Questions

The left atrium is the upper left chamber of the heart that receives blood from the pulmonary veins.

The heart is responsible for circulating blood throughout the body. The heart is divided into four chambers. The upper chamber is known as the atrium while the lower chamber is referred to as the ventricle.

Assassins (from Hashishin)

The study or scientific study of the structure, development, and abnormalities of the teeth is called Odontology. The science that studies teeth and their surrounding tissues, especially the prevention and cure of their diseases is called Dentology.
 

Area near active volcano or lake beds are best areas that lends itself to the formation of fossils.

Each year, the World Meteorological Organisation (WMO), its members and the worldwide meteorological community around the world celebrate World Meteorological Day on 23rd March around a chosen theme. And this year the theme is "Understanding the cloud".

Metonymy is a figure of speech in which a thing or concept is referred to by the name of something closely associated with that thing or concept. Hence it occurs when a word is replaced by a word that has an obvious relation to itself.

In the given example of the text, the bones refer to the human being.