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Biology and Human Welfare

Description: Thistest will help the students to revise the two prominent topics namely cancer and AIDS as it contains questions covering the vital part ot the topic.
Number of Questions: 25
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Tags: Cancer and AIDS Inverse Trigonometric Functions Trigonometric Ratios and Identities AID and Cancer -- Causes and Control AIDS Cancer
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In humans the specific binding of HIV to the CD 4 surface molecules of the host cell membrane is done about by

  1. p55

  2. gp32

  3. gp41

  4. gp120

  5. gp140


Correct Option: D
Explanation:

The surface protein gp120 conjoins the virus to the host lymphoid tissue by binding to the primary receptor CD4. It signals via several cell surface receptors.

Which of the following statements is WRONG regarding the human immune deficiency virus?

  1. Gag gene encodes for the lipid bilayer of the virus.

  2. p32 is an Integrase.

  3. p10 is a protease enzyme that breaks gag precursor.

  4. The reverse transcriptase enzyme is a prominent feature of retroviruses.

  5. HIV is roughly spherical in shape.


Correct Option: A
Explanation:

The gag gene is encoded as a large gag-pol protein with another gene then cleaved to the precursor protein assemblin, which is then cleaved to Gag. It is involved in virion assembly and produces some of the capsid and nucleocapsid proteins. It does not encode for the lipid bilayer of the virus.

Which of the following given molecules are involved in the gripping of cells to an extracellular matrix?

  1. Integrins

  2. Angiostatin

  3. Interleukins

  4. Cyclins

  5. Promegapoietin


Correct Option: A
Explanation:

Integrins are a family of transmembrane glycoprotein receptors that mediate cell-matrix. They are involved in the anchoring of cells to an extracellular matrix. They affect tumour progression has made them an appealing target for cancer therapy.

Angiogenesis is a physiological process entangling the growth of new blood vessels from pre-existing vessels. Which of the following inhibits angiogenesis?

  1. Oprelvekin

  2. VEGF

  3. FGF 2

  4. Interleukin-6

  5. Angiostatin


Correct Option: E
Explanation:

 Angiostatin is endogenously produced in the tumor stroma. Therefore, circulating levels can control metastatic cell proliferation until a primary tumor is removed. Angiostatin inhibits angiogenesis.

Which of the following is the anti cancer therapy entangling the administration of an antibody linked to an enzyme?

  1. RANKL

  2. GDEPT

  3. ADAPT

  4. ADEPT

  5. GDAPT


Correct Option: D
Explanation:

ADEPT stands for antibody-directed enzyme prodrug therapy entangling the association of an enzyme to an antibody. It is the use of monoclonal antibodies (or mAb) to specifically bind to target cells or proteins.

Which immune marker is observable during the window period of HIV infection?

  1. Antigen p17

  2. p24 antigen

  3. Antibodies to gp41

  4. Antibodies to gp120

  5. Antigen p17


Correct Option: B
Explanation:

The window period is the period between the onset of HIV infection and the appearance of detectable antibodies to the virus. The purpose of the p24 antigen portion of the test is to detect HIV before body has made antibodies, i.e., in the window period.

CD 4+ cells are dominant cells that are a indispensible part of human's immune system. Which of the following is NOT a CD 4+ cells?

  1. Monocytes

  2. T–helper cells

  3. T-Cytotoxic cells

  4. Macrophages

  5. Dendritic cells


Correct Option: C
Explanation:

These cells are the vital part of the cellular immune response,destroying the cells, which bears any foreign antigen on their surface, mainly virus-infected cells.

The pol gene in retroviruses does NOT encode for

  1. RNA polymerase

  2. Integrase

  3. Reverse transcriptase

  4. Proteases

  5. Neuraminidase


Correct Option: A
Explanation:

This enzyme is involved in the production of RNA from DNA through transcription. It adds ribonucleotides to growing RNA transcripts at the 3’ end. The pol gene does not encode for NA polymerase.

The immunoglobulin present in tears and saliva is

  1. IgM

  2. IgD

  3. IgE

  4. IgA

  5. IgG


Correct Option: D
Explanation:

This immunoglobulin being an antibody plays a vital role in mucosal immunity. It is dominately present in mucous secretions, including tears and saliva.

The structural component of HIV required for cell-cell fusion is ______________.

