Colourless, odourless liquid produced by dissolving carbon dioxide in water.
One of the oxoacids of nitrogen. A colourless compound with a pungent odour, a strong oxidant.
A crystalline allotrope of carbon which was discovered at the end of the 1980s.
A polynucleotid made up of phosphoric acid, ribose, and nucleobases (cytosine, uracil, adenine and guanine).
Solid, white substance, a constituent of vegetable oils and animal fats.
A white, water-soluble, sweet compound known as sugar.
The arms are moved by flexor and extensor muscles.
Formic acid is the simplest carboxylic acid.
Oxygen carrier protein in our red blood cells.
Neurons are cells specialised for transmitting electric signals.
The urinary system serves for the removal of harmful and useless materials from the body.
Bones of the lower limbs are connected to the trunk by the pelvis.
The two main parts of the central nervous system, the brain and the spinal cord are protected by the skull and the spinal column.
A group of fish characterised by a cartilaginous skeleton, well-known species include the great white shark and the great hammerhead shark.
The name of the Russian armoured cruiser became well known during the October Revolution of 1917.
The Earth is divided into geographical and climatic zones, which result in the zonation of vegetation.
Static warfare was one of the characteristics of WWI
Ziggurats were typical terraced step pyramids used as temples in ancient Mesopotamia.
The limbic system plays an important role in forming emotions and in learning.
Pearls, often used as gemstones, are the by-products of certain molluscs' protective mechanisms.