Q120.A carcinogen is best described as a substance or exposure that can do what?
(a) Cure all tumours
(b) Increase cancer risk
(c) Raise blood calcium
(d) Destroy all viruses
Answer: (b) Increase cancer risk
Explanation: Carcinogens can promote cancer through mechanisms including DNA damage and altered cell signalling. Examples of carcinogenic exposures include tobacco smoke, certain industrial chemicals, ultraviolet radiation and some infections. Early evaluation is important because clinical behaviour differs greatly between tumour types.
Q119.Which type of radiation is commonly associated with skin cancer risk after excessive sunlight exposure?
(a) Ultraviolet radiation
(b) Radio waves
(c) Audible sound
(d) Infrared only
Answer: (a) Ultraviolet radiation
Explanation: Ultraviolet radiation can damage DNA in skin cells. Repeated overexposure increases the risk of basal-cell carcinoma, squamous-cell carcinoma and melanoma. Protective clothing and avoiding excessive exposure reduce risk. The effects depend on the tissue involved and extent of spread.
Q118.A benign tumour is generally distinguished by which feature?
(a) It is always harmless
(b) It always metastasises
(c) It cannot contain dividing cells
(d) It usually remains confined to its original site
Answer: (d) It usually remains confined to its original site
Explanation: Benign tumours typically do not invade tissues or metastasise. Yet they may still produce serious effects by growing within the brain, blocking an organ, or secreting biologically active substances. Tumour type and stage guide decisions about diagnosis and treatment options.
Q117.Which virus is strongly associated with cervical cancer?
(a) Rabies virus
(b) Rotavirus
(c) Human papillomavirus
(d) Rhinovirus
Answer: (c) Human papillomavirus
Explanation: Persistent infection with certain high-risk human papillomavirus types is a major cause of cervical cancer. HPV vaccination and appropriate cervical screening substantially reduce the burden of this preventable malignancy. Early evaluation is important because clinical behaviour differs greatly between tumour types.
Q116.Which habit is an established major risk factor for lung cancer?
(a) Regular walking
(b) Tobacco smoking
(c) Washing hands
(d) Adequate sleep
Answer: (b) Tobacco smoking
Explanation: Tobacco smoke contains many carcinogenic compounds and is a major preventable cause of lung cancer. The risk generally rises with cumulative exposure; avoiding tobacco also protects against heart and lung diseases. The effects depend on the tissue involved and extent of spread.
Q115.What is an oncogene?
(a) A gene that can promote cancer when abnormally activated
(b) A hormone from the pancreas
(c) A normal red-cell pigment
(d) A mineral needed for bones
Answer: (a) A gene that can promote cancer when abnormally activated
Explanation: An oncogene is a gene whose abnormal activation can drive excessive cell growth or survival. Proto-oncogenes are normal genes involved in regulated signalling, and mutations or increased expression may convert them into oncogenes. Tumour type and stage guide decisions about diagnosis and treatment options.
Q114.Which process, when defective, can allow damaged cells to survive and contribute to tumour formation?
(a) Filtration
(b) Transpiration
(c) Osmosis
(d) Apoptosis
Answer: (d) Apoptosis
Explanation: Apoptosis is programmed cell death, which helps remove damaged or potentially dangerous cells. Some cancers evade this protective mechanism, enabling abnormal clones to survive and multiply instead of being eliminated. Early evaluation is important because clinical behaviour differs greatly between tumour types.
Q113.Cancer cells travelling through the lymphatic system may initially spread to which structures?
(a) Tooth enamel
(b) Lens of the eye
(c) Lymph nodes
(d) Hair shafts
Answer: (c) Lymph nodes
Explanation: Lymph nodes filter lymph and are a frequent early site of spread for some cancers. Examining relevant nodes helps clinicians evaluate tumour stage, although patterns differ among cancer types and locations. The effects depend on the tissue involved and extent of spread.
Q112.Which radioactive isotope has historically been used in selected forms of cancer brachytherapy?
(a) Nitrogen-14
(b) Gold-198
(c) Oxygen-16
(d) Carbon-12
Answer: (b) Gold-198
Explanation: Gold-198 is a radioactive isotope that has been used in certain brachytherapy applications. Cancer radiotherapy uses carefully controlled ionising radiation to damage tumour cells while limiting exposure to surrounding tissues. Tumour type and stage guide decisions about diagnosis and treatment options.
Q111.What is the principal purpose of chemotherapy for cancer?
(a) Use medicines to kill or inhibit rapidly growing cancer cells
(b) Increase iodine intake
(c) Replace all hormones
(d) Correct colour blindness
Answer: (a) Use medicines to kill or inhibit rapidly growing cancer cells
Explanation: Chemotherapy uses anticancer drugs to kill cancer cells or interrupt their growth and division. Some drugs also affect normal rapidly dividing tissues, which helps explain adverse effects such as low blood-cell counts. Early evaluation is important because clinical behaviour differs greatly between tumour types.
