Theory:

What happens if a piece of bread is stored at room temperature for four to five days? What are your observations?
 
We see green or black hairy growths on the bread. On leaving it undisturbed for a couple of days, the bread has green or black patches. What exactly are these?
 
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Growth of mould on bread
 
These are moulds. Moulds thrive on the surface of bread because it provides both nutrition and moisture. Why was there a hairy appearance at first, which then turned into patches over time? This is due to the fact that moulds reproduce. The moulds multiplied in number as a result of reproduction.
What is reproduction?
Reproduction is the biological process through which organisms produce offsprings that are genetically identical to themselves.
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Reproduction in hen
 
It is one of the most important aspects of living things to produce their own kind. In the living world, reproduction is observed in different forms.
 
Before looking into the mechanism by which organisms reproduce, let us know why organisms reproduce? As we have seen in the earlier chapter Life process in animals, reproduction is not essential for survival, unlike the process of nutrition, respiration and excretion.
 
On the other hand, if an organism reproduces, it will expend much energy in the process. So the question is, why does an organism expend energy on a process that is not necessary for survival? Let us look into the purpose and importance of reproduction.
 
Purpose of reproduction:
 
1. Reproduction is essential for the maintenance and continuity of species.
 
2. It is a process that maintains the population of young, adult and aged persons.
 
3. The process of reproduction introduces variations in the organisms. These variations are essential for adaptations and evolution.
 
4. The existence of life on earth is due to the process of reproduction. The inability of a species of an organism to reproduce results in species extinction.
 
During reproduction, animals and plants make copies of themselves. In the process of reproduction, organisms create new individuals who are similar to each other and carry the traits of their parents.
Reference:
https://www.flickr.com/photos/lynnfriedman/34296658593/in/photostream/
https://www.vecteezy.com/vector-art/684814-chickens-and-little-chicks-with-basket-of-eggs