physiology final revision
Which nerve cells carry impulses from the brain to the muscles? A. Sensory B. Motor C. Afferent D. Association
Answer is B: Motor (or efferent) nerves carry impulses away from the CNS to the muscles.
Which of the following is a function of membrane proteins? A. To process lipids and proteins for secretion through the plasma membrane B. To act as receptors for hormones C. To synthesise proteins from amino acids D. To act as a cytoskeleton to support and shape the cell
Answer is B: One function of membrane proteins is to receive (amino acid based) hormones that cannot pass through the plasma membrane.
Which of the following is the best definition of physiology? A. The microscopic study of tissues and cells B. The study of how the body works C. All the chemical processes that take place in the organelles of the body cells D. The body's automatic tendency to maintain a relatively constant internal environment
Answer is B: Physiology is indeed the study of how the (healthy) body functions
Name the largest family of cell surface receptor? A. GPCR B. Ion-channel receptor C. Enzyme-linked receptor D. Nuclear receptor
Answer :A
There is a space between a neuron and the cell it stimulates, that is crossed by a neurotransmitter. What is it called? A. Synaptic cleft B. Voltage-gated channel C. Synapse D. Postsynaptic membrane
Answer is A
In endocrine signaling, the signal molecule act on target cell only in close proximity. A. True B. False
Answer :B Explanation :Endocrine signaling always acts on the distant target cell or that cell which located distantly from their site of synthesis while paracrine signaling is used for the cells which are located in close proximity.
What does the process known as anabolism refer to? A. The use of energy for producing chemical substances B. The breaking down phase of metabolism C. All the chemical processes that take place in the organelles of the cells D. The supply of nutrients to the body cells
Answer is A
What is the last part of a nerve cell that is involved when a nerve impulse passes to another cell? A. Synaptic knob B. Axon hillock C. Dendrite D. Axon
Answer is A
Which of the listed term is described as ―All the chemical processes that take place in the organelles and cytoplasm cells of the body‖? A. Metabolism B. Cellular respiration C. Homeostasis D. Physiology
Answer is A
Which of the following is true regarding a transmembrane receptor? A. It has both hydrophobic and hydrophilic regions and the ligand binds on the hydrophobic regions B. It has both hydrophobic and hydrophilic regions and the ligand binds on the hydrophilic regions C. It has exclusively hydrophilic regions D. It has exclusively hydrophobic regions
Answer B: It has both hydrophobic and hydrophilic regions and the ligand binds on the hydrophilic regions
The plasma membrane of a cell contains molecules that have a hydrophobic end and a hydrophilic end. What are they called? A. Phospholipids B. Cholesterol C. Integral proteins D. Glycoproteins
Answer is A: The phosphate end is hydrophilic (water soluble) while the lipid end is hydrophobic (insoluble in water).
What term is used to describe the movement of dissolved particles along (or down) their concentration gradient? A. Endocytosis B. Active transport C. Osmosis D. Diffusion
Answer is D: Following the concentration gradient is a passive process. Choice C applies only to water molecules.
What is the active transport when applied to a cell? A. It is the movement of ions or molecules through a membrane against their concentration gradient using energy from ATP. B. It is the rapid movement of water molecules through channels called aquaporins. C. It is the process of bringing large substances (e.g. bacteria, proteins, polysaccharides) into cells by engulfing them in a vesicle enclosed by a membrane. D. It is the passage of blood cells through the intact walls of the capillaries.
Answer is A: "Active" means that energy is expended to accomplish the movement. This energy is required to shift particles from a solution where they are in a lower concentration to a solution where they are at a greater concentration. Choice B is osmosis; Choice C is endocytosis; Choice D is diapedesis.
The unit milliosmoles per litre (mOsm/L) refers to which of the following? A. The number of particles in solution, in multiples of 6 × 1020 per litre. B. 103 Times the number of moles of particles in a litre of solution. C. The number of molecules per litre of solution. D. The number of moles per millilitre of solution.
