Practice MCQs

Explanation: The Ring of Fire is a major area in the Pacific Ocean basin where many earthquakes and volcanic eruptions occur, containing about 90% of the world's earthquakes.

Explanation: Seasons are caused by Earth's axial tilt of 23.5°. As Earth orbits the Sun, different hemispheres receive more direct sunlight at different times of year.

Explanation: The ozone layer is located in the stratosphere, approximately 15-35 km above Earth's surface, and protects life by absorbing harmful UV radiation.

Explanation: The Richter scale (now largely replaced by the Moment Magnitude Scale) measures the magnitude or energy released by earthquakes.

Explanation: The crust is the outermost solid layer of Earth. It is 5-70 km thick and is divided into oceanic crust (thinner) and continental crust (thicker).

Explanation: Insulin is produced by the beta cells in the islets of Langerhans within the pancreas. Insulin regulates blood glucose levels.

Explanation: A normal human somatic (body) cell contains 46 chromosomes arranged in 23 pairs. Reproductive cells (eggs and sperm) contain 23 chromosomes each.

Explanation: Photosynthesis primarily produces glucose (C6H12O6) using CO2, water and sunlight. Oxygen is released as a by-product.

Explanation: O negative (O-) is the universal donor for red blood cells because it lacks A, B and Rh antigens, making it compatible with all blood types.

Explanation: A gene is the basic unit of heredity. Genes are segments of DNA that encode proteins and are passed from parents to offspring, determining traits.