Meristem

In the syllabus and the exam

Meristem is introduced in the topic of plant tissue organisation and growth as the specialised tissue responsible for producing new plant cells throughout a plant's life, unlike most animal growth which is limited to certain developmental stages. Candidates are expected to know that meristematic cells are small, thin-walled, densely cytoplasmic and capable of continuous mitotic division, and that they are located mainly at root tips and shoot tips (apical meristem), enabling plants to keep growing in length for as long as they live. Exam questions often ask candidates to explain why meristematic tissue, rather than mature tissue, is found specifically at growing points, with the expected link being that only actively dividing cells can add new cells for elongation. A frequently tested follow-on idea is that the new cells produced by a meristem later undergo cell differentiation to become specialised tissues such as xylem or phloem, so meristem questions are often paired with cell differentiation in the same structured item. A common misconception is describing meristem cells as already specialised or as dividing by meiosis; meristematic division is strictly mitotic, since the goal is growth through identical new cells, not the production of gametes. A further point sometimes tested is the difference between apical meristem, found at growing tips and responsible for increasing a plant's length, and lateral meristem, found around the stem and root and responsible for increasing girth, so candidates should not assume all meristematic tissue behaves identically. This is also why gardeners can propagate some plants from small cuttings taken near a growing tip, since the meristematic tissue there retains the capacity to divide and organise into a complete new root and shoot system under the right conditions.

Example

Identifying regions of growth, a candidate writes: 'The apical meristem at the root tip and shoot tip consists of small, thin-walled cells that divide continuously by mitosis, producing new cells for the plant to grow taller and its roots to grow deeper.'

Related terms

MitosisCell differentiationXylem

Source:SRC-DSKP-EN