Answer is A: A milliosmole (mOsm) is 10−3 × (6 × 1023) particles which is 6 × 1020 . Choice B means 1000× the correct answer. Choice D means 1/1000× the correct answer.
Which of the following is NOT a type of cell? A. Ribosome B. Haemocytoblast C. Neutrophil D. Phagocyte
Answer is A: A ribosome is a cell organelle, not a cell type
What is the major component of the plasma membrane of a cell? A. Phospholipid B. Glycolipid C. Integral protein D. Cholesterol
Answer is A: Cholesterol and proteins are also present in the plasma membrane but as more minor components.
Which of the following is NOT one of the organelles within a cell? A. Desmosome B. Endoplasmic reticulum C. Mitochondrion D. Golgi apparatus
Answer is A: Desmosome (despite having the suffix "-some") are not within the cell. They are structures that join adjacent plasma membranes to each other.
Which of the following is a list of four of the organelles found within a cell? A. Lysosomes, ribosomes, centrosomes, Golgi complex B. Ribosomes, centrosomes, Golgi complex, desmosomes C. Endoplasmic reticulum, mitochondria, nucleus D. Centrosomes, Golgi complex, peroxisomes, chromosomes
Answer is A: Desmosomes are not within a cell, they are structures that hold adjacent cells together. The nucleus is not regarded as an organelle. Chromosomes while within a cell are DNA and are not regarded as an organelle.
What type of transport utilizes a carrier protein to transport molecules across the cell membrane? A. Facilitated diffusion B. Diffusion C. Active diffusion D. Active transport
Answer is A: Facilitated diffusion is spontaneous passive transport of large molecules across a biological membrane via specific transmembrane integral proteins, from where they are in high concentration to where they are in lower concentration.
Membrane proteins perform the following functions EXCEPT one. Which one? A. Form glycocalyx B. Act as receptor proteins C. Form pores to allow the passage of small solutes D. Behave as enzymes
Answer is A: Glycocalyx refers to molecules in the plasma membrane that have a carbohydrate chain attached (prefix "glyco-").
What would be the concentration of a solution that causes red blood cells placed in it to swell? A. Hypotonic B. Isotonic C. Hypertonic D. Iso-osmotic
Answer is A: If the RBC swell, that means water is entering the cells; hence, the surrounding liquid is at a lower concentration (i.e. hypotonic) to the liquid inside RBC.
Homeostasis usually returns the body to a healthy state after stressful stimuli by: A. Negative feedback B. Positive feedback C. Means of the immune system D. Means of the nervous system
Answer is A: Negative feedback is far more common in maintaining homeostasis than is positive feedback
Except for one, the following are types of cells. Which one is NOT a type of cell? A. Platelets B. Leucocytes C. Macrophages D. Osteoblasts
Answer is A: Platelets are fragments of a cell (a megakaryocyte) bound by a membrane.
Which of the following statements could be applied to a hypertonic solution? A. It causes red blood cells to shrink and crenate. B. It causes red blood cells to swell and perhaps lyse. C. It is a solution with an osmolarity less than that of blood. D. It causes movement of water into red blood cells.
Answer is A: RBC placed in a hypertonic solution would lose water to the solution, so their volume would decrease (they would shrink). This would cause their membrane to become wrinkled (to crenate)
An intravenous fluid that is isotonic to blood would have what effect on the red blood cells? A. It would have no effect. B. It would cause red blood cells to crenate. C. Red blood cells would lyse. D. The blood volume would increase.
Answer is A: RBC would be unaffected by an isotonic solution as there will be no net flow of water into or out of the cells
Which one of the following is NOT a steroid compound? A. Stearic acid B. Oestrogen C. Cholesterol D. Testosterone
Answer is A: Stearic acid is a fatty acid. The sex hormones oestrogen and testosterone are derived from cholesterol.
The process of ―diffusion‖ through a membrane may be described by which of the following? A. The movement of ions and molecules away from regions where they are in high concentration towards regions where they are in lower concentration. B. The use of energy from ATP to move ions and small molecules into regions where they are in lower concentration. C. The plasma membrane engulfs the substance and moves it through the membrane. D. The use of energy from ATP to move water molecules against their concentration gradient.
