Chapter 5-9 MCB181
What is free energy (G)?
the energy that may be used to perform work
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.
A few unidentified seeds were found in a sealed clay jar during an archaeological dig. Radiocarbon dating showed that the seeds were 725 years old. When the seeds were planted, plants grew from them. Based on cell theory, what statements can confidently be made regarding these unidentified plants and seeds?
-Both the seeds and mature plants are composed of cells. -Living cells inside the seeds divide to generate the new plant cell/nod
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. -A concentration gradient forms as excited electrons help move H ions. -Light energy is used to excite electrons on specific chlorophyll molecules.
Glycolysis is a step in the breakdown of glucose. Which of the following statements describe glycolysis?
-It is common to aerobic and anaerobic respiration. -It produces a net gain of two ATP and two NADH.
Which of the following correctly describe the rough endoplasmic reticulum (rough ER)? Choose all the statements that apply.
-It synthesizes proteins that will be sent out of the cell. -It has ribosomes bound to its membrane. -It is connected to the membrane of the nucleus.
Which of the following statements about lysosomes are true? Select all that apply.
-Lysosomes are membrane spheres containing digestive enzymes. -Lysosomes are responsible for programmed cell death. -Lysosomes break down damaged organelles for recycling.
Compounds produced by the electron transport chain
-NAD+ -FAD -H2O -ATP
Compounds that enter the electron transport chain
-NAHD -FADH2 -O2 -ADP
What does the fluid mosaic model describe about the structure of plasma membranes?
-Phospholipids in the membrane are not covalently bonded to each other. -Proteins and other membrane components are embedded in the membrane.
Select all the choices that correctly describe the Golgi apparatus of the cell.
-Proteins are modified by this organelle and repackaged into transport vesicles. -This organelle is made up of flattened sacs of membrane.
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?
-Small, charged molecules and ions move down their concentration gradient out of a cell through proteins in the plasma membrane. -Solutes move across the membrane down their concentration gradient through specialized membrane proteins.
Which of the following are properties of protein-facilitated active transport?
-Substances can be moved across the plasma membrane against a concentration gradient. -Substances cross the plasma membrane by being pumped through a protein using ATP.
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.
Select the descriptions that apply to the smooth endoplasmic reticulum.
-a membranous structure that surrounds the nucleus without attached ribosomes -an organelle that synthesizes fatty acids, phospholipids, and steroids
Arrange the steps of a G-protein signal transduction in the order that they occur.
-a signal molecule binds to the receptor, activating it -the receptor changes conformation and binds an inactive G protein -the G protein is activated by the dissociation of GDP and binding of GTP -the G protein dissociates from the receptor -the G protein activates an effector protein, leading to a cellular response 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.
Which of the products of photosynthesis are used for cellular respiration? Select all that apply.
-carbohydrates -O2
Which of the following are produced during photosynthesis in plants?
-carbohydrates -oxygen
Which of the following molecules are reactants in photosynthesis in plants?
-carbon dioxide -water
Select the phrases that describe the plasma membrane.
-creates a barrier between the inside and outside of the cell -maintains the correct ion concentration inside the cell
Arrange the events of the light-dependent reactions of photosynthesis in the order that they occur.
-electrons on specific chlorophyll molecules are excited by light -electrons escape from chlorophyll molecules and move down an electron transport chain -hydrogen ions are pumped into the interior of the thylakoid -H+ ions pass through an enzyme as they move out of the thylakoid -ATP and NADPH are produced
Generates NADH or FADH2
-glycolysis -citric acid cycle -acetyl CoA production
Place the stages of cellular respiration in the order that they occur.
-glycolysis -conversion of pyruvate to acetyl-CoA -citric acid cycle -electron transport chain
Select the phrases that complete the following sentence. The mitochondrion
-has a double membrane, with ATP synthesis occurring at the inner membrane. -contains unique DNA that is different from the cell\'s nuclear DNA.
Plants synthesize their own food in the form of sugars during the process of photosynthesis. Which of the following statements describe photosynthesis?
-is a cellular process that occurs in the chloroplasts of plant cells -converts carbon dioxide to sugars, releasing oxygen -generates sugars from the energy contained in sunlight
Which of the following are characteristics of an exergonic reaction?
