Human Health And Disease

1. Biopsy and Histopathology:- A biopsy involves removing a small sample of tissue from a suspected tumor or abnormal growth. The tissue is then examined under a microscope through histopathology.- The role of biopsy and histopathology is essential for diagnosing cancer. They help identify the presence of cancerous cells, determine the type of cancer, and assess its stage and grade. This also provides critical information on the malignancy of the tumor and helps plan appropriate treatment options.

2. Magnetic Resonance Imaging (MRI):- MRI is a non-invasive imaging technique that uses magnetic fields and radio waves to produce detailed images of the inside of the body. It is especially useful in detecting soft tissue abnormalities such as brain, spinal cord, and breast cancers.- The role of MRI in cancer diagnosis includes identifying and locating tumors, determining their size, and assessing whether cancer has spread to other parts of the body (metastasis). It is also used to monitor treatment progress and plan surgeries or radiation therapy.

The genes that may become cancerous under certain conditions are oncogenes and tumor suppressor genes.
1. Oncogenes:- Oncogenes are mutated forms of normal genes called proto-oncogenes. Proto-oncogenes normally promote cell growth and division. However, when mutated or overexpressed, they become oncogenes, leading to uncontrolled cell division and potentially causing cancer.- Example: The Ras gene, when mutated, continuously signals the cell to divide, even when not needed, leading to uncontrolled cell proliferation.
2. Tumor Suppressor Genes:- Tumor suppressor genes are responsible for inhibiting cell growth and promoting the repair of damaged DNA or apoptosis (programmed cell death). If these genes are mutated or inactivated, cells can bypass growth control mechanisms and continue to divide.- Example: The p53 gene is a critical tumor suppressor gene. When it is mutated, it fails to prevent the division of cells with damaged DNA, which can lead to cancer development.

The gametocytes of Plasmodium ingested with human blood develop into gametes in the mosquito’s gut. Fertilisation occurs, forming a zygote which develops into an ookinete and then into an oocyst. The oocyst releases sporozoites which migrate to the mosquito’s salivary glands, ready to infect another human.

(A) Step 1: The thymus gland is a primary lymphoid organ responsible for the maturation of T-lymphocytes (T-cells), which play a central role in cell-mediated immunity.
Step 2: If thymus undergoes atrophy at an early stage of life, it results in reduced T-cell production.
Step 3: This weakens the body's immune response, making the person more susceptible to infections and immune-related disorders.
OR
(B) (i) Step 1: Interferons are proteins released by virus-infected cells.
Step 2: They inhibit viral replication in surrounding uninfected cells by activating antiviral enzymes, thus preventing the spread of infection.
Step 3: They also stimulate the immune cells such as natural killer cells and macrophages.
(ii) Step 1: Interferons are classified under the physiological barriers of innate immunity.
Step 2: These barriers include antimicrobial substances produced in the body that inhibit the growth of pathogens.

Around 292 million people used drugs in 2022, showing a 20% increase over the past decade.

Only 1 in 11 drug users receive treatment, with lower treatment rates for women (1 in 18) compared to men (1 in 7), indicating a significant treatment gap.

Drug injection increases the risk of transmission of blood-borne diseases such as HIV and Hepatitis C. Among 13.9 million people who inject drugs:

1.6 million are living with HIV.

1.4 million live with both HIV and Hepatitis C.

[(i)] The scientific name of (p) is Cannabis sativa. OR

[(ii)] The scientific name of (q) is Papaver somniferum.

(A):
Step 1: One situation is when a patient is exposed to tetanus (e.g., through a deep puncture wound). A doctor injects tetanus antitoxins to neutralize the toxin produced by Clostridium tetani, providing immediate protection.
Step 2: Another situation is in the case of snakebite (e.g., a venomous snake like a cobra). Antivenom (pre-formed antibodies) is injected to neutralize the snake venom, preventing systemic damage.
OR
(B):
Step 1: Malaria symptoms do not appear immediately because the Plasmodium sporozoites injected by the Anopheles mosquito first travel to the liver, where they multiply into merozoites during the pre-erythrocytic stage (about 5–16 days).
Step 2: Only after this incubation period do merozoites enter the bloodstream, infect red blood cells, and cause symptoms like fever and chills as they multiply and rupture the cells.
Thus, (A) includes tetanus and snakebite scenarios, while (B) explains the delayed onset of malaria due to the parasite’s life cycle.

(A) Step 1: An antibody is a Y-shaped glycoprotein made by B-lymphocytes in response to an antigen.
Step 2: Structure of an antibody molecule:

• Composed of four polypeptide chains — two identical light (L) chains and two identical heavy (H) chains.
• Chains are held together by disulfide bonds.
• Each chain has a variable region and a constant region.
• The variable region forms the antigen-binding site — specific to each antigen.
• The constant region determines the antibody class (IgA, IgG, etc.).

Step 3: The specificity of the antibody is due to the antigen-binding sites present on the variable regions of the light and heavy chains.
OR
(B) Step 1: Public awareness and counselling are essential to prevent HIV spread. In addition to these, the following measures are taken:

• Ensuring safe blood transfusion by proper screening.
• Use of disposable syringes and needles.
• Promoting safe sex practices (e.g., use of condoms).
• Providing antiretroviral therapy (ART) to infected individuals.

Step 2: Organizations like NACO and WHO also promote voluntary testing and confidentiality to reduce stigma and improve early diagnosis.

(i)
Step 1: Interferons are proteins released by virus-infected cells.
Step 2: They inhibit viral replication in surrounding uninfected cells by activating antiviral enzymes, thus preventing the spread of infection.
Step 3: They also stimulate the immune cells such as natural killer cells and macrophages.
(ii)
Step 1: Interferons are classified under the physiological barriers of innate immunity.
Step 2: These barriers include antimicrobial substances produced in the body that inhibit the growth of pathogens.

Step 1: The thymus gland is a primary lymphoid organ responsible for the maturation of T-lymphocytes (T-cells), which play a central role in cell-mediated immunity.
Step 2: If thymus undergoes atrophy at an early stage of life, it results in reduced T-cell production.
Step 3: This weakens the body's immune response, making the person more susceptible to infections and immune-related disorders.

Step 1: Understanding the Concept:
Plasmodium is a digenetic parasite, requiring two hosts to complete its life cycle: humans (asexual cycle) and mosquitoes (sexual cycle).
Step 2: Detailed Explanation:
1. Host: The sexual stages are completed in the female Anopheles mosquito.
2. Process:
- When a mosquito bites an infected person, it ingests gametocytes along with the blood meal.
- Fertilization and development take place in the mosquito's intestine/gut. The male and female gametes fuse to form a zygote.
- The zygote develops and undergoes multiple divisions to form mature infective stages called sporozoites.
- These sporozoites escape from the gut and migrate to the mosquito's salivary glands, where they are stored until the next bite.
Step 3: Final Answer:
Female Anopheles mosquito is the host where fertilization occurs in the gut, eventually producing sporozoites.