Answer is A: The choices with ATP are nonsense. While choice C refers to endocytosis.
Which one of the following is NOT a function of membrane proteins? A. They form a structure called a glycocalyx. B. They attach cells to each other. C. They form passageways to allow solutes to pass through the membrane. D. They from receptors which can bind messenger molecules.
Answer is A: The glycocalyx is thought of as being membrane carbohydrates.
What is the name given to the type of transport where glucose or an amino acid binds to a receptor protein on the plasma membrane, which then moves the molecule into the cell without the expenditure of energy? A. Facilitated diffusion B. Bulk transport C. Secondary active transport D. Active transport
Answer is A: The membrane protein facilitates the entry into the cell. No energy is expended so it is not active transport.
Active transport across the plasma membrane may be described by which statement? A. Active transport requires energy from ATP. B. Active transport is also known as endocytosis. C. Active transport moves molecules along their concentration gradient. D. Active transport is the movement of lipid-soluble molecules through the plasma membrane.
Answer is A: This is the only correct answer.
What term is applied to an intravenous solution that would cause a net movement of water out of red blood cells? A. Hypertonic B. Supertonic C. Epitonic D. Hypotonic
Answer is A: ―Hyper-‖ refers to greater (tonicity) than inside an RBC. Hence, water would move from the less concentrated solution (within the RBC) to the exterior.
What does the term "integral protein" refer to? A. Proteins that lie within the plasma membrane of a cell B. Proteins that must be included in the diet as they cannot be manufactured by the body C. Proteins found within the central nervous system D. Plasma proteins that exist in the blood but not in the interstitial fluid
Answer is A: ―Integral‖ refers to being within the cell membrane. The other choices are not even close to being correct
10. A major role for mitochondria is to: A. Transcribe the information in DNA (deoxyribonucleic acid) B. Produce ATP (adenosine triphosphate) C. Synthesise proteins from amino acids D. Use enzymes to lyse molecules
Answer is B: ATP is only produced within the mitochondria.
What is a function of carbohydrates in the body? A. To act as enzymes B. To provide energy C. To function as local hormones D. To provide the building blocks for proteins
Answer is B: Dietary carbohydrates are converted to simple sugars which are disassembled in mitochondria to produce ATP.
Why does the plasma membrane of a cell present a barrier to the movement of electrolytes through it? A. There are no channels in the membrane for the passage of electrolytes. B. Electrolytes are not soluble in the lipid of the membrane. C. Electrolytes are too large to pass through membrane channels. D. Membrane proteins electrically repel charged particles
Answer is B: Electrolytes, being charged particles, are not able to dissolve their way through the lipid plasma membrane (which is non-polar). Hence it is a barrier to them.
The human body's ability to maintain a relatively constant internal temperature is an example of what? A. Respiratory heat loss B. Homeostasis C. Vasodilation and evaporative heat loss D. Positive feedback
Answer is B: Homeostasis is derived from words that mean remaining similar and standing still and refers to physiological conditions remaining more or less the same.
What can be correctly said of an isotonic intravenous solution? An isotonic solution: A. Causes water to move out of red blood cells B. Causes no net movement of water into or out of red blood cells C. Has the same solutes in the same solution concentration as blood plasma D. Causes water to move into red blood cells
Answer is B: Isotonic means that the IV solution has the same concentration of particles (albeit the particles themselves may be different) as in RBC; hence, there is no net osmotic flow.
In which organelle of the cell do most aerobic respiration reactions happen? A. In the nucleus B. In the mitochondria C. In the ribosomes D. In the lysosomes
Answer is B: Mitochondria are the sites of aerobic respiration. That is, the production of ATP from pyruvic acid (via glucose) and oxygen.
What is a role performed by mitochondria? A. Contain enzymes capable of digesting molecules B. Produce ATP C. Synthesise proteins D. Synthesise fatty acids, phospholipids and cholesterol
Answer is B: Mitochondria produce ATP. The other tasks are performed by lysosomes, ribosomes and endoplasmic reticulum, respectively
What is the study of how body parts function called? A. Histology B. Physiology C. Homeostasis D. Metabolism
Answer is B: Physiology refers to function.