  1. p2 protein

  2. gp41

  3. p24

  4. gp120

  5. p70


Correct Option: B
Explanation:

For the HIV infection to occur the cell fusion is essential. This is done by the transmembrane glycoprotein gp41. HIV-1 utilises two major co-receptors along with CD4 to bind to, fuse with, and enter target cells.

A protein coded by a tumour suppressor gene in humans is

  1. the protein, which helps prevent apoptosis

  2. the protein, which codes for a DNA repair enzyme

  3. the protein, which controls progression through the cell cycle

  4. the protein, which forms fractions of a growth factor signalling pathway

  5. acts in the degradation of CD4 in the endoplasmic reticulum


Correct Option: C
Explanation:

Tumour suppressor genes code for proteins, which normally control progression through a cell cycle checkpoint. These genes only contribute to a cancer when both copies are mutated in a way, which produces an inactive protein product. A single mutation inactivating one gene only has no effect. They contribute to cancer because the absence of the protein product removes controls on cell division.

Which of the following is regarded as the best treatment for HIV infection?

  1. Reverse transcriptase inhibitors

  2. Protease inhibitors

  3. Integrase inhibitors

  4. Highly active antiretroviral therapy (HAART)

  5. Entry inhibitors


Correct Option: D
Explanation:

HAART is used to suppress HIV viral replication and the progression of HIV disease. It conjoins three or more different drugs, such as two nucleoside reverse transcriptase inhibitors (NRTIs) and a protease inhibitor. These HAART regimens have proven to reduce the amount of active virus and in many case.

Which of the following characterises an oncogene?

  1. In tumor cells, they are expressed at lower levels.

  2. It codes for a cell cycle control protein in a cell.

  3. It codes for a protein, which restricts the cell from apoptosis.

  4. It codes for a mutated form of a protein which creates fractions of a signal transduction pathway.

  5. It is a predominantly expressed mutation, which provides growth or survival advantage to a cell.


Correct Option: E
Explanation:

An oncogene is a mutated form of a normal cellular gene (the proto-oncogene) that codes for a protein, which is either controlled abnormally, so that it is expressed in abnormally large amounts or has gained activity. It is more active than the normal protein.

Busulfan is a well known anticancer agent. Its mode of action is

  1. alkylating agent

  2. Chain-terminator

  3. Intercalator

  4. Demethylating agent, 5-azacytidine

  5. Maturation inhibitors


Correct Option: A
Explanation:

Busulfan acts as an alkylating agent. It contains two sulfonyloxy groups,  which acts as  good leaving groups when the drug reacts with a nucleophile.

An oncogenic virus is capable of inducing the formation of tumors. Which of the following is a prominent oncogenic virus?

  1. Herpes zoster

  2. HIV-2

  3. Vesicular stomatitis virus

  4. Proteus mirabilis

  5. Epstein-Barr virus


Correct Option: E
Explanation:

Epstein-Barr virus is associated with Burkitt's lymphoma and with naso-pharyngeal carcinoma.

Which of the following is NOT associated with HIV infection in humans?

  1. EBV herpes virus

  2. An increased incidence in gliomas.

  3. CNS lymphoma

  4. Paraproteinemia

  5. An increased incidence of thrombocytopenia.


Correct Option: B
Explanation:

A glioma is a type of tumor that starts in the brain or spine. It is called a glioma because it arises from glial cells. An increased incidence in gliomas has no association with HIV infection.

Cancer immunology is a branch of immunology that studies interactions between the immune system and cancer cells. The normal immunological control of tumors is referred to as

  1. immunological tolerance

  2. immune surveillance

  3. type III hypersensitivity

  4. immunological silence

  5. superantigen recognition


Correct Option: B
Explanation:

It is a field of research that aims to discover cancer immunotherapies to treat and retard progression of cancer.

Which of the following is INCORRECT concerning lung cancer in human beings?

  1. Nearly 40% of lung cancers are adenocarcinoma, which usually originates in peripheral lung tissue.

  2. In small-cell lung carcinoma (SCLC), the cells contain dense neurosecretory granules.

  3. Lung cancer staging is an assessment of the degree of spread of the cancer from its original source.

  4. In a suffer about 80-90% of small cell carcinomas have spread beyond the thorax at the time of diagnosis.

  5. The original lung cancer never spreads to other body parts.


Correct Option: E
Explanation:

If the original lung cancer has spread, a person may feel symptoms in other places in the body. Common places for lung cancer to spread include other parts of the lungs, lymph nodes, bones, brain, liver, and adrenal glands.

