Biology MCQs
Topic Notes: Biology
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
1
Which of the following best describes the biological process of cancer?
Answer:
Uncontrolled multiplication of cells by which death of sound cells and finally death
Cancer is characterized by the uncontrolled division and proliferation of abnormal cells. These malignant cells bypass normal regulatory checkpoints, invade surrounding tissues, and often disrupt the function of healthy cells, leading to systemic failure and, if untreated, death. This process is driven by mutations in genes that control the cell cycle.
2
An abnormally high white blood cell count is a clinical indicator of which condition?
Answer:
Leukaemia
Leukemia is a type of cancer of the blood or bone marrow characterized by an abnormal proliferation of white blood cells. While infections like influenza or typhoid can cause a temporary increase in WBCs (leukocytosis), a persistently high count is a hallmark diagnostic feature of leukemia, where the bone marrow produces excessive, dysfunctional white blood cells.
3
What is the biological definition of hyperplasia?
Answer:
abnormal increase in number of cells
Hyperplasia refers to an increase in the number of cells in an organ or tissue, often resulting in increased tissue mass. This is distinct from hypertrophy, which refers to an increase in the size of individual cells. Hyperplasia can be a normal physiological response or a pathological process.
4
Which of the following agents can both induce and treat cancer depending on the intensity and application method?
Answer:
Ionized radiation
Ionizing radiation, such as X-rays or gamma rays, is a known carcinogen because it can damage cellular DNA, potentially leading to mutations and cancer. Conversely, in controlled clinical settings, high-energy ionizing radiation is used in radiotherapy to specifically target and destroy cancerous cells by causing lethal damage to their genetic material, thereby inhibiting tumor growth.
5
Why is the incidence of cancer observed to be higher in older populations?
Answer:
they have accumulated more mutations
Cancer is fundamentally a disease of accumulated genetic damage. Over a lifetime, cells are exposed to various mutagens and undergo replication, increasing the probability of acquiring somatic mutations in oncogenes or tumor suppressor genes. As individuals age, the cumulative burden of these mutations increases, raising the risk of malignant transformation.
6
Identify the disease described as a condition that begins as a single cell and grows into a life-threatening illness, which has become a major focus of modern medical research and therapeutic advancement.
Answer:
Cancer
Cancer is characterized by the uncontrolled division of abnormal cells that can invade surrounding tissues. The description of starting from a single cell and growing into a systemic threat is a hallmark definition of oncogenesis, distinguishing it from infectious diseases like AIDS or degenerative conditions like Alzheimer's.
7
Which of the following statements regarding tumors is accurate?
Answer:
Malignant tumours exhibit metastasis
Malignant tumors are characterized by their ability to invade surrounding tissues and spread to distant parts of the body through the blood or lymphatic system, a process known as metastasis. In contrast, benign tumors remain localized and do not spread. This property of metastasis is the primary clinical distinction between benign and malignant growths.
8
Which specific type of gene is directly responsible for the transformation of normal cells into cancerous cells?
Answer:
oncogene
An oncogene is a mutated or overexpressed form of a proto-oncogene. While proto-oncogenes are normal genes that regulate cell growth and division, their conversion into oncogenes leads to uncontrolled cellular proliferation, which is a hallmark of cancer development.
9
Leukaemia is a malignancy characterized by an abnormal proliferation of which specific cell type?
Answer:
White blood cells
Leukaemia is a type of cancer that originates in the blood-forming tissues, typically the bone marrow. It results in the overproduction of abnormal white blood cells (leukocytes), which crowd out healthy blood cells and impair the immune system's ability to function correctly.
10
Which of the following medical procedures is considered a definitive diagnostic test for cancer?
Answer:
Biopsy
A biopsy is the gold standard for diagnosing cancer. It involves the surgical removal and microscopic examination of a small sample of tissue from the suspected area. Pathologists analyze the cells to determine if they are malignant, which is essential for confirming a cancer diagnosis.