Explanation

• Ribosomes are small cell organelles responsible for protein synthesis.
• They read the genetic information from mRNA and join amino acids to form proteins.
• Ribosomes are found free in the cytoplasm or attached to the rough endoplasmic reticulum.
• They are present in both plant and animal cells.

Last verified on 15-03-2026

Explanation

• In cellular respiration, glucose reacts with oxygen to release energy.
• It producing carbon dioxide and water as main products.
• Respiration occurs mainly in the mitochondria of cells.
• The general respiration equation:
• Glucose + Oxygen → Carbon dioxide + Water + Energy (ATP).

Last verified on 15-03-2026

Explanation

• Stomata are tiny pores present mainly on the surface of leaves.
• They allow carbon dioxide (CO₂) to enter the plant for photosynthesis and release oxygen.
• Stomata are controlled by guard cells, which open and close the pores.

Last verified on 15-03-2026

Explanation

• The outer ear (pinna and ear canal) collects sound vibrations from the environment.
• These vibrations travel through the auditory canal to the eardrum (tympanic membrane).

Additional information:

Main Parts of the Ear

• Outer Ear – Pinna and auditory canal
• Middle Ear – Eardrum and three ossicles (malleus, incus, stapes)
• Inner Ear – Cochlea and semicircular canals (hearing and balance)

Last verified on 15-03-2026

Explanation

• Nitrogen (N2) makes up about 78% of the Earth's atmosphere.
• Making it the most abundant gas in the atmosphere.
• It is followed by oxygen (~21%), with other gases in much smaller amounts.

Last verified on 15-03-2026

Explanation

The atomic number (proton number) determines the element.

Both X (₁₉) and Y (₁₉) have the same proton number 19, so they represent the same element but different isotopes.

• ⁴⁰₁₉X → Proton number = 19, Mass number = 40
• ³⁹₁₉Y → Proton number = 19, Mass number = 39
• ³⁸₂₀Z → Proton number = 20, Mass number = 38

Last verified on 15-03-2026

Explanation

• Phosphorus molecule naturally exists as P₄.
• It means one molecule contains four phosphorus atoms bonded together.
• This form is commonly found in white phosphorus, where the atoms form a tetrahedral structure.

Additional information:

• O₂ – Oxygen molecule
• N₂ – Nitrogen molecule
• H₂ – Hydrogen molecule
• Cl₂ – Chlorine molecule

Last verified on 15-03-2026

Explanation

• The symbolic representation of a molecule of a compound is called a formula.
• It uses symbols and numbers to represent the composition of the molecule.
• For example, the formula for water is H₂O, indicating two hydrogen atoms and one oxygen atom.

Last verified on 15-03-2026

Explanation

• Nishan-e-Pakistan – Largest / highest civil award
• Hilal-i-Imtiaz – Second highest civil award
• Sitara-e-Imtiaz – Third highest civil award
• Tamgha-e-Khidmat – Smallest civil award

Additional information:

• Nishan-e-Haider – Highest military honor in Pakistan
• First recipient: Captain Raja Muhammad Sarwar

Last verified on 15-03-2026

Explanation

• An atom is the smallest possible particle of an element that can combine to form new compounds.
• Atoms are the building blocks of matter, and they cannot be broken down into smaller particles.

Last verified on 15-03-2026