R4RIN – MCQs, Mock Tests | Biochemistry Biochemistry MCQS PAPER SET 12

Which of the following is incorrect with regard to antigen epitopes?

1. An epitope may be shared by two different antigens
2. A protein molecule usually contains multiple epitopes
3. B cells bind only processed antigen epitopes
4. Epitopes may be linear or assembled

✅ Correct Answer: 3

Very low doses of antigen may induce

1. hypersensitivity
2. immunological ignorance
3. low zone tolerance
4. low zone immunity

✅ Correct Answer: 3

During the lag period between antigen contact and detection of adaptive immunity,

1. antigen is hidden from the immune system in macrophages
2. innate immune effectors are eliminating antigen
3. innate immunity blocks the activation of adaptive immune effector cells
4. new B and T cells with the appropriate antigen specificity must be produced in the bone marrow

✅ Correct Answer: 2

Lymphocytes are activated by antigen in the

1. blood stream
2. bone marrow
3. liver
4. lymph nodes

✅ Correct Answer: 4

A pathogen can be a (n)

1. agent that causes a disease
2. virus
3. bacteria
4. All of these

✅ Correct Answer: 4

CD antigens

1. allow leukocytes to recognize antigen
2. are each expressed on only one cell type
3. are expressed on immune cells to mark them for separation
4. function as receptors for cytokine and CAMs

✅ Correct Answer: 4

A virus vaccine that can activate cytotoxic T cells must contain

1. a high dose of virus particles
2. an adjuvant to stimulate T cell division
3. live virus
4. virus peptides

✅ Correct Answer: 3

The ability of an antigen to induce an immune response does not depend on the antigen's

1. ability to enter the thyroid
2. degree of aggregation
3. dose
4. size

✅ Correct Answer: 1

The antibiotic penicillin is a small molecule that does not induce antibody formation. However, penicillin binds to serum proteins and forms a complex that in some people induces antibody formation resulting in an allergic reaction. Penicillin is therefore

1. an antigen
2. a hapten
3. an immunogen
4. both an antigen and a hapten

✅ Correct Answer: 4

Which of the following immune cells would have an especially low count in a patient with advanced AIDS?

1. Killer T lymphocytes
2. Helper T lymphocyte
3. B lymphocytes
4. None of these

✅ Correct Answer: 2

In cellular immunity, T lymphocytes are responsible for the recognition and killing of foreign invaders. The cells

1. cytotoxic T lymphocytes (CTL)
2. killer T cells
3. both (a) and (b)
4. none of the above

✅ Correct Answer: 3

Plasma cells produce thousands of __________ that are released into the bloodstream

1. antigens
2. antibodies
3. helper T cells
4. virus fragments

✅ Correct Answer: 2

If a person is vaccinated against a disease sometime in the past, which of the following is currently in your body?

1. The disease organism itself and antigens for the disease organism
2. A very high level of antibodies against the disease antigens
3. Memory B lymphocytes for the antigen of this disease organism
4. All of the above

✅ Correct Answer: 4

What is a protein produced by host cells infected by viruses?

1. Interferon
2. Histamine
3. Antiserum
4. Vaccine

✅ Correct Answer: 1

Polysaccharides on the surface of infecting microorganisms can also activate complement directly in the absence of

1. antibody via the alternative pathway
2. antigen via the alternative pathway
3. antibody via metabolic pathway
4. none of the above

✅ Correct Answer: 1

Antibodies bound to an invading microorganism activate the complement system via

1. classical pathway
2. metabolic pathway
3. Embden Meyerhof pathway
4. Entner-Doudoroff pathway

✅ Correct Answer: 1

The immune response to a booster vaccine is called a(n)

1. cellular response
2. innate response
3. primary response
4. secondary response

✅ Correct Answer: 4

Immunological memory is due to

1. short lived macrophage that can recognize specific pathogens
2. long lived B cells that secrete a specific antibody
3. long lived B cells that secrete a specific antigen
4. short lived helper T cells that signal macrophage to divide

✅ Correct Answer: 2

What is the result of an abnormal response of the immune system to part of a person's own body?

1. Passive immunity
2. Cancer
3. An allergic response
4. An autoimmune disease

✅ Correct Answer: 4

What are the solutions prepared from weakened or dead microorganisms, viruses, or toxins that provide some immunity from diseases?

1. Vaccines
2. Histamines
3. Drugs
4. Antibiotics

✅ Correct Answer: 1

During exposure to a foreign invader, there are more __________ present in the vertebrate body than before exposure

1. antibodies
2. lymphocytes
3. macrophages and antigens
4. all of these

✅ Correct Answer: 4

To elicit the best antibodies to mouse MHC I, it should be injected into a

1. goat
2. mouse of the same genetic background (strain)
3. mouse of a different strain
4. rat

✅ Correct Answer: 1

To detect a humoral immune response to influenza virus, it is possible to measure

1. cytotoxicity of virus-infected cells in tissue culture
2. dividing T cells in the draining lymph nodes
3. plasma cytokine levels
4. serum antibody titer

✅ Correct Answer: 4

Which of the following is in the lymph nodes of a person battling a cold virus?

