MCB 181 Exam 2

Glycolysis is a series of chemical reactions that convert glucose to pyruvic acid. Glycolysis also uses and generates chemical energy. Several compounds are necessary for glycolysis. These compounds are also components of other metabolic pathways in the cell. Match the compounds in the drop-down menus on the right with the descriptions on the left. You will not select all the compounds. You may select any compound more than once.

--A carbohydrate that enters glycolysis directly = glucose --The direct energy source of glycolysis = ATP --An end product that is modified to enter the citric acid cycle = pyruvic acid --A product that donates electrons to the electron transport chain = NADH --A product that can be used directly for energy = ATP

Which statements describe examples of facilitated diffusion?

--A kidney cell absorbs water molecules down their concentration gradient using a membrane protein. --A neuron allows sodium ions to enter the cell down their concentration gradient using a membrane channel. --An inner ear hair cell allows potassium ions to flow down their concentration gradient after sound waves stimulate a membrane protein.

Which of the following descriptions apply to a chloroplast? Select all that apply.

--A membrane-bound organelle with stacks of thylakoid discs called grana --The main site of photosynthesis in a plant cell

Select the descriptions that apply to the smooth endoplasmic reticulum.

--A membranous structure that surrounds the nucleus without attached ribosomes --An organelle that is responsible for the detoxification of drugs

Match each structure of the mitochondrion and chloroplast on the right to its description on the left. Place all answers.

--A semi-fluid space enclosed by an inner membrane that contains DNA, ribosomes, and enzymes used in the citric acid cycle = matrix --Stacks of thylakoid = grana --Folds in an inner membrane that contain proteins used in ATP synthesis = Cristae --An oval sac with chlorophyll contained within its membrane = thylakoid --Fluid located within an inner membrane that contains DNA, ribosomes, and grana used in photosynthesis = stroma

Which of the following are produced during photosynthesis in plants?

--Carbohydrates --Oxygen

Select the phrases that complete the following sentence. The mitochondrion

--Contains unique DNA that is different from the cell's nuclear DNA. --Has a double membrane, with ATP synthesis occurring at the inner membrane.

Below are events that occur during cellular respiration. Identify where each of the events occur within a eukaryotic cell. Each cellular location may be used once, more than once, or not at all.

--Conversion of pyruvate to acetyl-CoA = Mitochondrial matrix --Electron transport chain = mitochondrial membrane --Breakdown of glucose to pyruvate = cytosol --Citric acid cycle = mitochondrial matrix

Select the phrases that describe the Calvin cycle.

--Converts carbon dioxide to simple sugars --Is a light-independent metabolic pathway --Occurs in the stroma of the chloroplast

Plants synthesize their own food in the form of sugars during the process of photosynthesis. Which of the following statements describe photosynthesis?

--Generates sugars from the energy contained in sunlight --Is a cellular process that occurs in the chloroplasts of plant cells --Cannot convert sunlight energy to sugars without the direct input of carbon dioxide

Choose all the events that occur during the light-dependent reactions of photosynthesis.

--H+ ions are used to help produce the energy carriers, ATP and NADPH. --Light energy is used to excite electrons on specific chlorophyll molecules --Excited electrons help move H+ ions to create a concentration gradient.

What does the fluid mosaic model describe about the structure of plasma membranes?

--Individual phospholipids are not strongly attached to neighboring phospholipids --A membrane has proteins and other components embedded among the phospholipids

Which of the following correctly describe the rough endoplasmic reticulum (rough ER)? Choose all the statements that apply

--It has ribosomes bound to its membrane --It is connected to the membrane of the nucleus --It synthesizes proteins that will be sent out of the cell

Glycolysis is a step in the breakdown of glucose. Which of the following statements describe glycolysis?

--It produces a net gain of two ATP and two NADH. --It is common to aerobic and anaerobic respiration.

Which of the following statements about lysosomes are true? Select all that apply.

--Lysosomes occasionally break down healthy cells. --Lysosomes break down intruding bacteria and viruses. --Lysosomes are lipid spheres filled with digestive enzymes.

Select the phrases that describe the plasma membrane.

--Maintains the correct ion concentration inside the cell --Creates a barrier between the inside and outside of the cell

Which of the products of photosynthesis are used for cellular respiration? Select all that apply.

--Oxygen (O2) --Carbohydrates

Which of the following are mechanisms that a cell uses to relay an external signal during signal transduction?

--Second messengers --Protein diphosphorylation

Facilitated diffusion is a type of passive transport that allows solutes to move across the plasma membrane of a cell. Which statements describe facilitated diffusion?