-is spontaneous -releases energy -has negative free energy
Select the phrases that describe the Calvin cycle.
-occurs in the stroma of the chloroplast -does not directly use sunlight energy -converts carbon dioxide to simple sugars
Which of the following are mechanisms that a cell uses to relay an external signal during signal transduction?
-protein dephosphorylation -second messengers
What is the role of second messengers in signal-transduction pathways?
-small molecules or ions that relay a signal from the cell\'s surface to the cell\'s interior
Which of the following describes the way in which phosphorylation directly contributes to signal transduction?
Addition of phosphate groups alters the three-dimensional protein structure, which allows the protein to interact with new binding partners.
Which tenet of cell theory is described by the following paragraph about the historical observations of cells? Cell theory began to develop in 1839, following the research of Marrhias Schleiden and Theodor Schwann into plant and animal tissues. Both the botanist Schleiden and the physiologist Schwann noticed that every organism they viewed under a microscope, whether plant or animal, was composed of cells. Their observations that all living species are made up of one or more cells led to the early formation of cell theory.
All organisms are composed of one or more cells.
In general, what happens during an oxidation-reduction reaction between two molecules?
An atom in the oxidized molecule donates an electron as an atom in the reduced molecule attracts the electron.
Which of the following correctly contrasts anabolic and catabolic pathways?
Anabolic pathways require energy, whereas catabolic pathways release energy.
Classify each description as applying to either autotrophs or heterotrophs.
Autotrophs: -producers -many use photosynthesis to produce organic compounds -use inorganic materials to produce energy -synthesize their own food Heterotrophs: -consumers -unable to produce organic compounds from inorganic materials -obtain their food by consuming other organisms -depend on other organisms for energy
Determine whether each phrase describes an enzyme, an active site, or a substrate
Enzyme: -increases the rate of biochemical reactions -is a protein containing an active site Active site: -is a specific enzyme location that binds with the substrate Substrate: -is a substance that the enzyme acts upon -may be a lipid
A specialized protein in saliva breaks up starch molecules in food into smaller chains of simple sugars. In this reaction, which molecule is the enzyme, which is the substrate, and which is the product? One of the four answer choices will not be used.
Enzyme: -the specialized protein Substrate: -the starch molecules Product: -the small chains of simple sugars
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 formation: -used by yeast cells -generates ethanol Both: -occurs under anaerobic conditions -regenerates NAD+ that can be used in glycolysis Lactic acid fermentation: -used in animal cells -produces lactic acid (lactate)
What does the second law of thermodynamics state about energy?
Given the opportunity, energy disperses away from a concentrated source into places with less energy.
A phospholipid bilayer is depicted in the diagram below.
Heads: -interact with water -polar Tails: -hydrophobic -hydrocarbon-rich
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.
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 Chloroplasts only -perform photosynthesis -contain grana Both -contains DNA -produce energy -mobile within the cell
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 -chloroplasts and sunlight Cellular respiration only -mitochondria Both -CO2 and electron transport chain
Classify the following statements as describing a protein kinase or a protein phosphatase.
Protein kinase: -phosphorylates a protein -binds to ATP Protein phosphatase -releases inorganic phosphate -removes a phosphate group from a protein
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.
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.
How does adenosine triphosphate (ATP) drive energy-required reactions in the cell?
The hydrolysis of ATP is coupled to a non-spontaneous reaction.
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 capture light energy and remove electrons from a donor.
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
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.
How do enzymes recognize their substrates?
a binding site that fits the shape and complements the charge of the substrate
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.
What is the proton gradient in cellular respiration?
a higher concentration of protons (H ) on one side of a membrane than the other
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 describes an endergonic reaction?
a reaction that requires energy to be completed
Which of the following best describes a ligand?
a small molecule that binds to a protein and affects the protein\'s function
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?
chloroplasts
Classify the following as examples of kinetic energy or examples of potential energy.
endergonic: -generating carbohydrates in photosynthesis -hiking to the top of a mountain -constructing DNA from nucleotides exergonic: -a boulder falling off a cliff -breaking down glucose in cellular respiration -metabolizing a protein into amino acids
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
a carbohydrate that enters glycolysis directly
glucose
Which of the following is a simplified equation for cellular respiration?
glucose + oxygen = carbon dioxide + water
stacks of thylakoids
grana
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
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
Activation energy is best defined as the energy that
is required to bring the reactant molecules to a transition state.
