharide, and monosaccharides can be absorbed without having to be broken down into smaller units.

The highlighted part of this molecule is derived from ...

glycerol.

In fat synthesis,________and fatty acids combine to make fats plus________.

glycerol;water

Identify Structure A

glycoprotein

Which of these are by-products of cellular respiration?

heat, carbon dioxide, and water

What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?

hydrolysis

What holds phospholipids together in a bilayer formation?

hydrophilic and hydrophobic interactions with water Explanation: The hydrophobic tails interact with each other and are repelled by water, while the heads are hydrophilic and are attracted to water. This dual nature causes groups of phospholipids to assemble into distinct layers to minimize tail contact with water and maximize head contact with water.

In the reaction that builds a fat,________ groups react with ________ groups.

hydroxyl; carboxyl

This cell is in a(n) _____ solution.

hypertonic There is a greater concentration of solute outside the cell.

You know that this cell is in a(n) _____ solution because it _____.

hypertonic solution ... lost water

You know that this cell is in a(n) _____ solution because it _____

hypertonic solution ... lost water Explanation: A cell will lose water when placed in a hypertonic solution.

If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?

hypotonic

You know that this cell is in a(n) _____ solution because the cell _____

hypotonic ... swelled

Choose the list that presents the four stages of food processing in the order in which they naturally occur.

ingestion → digestion → absorption → elimination Explanation: This is the order for organisms that require all four steps. Fungi begin the process with digestion and end with absorption.

What type of protein is ATP synthase?

integral protein

What type of protein is Photosystem II?

integral protein

Many cell organelles, ___most notably the nucleus, are anchored by Blank which are assembled from a diverse class of proteins.

intermediate filaments

The only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion are the

intermediate filaments

Endocytosis moves materials _____ a cell via _____.

into ... membranous vesicles

An enzyme ___

is an organic catalyst Explanation: Enzymes are proteins that behave as catalysts

As a result of its involvement in a reaction, an enzyme

is unchanged Explanation: Enzymes are not changed as a result of their participation in a reaction.

What happens to pyruvic acid (pyruvate) during the citric acid cycle (CAC)?​[Note: To save space in this slide and the slides that follow, "Citric Acid Cycle and pyruvate transport into the mitochondrion" is abbreviated simply as "Citric Acid Cycle (CAC)..."]

it is broken down into 3 CO2

In glycolysis, what happens to glucose after it is transported across the plasma membrane into the cytoplasm?

it is catabolized to pyruvate

Which set of reactions uses H2O and produces O2?

light dependent reactions

Which of these can RAPIDLY pass directly through the phospholipids of the plasma membrane, without the help of a transport protein?

lipid soluble molecule Explanation: Small, nonpolar, lipid-soluble molecules can pass rapidly through the phospholipids of the plasma membrane. Ions, such as hydrogen ions, and hydrophilic molecules, such as water and glucose, cannot rapidly pass directly through the phospholipids of the membrane. To move rapidly through the membrane, they must pass through membrane transport proteins.

Smooth ER function

lipid synthesis, detoxification, calcium storage

What do fats, steroids, and waxes have in common?

low solubility in water Explanation: Low water solubility is the trait that defines lipids.

Which organelle plays a role in intracellular digestion?

lyosome

A food company hydrogenated a barrel of fat. The treatment ...

made the fat less fluid Exaplanation: Hydrogenation removes double bonds, so the tails can straighten.

chloroplast

makes sugar by converting light energy into chemical energy

Starch can be broken down into the disaccharide known as _

maltose Explanation: Starch is composed of many maltose units

During muscle contractions, myosin motor proteins move across tracks of

microfilaments

The extension of pseudopodia in amoeba is due to the regulated assembly and destruction of

microfilaments

Centrosomes are sites where protein dimers assemble into ___

microtubles

In eukaryotic flagella, the fibers that slide past one another due to the activity of dynein proteins are

microtubles

The cilia and flagella of eukaryotic cells are composed of __

microtubles Explanation: Eukaryotic cilia and flagella are composed of microtubules.

Which of these are hollow rods that shape and support the cell?

microtubles Explanation: Microtubules are rods that also play a role in organelle movement.

Which of these organelles carries out cellular respiration?

mitochondrian Explanation: Mitochondria convert the chemical energy of organic molecules to chemical energy in the form of ATP.

Where is isocitrate dehydrogenase located?

mitochondrion

Golgi apparatus

modifies and packages proteins

When molecules move down their concentration gradient, they move from where they are _____ to where they are_____

more concentrated;less concentrated

The characteristic that all lipids have in common is that _____.

none of them dissolves in water

Where is a bacterial cell's DNA found?

nucleiod region

Ribosomal subunits are manufactured by the _____.

nucleolus Ribosomes are manufactured by the nucleolus.

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis

Diffusion across a biological membrane is called

passive transport

What type of protein is Pc?

peripheral protein

Which of these organelles produces H2O2 as a by-product?

peroxisome Explanation: Peroxisomes produce hydrogen peroxide as a by-product of their metabolic processes.

