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

Frequency is the number of occurrences of a repeating event per unit of time.

SI unit hertz (Hz)

In SI base units: s−1

Derivations from other quantities: f = 1 / T

Dimension T^−1

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Explanation

• The primary component of natural gas is methane (CH4).
• Making up 70% to 90% or more of its composition.
• It is a colorless, odorless, and highly flammable hydrocarbon gas.
• Characteristics: It is a fossil fuel, often found in rock formations alongside oil or on its own. 

Last updated question 15 March2026

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.

Explanation

Glucose (C6H12O6) is a type of carbohydrate, specifically a simple sugar or monosaccharide.

It is a vital source of energy for many living organisms, including humans.

Glucose is a primary component of many carbohydrates, such as starch, cellulose, and glycogen.

Explanation

Sulfur dioxide (SO₂) and nitrogen dioxide (NO₂) are primary precursors of acid rain.

Acid rain is a consequence of these atmospheric pollutants reacting with water, oxygen, and other chemicals to form acidic compounds. 

These acids contribute to environmental damage.

Explanation

Jupiter, Uranus, and Neptune have rings, too.

But Saturn's rings are the biggest and brightest.

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