define emergent properties with an example and explain why multicellular organis

Emergent properties are properties of a "whole" that cannot be seen in the sum of its parts when taken individually. For example, thought is an emergent property of the brain, and chemical behaviour is an emergent property of atoms.

As simple as possible....

Emergent property is like this:

Cell Tissue Organ Organ System Animal

It's the property where living things become more and more complex as it goes from cellular level (exp humans are made of cells) to organ system (exp humans are made of organ system composed of millions of cells).

It's based on the concept that "the whole is greater than the composition of its parts." Exp: heart is made of cells only, but if you just have heart cells (sum of its parts) it won't do anything but if the whole heart is there, it will perform the function of pumping blood (the whole is greater).

Hope that helped! :-)

Emergent properties’ represent one of the most significant challenges for the engineering of complex systems. They can be thought of as unexpected behaviors that stem from interaction between the components of an application and their environment. A broader example of emergent properties in biology is the combination of individual atoms to form molecules such as polypeptide chains, which in turn fold and refold to form proteins. These proteins, assuming their functional status from their spatial conformation, interact together to achieve higher biological functions and eventually create - organelles, cells, tissues, organs, organ systems, organisms.