Glands of the endocrine system secrete hormones into the blood.
A two-stroke engine is a type of internal combustion engine with a cycle of only two (power) strokes.
The most ancient group of animals, they live underwater, lack real tissues and body symmetry.
Widespread heterotrophic unicellular organisms with constantly changing shapes
One of the most important monocot crops.
This animation demonstrates the anatomy of amphibians through the example of a common species of frogs.
Three saturated fatty acid molecules linked to a glycerol molecule.
This animation demonstrates how horse chestnut trees change throughout the seasons
Triglycerides containing unsaturated fatty acids are liquid at room temperature.
Polypeptide chains are composed of amino acids and can appear in alpha-helix or beta-sheet form.
Types of bridges include beam-, arch-, suspension-, cantilever and truss bridges.
Two meshing gears transmit torque during their rotational motion.
This animation shows optical and radiotelescopes used in astronomical observation.
The battle ended with the overwhelming victory of the Macedonian army over the Persian army led by Darius III.
This animation demonstrates how solar energy can be utilised.
The anatomy of annelids is demonstrated through the example of the common earthworm.
The Emperor of the vast Far-Eastern empire was the lord of life and death.
Observatories are often built at high elevations to minimise the effects of atmospheric turbulence
The capacity of data storage devices have increased at an incredible rate during the past decades.
A wide variety of optical instruments are in use today, ranging from microscopes to telescopes.