Answer:
2%
Explanation:
The scientist believe that around 2% of the species that existed on Earth have been preserved in the fossil records. It is still a hot debate about it though, as there are only around 250,000 species identified in the fossil records so far, which is less than a quarter from the species that live in the present.
The reason why scientists believe that the majority of the species have not been preserved are very logical though. One of the reasons is that lot of species existed very long time ago, so their remains just didn't lasted so long. Other reason is the movement of the plates, where we have situation where plates that existed in the past have been totally suducted and melted in the mantle, while others are at the verge of it, so every fossil with them is melted and destroyed too. Another reason is that lot of species do not have hard parts, solid bone structure, so their preservation has been pretty much impossible,
The answer is false
When the cells are differentiating in the embryo, they retain the same genetic material. However, certain genes in the differentiating cells are silenced using protein complexes called histones. This makes the genes inaccessible to RNA. Therefore, the process of transcription required in the expression of genes is restricted.
Mucus traps foreign particles and germs, protecting the body (especially the trachea)
The Olecranon fossa. It is the large depression at the distal end of the humerus. The olecranon fossa of the humerus together with the olecranon process of the ulna permit full extension of the forearm. The two depression is the olecranon fossa that behind and above the trochlea, and the coronoid fossa.