--Solutes move across the membrane down their concentration gradient through specialized membrane proteins. --Small, charged molecules and ions move down their concentration gradient out of a cell through proteins in the plasma membrane.

Which of the following are properties of protein-facilitated active transport?

--Substances move from an area of lower concentration to an area of higher concentration. --The cell spends energy to move substances through a protein across the plasma membrane

Select the descriptions that apply to the thylakoid.

--The thylakoid membrane is the site of the light-dependent reactions of photosynthesis. --The thylakoid membrane is the site of an electron transport chain that generates cellular energy from light energy. --Thylakoids are arranged within the chloroplast into stacks of coin-shaped discs called grana.

Select all the choices that correctly describe the Golgi apparatus of the cell.

--This organelle is made up of flattened sacs of membrane. --Proteins are modified by this organelle and repackaged into transport vesicles.

Which of the following molecules are reactants in photosynthesis in plants?

--Water --Carbon dioxide

Arrange the steps of a G-protein signal transduction in the order that they occur.

1) A signal molecule binds to the receptor, activating it 2) The receptor changes conformation and binds an inactive G protein 3) The G protein is activated by the disassociation of GDP and binds to GTP 4) The G protein dissociates from the receptor 5) The G protein activates and effector protein, leading to a cellular response

Arrange the events of the light-dependent reactions of photosynthesis in the order that they occur.

1) Electrons on specific chlorophyll molecules are excited by light 2) Chlorophyll molecules release electrons that travel down an electron transport chain 3) Hydrogen ions are pumped into the into the interiors of the thylakoid 4) H+ ions pass through an enzyme as they move out of the thylakoid 5) ATP and NADPH are produced

Place the stages of cellular respiration in the order that they occur.

1) Glycolysis 2) Conversion of pyruvate to acetyl CoA 3)Citric acid cycle 4) Electron transport chain

The cells that make up multicellular organims send, receive, and respond to a variety of signals. Paracrine signaling is a form of cell-to-cell communication in which...

A cell produces a signal that induces changes in local, nearby, cells.

At any given time, there is an array of signaling molecules in a cell\'s environment. How does a cell "know" which signaling molecules to respond to?

A cell responds to a signaling molecule only if the cell has the appropriate receptor.

What is the proton gradient in cellular respiration?

A difference in the concentration of protons (H ) on either side of a membrane

Which of the following describes the fluid mosaic model?

A phospholipid bilayer with various molecules embedded within and floating between the layers

Which of the following best describes a ligand?

A small molecule that influences a larger molecule when the two bind

In general, what happens during an oxidation-reduction reaction between two molecules?

An atom in the reduced molecule attracts an electron that an atom in the oxidized molecule donates.

Which of the following is an organelle, is characterized by stacked, disc shaped structures, and converts energy from the sun into usable sugars for plants?

Chloroplast

Identify compounds that are required for the electron transport chain and compounds that are produced by the electron transport chain. Not all the potential reactants or products are given. Place all the compounds.

Compounds that enter the electron transport chain --NADH --FADH2 --O2 --ADP Compounds produced by the electron transport chain --NAD+ --FAD --H2O --ATP

Classify the following statements as describing endocrine signaling or paracrine signaling.

Endocrine Signaling --Gland releases hormone into the bloodstream --Signal received by most cells in the body --Release of adrenaline by the adrenal gland is an example Paracrine Signaling --Cell releases signal into its local environment --Signal received by only by cells nearby --Release of growth factor to promote scar formation after a wound is an example

Compare and contrast lactic acid fermentation and ethanol fermentation (alcohol fermentation). Move each phrase to the appropriate category. If a phrase describes both types of fermentation, classify it as both.

Ethanol Fermentation --Used by yeast cells --Generates ethanol Lactic Acid Fermentation --Used by animal cells --Produces lactic acid Both --Considered to be an anaerobic process --Regenerates NAD+ that can be used in glycolysis

What is the primary difference between prokaryotic and eukaryotic cells?

Eukaryotic cells have membrane-bound compartments called organelles, whereas prokaryotic cells do not.

Use the cellular respiration lab to help you answer this question. Which steps of cellular respiration generate NADH or FADH2 as products, and which steps receive those molecules as inputs?

Generate NADH or FADH2 --Glysoysis --Citric acid cycle --Acetyl CoA Production Receives NADH or FADH2 --Oxidative phosphorylation

A proton gradient is formed in the mitochondria such that the concentration of protons (H ) is higher on one side of the inner mitochondrial membrane than on the other side. What is the purpose of this proton gradient?

Generates ATP in the electron transport chain

Which of the following is a simplified equation for cellular respiration?

