Generally a protein molecule consists of around 20 essential amino acids.
complete proteins
Vegetables are not the best source for essential amino acids because they do not contain all the essential amino acids in sufficient amounts. Animal sources like meat, fish, eggs, and dairy products are considered complete proteins because they contain all the essential amino acids in the right proportions.
There are two groups of protein. Proteins from animal foods contain all the essential amino acids in the proportions required by the body they are therefore known as "complete" or 1st class protein. Protein from plants do not always contain all the essential amino acids, and are known as "incomplete" or 2nd class proteins.
Animal proteins are considered "first class" or "high quality" proteins because they contain all the essential amino acids required by the human body in the right proportions. This makes animal proteins more easily digestible and more readily absorbed compared to plant proteins. Additionally, animal proteins tend to have higher biological value, meaning they provide a more complete source of amino acids for human nutrition.
Foods from animal sources provide complete proteins, which contain all essential amino acids needed by the body.
Amino acids
Plant proteins typically contain less than adequate amounts of all essential amino acids, particularly lysine and methionine. Consuming a variety of plant protein sources throughout the day can help ensure a complete amino acid profile.
The term "complete protein" refers to amino acids, the building blocks of protein. A protein must contain all nine of these essential amino acids in roughly equal amounts.
meat
Foods such as meat, fish, eggs and dairy products contain all the essential amino acids. However plant sources of protein only contain a few of the amino acids needed.
I believe hemp seeds contain all 9 amino-acids.
No. Almost all vegetarian foods have a variety of amino acids.