Explanation

• The study of the structure of tissues of plants and animals is known as Histology.
• It involves examining the structure, composition, and function of cells and tissues under a microscope.
  

Additional information:

• Geology is the study of rocks and Earth's structure.
• Radiology is the study of medical imaging techniques like X-rays and MRI.

Last verified on 22-01-2026

Explanation

• The nucleolus is a dense region inside the nucleus where ribosomal RNA (rRNA) is produced and ribosomal subunits are assembled.
• Ribosomes are responsible for protein synthesis in the cell.

Last verified on 27-10-2026

Explanation

• Frequency is the number of occurrences of a repeating event per unit of time.
• The SI unit of frequency is the hertz (Hz).
• 1 Hz = 1 cycle or vibration per second
• Unit: Hz = s⁻¹ (per second)
• Named after physicist Heinrich Hertz
• Used for waves, oscillations, sound, and electromagnetic radiation
• Derivations from other quantities: f = 1 / T
• Dimension T^−1

Explanation

• Elastic potential energy is stored when a spring is stretched or compressed.
• This energy is released when the spring returns to its original shape.

Additional information:

• Kinetic energy is the energy of motion.
• Chemical energy is stored in chemical substances.

Last verified on 23-10-2026

Explanation

• The Total Fertility Rate (TFR) is the average number of children a woman is expected to have during her reproductive years, based on current age-specific fertility rates.
• It is generally expressed as the number of children per woman.

Additional information:

• The Crude Birth Rate (CBR) measures the number of live births per 1,000 people in a population per year.
• The Dependency Ratio compares the dependent-age population with the working-age population.

Last verified on 23-10-2026

Explanation

• Most skull bones are connected by fixed joints, also called suture joints.
• These are fibrous, immovable joints that hold the skull bones firmly together and protect the brain.
• The lower jaw is an exception because it forms a movable joint with the skull.

Last verified on 23-10-2026

Explanation

• Light travels at approximately 300,000 kilometres per second in a vacuum.
• While sound travels through air at about 343 metres per second at 20°C.
• Lightning produces a flash of light and heats the surrounding air rapidly, causing the thunder we hear.
• Light reaches our eyes almost instantly over ordinary storm distances, whereas sound takes longer to reach our ears.

Last verified on 22-10-2026

Explanation

• An electron carries a negative electric charge.
• Its charge is approximately −1.602 × 10⁻¹⁹ C.
• A proton has an equal magnitude of positive charge, while a neutron has zero electric charge.
• The charge of an electron is called the elementary charge with a negative sign.

Explanation

• The ozone layer protects the Earth from the sun.
• It is a part of the atmosphere that absorbs most of the harmful ultraviolet light from the sun.
• It sits in the stratosphere.
• It is about 9 to 18 miles above the Earth.
• It stops dangerous UV rays from hurting living things.

Last updated by NS on 14-8-2026

Explanation

• Intermediate-focus earthquakes: occur at depths of 70–300 km.

Additional information:

• Shallow-focus earthquakes: occur at depths of 0–70 km.
• Deep-focus earthquakes: occur at depths of 300–700 km.

Last verified on 22-10-2026