Which of the following is a naturally occurring product being studied as an anticancer agent in humans?

  1. Aclarubicin

  2. Fumagillin

  3. Depsipeptide

  4. Erythropoietin

  5. Thalidomide


Correct Option: C
Explanation:

Depsipeptide is derived from a bacterial strain and is reduced to an active compound that promotes apoptosis and inhibits cell proliferation and angiogenesis.

 Which tumour suppressor gene is mutated in families with familial adenomatous polyposis?

  1. APC

  2. p53

  3. BRCA1

  4. BRCA2

  5. VHL


Correct Option: A
Explanation:

Mutations in the APC (adenomatous polyposis coli) gene cause both classic and attenuated familial adenomatous polyposis. These mutations affect the ability of the cell to maintain normal growth and function. Cell overgrowth resulting from mutations in the APC gene leads to the development of multiple colonic polyps. These polyps are not themselves malignant but are prone to develop frank carcinoma through the accumulation of further genetic mutations.

The ras oncogene contribute to the development of cancers by which of the following?

  1. Coding for an anti-apoptotic protein in the cell.

  2. Coding for an enzyme known as GTPase switch protein, which cannot be turn off in its mutated form.

  3. Coding Ras gene products which are involved in lipid signaling pathways.

  4. Coding for a transcription factor, being synthesised in enormous amount in the body.

  5. Coding for a abbreviated form of a growth factor receptor which is continually active.


Correct Option: B
Explanation:

The ras gene codes for a GTPase switch protein, which forms part of a growth factor signalling pathway. Stimulation of this protein via an occupied growth factor receptor causes it to activate by exchanging a molecule of GDP for GTP. The activated ras protein then activates downstream proteins, which ultimately activate transcription factors. Normally the ras signal is self limiting because the protein has intrinsic GTPase activity, so it hydrolyses its bound GTP to GDP, switching the signal off.

Which of the following techniques is utilised in detecting viral nucleic acids?

  1. ELISA

  2. Dot blot assays

  3. Western blot

  4. Viral isolation

  5. Polymerase chain reaction (PCR)


Correct Option: E
Explanation:

In case of HIV infection this test finds either the RNA of the HIV virus or the HIV DNA in white blood cells infected with the virus. The PCR test is very useful to find a very recent infection.

A receptor is a protein molecule usually found embedded within the plasma membrane surface of a cell. Which of the following statements does not characterise receptors?

  1. The nuclear receptors are located in the cytosol.

  2. They speed up reactions on chemical messengers.

  3. Many of them are proteins being lying in the cell membrane.

  4. They get attached to the chemical messengers, such as neurotransmitters or hormones.

  5. Receptors accomodates a shallow cleft on their surface, which is particularly known as a binding site.


Correct Option: A
Explanation:

While they are called nuclear receptors, these are actually located in the cytosol and migrate to the nucleus after binding with their ligands.

Which of the following given terms is used to signify the ability of a cancer to invade other body parts of an individual and to produce secondary tumours?

  1. Epigenesis

  2. Mutagenesis

  3. Metastasis

  4. Apoptosis

  5. Carcinogenesis


Correct Option: C
Explanation:

Metastasis refers to the spread of a cancer to different parts of the body and the appearance of secondary tumours.

Which of the following statements is INCORRECT regarding cancer in humans?

  1. Cancer is regarded a disease of old age.

  2. Skin cancers may bleed and look like sores.

  3. A cancer is a genetic disease, frequently being inherited.

  4. A cancer is caused by agglomeration of a small number of mutations, each of which boosts the cell with a growth advantage.

  5. A tumour in a cell is not considered malignant until it spreads to other parts of the body forming secondary tumours.


Correct Option: C
Explanation:

Cancer is regarded as a genetic disease because it is caused by mutations in the genome. However, these mutations are normally in somatic cells, not the germ cells and mutations contributing to cancer are rarely inherited. To form a malignant cancer, a cell must acquire a small number of mutations (probably about six) each of which gives the cell a growth or survival advantage.

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