Growth, differentiation and stem cells — Edexcel GCSE Biology
How animals and plants grow, why cells differentiate, using percentile charts, and the types and medical uses of stem cells.
Revision notes
5 short notes, in the order of the specification. Each one in short:
Growth is an increase in the size or mass of an organism. Animals grow by cell division and differentiation. Plants grow by cell division, elongation and differentiation. In elongation, plant cells made by mitosis get longer, mostly by taking in water, which is what makes plants grow taller and roots grow longer.
Differentiation is the process by which a cell becomes specialised for a particular job by gaining the sub-cellular structures it needs. For example, a nerve cell has a long axon. Differentiation is important because a multicellular organism needs many different cell types, which form tissues and organs, so that each job is carried out efficiently.
A percentile chart is used to monitor the growth of a baby or child by comparing their measurements, such as mass, with those of many children of the same age and sex. On the 50th percentile, half of children have a lower value and half a higher value. A child who moves across to a different curve may need investigating.
A stem cell is an undifferentiated cell that can divide to make more cells and differentiate into specialised cells. Embryonic stem cells can become any type of cell, while adult stem cells, such as those in bone marrow, can only become a limited range. In plants, meristems at root and shoot tips can produce any type of plant cell.
Stem cells could be used in medicine to replace damaged or diseased cells, for example to treat diabetes or paralysis, or to grow replacement tissues. The risks are that stem cells may divide out of control and form a tumour, viruses in donated cells could infect the patient, and the patient's immune system may reject the cells.
Exam questions
7 exam-style questions (20 marks), each with its mark scheme.
Answer the questionsFlashcards
15 cards: flip them, mark what you knew, and practise the rest.
Practise the cardsMind map
The whole of cells and control on one page, so you can see where this subtopic fits.
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Quick check questions
Which process in plant growth does not happen in animals?
Show answer
Elongation (cells getting longer).
What does the 50th percentile mean?
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50% of children have a lower value and 50% have a higher value.
What is a stem cell?
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An undifferentiated cell that can divide and can differentiate into specialised cells.
What is the function of a meristem?
Show answer
Its cells divide and can differentiate into any type of plant cell, so the plant can keep growing throughout its life.
Give one risk of using stem cells in medicine.
Show answer
Any one of: tumour formation, viral infection from donor cells, immune rejection, ethical or religious objections.
Frequently asked questions
Why are stem cells useful in medicine?
Stem cells are useful in medicine because they are undifferentiated, so they could divide and differentiate to replace damaged or diseased cells. Possible uses include treating diabetes and paralysis and growing replacement tissues. The risks are that they may form tumours, pass on viruses from donated cells or be rejected by the immune system.
What is the difference between embryonic and adult stem cells?
Embryonic stem cells, found in early embryos, can differentiate into any type of cell. Adult stem cells, found in some tissues such as bone marrow, can only differentiate into a limited range of cell types. Adult stem cells replace cells that are damaged or worn out, for example bone marrow makes new blood cells.
How do plants grow differently from animals?
Plants grow by cell division, elongation and differentiation, while animals grow only by cell division and differentiation. Elongation is when plant cells made by mitosis get longer, mostly by taking in water. This makes plants grow taller and roots grow longer. Meristems also let plants keep growing throughout their life.
Why is cell differentiation important?
Cell differentiation is important because a multicellular organism needs many different specialised cell types to do different jobs. As a cell differentiates, it gains the sub-cellular structures it needs, such as the long axon of a nerve cell. Specialised cells form tissues, which make up organs, so each job is done efficiently.
How do you read a percentile chart?
A percentile chart shows curves for a measurement, such as mass, from many children of the same age and sex. A child on the 25th percentile has a value higher than 25% of children and lower than 75% of children. Plotting measurements over time shows whether the child follows one curve or moves across to another.
Written and checked against the Edexcel GCSE Biology (1BI0) specification · Updated October 2026