How will a harmful drug affect the embryo if it was introduced during the 4th week of pregnancy?

it can cause defects embryo or death which leads to a miscarriage

It is an important part of many cells and processes such as amino acids, proteins, and even our DNA. It is also needed to make chlorophyll in plants, which is used in photosynthesis to make their food. As part of these life processes, nitrogen is transformed from one chemical form to another.

Explanation:

Some questions to clarify;

How does nitrogen help plants?

Nitrogen is so vital because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (i.e., photosynthesis). It is also a major component of amino acids, the building blocks of proteins. Without proteins, plants wither and die.

How does nitrogen help humans?

It is used to make amino acids in our body which in turn make proteins. It is also needed to make nucleic acids, which form DNA and RNA. Humans or other species on earth require nitrogen in a 'fixed' reactive form. Till 1900 we had an access to use naturally occurring nitrogen for processing food like manure

Nitrogen also:

Nitrogen is a key element in the nucleic acids DNA and RNA, which are the most important of all biological molecules and crucial for all living things. DNA carries the genetic information, which means the instructions for how to make up a life form

Nitrogen is also helps runs power plants.