What roles do proteins play in a cell's plasma membrane? A. They catalyse reactions and perform endocytosis. B. Receptors for hormones and selectively allow entry to some solutes via the channels they form. C. They allow cells to adhere to each other and allow lipid-soluble molecules to pass through the lipid bilayer. D. Glycoproteins act as recognisers or identification tags and are responsible for movement of the cell.
Answer is B: Some proteins are receptor sites for hormones, others form pores and selectively allow some solutes to pass through the channels they form. They do not perform endocytosis or move the cell around. Lipid-soluble molecules can pass through the lipid bilayer on their own
Which statement about the plasma membrane is INCORRECT? A. It is selectively permeable. B. It is composed of two layers of glycoprotein molecules. C. It contains receptors for specific signalling molecules. D. The plasma membranes of adjacent cells are held together by desmosomes.
Answer is B: The PM is indeed made of two layers, but they are phospholipid (not glycoprotein) molecules.
Homeostasis refers to maintaining: A. A constant internal body environment through negative feedback B. Body conditions relatively constant within a narrow range through negative and positive feedback C. Adequate concentrations of respiratory gases D. Blood glucose level within the healthy range
Answer is B: The maintenance of body conditions through feedback which is usuall negative but is positive in some rare situations.
Which of the following is NOT an example of a cell? A. Macrophages B. Lysosomes C. Plasmocytes D. Chondroblasts
Answer is B: The suffix "-some" refers to an organelle within a cell. The other suffixes all indicate a type of cell.
What are lysosomes, centrosomes, and ribosomes example of? A. Stem cells B. Organelles within a cell C. Sensory receptors in the dermis D. Exocrine glands
Answer is B: The suffix "-some" refers to small body or organelle within a cell.
What is the name of the mechanism that ensures that there is a higher concentration of sodium ions in the extracellular fluid than in the intracellular fluid? A. Facilitated diffusion B. The sodium-potassium pump C. Secondary active transport D. Osmosis
Answer is B: The ―pump‖ exchanges Na for K and uses energy from ATP to function.
Which one of the following best describes what a cell membrane consists of? A. Lipids, proteins, ribosomes B. Lipids, cholesterol, proteins C. Cholesterol, proteins, cytoplasm D. Lipids, proteins, cytoplasm
Answer is B: These are the three major constituents. Ribosomes and cytoplasm are found inside the cell
What does the term ―homeostasis‖ refer to? A. The chemical processes that take place in the organelles of the cells B. The body's tendency to maintain a relatively constant internal environment C. The body's use of energy to produce chemical substances and parts for growth D. Anybody response that opposes the stimulus that initiated the response
Answer is B: This is the best definition of homeostasis. Choice D refers to negative feedback.
What does the word ―homeostasis‖ refer to? A. The steps leading to repair of a blood vessel and the coagulation of blood B. The maintenance of internal body conditions within narrow limits C. The controlled response that opposes the influence that caused it D. The production of blood cells in active bone marrow
Answer is B: This is the best definition. Choice C refers to negative feedback only
Which of the following is a correct definition of ―negative feedback‖? A. The process by which the body maintains homeostasis B. A mechanism in which the body's response opposes the stimulus C. A mechanism whereby the body responds to a stimulus by acting to enhance the stimulus D. The dynamic equilibrium maintained by an integrating centre which causes an effector to respond to the stimulus received by the receptor
Answer is B: When an action is taken to cause the stimulus to be reduced, the feedback is termed ―negative‖
What is the term used to describe the bulk movement of a large number of molecules out of a cell? A. Lymphocytosis B. Exocytosis C. Thrombocytosis D. Endocytosis
Answer is B: ―Exo-‖ refers to movement from inside to the outside (-cytosis is a suffix that means in reference to cells)
Homeostasis relies on feedback to achieve its aims. ―Negative‖ feedback refers to which situation below? The body's response: A. Travels from the effector to the integrating centre via the afferent pathway B. Opposes the stressful stimulus C. Is to decrease the set point D. Enhances the stressful stimulus
Answer is B: ―Negative‖ refers to the opposing nature of the response
In which part of a cell does the process of making ATP from oxygen and glucose take place? A. Lysosomes B. Ribosomes C. Mitochondria D. Golgi apparatus
Answer is C
What is the gap between the plasma membranes of a neuron that conducts an incoming signal and the cell that is going to receive the signal called?A. Neuromuscular junction B. Intercellular cleft C. Synaptic cleft D. Intercalated disc
Answer is C
Which of the following enables ions such as sodium to cross a plasma membrane? A. Phospholipid bilayer B. Peripheral proteins C. Integral proteins D. Desmosomes
Answer is C
Which structure carries incoming impulses towards the nerve cell body? A. Axon hillock B. Axon C. Dendrite D. Synaptic knobs
Answer is C
Which of the following is NOT a part of the plasma membrane of a cell? A. Integral proteins B. Glycoproteins C. Plasma proteins D. Peripheral proteins
Answer is C: As the name implies, plasma proteins are found in the blood plasma. Not to be confused with the plasma membrane.
