Explanation

Goiter is caused by iodine deficiency.

It results in an enlarged thyroid gland.

Iodine deficiency can cause mental retardation in children.

Particularly if the deficiency occurs during fetal development or early childhood.

This is because iodine is essential for brain development and thyroid function.

The effects of the thyroid come from two iodine-containing hormones.

Explanation

The cell wall provides structural support and protection to plant cells.

Removing it would compromise the cell’s shape, make it vulnerable to damage, and likely cause it to burst due to osmotic pressure, leading to cell death.

Explanation

Tetanus is caused by Clostridium tetani, a bacterium that can enter the body through cuts or wounds, especially from soil or dirty surfaces—common when a child gets scratched while playing outside.

Explanation

Vaccines work by introducing a harmless version of a germ (an antigen) into the body to trigger an immune response.

The immune system then produces antibodies that will protect the body if it is ever exposed to the full-strength pathogen in the future.

The specific type of vaccine determines the form of the antigen used:

• Live-attenuated vaccines contain a weakened (or attenuated) form of the germ.
• These typically provide strong, long-lasting immunity with just one or two doses.
• Inactivated vaccines use the killed version of the germ.
• These often require multiple doses over time to maintain immunity.

Explanation

Tuberculosis is caused by bacteria, while AIDS is caused by a virus. 

Tuberculosis (TB)

• Caused by: The bacterium Mycobacterium tuberculosis.
• How it spreads: TB bacteria are spread through the air when an infected person coughs, sneezes, or talks. 

Acquired Immunodeficiency Syndrome (AIDS)

• Caused by: The human immunodeficiency virus (HIV).
• How it spreads: HIV is spread through contact with infected body fluids, such as during sex or by sharing needles.

Explanation

Explanation

For a cut hand, both histamine and interleukin-1 (IL-1) cause inflammation.

Interleukin-2 (IL-2), while important for immune regulation, is not a primary or direct cause of the initial inflammatory response to an injury. 

Histamine

• Released immediately by mast cells, which are a type of white blood cell located under the skin and near blood vessels.
• Acts quickly to increase blood flow to the injured area, causing the redness and swelling associated with inflammation.

Interleukin-1 (IL-1)

• A "master cytokine" for inflammation that is released by white blood cells like macrophages and monocytes.
• The IL-1α precursor is stored in skin cells (keratinocytes) and released rapidly upon injury.

Interleukin-2 (IL-2)

• A cytokine that promotes the growth and proliferation of T-cells and other lymphocytes
• It is part of the later adaptive immune response.
• IL-2 deficiency is linked to autoimmune diseases because it helps to maintain immune tolerance by promoting regulatory T-cells.

Explanation

Explanation

The medical condition characterized by the complete absence of sperm in the semen is called azoospermia. 

Explanation

Scurvy

Cause: Vitamin C (ascorbic acid) deficiency. 

Symptoms: Fatigue, weak and sore limbs, bleeding gums, easy bruising, delayed wound healing, and anemia. 

Other Vitamin Deficiencies 

Rickets: Caused by a deficiency in Vitamin D.

Beriberi: Caused by a deficiency in Vitamin B1 (Thiamine).

Night Blindness: Caused by a deficiency in Vitamin A.