Form 5 · Paper 2 essay guide

Organisation of Plant Tissues and Growth, Paper 2 essay guide

How Organisation of Plant Tissues and Growth appears in Paper 2 essays: themes, a planning grid, a model answer structure and the keyword list.

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Essay themes this chapter supports

Classifying plant tissues and describing the simple permanent tissues: State the two broad groups: meristematic and permanent tissue. → Divide permanent tissue into simple and complex. → Describe parenchyma, its wall and its functions. → Describe collenchyma and its flexible support of young parts. → Describe sclerenchyma and its rigid support, and contrast it with collenchyma.
Comparing xylem and phloem in structure and function: State that xylem and phloem form the vascular system. → Describe what xylem transports and that its cells are dead and lignified. → Describe what phloem transports and that its sieve tubes are living. → Explain the role of companion cells in phloem. → Summarise the key difference: dead conducting cells versus living ones.
Explaining growth at the root tip and the difference between primary and secondary growth: Name the root cap and its protective role. → Describe the zones of cell division, elongation and differentiation in order. → Define primary growth at the apical meristems. → Define secondary growth at the vascular cambium. → Contrast increase in length with increase in girth.
Interpreting growth curves and explaining tropisms: Describe the sigmoid absolute growth curve and its three phases. → Explain why dry mass is the more reliable measure. → Explain what limits growth in the stationary phase. → Explain phototropism in terms of uneven auxin distribution. → Explain gravitropism in a root and why the same hormone bends root and shoot differently.

How to structure your essay

Open with one or two sentences that define the topic and set the scope.
Devote one paragraph to each key concept, in a logical order.
Use precise biological terms and, where relevant, a labelled diagram.
Give an example or state where the process happens in the body or plant.
Close by linking the ideas back to the question.

Planning grid

Question	Answer
Introduction	State what the question asks and define its key term, such as 'tissue', 'xylem' or 'growth curve', in one sentence.
Point 1	Name the tissues, zones or phases involved and state clearly what each one is.
Point 2	Develop the description or comparison the question asks for, such as xylem against phloem or primary against secondary growth.
Point 3	Support the answer with the correct detail or a named structure, such as a lignified vessel, the vascular cambium or the exponential phase.
Conclusion	Draw the ideas together, linking the tissue or process to its role in transport, support or growth.

Key terms to include

meristematic tissue
permanent tissue
parenchyma
collenchyma
sclerenchyma
lignified
xylem
phloem
vessel
sieve tube
companion cell
translocation
apical meristem
root cap
zone of cell division
zone of elongation
zone of differentiation
primary growth
secondary growth
vascular cambium
sigmoid curve
lag phase
exponential phase
stationary phase
auxin
phototropism
gravitropism
dry mass

A model essay outline

Plant tissues, Meristematic tissue divides to make new cells; permanent tissues include epidermis, parenchyma, xylem and phloem.
Meristematic tissue, Found at root and shoot tips (apical) and in the cambium; its cells divide by mitosis to make the plant grow.
Xylem and phloem, Xylem transports water and mineral salts; phloem transports the products of photosynthesis.
Primary growth, Growth in length from the apical meristems at the tips of roots and shoots.
Zones of growth, Behind a root tip are the zones of cell division, cell elongation and cell differentiation.

Frequently asked questions

What is the difference between meristematic and permanent tissue?

Meristematic tissue is made of small, thin-walled cells that keep dividing by mitosis to produce new cells, and it is found at the tips of roots and shoots and in the cambium. Permanent tissue is made of cells that have stopped dividing and become specialised for a job, such as the epidermis for protection or xylem for transport. Meristematic tissue makes the plant grow; permanent tissue carries out functions.

What are the zones of growth in a root?

Just behind the root tip there are three zones. In the zone of cell division, meristematic cells divide to make new cells. In the zone of cell elongation, the new cells grow longer, pushing the root through the soil. In the zone of cell differentiation, the cells become specialised, such as into root hair cells or xylem.

What do xylem and phloem transport?

Xylem transports water and dissolved mineral salts from the roots upward to the leaves. Phloem transports the sugars made in photosynthesis from the leaves to other parts of the plant that need energy or storage. The two tissues together form the plant's vascular system.