Aids and Cancer MCQ Quiz in বাংলা - Objective Question with Answer for Aids and Cancer - বিনামূল্যে ডাউনলোড করুন [PDF]

Concept:

• The uncontrolled division of cells that have the ability to spread to other parts of the body is known as cancer. It is a non-infectious disease.
• It is caused mainly due to various physical, chemical, or biological agents which are known as carcinogens:

1. physical - X-rays, gamma ray and UV that causes DNA mutation are physical carcinogens.
2. chemical - Benzene, asbestos etc. are chemical carcinogens. The major cause of lung cancer is identified as chemical carcinogens like nicotine present in tobacco smoke.
3. biological - Oncogenic viruses are biological carcinogens. They have genes called viral oncogenes.

• Carcinogens induce the transformation of normal cells into cancerous neoplastic cells.
• Cellular oncogenes (c-onc) or proto-oncogenes have been identified in normal cells. These cells undergo programmed cell death and do not cause cancer.
• When activated under certain conditions this proto-oncogene could lead to oncogenic transformation to oncogenic cells.

Explanation:

Option (1) structural genes

• The genes that code for proteins and most RNAs except regulatory factors are known as structural genes.
• It encodes the genes required for structural and functional uses.
• This option is incorrect.

Option (2) expressor genes

• It helps in the expression of genes.
• This option is incorrect.

Option (3) oncogenes

• Oncogenes are genes that cause cancer.
• In normal cells, they undergo programmed cell death and do not lead to cancer.
• But in tumor cells, they lead to uncontrolled division of cells which eventually leads to cancer.
• This option is correct.

Option (4) regulatory genes

• The genes that code for proteins or factors that control the expression of structural genes are known as regulatory genes.
• Factors/proteins that control the expression of structural genes is encoded by it.
• This option is incorrect.

So, the correct answer is option 3).

Concept:

• AIDS stands for Acquired Immuno-Deficiency Syndrome.
• AIDS was first reported in 1981 and now it has spread all over the world killing more than 25 million persons.
• It is caused by the Human Immunodeficiency Virus (HIV), a member of a group of viruses called a retrovirus, which has an envelope enclosing the RNA genome.

• People who are affected by this infection are -
  • persons who have multiple sexual partners
  • drug-addicted people who take drugs intravenously
  • persons who require repeated blood transfusions
  • children born to an HIV-infected mother.

Explanation:

• It is generally transmitted by
  • sexual contact with an infected person,
  • transfusion of contaminated blood and blood products
  • sharing of infected needles as in the case of intravenous drug abusers
  • transmission of the virus from the infected mother to her child through the placenta.
• It is not spread by mere touch or physical contact; it is transmitted only through body fluids.
• For physical and psychological well-being HIV/AIDS-infected persons are not isolated from family and society.
• Therefore, AIDS cannot spread by shaking hands as there is no body fluids involved in the process.

So, the correct answer is option (3).

Additional Information

Steps of HIV infection -

Concept:

• Cancer is a disease which is caused when some of the body's cells starts dividing and growing in an uncontrolled manner.
• In normal body the growth and differentiation of cells is controlled and regulated through different mechanisms, but in cancer cells, there is total breakdown of these regulatory mechanisms.
• As a result they continuously divide to form a mass of cells called tumor.
• The cancer cells grow speedily and invade and start damaging the surrounding normal tissues.
• The physical, chemical or biological agents which cause the transformation of normal cells into cancerous cells are called carcinogens.
• The tumor can be of two types:

1. Benign tumor
   • They remain confined to their original location.
   • They do not spread to other parts of the body and therefore cause less damage.
2. Malignant tumor
   • They spread to other parts of the body and therefore have the potential to cause greater damage to the body
   • The cells from the tumor get detached and they travel through the blood.
   • Wherever they get lodged, they start forming a new tumor at that site in the body.
   • This property of malignant tumor is called metastasis.​

Explanation:

Option 1) Cell division

• Cell division is the process by which parent cell divides into two daughter cells.
• The cancerous cells go on continuously dividing in a uncontrolled manner as the regulatory mechanism to stop cell division does not work in cancer causing cells.
• Hence, this option is incorrect.

Option 2) Cell growth

• Cell growth refers to the increase in the cell size.
• Cell growth occurs in the G1 phase of the cell cycle.
• Hence, this option is incorrect.

Option 3) Contact Inhibition

• Normal cells are known to have the property of contact inhibition.
• This property restricts the cells from growing uncontrollably.
• The cells with this property stop growth when they come in contact with the neighbouring cells.
• The cancerous cells lose this property and hence, show uncontrolled growth to form a tumor.
• Hence, this option is correct.

Option 4) Cell communication

• Cell communication refers to the transfer of information from one cell to another.
• Cells signal each other and this is important for the cells to grow and work normally.
• Hence, this option is incorrect.

Hence, the correct answer is option (3).