Explanation

• The Gravitational constant (G) was first measured by Henry Cavendish in 1798.
• He used a torsion balance experiment to calculate Earth's density and gravitational force.
• His experiment is called the Cavendish experiment.
• Newton proposed the law of gravitation, but did not measure the value of G.
• Value of G is approximately 6.674 × 10⁻¹¹ N m²/kg².

Last verified on 09-06-2026

Explanation

• Iron (Fe) is a trace element required in very small amounts in the body.
• It is essential for forming hemoglobin in blood.
• It helps in oxygen transport in red blood cells.
• Other trace elements include: Zinc, Copper, Iodine, Manganese, Cobalt.

Last verified on 09-06-2026

Explanation

There are 3 main types of chemical bonds based on electron behavior.

1. Ionic bond → electrons are transferred (lost or gained).
2. Covalent bond → electrons are shared between atoms.
3. Metallic bond → electrons are delocalized (free-moving) in metals.

Last verified on 09-06-2026

Explanation

• Acromegaly is caused by excess secretion of Growth Hormone (GH).
• This hormone is released from the anterior pituitary gland.
• It usually occurs due to a pituitary tumor (adenoma).
• It leads to abnormal growth of hands, feet, and facial bones in adults.
• It develops after puberty when bone growth plates are already closed.

Last verified on 09-06-2026

Explanation

• The thickness of Earth is about 13,700 kilometers (8,500 miles).
• The mantle, which is the biggest part of Earth by volume.
• It is approximately 2,900 kilometers (1,800 miles) thick. 

Last verified on 09-06-2026

Explanation

• Nm⁻² (Newton per square meter) is the SI unit of pressure.
• It is also called Pascal (Pa).
• 1 Pa = 1 N/m².
• Pressure is defined as force per unit area.
• Example: Atmospheric pressure is about 101,325 Pa (1 atm).

Last verified on 09-06-2026

Explanation

• Leucocytes (WBCs) increase in number when the body is fighting an infection.
• This condition is called Leukocytosis.
• It usually occurs due to bacterial or viral infections.
• WBCs help the body in defense against disease-causing germs.
• It is a sign that the immune system is actively responding to illness.

Last verified on 09-06-2026

Explanation

• The Tundra is a cold, treeless region found in high latitudes (Arctic) or high mountains.
• It has very low temperatures and a short growing season.
• Soil remains frozen for most of the year (permafrost).
• Common vegetation includes mosses, lichens, and small shrubs.
• It is found in regions like Arctic Canada, Siberia, and Alaska.

Last verified on 09-06-2026

Explanation

• Herpetology is the branch of zoology that studies reptiles and amphibians.
• Reptiles include: snakes, lizards, crocodiles, turtles.
• Amphibians include: frogs, toads, salamanders.
• The word comes from Greek “herpeton” meaning creeping animal.

Last verified on 09-06-2026

Explanation

• In glycolysis, 2 ATP molecules are used (investment phase) at the beginning.
• Later, 4 ATP are produced, so net gain is 2 ATP.
• Glycolysis takes place in the cytoplasm of the cell.
• It is the first step of cellular respiration and does not require oxygen.
• Final products: 2 pyruvate + 2 NADH + net 2 ATP.

Last verified on 09-06-2026