What prevents organisms from reproducing an unlimited number of offspring?

The primary reason living organisms cannot produce an unlimited number of offspring is senescence, otherwise known as old age.

Cells of the reproductive organs divide and continually make it possible for organisms to reproduce. As time goes on, the old cell dies and new cells replace them through mitotic or meiotic cell division of young cells that still has the ability to divide.

However, as programmed cell deaths occur with old age, the reproductive cells start losing the ability to divide, and when this happens, the ability for organisms to reproduce becomes limited.

More on reproduction can be found here: link

Human Hunting

Natural predators

Old age

diseases

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.