Biology 11–12 · Year 12

Asexual reproduction and whole-plant cloning from stem cuttings

Module 5: Heredity (Reproduction); also Module 6 (Genetic Technologies: whole organism cloning)

PracticalLow risk

The idea

A stem cutting regrows roots and becomes a genetically identical plant, which is asexual reproduction put to use as cloning.

What you need

Parent plants: busy lizzie (Impatiens) or pot geranium (Pelargonium), the species named in the source
10 cm pots with compost, 1 per cutting; rooting powder; powdered chalk as a look-alike control (the source's rooting powder B); scalpel on a white tile; clear plastic bags; water; labels; ruler

How to do it

Cut a non-flowering stem about 10 cm long; remove all but the top one or two pairs of leaves and make a clean oblique cut just below a leaf junction.
Dip the cut end in rooting powder and push it firmly into the compost; water, enclose the pot in the bag and seal.
Set up at least six cuttings per parent: three dipped in rooting powder and three in powdered chalk, or three in the bag and three uncovered.
Keep on a windowsill, watering every two or three days, for two to three weeks.
Gently lift each cutting, record whether roots have formed, measure the longest root, and compare treatments.
Compare a flower on the parent and on a rooted cutting later in the season to confirm they match.

What you should see

After two to three weeks rooted cuttings show white roots at the base, and the proportion rooted and the longest root can be compared between treatments; the source notes that rooting powder may help mainly through its fungicide rather than its hormone, which the chalk control tests. Every rooted cutting is a clone of its parent and later matches it in leaf and flower. The learner knows it worked when roots have formed on at least some cuttings, matched cuttings received each treatment, and each rooted cutting's leaves match its parent's.

What changes

What you change: rooting powder or powdered chalk, or humidity (bagged or open)
What you measure: percentage of cuttings that root, and longest root length
What you keep the same: parent plant
cutting length and leaves retained
compost and watering
light and temperature

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

Cuttings are a different kind of reproduction from cloning; a rooted cutting is a clone.
Clones are identical in every way; the genotype is identical, the phenotype still responds to the environment.
Plants need seeds to reproduce; many propagate without any.

Safety card

Low riskLearners carry it out

Hazards

Scalpel cuts
Rooting powder dust (a fungicide-containing product)
Plant sap irritation

Controls

Carry scalpels on a tile; cut away from the body
Avoid raising dust; wash hands after use

Note

Rooting powder: RiskAssess (https://www.riskassess.com.au/).

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Biology Stage 6 Syllabus (2017), current: Year 11 taught to the end of 2026 and Year 12 to Term 3 2027BIO12-12 BIO12-13 BIO11/12-4
Biology 11–12 Syllabus (2025), Year 12 focus area Biodiversity; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-12-03
Biology 11–12 Syllabus (2025), Year 12 Working scientifically; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-12WS-03
Australian Curriculum v9No Australian Curriculum v9 code is listed.

Sources

The pages the author read to write this activity.

All Concept Studio activities