Explanation

• Chloroplast is the plant cell organelle that performs photosynthesis.
• It contains chlorophyll, the green pigment that captures sunlight to produce food (glucose) for the plant.

Additional information:

• Mitochondria: Powerhouse of the cell, produces energy via respiration
• Nucleus: Controls cell activities and stores DNA

Last verified on 11-02-2026

Explanation

• Programmed cell death is known as apoptosis.
• It is a controlled process that allows the body to eliminate damaged or unnecessary cells without causing inflammation.

Last verified on 11-02-2026

Explanation

• Pressure is a fundamental physical quantity that is defined as the force exerted per unit area.
• It is a measure of the strength of a force acting on a surface.
• It is typically measured in units such as Pascals (Pa) or pounds per square inch (PSI).

Last verified on 10-02-2026

Explanation

• The ozone layer absorbs and blocks the majority of the Sun’s harmful ultraviolet (UV) radiation.
• This protection helps prevent skin cancer, cataracts, and damage to ecosystems.

Last verified on 09-02-2026

Explanation

Scalar quantities are physical quantities that have only magnitude (amount or size) but no direction.

Examples of scalar quantities include:

• Mass
• Temperature
• Time
• Energy
• Distance

Last verified on 07-02-2026

Explanation

• Flame cells are specialized excretory organs in flatworms (Planaria (Platyhelminthes)
  • They remove waste and excess water from the body.
  • Called “flame cells” because cilia inside them flicker like a flame.
  • Part of the protonephridial system in invertebrates.

Last verified on 07-02-2026

Explanation

The Earth was formed about 4.5 billion years ago.

Additional information:

• Method Used: Radiometric dating
• Oldest Materials: Meteorites and ancient Earth rocks
• Scientific Consensus: Supported by geology and astronomy

Last verified on 16-01-2026

Explanation

• Crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes.
  • Occurs during prophase I of meiosis.
  • Increases genetic variation in gametes.
  • Ensures diverse traits in offspring.
  • Essential for evolution and natural selection.

Last verified on 06-02-2026

Explanation

• Humidity is the amount of water vapor present in the air.
  • It affects weather, climate, and comfort levels.
  • High humidity can make the air feel hotter, low humidity feels drier.
  • Measured using a hygrometer.
  • Important in agriculture, meteorology, and human health.

Last verified on 05-02-2026

Explanation

Cotton cultivation requires a significant number of frost-free days, typically around 210

It is the crop that requires high temperatures (21°C to 30°C)

It thrives in tropical and subtropical climates

It's grown in the Kharif season