Test: Cancer (NCERT) - NEET MCQ

Benign tumour remains confined to the site of its orgin and does not spread to other parts of the boyd. It causes limited damage to the body and is non-cancerous. Malignant tumor is a cancerous tumour and spreads to other parts of the body from the site of its origin. Cancer arising from epithelial tissues is referred to as carcinoma e.g., breast cancer, cervical cancer, etc.

Proto-oncogene is a normal gene which, when altered by mutation, becomes an oncogene that can contribute to cancer. Proto-oncogenes may have many different functions in the cell. Some proto-oncogenes provide signals that lead to cell division. Other proto-oncogenes regulate programmed cell death (apoptosis). The defective versions of proto-oncogenes, known as oncogenes, can cause a cell to divide in an unregulated manner. This growth can occur in the absence of normal growth signals such as those provided by growth factors. A key feature of oncogene activity is that a single altered copy leads to unregulated growth.

NCERT Topic: Cellular oncogenes and proto oncogenes

NCERT Line: "Furthermore, several genes called cellular oncogenes (c-onc) or proto oncogenes have been identified in normal cells which, when activated under certain conditions, could lead to oncogenic transformation of the cells."

Normal cels have the prperty of contact inhibition Due to this property they contact with other cells, and inhibit their uncontrolled growth. Cancel cells seem to have lost this property and thus undergo uncontrolled growth.

NCERT Topic: Contact inhibition

NCERT Line: "Normal cells show a property called contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth. Cancer cells appears to have lost this property."

• Certain viruses like Rous Sarcoma Virus, Papilloma viruses that cause cancer in human body, have a gene called viral oncogene or v-onc, which allow the virus to cause cancer. 
• Tumours are of two main types: (i) Benign tumours are those which keep on growing, but remain confined to their origin, and (ii) Malignant tumours are those which keep on growing and can invade other places away from their origin.
• One of the major properties of cancer cells is that they do not show contact inhibition. Normal cells show contact inhibition i.e., after coming in contact with other cells, these inhibit their uncontrolled growth.
• Carcinogens are biological, chemical, or physical agents which can stimulate carcinogenesis or induction to cancer in a normal cell. Benzene, different types of aldehydes are chemical carcinogens. UV-rays, X-rays are potent physical carcinogens. Viruses, like Papillomavirus virus, are potent biological carcinogens.
• Biopsy is one of the main methods to detect cancer. In this process, a piece of the suspected tissue is cut into thin sections, stained with appropriate stains and is examined under microscope by a pathologist

NCERT Topic: Cancer detection and diagnosis

NCERT Line: "Benign tumors normally remain confined to their original location and do not spread to other parts of the body and cause little damage." "Cancer cells appear to have lost this property." "Cancer detection is based on biopsy and histopathological studies of the tissue and blood and bone marrow tests for increased cell counts in the case of leukemias."

A person suffeing from leukaemia has abnormal increase in the number of WBCs due to their increased formation in the bone marrow.

NCERT Topic: Blood and bone marrow tests for increased cell counts in the case of leukemias

NCERT Line: "and blood and bone marrow tests for increased cell counts in the case of leukemias."

Cancer patients are given substances called biological response modifiers like α-interferon which activate their immune system and help in destroying the tumours.

NCERT Topic: Treatment of cancer

NCERT Line: "Tumor cells have been shown to avoid detection and destruction by immune system. Therefore, the patients are given substances called biological response modifiers such as α-interferon which activates their immune system and helps in destroying the tumor."

Fetus receiving antibodies from mother through placenta is an example of passive immunity.

NCERT Topic: Active and passive immunity

NCERT Line: "B: Fetus receives antibodies from its mother through placenta, is an example of active immunity."

    A: A−(iv), B−(i), C−(v), D−(iii), E−(ii)

B: A−(ii), B−(i), C−(v), D−(iii), E−(iv)

C: A−(iv), B−(v), C−(iii), D−(ii), E−(i)

D: A−(ii), B−(v), C−(iii), D−(i), E−(iv)

Allergy: Linked to IgE, which is responsible for allergic reactions.

Helper T-cells: Linked to activation of B-cells, crucial for immune response.

AIDS virus: HIV is a single-stranded RNA virus.

X-rays: Known carcinogens that can cause cancer.

Treatment of cancer: Often involves immunotherapy.

The correct option is: A: A−(iv), B−(i), C−(v), D−(iii), E−(ii)

Life span of normal cells is definite while life span of cancerous cells is not definite.

Sarcoma is a cancer of connective tissues and muscular tissues. Fibroblasts are the cells present in the connective tissue that act as precursors of collagen, elastic and reticular fibres.