Glucose + Oxygen --> Carbon Dioxide + Water

What is the source of the electrons that replace the excited electrons lost from chlorophyll?

H2O

Cell membranes are composed of phospholipids that have head and tail regions. The phospholipid tail is hydrophobic and spontaneously orients to the inside of the membrane. Which of the following phrases best describes the hydrophobic portion of a phospholipid?

Has few interactions with water

Consider what happens to energy in photosynthesis. How does this differ from what happens to energy in cellular respiration?

In photosynthesis, energy is captured from light, whereas in cellular respiration energy is transferred from storage molecules to ATP.

Integral membrane proteins have different characteristics and functions than peripheral membrane proteins. Sort the statements into those that are properties of integral membrane proteins and those that are properties of peripheral membrane proteins

Integral Membrane Proteins: --Reach through all or part of the membrane --Can move laterally (sideways) in the hydrophobic part of the membrane --Acts as tunnels through the cell membrane Peripheral Membrane Proteins --Found at the surface of the cell membrane

Cell membranes are composed of phospholipids that have head and tail regions. The phospholipid head is hydrophilic and spontaneously orients toward the environment. Which of the following phrases best describes the hydrophilic region of a phospholipid?

Interacts with Water

Assume that one molecule of glucose enters glycolysis and that all of its metabolites are used in generating adenosine triphosphate (ATP) by cellular respiration. What percentage of ATP generated in cellular respiration is produced directly by the reactions of glycolysis?

Less than 15%

Which cellular component is a membrane-bound organelle that digests nutrients and cellular waste?

Lysosome

Identify which of the following are traits of mitochondria, chloroplasts, or both organelles.

Mitochondria --Convert glucose to ATP --Contains folded inner membrane --Found in all animal cells Chloroplast --Turns sunlight into sugars --Filled with thylakoid Both --Occur in plant cells --Has its own genetic material

Classify each of the descriptions below as a characteristic of mitochondria only, chloroplasts only, or both mitochondria and chloroplasts.

Mitochondria Only --Perform cellular respiration --Contain cristae Chloroplast Only --Perform photosynthesis --Contain grana Both --Contain DNA --Produce energy --Enclosed by a double membrane

Which organelle has a smooth outer membrane, an extensively folder inner membrane, and is the site of ATP production in eukaryotic cells?

Mitochondrion

The light-independent reactions of photosynthesis, also known as the Calvin cycle, use and produce a variety of molecules. Sort the molecules below into three categories: molecules brought in and used in the Calvin cycle, molecules produced during the Calvin cycle that leave the cycle, and molecules used and regenerated within the Calvin cycle.

Molecules brought in and used in the Calvin cycle --CO2 --NADPH Molecules produced during the Calvin cycle that leave the cycle --NADP+ --A few of the glyceraldehyde 3-phosphate (G3P) Molecules used and regenerated within the Calvin cycle --Most of the glyceraldehyde 3-phosphate (G3P) --Ribulose biphosphate (RuBP)

The light-independent reactions of photosynthesis, also called the Calvin cycle, use and produce a variety of molecules. Sort the molecules below into three categories, molecules brought in and used in the Calvin cycle, molecules produced during the Calvin cycle that leave the cycle, and molecules made in the cytoplasm from the products of the Calvin cycle.

Molecules brought in and used in the Calvin cycle --Carbon dioxide from the environment --Energy-carrier molecules formed in the light-dependent reactions Molecules produced in the Calvin cycle that leave the cycle --3-carbon molecules that store energy --Energy-carries molecules that have lost some energy Molecules made in the cytoplasm from the products of the Calvin cycle --Organic molecules such as glucose

What is needed for the light-dependent reactions of photosynthesis to take place? What is produced during the light-dependent reactions? Not all of the answer choices will be placed.

Needed for light-dependent reaction --Light --Water --Chlorophyll Produced by light-dependent reaction --Energy-rich ATP and NADPH

Which of the following describes the way in which phosphorylation directly contributes to signal transduction?

Phosphorylation changes the shape of the protein to which it is added, allowing the protein to interact with new binding partners.

The processes of photosynthesis and cellular respiration involve many of the same substances. Which of the following are involved only in photosynthesis, which are involved only in cellular respiration, and which take part in both?

Photosynthesis Only --Sunlight --Chloroplast Cellular Respiration Only --Mitochondria Both --Electron transport chain --Oxygen (O2)

Classify the following statements as describing a protein kinase or a protein phosphatase.

