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Cooking of food is irreversible, as the ingredients cannot be obtained back in their original form. However, cooked food provides us with essential nutrients, which is why it is a desirable change. [1 Mark]
Another example of irreversible and desirable change is growth. Growing up is good for us in many ways, which is why it is desirable. But we cannot go back to being a small kid, which is why growth is irreversible too. [1 Mark]