1. Huge numbers of white blood cells
2. Trapped viruses that have been roaming the body
3. Lymph ducts that enter and exit the nodes and Lymph fluid
4. All of the above

✅ Correct Answer: 4

Immunogenicity

1. depends on the ability of the native antigen to be presented by MHC
2. is usually a property of self antigens such as eye tissue
3. is not a property of antibodies
4. is not a property of haptens

✅ Correct Answer: 4

The HIV virus infects primarily

1. brain cells
2. cells in the immune system
3. red blood cells
4. liver cells

✅ Correct Answer: 2

Chronic granulomatous disease results from a failure to perform oxidative burst. This deficiency would be most likely to interfere with

1. CTL killing of viruses
2. dendritic cell activation to become a mature APC
3. infected cell processing of virus peptides
4. macrophage intracellular killing of bacteria

✅ Correct Answer: 4

Difficulties with somatic gene therapy arise from all of the following except

1. GVHD caused by mature T cells in the transplanted cells
2. inserting a gene so that it will function properly
3. limited life span of more mature hematopoietic cells
4. transducing genetic material into stem cells

✅ Correct Answer: 1

A monoclonal antibody (mAb) specific for the 2,4-dinitrophenyl (DNP) hapten might also bind

1. Leu or Ileu
2. His or Pro
3. Tyr or Phe
4. Ser or Thr

✅ Correct Answer: 3

Retinoblastoma is due to a mutation in a

1. kinase
2. tumor supressor
3. cyclin
4. viral gene

✅ Correct Answer: 2

An autoimmune disease is

1. AIDS
2. Measles
3. Lupus
4. Mumps

✅ Correct Answer: 3

If Class IIMHC is not expressed in the thymus, the resulting immune deficiencies would include all of the following except reduced

1. alternative complement activation.
2. CD8 T cell-mediated cytotoxicity
3. macrophage activation to vesicular pathogens
4. IgG synthesis

✅ Correct Answer: 1

Specific translocations are associated with

1. colon cancer
2. breast cancer
3. pancreatic cancer
4. some leukemias

✅ Correct Answer: 4

To treat HIV infections using drugs, the major problem is that

1. the drugs that are good inhibitors cannot by synthesized
2. the drugs interfere with normal digestion
3. the virus particles with altered (mutant) proteases arise
4. the drugs are rapidly degraded

✅ Correct Answer: 3

The primary reason for AIDS, a deadly disease is that it

1. is caused by a virus
2. is caused by a bacterium
3. destroys key components of the body's internal defense system
4. causes a breakdown of the body's inflammatory response

✅ Correct Answer: 3

A selective IgA deficiency would be expected to result in problems with

1. bacterial infections
2. infections following dental work due to bacteria entering the bloodstream
3. mucosal pathogens
4. pathogens which can survive inside macrophages

✅ Correct Answer: 3

Combined cellular and humoral immune deficiencies result from lack of all of the following except

1. a thymus
2. class II MHC
3. HIV infection of CD4+ T cells
4. transporter of antigen peptides (TAP)

✅ Correct Answer: 4

An example of an immunodeficiency disorder is

1. thyroiditis
2. rheumatic fever
3. systemic lupus erythematosus
4. AIDS

✅ Correct Answer: 4

Bone marrow given to an infant with SCID must

1. be irradiated to eliminate GVHD
2. contain mature T cells that can begin making immune responses immediately
3. come from a donor that shares some MHC alleles with the recipient
4. come from one of the child's parents

✅ Correct Answer: 3

X-linked hyper IgM syndrome, resulting in high levels of serum IgM and low levels of serum IgG, is caused by a defect in CD40L expression. The specific immune event that would be prevented by a defective CD40L would be

1. activation of B cells by T-independent antigens
2. failure of B cells to provide co-stimulation for Th2 activation
3. failure of Th2 cells to provide co-stimulation for B cell isotype switching
4. failure of Th2 cells to provide co-stimulation for B cell proliferation

✅ Correct Answer: 3

DiGeorge's syndrome is characterized by the lack of a thymus The mouse model closest to this human disease would be a

1. knock-out mouse for RAG-1 and RAG-2
2. knock-out mouse for a thymus
3. nude mouse
4. recombinant mouse for CD3

✅ Correct Answer: 3

Which of the Rous sarcoma virus has a homologous cellular protein?

