World facts, geography, history.
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The cell is the smallest structural and functional unit of living organisms.
All living things are made of one or more cells.
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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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The Industrial Revolution first developed in Great Britain.
It transformed manufacturing through machines and factories.
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The heart pumps blood through the circulatory system.
Its contractions deliver oxygen and nutrients to tissues.
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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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The French Revolution began in 1789.
The storming of the Bastille became one of its defining events.
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The skin is the body's largest organ by surface area and mass.
It protects internal tissues and helps regulate temperature.
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Human cells use oxygen in cellular respiration.
The process releases energy from food molecules.
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The Declaration of Independence was adopted on 4 July 1776.
It announced the colonies' separation from Britain.
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The femur is the thigh bone.
It is the longest and one of the strongest bones in the body.
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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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Riyadh is the political and administrative capital of Saudi Arabia.
It is located in the central Najd region.
