Summary
An increase in cell number and size that produces a larger organism.
In depth
Growth involves hyperplasia (cell number), hypertrophy (size) and accretion. It is regulated by growth hormone, IGF-1, thyroid hormone and sex steroids; growth plates in bones close after puberty.
Growth patterns differ among organs: neural tissue grows early, lymphoid tissue peaks in childhood, reproductive tissue matures at puberty. Catch-up growth follows illness. Nutrition and hormones are major determinants.
Example: IGF-1 mediates many effects of growth hormone.
Growth increases an organism's size by cell division, cell enlargement and deposition of material. Animals mostly grow by division and enlargement of cells, plants by division in meristems followed by elongation.
Growth is controlled by genes, hormones such as growth hormone, IGF-1 and thyroid hormone, nutrition and environment. Patterns can be isometric (all parts at the same rate) or allometric (different parts at different rates, as human head size relative to body). A growth curve is often S-shaped.
Example: puberty growth spurts are driven by sex hormones.
Common mistake: confusing growth with development; development involves changes in form and specialisation, not just size.
Frequently asked questions
What is Growth?
An increase in cell number and size that produces a larger organism.
Which area of biology covers Growth, and how advanced is it?
Growth is one of the 54 topics in Developmental Biology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Cloning, Ageing and Development, Embryo.
Can you give an example of Growth?
A growth curve of height is S-shaped, with infant and pubertal spurts.
What should I learn before Growth?
Growth is a Beginner topic, so no earlier topic is required. Other Beginner topics in Developmental Biology that pair well with it include Fertilisation, Zygote, Embryo.
What topics are related to Growth?
The closest topics to Growth are Cloning, Ageing and Development, Embryo, Zygote. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Growth?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Growth. To practise the whole of Developmental Biology, use the Developmental Biology quiz.
How is Growth different from Cloning?
Growth: An increase in cell number and size that produces a larger organism. Cloning: Producing a genetically identical organism or cell, as with Dolly the sheep by nuclear transfer. Read both side by side and note what each one explains.
What is a common mistake about Growth?
Confusing growth with development; development involves changes in form and specialisation, not just size.
How should I study Growth step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Cloning and explain the difference aloud. Finally, take the Developmental Biology quiz and come back to this page for any question you miss.