Question

Q13 Cyanide is a deadly poison that attaches to cytochrome c oxidase, the last protein in the electron transport chain before the terminal electron acceptor. Based on your knowledge of the electron transport chain, which statement below best describes the action of cyanide on the body?

A. Cyanide does not allow the Krebs cycle to be completed by blocking acetyl CoA from entering this cycle. This action shuts down the entire process of cellular metabolism.

B. Cyanide does not allow H⁺ ions to be pumped into the outer membrane of the mitochondria and, therefore, they are never able to go down their concentration gradient and produce ATP.

C. Cyanide prevents NADH and FADH₂ from dropping off their electrons at the beginning of the electron transport chain by causing a backup of electrons in the Krebs cycle.

D Cyanide blocks the terminal electron acceptor, oxygen, causing an accumulation of CO₂ in the tissues from cellular metabolism, and poisons the system due to excess waste products.

E Cyanide blocks the terminal electron acceptor oxygen and therefore will halt the production of ATP. The majority of ATP is normally produced in the electron transport chain and without it the body will begin to only go through glycolysis and start producing lactic acid and will eventually shut down due to a lack of ATP to run the body and because of the buildup of acid in the system.

Q19 Which of the following is NOT true for all three of these transport mechanisms: facilitated diffusion, primary active transport, and secondary active transport?

A. The transport mechanism is specific for (a) particular solute(s)

B. The transport mechanism requires a protein

C The transport mechanism has a limit to the total number of molecules that can be transported per unit of time

D The transport mechanism requires energy

E The transport mechanism requires energy

Q20 As the molecular weight of a molecule increases, its

A concentration in a solution decreases. B rate of diffusion will also increase. C ability to dissolve in lipid will also increase. D ability to form a charge decreases. E membrane permeability decreases. Q21 Most water molecules that cross the plasma membrane do so by A. diffusion through the plasma membrane. B diffusion through ion channels. C diffusion through aquaporins D active transport by ion channels E active trasnport by aquaporins Q22 Which of the following will NOT affect the magnitude of a cell's response to a specific hydrophilic ligand? A ligand concentration B number of receptors C receptor upregulation D affinity of the receptor for the ligand E lipid solubility of the ligand Q23 What is a molecule that is similar in structure to a messenger and binds with that messenger's receptor to stimulate a similar response from the target cell? blocker, synergist, antagonist, agonist , or protagonist Q24 What organelle packages peptide/protein messengers into secretory vesicles? golgi apparatus, rough ER, smooth ER, nucleus , or lysosomes Q25 Aspirin is a nonsteroidal anti-inflammatory drug (NSAID) that relieves pain. Which mechanism best describes how NSAIDs work? A When aspirin dissolves in the interstitial fluid it causes a concentration gradient and fluid is pulled from the cell reducing inflammation. B The COX receptors have a greater affinity for aspirin and these speed up the reactions of healing. C Prostaglandins (PG) are eicosanoids that produce pain and inflammation. Cyclooxygenase (COX) is an essential enzyme in the production of PG and aspirin inhibits COX and therefore relieves pain due to the reduced production of PG. D Leukotrienes are eicosanoids that produce pain and inflammation. COX is used in the lipoxygenase pathway and therefore NSAIDs stop the conversion of arachidonic acid to leukotrienes thereby reducing inflammation E Aspirin decreases the production of thromboxane A2, a chemical involved in blot clot formation, and COX inhibits A2 and, therefore, blood clots do not form and cause pain

Answer 1

A13:

Option E

Explanation: The electron transport chain functions inside the mitochondria. The inner membrane contains the respiratory chain. where the electrons are transferred from NADH to a chain of electron carriers. The electrons are carried from a higher potential to a lower potential and finally, energy is trapped as ATP.  

The four complexes in the ETC are complex I, II, III and IV, connected by two carriers, coenzyme Q, and cytochrome c.

The toxicity of cyanide is due to its inhibitory effect on the terminal cytochrome; site 3(complex IV) which brings cellular respiration to a standstill, thereby inhibiting the synthesis of ATP and due to which the body begins to shut down.

A19:

Option C

Explanation: All the three forms of transport are based on concentration gradient which decides the number of molecules passing through and is not time-dependent. Although in facilitated diffusion, The mechanism is along a concentration gradient and in active transport, it is against a concentration gradient which requires energy.

All three mechanisms work with the help of specialized proteins which helps in the transport of solutes across the membrane.It is also specific for a particular solute, for e.g, passive transport of water occurs through channels called aquaporins, the transport of glucose occur by specific channels called GLUT transporters;Glut 2 releases glucose into bloodstream by facilitated diffusion but sodium-dependent glucose transporter SGluT 1 actively transports glucose from intestinal lumen into the cell by cotransport(secondary active transport).