Explanation

A comet moves fastest when it is closest to the Sun, called perihelion.

The Sun’s gravity pulls the comet strongly, increasing its speed.

At aphelion (farthest point from the Sun), its speed is much slower.

This follows Kepler’s laws of planetary motion.

The increase in speed also causes the comet’s tail to become more visible.

Explanation

The Sun produces energy through nuclear fusion in its core.

In fusion, hydrogen nuclei combine to form helium, releasing huge energy.

This energy radiates as sunlight, heat, and solar radiation.

Fusion is different from fission, which splits heavy nuclei.

Solar energy powers life on Earth and can be harnessed for electricity.

Explanation

Submandible refers to the area under the lower jaw (mandible).

It is close to the ear region.

It contains submandibular glands, which are salivary glands.

Explanation

• Nitrobacter bacteria convert nitrite (NO₂⁻) into nitrate (NO₃⁻) in the soil.
• This is the second step of the nitrification process, which is important for plant nutrition.
• Nitrite is toxic to plants, but nitrate is easily absorbed as a nutrient.

Last verified on 22-01-2026

Explanation

Perihelion is the point in a comet’s orbit closest to the Sun.

According to Kepler’s Second Law, a comet moves faster when closer to the Sun.

Aphelion is the farthest point from the Sun, where speed is minimum.

The increase in speed is due to Sun’s gravitational pull.

This principle applies to all celestial bodies in elliptical orbits.

Explanation

A cell is the basic structural and functional unit of life.

All plant and animal tissues are made up of cells.

Nitrogen, phosphorus, and oxygen are elements, not units of tissue.

Explanation

• The seed coat protects the embryo inside the seed.
• The outermost layer of the seed coat is called Testa.
• It acts as a barrier against mechanical damage, pathogens, and water loss.

Additional information:

• Testa may have hair, wax, or spines in some seeds.
• Plays a role in seed dormancy and protection.

Last verified on 25-01-2026

Explanation

• Sedimentary rocks are rocks formed by the deposition and compression of sediments over time.
• Also called stratified rocks because they are formed in layers (strata).
• Often porous, meaning they have small holes (pores) that can contain water or other fluids.

Additional information:

• Cover about 75% of the Earth's surface.
• Examples: Sandstone, Limestone, Shale.
• Usually softer and less dense than igneous rocks.

Explanation

• The camel is called the “ship of the desert”
• Because it travels easily on sand.
• It can survive long periods without water, making it ideal for desert transport.

Last updated 25-07-2026 by NA

Explanation

Glycolysis, the metabolic pathway that converts glucose into pyruvate

Takes place in the cytoplasm (specifically the cytosol) of both prokaryotic and eukaryotic cells.

It acts as the initial stage of cellular respiration, occurring independently of oxygen to produce a net gain of 2 ATP and 2 NADH molecules. 

Additional Products: Generates 2 NADH.