Which of the following is NOT a part of the plasma membrane of a cell? A. Phospholipid B. Glycoprotein C. Chromatin D. Cholesterol
Answer is C: Chromatin makes up chromosomes
. Facilitated diffusion differs from active transport because facilitated diffusion: A. Requires energy from ATP B. Moves molecules from where they are in lower concentration to higher concentration C. Moves molecules from where they are in higher concentration to lower concentration D. Involves ions and molecules that pass through membrane channels
Answer is C: Diffusion always refers to movement from high to low concentration (without energy expenditure). Facilitated refers to the assistance provided by a transport molecule that is designed for the purpose.
Which of the following is NOT found in the plasma membrane? A. Proteins B. Cholesterol C. Endoplasmic reticulum D. Phospholipids
Answer is C: Endoplasmic reticulum is an organelle and found within the cell
A solution that is said to be isotonic to blood has the same: A. Percent concentration as blood B. Number of moles of dissolved particles as blood C. Number of osmoles per litre of dissolved particles as blood D. Number of dissolved particles as blood
Answer is C: Isotonic means the same number of solute particles per litre. Choice B would also be correct if "moles" was replaced with "moles per litre"
Which one of the following organelles is considered as the "energy producing" centre of the cell? A. Rough endoplasmic reticulum B. Golgi apparatus C. Mitochondria D. Ribosomes
Answer is C: Mitochondria are where ATP molecules are produced from glucose.
What name is given to the cells in the nervous system that produce nerve impulses? A. Neurotransmitters B. Nerves C. Neurons D. Neuroglia
Answer is C: Neurons produce nerve impulses, nerves are bundles of neurones. Neuroglia are cells that support and protect neurons.
Which of the following enables ions such as sodium to cross a plasma membrane (PM)? A. Phospholipid bilayer B. Peripheral proteins C. Integral proteins D. Desmosomes
Answer is C: One function of integral protein in the PM is to form channels to allow for the passage of ions
The diffusion of water through a membrane is referred to as: A. Secondary active transport B. Bulk transport C. Osmosis D. Endocytosis
Answer is C: Osmosis is a word that is reserved for the movement of water through a membrane.
