Describe the function of embryonic stem cells, stem cells in animals and…

The idea

Stem cells are unspecialised cells that can divide repeatedly and, in the right conditions, differentiate into specialised cell types. Embryonic stem cells come from an early embryo; they are pluripotent, meaning they can develop into almost any cell type of the body, which is why they can replace damaged tissues in principle. Stem cells in animals (adult stem cells) are found in tissues such as bone marrow; they are more limited, typically replacing the cell types of the tissue they sit in, for example blood cells. Meristems are the plant equivalent: regions of unspecialised dividing cells at root and shoot tips that supply new cells for growth, allowing roots and shoots to lengthen and new leaves and flowers to form. Match each stem-cell type to its location and its range of possible fates.

What earns the marks

• Embryonic stem cells are unspecialised cells from an early embryo that can divide and differentiate into almost any specialised cell type (pluripotent).
• Stem cells in animals (adult stem cells), such as those in bone marrow, divide to replace worn or damaged cells but are usually restricted to the cell types of their tissue.
• Meristems are regions of unspecialised, dividing cells at root and shoot tips in plants that provide cells for growth and differentiation into plant tissues.
• Stem cells share the key property of being able to divide repeatedly (self-renew) while some daughter cells differentiate into specialised cells.
• Correctly distinguishing plant meristems (growth regions) from animal stem cells (tissue repair and replacement) when selecting an option.

Common mistakes and how to put them right

• Confusing meristems with animal stem cells.

  Put it right: Meristems are plant growth regions at root and shoot tips, not animal tissue-repair cells.

• Claiming adult animal stem cells can form any cell type.

  Put it right: They are usually limited to the cell types of their own tissue, unlike pluripotent embryonic stem cells.

• Describing stem cells as already specialised.

  Put it right: Stem cells are unspecialised and become specialised through differentiation.

Exam tips

• Read the question stem to identify whether it asks about embryonic, adult animal or plant meristem cells before choosing.
• Link each option to a location (embryo, bone marrow, root/shoot tip) to eliminate wrong choices quickly.
• Remember the shared feature: ability to divide and differentiate; use it to reject options that deny this.