Life Cycles
Organisms pass through stages of growth and reproduction.
About this topic
A life cycle shows the stages an organism passes through from birth to reproduction. In complete metamorphosis, insects such as butterflies pass through egg, larva, pupa and adult; in incomplete metamorphosis (grasshopper) the nymph resembles a small adult. Amphibians change from tadpole to adult.
Life cycles differ widely. Flowering plants alternate between growth, flowering, pollination, fertilisation, seed formation and germination. Mammals have direct development, with young resembling small adults. Many parasites, such as tapeworms and malaria protists, need two or more hosts to complete their cycle.
In a butterfly, the egg hatches into a caterpillar, which eats ravenously and grows; it then forms a pupa or chrysalis, within which its body is rebuilt, and finally an adult emerges to reproduce. Larvae and adults often eat different foods, reducing competition within the species. Annual plants complete their cycle in one year, biennials in two, and perennials live many years.
Knowing life cycles helps control pests and disease, for instance by targeting mosquito larvae in water. A frequent mistake is calling the pupa a resting stage; it is a time of dramatic change inside. Also, do not confuse life cycle with food chain.
Key ideas
- Butterfly: egg, larva, pupa, adult
- Complete vs incomplete metamorphosis
- Plants alternate generations
Quick check
Use cases: where Life Cycles helps
- Homework: review the key idea behind Life Cycles before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Life Cycles without notes.
- Visual learning: play with the interactive lab to see how Life Cycles changes when you adjust its inputs.
- Teaching a friend: explain Life Cycles in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is Life Cycles?
Organisms pass through stages of growth and reproduction.
What will I learn in Life Cycles?
Butterfly: egg, larva, pupa, adult. Complete vs incomplete metamorphosis. Plants alternate generations.
Is Life Cycles part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Life Cycles lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Life Cycles?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.