Which of the following describes the structure of the plasma membrane (cell membrane)? A. A bilayer of lipoproteins with cholesterol molecules and plasma proteins forming pores B. A double layer of glycolipid molecules, with cholesterol molecules and plasma proteins C. A double layer of phospholipid molecules, with cholesterol molecules and membrane proteins D. A bilayer of cholesterol molecules and plasma proteins, with pores of phospholipid
Answer is C: Phospholipid molecules each with a hydrophilic end and a hydrophobic end arrange themselves as a double wall (a bilayer). Cholesterol molecules are interspersed among the phospholipids and give the membrane additional strength. Protein molecules form the pores or channels through which water-soluble materials may enter and leave the cell. ―Plasma proteins‖ exist in the blood, not in the cell membrane
Which one of the following terms best describes a phospholipid? It consists of a: A. Polar head and polar tail B. Non-polar head and a polar tail C. Polar head and non-polar tail D. Non-polar head and a non-polar tail
Answer is C: Polar = hydrophilic head of phosphate (which can dissolve in the aqueous extracellular solution because water molecules are polar); nonpolar = hydrophobic tails of lipid, which being non-polar cannot dissolve in aqueous solutions
What is the function of the cell plasma membrane? A. It maintains an intracellular environment that is hypotonic compared to the extracellular fluid. B. It protects the cell from dehydration by limiting water flow from the cell. C. It regulates the passage of molecules and ions into and out of the cell. D. It provides the supportive medium for membrane proteins.
Answer is C: The plasma membrane is made of lipid and separates the aqueous intracellular fluid from the aqueous extracellular fluid. Substances cannot enter or leave the cell unless they are lipid soluble or by endo/exo-cytosis or have a membrane protein pore or transport mechanism that can move them through the membrane.
Which of the following molecules cannot pass through the plasma membrane? A. Water molecules B. Non-polar molecules C. Amino acid-based hormones D. Fat-soluble molecules
Answer is C: These hormones are not lipid soluble and too large to pass through channels.
Which of the following is a correct definition of "positive feedback"? A. The process by which the body maintains homeostasis B. A mechanism in which the body's response to a stimulus opposes the stimulus C. A mechanism whereby the body responds to a stimulus by acting to enhance the stimulus D. The dynamic equilibrium maintained by an integrating centre which causes an effector to respond to the stimulus received by the receptor
Answer is C: When the stimulus is enhanced, the feedback is termed ―positive
An isotonic solution is one which: A. Has an osmotic pressure that is different to red blood cells B. Has an osmolarity less than that of red blood cells C. Causes no net movement of water between the solution and red blood cells D. Has an osmolarity greater than that of red blood cells
Answer is C: ―Iso‖ means ―the same‖. When the concentration of the surrounding liquid is the same as that inside a RBC, then no net water movement occurs.
. Some of the body's homeostatic responses rely on ―negative feedback‖. Which of the following happens in negative feedback? A. The body ignores changes in a physiological variable that are directed towards the set point for that variable. B. The body ignores changes in a physiological variable that are directed away from the set point for that variable. C. The body's response acts to oppose the change in the physiological variable. D. The body's response acts to enhance the change in the physiological variable
Answer is C: ―Negative‖ refers to the response being in the opposite direction to the stimulus. Thus if a variable is increasing, then the body's response is to produce a change that causes the variable to decrease. The body does not ―ignore‖ stimuli.
What is the major function of lysosomes? A. Package proteins B. Detoxify toxic substances C. Catalyse lipid metabolism D. Digest unwanted particles within the cell
Answer is D
When an action potential arrives at a synapse, what happens first? A. A neurotransmitter is released into the synaptic cleft. B. Extracellular Na+ crosses the postsynaptic membrane. C. Choline in the synaptic cleft enters the nerve cell and is converted to acetyl choline. D. Extracellular Ca++ enters the nerve cell.
Answer is D
Which statement about endoplasmic reticulum (ER) and Golgi apparatus (GA) is incorrect? A. Rough ER contains structures called ribosomes. B. ER packages newly synthesised proteins. C. GA packages enzymes for use in the cytoplasm. D. GA is a site for ATP synthesis.
Answer is D: ATP is produced in the mitochondria, not the Golgi apparatus.
Human blood has an osmolarity that lies within the range 280- 300 mOsm/L. Which of the following statements is correct? A. An isotonic solution has osmolarity that is either less than 280 or greater than 300 mOsm/L. B. A hypotonic solution has osmolarity between 280 and 300 mOsm/L. C. A hypertonic solution has osmolarity between 280 and 300 mOsm/L. D. An isotonic solution has osmolarity between 280 and 300 mOsm/L.
Answer is D: An isotonic solution has the same osmolarity as blood.
