Explanation

• Solar panels convert sunlight into electrical energy using special cells.
• Solar energy is a renewable and clean source of energy.
• These cells are called photovoltaic (PV) cells because they generate electricity when exposed to light.
• The technology is based on the photovoltaic effect, discovered in 1839.

Last verified on 11-03-2026

Explanation

• A convex lens is a transparent optical lens that is thicker in the middle and thinner at the edges.
• It bends parallel rays of light towards a single point called the focus.
• Because it brings light rays together, it is called a converging lens.

Additional information:

• Concave lens is also called a diverging lens.

Last verified on 11-03-2026

Explanation

• Bacteria are prokaryotic organisms, meaning they do not have a true nucleus.
• Their genetic material (DNA) is not enclosed in a membrane-bound nucleus.
• Instead, the DNA is present in a region called the nucleoid within the cytoplasm.
• Therefore, bacterial DNA is found floating in the cytoplasm of the cell.

Additional information:

• In contrast, eukaryotic cells (plants, animals, fungi) have DNA enclosed inside a nucleus.

Last verified on 11-03-2026

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

• Gene Definition: Basic physical and functional unit of heredity
• Location: Found on chromosomes within DNA
• Function: Codes for proteins or RNA molecules that determine traits
• Types: Structural genes (proteins), regulatory genes (control expression)
• Inheritance: Passed from parents to offspring during reproduction

Last verified on 05-02-2026

Explanation

• A chemical reaction that releases heat energy to the surroundings is called an Exothermic Reaction.
• In such reactions, energy is produced in the form of heat, light, or flames.
• Examples include combustion of fuel, respiration, and neutralization reactions.

Additional information:

• An endothermic reaction, which absorbs heat from the surroundings.

Last verified on 11-03-2026

Explanation

• The formation of hydrogen and oxygen from water, which is an example of a decomposition reaction: 2H2O → 2H2 + O2
• In this reaction, water (H2O) decomposes into hydrogen (H2) and oxygen (O2).

Last verified on 11-03-2026

Explanation

• When water cools from 4°C to 0°C, it expands as it freezes into ice.
• Unlike most substances, water’s maximum density is at 4°C; below this temperature, the volume increases and density decreases.
• This is why ice floats on water.

Last verified on 10-03-2026

Explanation

• Antoine Lavoisier, a French chemist, is credited with discovering the law of conservation of mass in 1789 (1785).
• He demonstrated that matter cannot be created or destroyed in a chemical reaction, only transformed from one substance to another.

Last verified on 10-03-2026

Explanation

• Photosynthesis is the process by which green plants, algae, and some bacteria convert sunlight, water, and carbon dioxide into food (glucose).
• It occurs in the chloroplasts of plant cells using chlorophyll.
• The byproduct of this process is oxygen, which is released into the atmosphere.

Last verified on 10-03-2026