1. c-src
2. v-src
3. v-ha-src
4. v-ha-ras

✅ Correct Answer: 1

Infants are most susceptible to bacterial infection due to low circulating levels of IgG

1. in utero (before birth)
2. at 0-3 months of age
3. at 3-12 months of age
4. at 12-24 months of age

✅ Correct Answer: 3

The chemical, typically released by the body in an allergic response is

1. histamine
2. allergens
3. antihistamines
4. perforins

✅ Correct Answer: 1

Small charged molecules, often biogenic amines function as

1. hormones
2. neurotransmitters
3. both (a) and (b)
4. none of these

✅ Correct Answer: 3

SH2 domains specifically bind to

1. phosphorylated serine residues
2. phosphorylated tyrosine residues
3. GDP
4. Ca2+

✅ Correct Answer: 2

In paracrine signaling, the signaling molecules affects only

1. target cells close to the cell from which it was secreted
2. target cells distant from its site of synthesis in cells of an endocrine organ
3. both (a) and (b)
4. none of the above

✅ Correct Answer: 1

Simple nerve reflexes use signaling molecules called

1. neurotransmitters
2. nitric oxides
3. G proteins
4. proteases

✅ Correct Answer: 1

Which of the following is not a type of signaling

1. Testosterone
2. Insulin
3. Thyroxin
4. Adenylate cyclase

✅ Correct Answer: 4

Self-phosphorylation is an excellent mechanism for triggering specific catalytic function of the proteins involved in signal cascades because

1. changes the shape and thus the enzymatic activity of the proteins involved
2. makes the receptor more likely to capture the signaling, molecule
3. allows hydrophilic signaling molecules to cross the plasma membrane
4. None of the above

✅ Correct Answer: 1

Which of the following statements about G proteins is false?

1. They are involved in signal cascades
2. They bind to and are regulated by guanine nucleotides
3. They become activated when bound to GDP
4. They must be active before the cell can make needed cAMP

✅ Correct Answer: 3

When a __________ reaches its __________ , there is a specific means of receiving it and acting on the message. This task is the responsibility of specialized proteins called __________ .

1. signaling molecule; receptor; G proteins
2. signaling molecule; target cell; G proteins
3. signaling molecule; target cell; receptors
4. kinase; receptor; proteases

✅ Correct Answer: 3

Why is it that inhaling nitric oxide reduces blood pressure only in the lung tissue and not elsewhere in the body*?

1. Because other body tissues use a different signaling molecule
2. Because nitric oxide cannot cross cell membranes and enter the blood
3. Because nitric oxide breaks down quickly and thus cannot travel far
4. None of the above

✅ Correct Answer: 3

Which of the following comes under the category of cell surface receptor?

1. Enzyme linked receptors
2. Ion-channel linked receptors
3. G protein linked receptors
4. All of these

✅ Correct Answer: 4

Which of the following is true about a hydrophilic signaling molecule?

1. Its receptor is located in the cytosol of the target cell
2. It might trigger a signal cascade that causes some effect in a cell
3. Since it can enter the cell, it directly affects some specific cell process
4. It is a steroid

✅ Correct Answer: 2

cAMP and cGMP are derived from

1. ATP and GTP by the actions of adenylate cyclase and guanylate cyclase respectively
2. GTP and ATP by the actions of adenylate cyclase and guanylate cyclase respectively
3. ATP and GTP by the actions of guanylate cyclase and adenylate cyclase respectively
4. none of the above

✅ Correct Answer: 1

Nitroglycerin has long been administered to human patients suffering from chronic chest pain (angina). This medication works because it

1. mimics the action of signal receptors
2. is broken down into hormones that affect the heart
3. interferes with chemical cascades that trigger contraction of heart muscle
4. breaks down into nitric oxide, which increases blood flow to the heart

✅ Correct Answer: 4

If a disease of the blood vessels caused the endothelial cells of the vessel to die, what effect would that have on the cellular activities associated with vasodilation?

1. Nitric oxide would no longer be produced
2. Smooth muscle cells could not be made to relax
3. blood flow and reduce blood pressure
4. All of the above

✅ Correct Answer: 4

In terms of cell communication, what do bacterial pathogens such as cholera and anthrax have in common?

1. They destroy the receptors for key signaling molecules
2. They prevent the production of key signaling molecules
3. They alter the chemical structure of key signaling molecules
4. They block the normal functioning of signal transduction mechanisms

✅ Correct Answer: 4

What is the name of the protein signaling molecule that alters glucose uptake, and where would its receptors be located?

