How do organisms grow, and what are stem cells used for?
Describe growth in organisms and the use of percentile charts, explain the importance of cell differentiation, describe the function of embryonic stem cells, adult stem cells and meristems, and discuss the benefits and risks of using stem cells in medicine.
A focused answer to Edexcel GCSE Biology 2.5 to 2.9, covering growth by cell division, differentiation and elongation, percentile charts, cell differentiation, embryonic and adult stem cells, meristems, and the benefits and risks of stem cells.
Reviewed by: AI editorial process; not yet individually human-reviewed
Have a quick question? Jump to the Q&A page
Jump to a section
What this dot point is asking
Edexcel statements 2.5 to 2.9 want you to describe how organisms grow, interpret percentile charts, explain why cell differentiation matters, describe the role of embryonic stem cells, adult stem cells and plant meristems, and discuss the benefits and risks of using stem cells in medicine.
How organisms grow
Percentile charts
Doctors use percentile charts to monitor a child's growth. A child's mass, length or head size is plotted against age and compared with curves showing how a large population grows. The 50th percentile is the median: half of children of that age are above it and half below. What matters most is the trend over time: a child who follows the same percentile is growing steadily, but one who suddenly crosses several percentile lines may need investigation. This is a data-interpretation skill, so practise reading values off the curves.
Cell differentiation
In animals, most cells differentiate at an early stage and then mainly divide only to repair and replace. In plants, many cells keep the ability to differentiate throughout life, which is why a cutting can grow into a whole new plant.
Stem cells
Benefits and risks of stem cells
Stem cells could be grown into specialised cells to replace damaged ones: insulin-producing cells for type 1 diabetes, nerve cells for paralysis, or whole tissues for transplant. The benefits must be weighed against the risks: transplanted cells may be rejected by the immune system, may carry a viral infection, or (rarely) could divide uncontrollably. There are also ethical objections to using embryos, since each embryo is a potential life. Edexcel wants a balanced "discuss", giving points on both sides.
Try this
Q1. State one way growth in plants differs from growth in animals. [1 mark]
- Cue. Plants also grow by cell elongation and keep dividing at meristems throughout life, whereas animals mainly stop growing as adults.
Q2. Give one benefit and one risk of using stem cells to treat disease. [2 marks]
- Cue. Benefit: replace damaged cells to treat conditions such as diabetes or paralysis. Risk: rejection, transfer of infection, or ethical objections to embryonic sources.
Exam-style practice questions
Practice questions written in the style of Pearson Edexcel exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Edexcel 20184 marksDescribe the function of stem cells in animals and explain why they could be useful in medicine.Show worked answer →
A 4-mark question rewards the definition plus medical uses.
Stem cells are undifferentiated cells that can keep dividing and can differentiate into specialised cells. Embryonic stem cells can become any cell type; adult stem cells, such as those in bone marrow, form a limited range.
They could be useful in medicine because they could be grown into specialised cells to replace damaged ones, for example to treat type 1 diabetes (making insulin-producing cells) or paralysis (making nerve cells), or to grow replacement tissues for transplants.
Markers reward the idea of undifferentiated cells that differentiate, plus at least one realistic medical use. Saying stem cells cure everything, without a mechanism, scores little.
Edexcel 20212 marksA doctor plots a baby's mass on a percentile chart. The baby is on the 50th percentile. Explain what this tells the doctor.Show worked answer →
A 2-mark explain question rewards reading the chart correctly.
Being on the 50th percentile means the baby's mass is the median: 50% of babies of that age are lighter and 50% are heavier, so the baby is growing at an average rate for its age.
Percentile charts let doctors monitor growth over time; a baby that suddenly crosses several percentile lines downwards may have a health problem. Markers reward the correct meaning of 50th percentile (average, half above and half below). Saying the baby is exactly average weight for all ages misreads the chart.
Related dot points
- Describe mitosis as part of the cell cycle, including the stages and the production of two genetically identical daughter cells, its importance in growth, repair and asexual reproduction, and cancer as uncontrolled cell division.
A focused answer to Edexcel GCSE Biology 2.1 to 2.4, covering the cell cycle and the stages of mitosis, the production of two genetically identical daughter cells, its role in growth, repair and asexual reproduction, and cancer.
- Explain how the sub-cellular structures of eukaryotic and prokaryotic cells are related to their functions, including the nucleus, cell membrane, cytoplasm, mitochondria, ribosomes, chloroplasts, cell wall, vacuole, plasmids and flagella.
A focused answer to Edexcel GCSE Biology 1.1, covering eukaryotic and prokaryotic cells, the sub-cellular structures of animal, plant and bacterial cells, and how each structure is related to its function.
- Describe how specialised cells are adapted to their function, explain how microscope technology has improved our understanding of cells, and use the magnification equation with the correct units.
A focused answer to Edexcel GCSE Biology 1.2 to 1.6, covering how specialised cells are adapted to their function, how light and electron microscopes differ, and the magnification equation with unit conversion.
- Explain the structure and function of sensory, relay and motor neurones and synapses in the transmission of electrical impulses, and the structure and function of a reflex arc.
A focused answer to Edexcel GCSE Biology 2.13 to 2.14, covering sensory, relay and motor neurones, how synapses transmit signals, and the structure and function of a reflex arc.
Sources & how we know this
- Pearson Edexcel GCSE (9-1) Biology (1BI0) specification — Pearson (2016)