Question

organisms that can synthesise their own food with the help of simple in organic substance called???​

Answer 1

Answer:

Organisms which can make their own food from simple substances are called autotrophs. Organisms which can not make their own food and obtain it directly or indirectly from green plants are called heterotrophs. They are producers.

Explanation:

Answer 2

Substance synthesis their own food from simple inorganic substances like carbon dioxide and water to produce complex inorganic food. this process is called Autotrophic mode of nutrition. and the organism is called autotroph.

[NOTE : your question mentions food made from simple organic substances which is wrong as food can be synthesized only by simple inorganic substances or inorganic chemical reactions]