Protein Kinase --Transfers a phosphate group to a protein --Binds adenine triphosphate (ATP) Protein Phosphatase --Dephosphorylates a protein --Releases inorganic phosphate

Cellular respiration consumes glucose during glycolysis. What product of glycolysis can be subsequently modified to enter the citric acid cycle under aerobic conditions?

Pyruvate

During one of the three phases of the Calvin cycle, six molecules of ATP and six molecules of NADPH transfer electrons to six three-carbon sugars known as 3-phosphoglyceric acid (3PGA). The transfer of electrons transforms the six 3PGA molecules into six molecules of a three-carbon sugar called glyceraldehyde-3-phosphate (G3P). In which phase of the Calvin cycle does this occur?

Reduction

During one of the three phases of the Calvin cycle, three molecules of ATP are used to catalyze the rearrangement of five three-carbon sugars, known as glyceraldehyde-3-phosphate (G3P), into three five-carbon sugars, known as ribulose bisphosphate (RuBP). One other molecule of G3P is exported to the cytoplasm to form glucose. In which phase of the Calvin cycle does this occur?

Regeneration

Which of the following is a function of cholesterol in a cell's plasma membrane?

Regulating membrane fluidity

Some ribosomes are used to make proteins, such as insulin, that will be modified and sent out of the cell. Where in the cell are these ribosomes most likely found?

Rough endoplasmic reticulum

How does a signaling molecule present in low concentrations cause a significant response in the cell?

Signal Amplification

What happens in the transduction phase of cell signaling when protein signal molecules are present?

Signal molecules induce a change in membrane proteins that activates other proteins within the cell.

Small molecules and proteins can act as cellular communication signals by binding to cell receptors. A protein binds to its receptor on a cell surface and starts a biochemical chain reaction within the cell. What is the general term for this type of pathway?

Signal transduction

Sort the statements into those that describe similarities between the two photosystems in the light-dependent reactions of photosynthesis and those that are unique to each of the photosystems.

Similarities between the two Photosystems --Light energy is used to excite an electron on specialized chlorophyll molecules Unique to Photosystem II --The bonds of water molecules are broken, producing H+, O2, and replacement electrons for chlorophyll molecules --The energized electrons leaving this photosystem help pump H+ ions into the thylakoid so that they can be used in ATP production Unique to Photosystem I --The energized electrons are used to form NADPH after leaving this photosystem --Replacement electrons for chlorophyll molecules come from the electron transport chain

What is the role of second messengers in signal-transduction pathways?

Small molecules or ions that transmit a signal from the exterior of the cell to the interior of a cell

Which centrally located organelle produces lipids, detoxifies drugs in the liver, and is composed of a membrane network?

Smooth endoplasmic reticulum

What happens in the reception phase of cell signaling when protein signal molecules are present?

Specialized cell surface proteins bind to specific protein signal molecules outside the cell.

Select the statement that describes an electrochemical gradient

Sum of the differences in charge and chemical concentration of ions across a membrane

What provides the energy that excites the electrons in the chlorophyll molecules?

Sunlight

Which statement accurately describes the Calvin cycle?

The Calvin cycle is a light-independent metabolic pathway occurring in the chloroplast stroma that converts carbon from carbon dioxide into sugar.

Phospholipids have the ability to spontaneously form complex structures such as lipid bilayers. What is a property of phospholipids that explains why lipids self-assemble into a bilayer?

The hydrophilic heads of lipids are exposed to water at the membrane\'s surface.

Which choice describes diffusion?

The movement of a substance from a region where it is more concentrated to a region where it is less concentrated down its concentration gradient.

Which statement describes the function of photosynthetic pigments in leaves?

They absorb light energy and trap high energy electrons.

Select the component of choloroplast that is the site of light-dependent reactions.

Thylakoid

Classify the following statements about the role of ADP, ATP, and phosphate groups in cellular respiration as true or false.

True --ATP is composed of ribose, adenine, and three phosphate groups --During cellular respiration, a phosphate group is added to ADP to form ATP False --Hydrolysis of ADP provides the energy to split the glucose molecule during glycolysis --ATP is not required for energy-generating processes, such as glycolysis

What provides nonwoody plants with the support they need to stand erect?

Turgor pressure

Although the path of one glucose molecule through glycolysis generates a total of four ATP molecules, there is a net gain of only two ATP for each glucose molecule that enters the pathway. Why does the passage of one glucose molecule through glycolysis have a payoff of only two ATP molecules?

Two ATP molecules are used in the initial phase of glycolysis, reducing the net gain to two ATP.

The cells that make up multicellular organims send, receive, and respond to a variety of signals. Endocrine signaling is a form of cell-to-cell communication in which...

a cell produces a signal released into the bloodstream to be carried to specific distant organ.