Practice Pakistan questions with answers and explanations.
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Mitochondria produce much of the cell's usable energy as ATP.
They are therefore called the powerhouse of the cell.
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Roots anchor the plant and absorb water and minerals.
Root hairs increase the absorbing surface.
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Transpiration is the loss of water vapor through plant surfaces.
Most of it occurs through leaf stomata.
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Nitrogen makes up about 78% of Earth's atmosphere.
Oxygen is the second-most abundant gas.
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Most atmospheric ozone is concentrated in the stratosphere.
It absorbs much of the Sun's harmful ultraviolet radiation.
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A water molecule contains two hydrogen atoms and one oxygen atom.
Its formula is H₂O.
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Common salt is sodium chloride.
Its chemical formula is NaCl.
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Human cells use oxygen in cellular respiration.
The process releases energy from food molecules.
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Solar radiation drives weather, climate, and photosynthesis.
Other energy sources are much smaller for the surface system.
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Sunlight helps the skin produce vitamin D.
This vitamin supports calcium absorption and bone health.
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The Silk Road was a network of overland and maritime routes.
It carried goods, ideas, and technologies across Eurasia.
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Hammurabi was a king of Babylon.
His law code is one of the best-known ancient legal collections.
