Explanation

• The molecular structure (double-helix model) of DNA was proposed in 1953.
• This model explained how DNA replicates and carries genetic information in living organisms.
• The discovery was made by James Watson and Francis Crick, two molecular biologists.

Last verified on 11-03-2026

Explanation

• Chlorofluorocarbons (CFCs) are chemical compounds used in refrigerators, air conditioners, and aerosol sprays.
• When released into the atmosphere, CFCs destroy the ozone layer by breaking down O₃ molecules.
• The ozone layer protects Earth from harmful ultraviolet (UV) radiation.

Last verified on 10-03-2026

Explanation

• Mitosis is the process by which a single cell divides to produce two identical daughter cells.
• It is essential for growth, tissue repair, and development in multicellular organisms.
• Mitosis maintains the same number of chromosomes in each new cell.

Additional information:

• Meiosis is different; it occurs in sex cells and reduces chromosome number by half.

Last verified on 10-03-2026

Explanation

• Human Kidney organs are bean-shaped structures in the body.
• They are located on both sides of the spine in the lower back region.
• Kidneys filter waste products and extra water from blood to form urine.
• A healthy adult normally has two kidneys.

Last verified on 10-03-2026

Explanation

• The stomach is an organ involved in digestion, not waste elimination.

1. Lungs: remove carbon dioxide through exhalation
2. Kidneys: filter waste and excess substances from the blood, producing urine
3. Skin: removes waste through sweating
4. Liver: detoxifies harmful substances and aids in their removal

Last verified on 10-03-2026

Explanation

• Reflex actions are rapid, automatic responses to stimuli that occur without the involvement of the brain.
• Instead, they are mediated by the spinal cord or peripheral nerves.

Last verified on 09-03-2026

Explanation

The structure of the brain is similar to the structure of a Walnut, with both having:

• A hard outer layer (cranium vs. shell)
• A wrinkled surface (brain's cerebral cortex vs. walnut's surface)
• A distinct left and right half (brain's hemispheres vs. walnut's halves)

Last verified on 09-03-2026

Explanation

• The nervous system is the body system that controls and coordinates the functions of all other organ systems.
• It allowing for integration and regulation of various bodily functions.
• It consists of the brain, spinal cord, nerves, and sensory organs.

Last verified on 09-03-2026

Explanation

• 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.

Last verified on 08-03-2026

Explanation

• Peanuts are a legume and a good source of protein,
• It containing about 20.5 grams of protein per 100 grams.

Additional information:

• Apples: 0.3 grams of protein per medium-sized fruit
• Watermelon: 0.6 grams of protein per cup
• Mango: 1.4 grams of protein per cup

Last verified on 08-03-2026