Question

1. what do you mean "in vitro" ? specifically on sentences"Cell division occurs in certain tissues to replace lost cells.Unicellular organisms grow by cell division .One can easily observe this in IN VITRO cultures by simply counting the number of cells under microscope".

And on sentence "Metabolism is a defining feature of all living organisms without exception ,isolated metabolic reactions IN VITRO are not living things but surely living reactions."

Answer 1

Dear student,

In vitro (meaning: in the glass) studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test tube experiments", these studies in biology and its subdisciplines are traditionally done in labware such as test tubes, flasksetc.

Eg;cloned plants in vitro



Clarifying second sentence


All-living organisms are made of chemicals.
• There are thousands of metabolic reactions occurring simultaneously inside all living organisms, be they are unicellular or multicellular. The sum total of all the chemical reactions occurring in our body is metabolism. All plants, animals, fungi and microbes exhibit metabolism.
• No non-living objects exhibit metabolism. Metabolic reactions can be demonstrated outside the body in cell free system.

Hence, while metabolism is a defining feature of all living organisms without exception, isolated metabolic reactions in vitro represent the non living things

but it involves the same environment required to carry out reaction within a cell. Like the reaction can also be carried outside the body in a cell free system and includes building cell components ,taking up raw materials and converting into the energy that is available with the molecule and finally releasing the end product. Hence it shows that in vitro reactions represent non living things but living reactions.

Hope you understood

Regards