Explanation

• Digestion begins in the mouth, starting immediately when food is ingested.
• Both mechanical digestion (chewing) and chemical digestion (salivary amylase breaking down carbohydrates) 

Additional information:

• Mouth: Food is chewed and mixed with saliva that contains enzymes to break down carbohydrates.
• Esophagus: Food is swallowed and passes through the esophagus into the stomach.
• Stomach: Food is mixed with stomach acid and enzymes to break down proteins and fats.
• Small Intestine: Nutrients are absorbed into the bloodstream.
• Large Intestine: Water and electrolytes are absorbed, and waste is eliminated.

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Last updated by NS on 01 MAY 2026

Explanation

• The stratosphere is heated mainly by ozone.
• Ozone layer absorbs harmful ultraviolet (UV) radiation from the Sun.
• This absorption converts solar energy into heat.
• It causes warming in the stratosphere instead of cooling.
• This layer protects Earth from dangerous UV rays.

Last verified on 01-05-2026

Explanation

Composition of Air:

• Nitrogen → 78%
• Oxygen → 20.95%
• Argon → 0.93%
• Carbon dioxide → 0.04%
• Other gases → very small traces

Last verified on 30-04-2026

Explanation

• Vitamin A is essential for vision, skin health, and immune function.
• Its deficiency can lead to night blindness (poor ight vision) and other health problems.

Additional information:

• Dry skin and eyes
• Impaired immune function
• Poor wound healing
• Increased risk of respiratory and urinary tract infections

Last verified on 17-01-2026

Explanation

• Vitamin K helps to make various proteins that are needed for blood clotting and the building of bones.
• Prothrombin is a vitamin K-dependent protein directly involved with blood clotting.

• Vitamin C may protect the body against the effects of pollution.
• It may also prevent blood clots and reduce bruising.

Last verified on 31-03-2026