Which of the following is the smallest living structural unit of the body? A. Atom B. Molecule C. Organelle D. Cell
Answer is D: Cell is the smallest structural unit that is deemed to be alive
What may be said of isotonic solutions? They have: A. Had added the same number of moles of solid substance per volume of solution B. The same number of grams of solute per volume of solution C. The same percent concentration D. The same number of dissolved particles per volume of solution
Answer is D: Choice A is incorrect as a mole of an ionic substance will result in 2 or 3 Osm of dissolved particles. (Choices B and C are incorrect.)
Which of the following is a component of the plasma membrane of a cell? A. Plasma B. Glycolipid C. Plasma proteins D. Cholesterol
Answer is D: Despite the term "plasma", A and C are wrong. And it is phospholipids, not glycolipids that occur in the membrane
The process of ―active transport‖ through a membrane may be described by which of the following? A. The movement of ions and small molecules away from regions where they are in high concentration. B. The use of energy from ATP to move ions and small molecules into regions where they are in lower concentration. C. The plasma membrane engulfs the substance and moves it through the membrane. D. The use of energy from ATP to move ions and small molecules against their concentration gradient.
Answer is D: Energy (ATP) is required to force molecules against their concentration gradient.
Facilitated diffusion through a membrane involves which of the following scenarios? A. The diffusion of water through a selectively permeable membrane along its concentration gradient. B. The movement of a molecule against its concentration gradient with the expenditure of energy C. The plasma membrane surrounding (engulfing) the molecule and the molecule moving into the cell D. A molecule binding to a receptor which moves the molecule through the membrane without the outflow of energy.
Answer is D: Facilitation is by binding to a membrane protein without need to use energy.
Which of the following is correct? A. Lipids form channels in the cell membrane. B. Sodium and potassium are found at equal concentration in the cytoplasm C. Hydrophobic tails of phospholipids in the cell membrane contact the cytoplasm. D. Hydrophilic heads of phospholipids in the cell membrane contact the cytoplasm
Answer is D: Hydrophilic means water loving, so the phospholipid head dissolves in the aqueous solution of the cytoplasm. It is proteins that form the channels. And K is in much greater concentration in the cytoplasm than is Na.
Which of the following is an example of negative feedback? A. The uterine contractions during childbirth push the baby's head against the cervix which stimulates the uterus to contract. B. The release by platelets that aggregate at the site of a blood vessel injury, of compounds that promote platelet aggregation. C. As resting membrane potential rises, voltage-gated ion channels open which allow ions to enter the axon which causes further rise in the membrane potential and more ion channels to open. D. As blood sugar level rises, insulin is released which promotes the absorption of glucose from the blood by liver, muscle and fat cells.
Answer is D: In this choice, the response to rising glucose is the release of insulin, which promotes a decrease in blood glucose by causing it to be absorbed from the blood. That is, the response is to oppose the change that initiated the response. This is termed ―negative‖ feedback. The other three choices are examples of positive feedback
A major role for mitochondria is to: A. Synthesise fatty acids, phospholipids and steroids B. Deliver lipids and proteins to plasma membrane for secretion C. Synthesise proteins from amino acids D. Produce ATP (adenosine triphosphate)
Answer is D: Mitochondria produce ATP from glucose
What is the function of phospholipids in the plasma membrane? A. To maintain the intracellular fluid at a similar composition to that of the interstitial fluid. B. To form channels to selectively allow passage of small molecules. C. To act as receptors for signalling chemicals. D. To present a barrier to the passage of water-soluble molecules.
Answer is D: Molecules that are soluble in water cannot pass through lipid (fat). So the phospholipids are a barrier. The functions described by B and C are performed by other molecules in the plasma membrane.
What are generally referred to as organelles? A. Small exocrine organs such as salivary glands and sudoriferous glands B. Small endocrine glands such as the pituitary and adrenal glands C. Structures of the general senses such as lamellated corpuscles and muscle spindles D. Structures within a cell such as ribosomes and endoplasmic reticulum
Answer is D: Organelles are not glands. They are structures within a cell
Which is NOT a feature of a mitochondrion? A. It contains DNA and RNA. B. Its outer membrane contains pores. C. It produces ATP. D. It packages and stores protein
Answer is D: Protein is produced and stored by the endoplasmic reticulum and Golgi apparatus (GA). Mitochondria do have DNA (derived from the mother) and RNA.