A white blood cell engulfing a bacterium is an example of _____.

phagocytosis

Choose the correct anatomical sequence that presents the order in which food in the digestive system passes through.

pharynx → esophagus → stomach → small intestine → large intestine Explanation: From the oral cavity, food moves to the pharynx, then on to the stomach via the esophagus, then the small intestine, and finally the large intestine.

Identify Structure D.

phospholipid bilayer of membrane

In C3 plants the conservation of water promotes

photorespiration; Conserving water simultaneously reduces the amount of carbon dioxide available to the plant.

What functional feature(s) does the phosphate group contribute to the structure of a phospholipid?

place to attach another small charged molecule and negative charge to interact with water Explanation: The phosphate attaches to the glycerol and provides a place for another small molecule to attach to the phospholipid. The phosphate has a charge, so it interacts with polar water molecules.

The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.

plasma membrane

The _____ is a selective barrier, regulating the passage of material into and out of the cell.

plasma membrane Explanation: The plasma membrane regulates the passage of material into and out of the cell.

Starch is a type of _____.

polysaccharide Starch is a carbohydrate composed of many monomers (many monosaccharide units).

Chemical energy is a form of _____ energy.

potential

Mitochondrion

produces chemical energy (ATP) that can power the cell

What is a function of a bacterium's capsule?

protection -A bacterium's capsule has a protective role.

Golgi Apparatus Function

protein modification and sorting, cisternal maturation

Rough ER function

protein synthesis

In general, enzymes are what kinds of molecules?

proteins

Enzymes work by _____.

reducing EA

How do enzymes speed up reactions?

reducing the amount of energy needed

central vacuole

regulates cytoplasm composition, creates internal pressure, and stores cell compounds

Which molecules and cellular components pass through the nuclear pore during normal cellular activity?

ribosomal subunits and mRNA Explanation: Ribosomal subunits (made from rRNA and protein) and mRNA are synthesized within the nucleus for use in the cytoplasm. The gateway between the nucleus and the cytoplasm is the nuclear pore.

In a bacterium, where are proteins synthesized?

ribosomes -Ribosomes are involved in the manufacture of polypeptides (proteins).

The presence of many C-C and C-H bonds causes fats to be .

rich in energy and insoluble in water Explanation: The many C-C and C-H bonds make fats nonpolar and insoluble in water. They can also be oxidized, releasing much energy

Which of these organelles manufactures proteins bound for secretion out of the cell?

rough endoplasmic reticulum Explanation: The ribosomes associated with the rough ER synthesize secretory proteins bound for the exterior of the cell. Further processing and packaging occurs in the Golgi apparatus

This figure is an example of a(n) _____.

saturated fat explanation: The fatty acid tails lack double bonds.

Where is calcium stored?

smooth endoplasmic reticulum In addition to storing calcium, the smooth ER also plays a role in detoxification and lipid synthesis.

. An enzyme is considered ____because of its ability to recognize the shape of a particular molecule.

specific

Plant cell wall

strong, protective structure made from cellulose fibrils

In a catalyzed reaction a reactant is often called a _____

substrate

What name is given to the reactants in an enzymatically catalyzed reaction?

substrate

You can recognize the process of pinocytosis when _____.

the cell is engulfing extracellular fluid

The most unsaturated fats have ...

the most double bonds.

What changes when an enzyme (a protein catalyst) is added to a reaction, and what stays the same?

the reaction rate changes, but the free energy stays the same

You are working on a team that is designing a new drug. For this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would be a factor that determines whether the molecule selectively enters the target cells?

the similarity of the drug molecule to other molecules that are transported into the target cells Explanation: If the target cells have transport proteins that specifically bind to certain molecules, they may bind with and transport a drug that is similar in structure.

The permeability of a biological membrane to a specific polar solute depends primarily on which of the following?

the types of transport proteins in the membrane Explanation: The lipid bilayer will be impermeable or very poorly permeable to polar or charged solutes. The presence of the correct transport protein will determine the permeability.

What is energy coupling?

the use of energy released from an exergonic reaction to drive an endergonic reaction

Which of these cell junctions form a barrier to the passage of materials?

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

C4 plants differ from C3 and CAM plants in that C4 plant

transfer fixed carbon dioxide to cells in which the Calvin cycle occurs Explanation: In C3 and CAM plants carbon dioxide fixation and the Calvin cycle occur in the same cells

Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____.

transferring of information from DNA to messenger RNA Explanation: Transcription is the first of the two main steps of protein synthesis.

Structure A in the figure is an...

transport protein

Structure A in the figure is a(n)

transport protein Explanation: The protein is allowing solute molecules to enter the cell.

Which of the following molecular movements is due to diffusion or osmosis?

when a plant cell is placed in concentratedv salt water, water moves out of the cell Explanation: If the salt water is hypertonic to the plant cell's contents, water moves out of the cell by osmosis, a form of diffusion.