Classify the following as examples of kinetic energy or examples of potential energy.
kinetic energy: -vesicle transport in a cell -muscle contraction Potential energy: -fat molecules stored in cells -ATP
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
where this happens: citric acid cycle
mitochondrial matrix
where this happens: conversion of pyruvate to acetyl-CoA
mitochondrial matrix
where this happens: electron transport chain
mitochondrial membrane
Which organelle has a smooth outer membrane, an extensively folder inner membrane, and is the site of ATP production in eukaryotic cells?
mitochondrion
molecules brought in and used in the calvin cycle molecules produced during the calvin cycle that leave the cycle molecules used and regenerated within the calvin cycle
molecules brought in and used in the calvin cycle -co2 -atp molecules produced during the calvin cycle that leave the cycle -a few of the G3P -ADP molecules used and regenerated within the calvin cycle -most of the G3P
Receives NADH or FADH2
oxidative phosphorylation
2,4-dinitrophenol (DNP) causes to ___ pass directly across the inner mitochondrial membrane instead of returning to the mitochondrial matrix through____ proteins. Because of DNP\'s effect on the mitochondrion, less energy is captured in the form of____ and more energy is instead wasted as heat.
protons, ATP synthase, ATP
Cellular respiration consumes glucose during glycolysis. What product of glycolysis can be subsequently modified to enter the citric acid cycle under aerobic conditions?
pyruvate
an end product that is modified to enter the citric acid cycle
pyruvic acid
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
fluid located within an inner membrane that contains DNA, ribosomes, and grana used in photosynthesis
stroma
What provides the energy that excites the electrons in the chlorophyll molecules?
sunlight
Complete the following sentence. Entropy is ___________________.
the amount of energy in a system that cannot be converted into work
Choose the best description of kinetic energy.
the energy an object has due to its motion
Which statement best describes free energy?
the energy from a reaction that is available to do work
a semi-fluid space enclosed by an inner membrane that contains DNA, ribosomes, and enzymes used in the citric acid cycle
thylakoid
You have been hired to develop a drug to inhibit the action of a certain enzyme. Where should the drug bind to competitively inhibit the enzyme?
to the active site of the enzyme
What provides nonwoody plants with the support they need to stand erect?
turgor pressure
What is the source of the electrons that replace the excited electrons lost from chlorophyll?
water
Select the statement that describes an electrochemical gradient.
combined chemical and electrical forces acting on ions across a membrane
folds in an inner membrane that contain proteins used in ATP synthesis
cristae
where this happens: breakdown of glucose to pyruvate
cytosol
Which centrally located organelle produces lipids, detoxifies drugs in the liver, and is composed of a membrane network?
smooth endoplasmic reticulum
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 reactions: -chlorophyll, h20 molecules, light produced by light-dependent reactions -high energy NADPH and ATP
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
Select the descriptions that apply to the thylakoid.
-The thylakoid membrane contains the chlorophyll pigments which capture the energy from light during photosynthesis. -The thylakoid membrane is the site of the light-dependent reactions of photosynthesis. -Thylakoids are arranged within the chloroplast into stacks of coin-shaped discs called grana.
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
a product that can be used directly for energy
ATP
the direct energy source for glycolysis
ATP
The cells that make up multicellular organims send, receive, and respond to a variety of signals. Which of the following is an example of paracrine signaling?
During wound healing, platelet cells produce a growth factor that induces nearby cells to divide.
Classify the following statements as describing endocrine signaling or paracrine signaling.
Endocrine signaling: -signals received by most cells in the body -glands releases hormone into the bloodstream -release of adrenaline by the adrenal gland is an example Paracrine signaling: -cell releases signal into its local environment -signal received only by cells nearby -promotion of local blood vessel growth in a tumor is an example
What does the first law of thermodynamics state about energy?
Energy can be transformed, but it cannot be either created or destroyed.
What is the primary difference between prokaryotic and eukaryotic cells?
Eukaryotic cells have membrane-bound compartments called organelles, whereas prokaryotic cells do not.
a product that donates electrons to the electron transport chain
NADH