An intravenous fluid that is hypertonic to blood would have what effect on the red blood cells? A. It would have no effect. B. The number of red blood cells would increase C. Red blood cells would lyse. D. It would cause red blood cells to crenate.
Answer is D: RBC in contact with a hypertonic solution would lose water to the solution and shrink. This would cause their plasma membrane to crenate (wrinkle).
One of the functions of integral proteins in cell membranes is to: A. Maintain the rigid structure of the cell B. Support mechanically the phospholipids C. Interact with the cytoplasm D. Form channels for transport functions
Answer is D: Some proteins form channels which allow molecules and ions to enter the cell.
A solution that is isotonic to blood plasma is one which A. Contains 0.5% glucose B. Must contain the same solutes as blood and in the same concentration as in blood C. Has an osmolarity between 280 and 300 mOsm/L D. Causes no net movement of water into or out of cells
Answer is D: The concept of tonicity involves reference to a membrane (in this case the plasma membrane of a RBC). Osmolarity is a property of the solution (and of how much solute is dissolved in it) and exists whether a semipermeable membrane is present or not.
What is the name given to the movement of glucose or amino acids from the gut into the cells lining the gut, when they bind to a transport protein that has also bound a sodium ion. The sodium ion is entering the cell along its concentration gradient. A. Facilitated diffusion B. Sodium-potassium pump C. Active transport D. Secondary active transport
Answer is D: The sodium ion was transported out of the cell with the use of energy in order to set up the sodium concentration gradient. This gradient then allows other molecules to enter the cell along with the re-entry of sodium. This is active (because energy used), but secondary as it occurs as a result of the previous active transport event.
A hypertonic solution is one which: A. Has an osmotic pressure that is different to that inside red blood cells B. Has an osmolarity less than that of red blood cells C. Causes no net movement of water through the membrane of red blood cells D. Has an osmolarity greater than that of red blood cells
Answer is D: ―Hyper‖ means greater than the tonicity (or osmolarity) inside an RBC.
A hypotonic solution may be characterised by which of the following? A. A solution whose osmolarity is greater than that of blood B. One that causes red blood cells to crenate C. A solution within the range 280-300 mOsm/L D. One that causes a net water movement into red blood cells
Answer is D: ―Hypo‖ means less concentrated than the solution inside a RBC. This in turn means that the concentration of water molecules is greater outside the cell than inside. So there will be a net water flow by osmosis into the RBC.
Choose one answer below that completes the sentence so that it makes a true statement. Positive feedback: A. Is the way the body maintains homeostasis B. Is a response that opposes a stimulus C. Is a response that maintains a dynamic state of equilibrium D. Is a response that enhances a stimulus
Answer is D: ―Positive‖ feedback will reinforce the stimulus, making it greater or more insistent.
Which of the following are the basic categories of chemical signaling found in multicellular organisms? A. Paracrine signaling B. Autocrine signaling C. Endocrine signaling D. All of the above
Answer( d) All of the above
Cell signaling is .__ A. Intercellular B. Intracellular C. Both A and B D. None of the above
Answer: C
Some evidence shows that the unfolded protein response can be promoted by an inflammatory state . Cytokines are released from cells exposed to stress ,thus inducing the unfolded protein response in neighboring cells .Which of the following best defines this process? A. Endocrine signaling B. Autocrine signaling C. Autologous signaling D. Paracrine signaling
Answer: D
Which of the following is a cell surface receptor? A. Enzyme-linked receptors B. G protein-linked receptors C. Ion-channel linked receptors D. All of the above
Answer: D )All of the above)
Which organelle is the site of ATP production? A. Nucleus B. Endoplasmic reticulum C. Mitochondria D. Golgi apparatus
answer is C : the mitochondria are where ATP is produced