1. Insulin; many different cell types that use glucose for fuel
2. Insulin; beta cells of the pancreas
3. PDGF; the blood
4. NGF; the nerves involved in simple reflexes

✅ Correct Answer: 1

In the signal transduction mechanism known as protein phosphorylation

1. the signaling molecule binds to a surface receptor
2. receptor kinases play a key role in triggering the signal cascade
3. phosphorylated proteins act with enzymes to trigger the signal cascade
4. All of the above

✅ Correct Answer: 4

Cell signaling can be classified into

1. three distinct types based on the distance over which the signaling molecules act
2. two distinct types based on the distance over which the signaling molecules act
3. three distinct types based on the signaling molecules
4. none of the above

✅ Correct Answer: 1

Which of the following statement is correct?

1. Cell communicate with one another in multicellular organisms using extracellular signaling molecules or hormones
2. Cell communicate with one another in unicellular organisms using extracellular signaling antigen and antibody
3. Cell communicate with one another in multicellular organisms using intracellular signaling molecules only
4. Cell communicate with one another in unicellular organisms using intracellular signaling antigen and antibody

✅ Correct Answer: 1

In vasodilation, proper nerve signals sent to blood vessels cause

1. the release of nitric oxide from endothelial cells
2. relaxation of smooth muscle cells
3. reduced blood pressure
4. All of the above

✅ Correct Answer: 4

A cell is known to respond to a particular signaling molecule. Which of the following must be true of this cell?

1. It is in the heart muscle
2. It is also the site of production for the signaling molecule
3. It contains the receptor for the signaling molecule
4. It is incapable of signal transduction

✅ Correct Answer: 3

The enzyme that catalyzes the splitting of PIP2 into two molecules of inositol triphosphate (IP3) and diacylglycerol in cell signaling, is

1. phosphokinase C
2. phospholipase C
3. phosphodiesterase C
4. lipokinase

✅ Correct Answer: 2

The binding of ligands to many G-proteins linked receptors leads to shortlived

1. increase in the concentration of certain intracellular signaling molecules called second messenger
2. decrease in the concentration of certain intracellular signaling molecules called second messenger
3. increase in the concentration of certain extracellular signaling molecules called first messenger
4. decrease in the concentration of certain extracellular signaling molecules called first messenger

✅ Correct Answer: 1

Which of the following processes involve the combining of a message from one signaling molecule with that of another to either enhance or inhibit a cellular effect?

1. Signal transduction
2. Signal reception
3. Signal integration
4. Signal amplification

✅ Correct Answer: 3

A signal cascade induced by adrenaline or thyroxine

1. must begin with receipt of the signal molecule by a surface receptor
2. involves the activation of a G protein
3. results in the activation of a sequence of enzymes needed for the cell effect
4. all of the above

✅ Correct Answer: 4

Which of the following is a second messenger?

1. lnositol 1,4,5-triphosphate
2. Diacyl glycerol
3. Phospholipase C
4. Both (a) and (b)

✅ Correct Answer: 4

Which of the following statement is incorrect?

1. The principal lipophilic hormones that binds to receptors located in the plasma membranes are prostaglandins
2. Prostaglandins are synthesized from arachidonic acid
3. Prostaglandins act as paracrine signaling molecules
4. None of the above

✅ Correct Answer: 4

Two key organizing principles for large multicellular organisms are

1. prokaryotic cell structure and cell specialization
2. cell specialization and communication between cells
3. communication between cells and simple nerve reflexes
4. simple nerve reflexes and cell specialization

✅ Correct Answer: 2

Which of the following is a hormone whose action requires a cell surface receptor?

1. Nitric oxide
2. Progesterone
3. Adrenaline
4. Growth factors

✅ Correct Answer: 3

The hormone or ligand can be considered as

1. first messenger
2. second messenger
3. both (a) and (b)
4. none of these

✅ Correct Answer: 1

The major second messengers are

1. cAMP
2. cGMP
3. DAG
4. All of these

✅ Correct Answer: 4

he signaling molecules called steroid hormones

1. are made in one location of the body but have their effects some distance away
2. are hydrophilic and so cannot penetrate the plasma membrane
3. bind to cell surface receptors to trigger chemical cascades
4. never enter the blood of humans

✅ Correct Answer: 1

The accepted hypothesis for DNA replication is

1. conservative theory
2. dispersive theory
3. semi-conservative theory
4. evolutionary theory

✅ Correct Answer: 3

When DNA polymerase is in contact with guanine in the parental strand, what does it add to the growing daughter strand?

1. Phosphate
2. Cytosine
3. Uracil
4. Guanine

✅ Correct Answer: 2

Telomeres are usually rich in which nucleotide?

1. Adenine
2. Guanine
3. Thymine
4. Cytosine

✅ Correct Answer: 2

Which is the largest among the followings?

1. Nucleotide
2. Nitrogenous base
3. Phosphate
4. Carbon

✅ Correct Answer: 1