Biology · Glossary

What is Life cycle?

Also known as: stage · birth · young · adult · old age · death

Definition 7.1 Primary & Middle School Biology · Chapter 7 — Born, Growing, Dying

The life cycle of a living thing is the row of stages its life goes through:

  1. it is born — the beginning;
  2. it is young — it grows and changes fast;
  3. it is an adult — fully grown; adults can have young of their own;
  4. it grows old, and at the end it dies.
The beginning of three life cycles at once: newborn kittens at their mother’s milk.
The beginning of three life cycles at once: newborn kittens at their mother’s milk.
The stages of a life — and the arrow that starts the road again with the next generation.
The stages of a life — and the arrow that starts the road again with the next generation.

Examples

Example 7.2 (Three lives, same road)

A kitten is born, plays and grows into a cat, who may have kittens herself, and grows old. A cherry seed sprouts, the young tree grows taller for years, the adult tree makes blossom and cherries, and after many tens of years it dies. And you: baby, child, then one day a grown-up. Kitten, cherry tree, child — the same four stages.

Example 7.5 (The photograph test)

On Grandpa’s old photographs you can follow one person through every stage: baby, schoolchild, young man, father, grandfather. Same person, changing body. Photographs are little time machines for watching a life cycle.

Example 7.8 (The old apple tree)

The bent old apple tree at the end of the garden gives fewer apples each year — it is in its old age. But its apples have pips, and one pip, planted, is already a young apple tree beginning the road. When the old tree dies, apple trees will not be gone: its young carry on.

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