General Science Questions

A clade is a group of ancestral species and all its descendants. Hence it is a branch of one same species and so monophyletic.

When water is cooled from 4°C to 0°C, its density decreases.

When water cools from 4°C to 0°C, ice crystals begin to form because the water is approaching its freezing point. When water freezes, the water molecules form a lattice that increases the volume. As a result, the density decreases. This is why ice will float on top of water; ice has a lower density than the water.

Collisions occur at curves because speed on the approach is too great.

The air around us is a mixture of gases, mainly nitrogen and oxygen, but containing much smaller amounts of water and other gases.

Earth's atmosphere is composed of many gases. Their percentages by volume is given by::

 
78% Nitrogen,

21% Oxygen,

0.9% Argon, and

0.03% Carbon dioxide 

And very small percentages of other elements.

The foods that are good source of fat and incredibly healthy to the body ar fatty fish, eggs, nuts, cheese, avocados, dark chocolates, etc...

Polypeptides are assembled from Aminoacids.