JSSS Teacher material
Plant reproduction OB52-58
This section of the syllabus is ideal for active learning. It lends itself to a wide scope and variety of investigation and experiment. Students encounter plant reproduction in their everyday life –
flowers, fruits and seeds are everywhere. Prior knowledge is usually well founded – it is part of
the Primary syllabus from Infants upwards - although misconceptions can be present. There are plenty of links to other parts of the syllabus.
A lot of students have more knowledge of plant reproduction that they realise – who, for instance,
has not used a dandelion as a ‘clock’ in their youth? Most students will have grown plants from
seed in Primary school, and many will have observed reproduction of plants in the garden. Topics from the syllabus that students would need to have already studied are 1C1 Living things and 1C3 Plant structure, as well as OB51, distinuishing between asexual and sexual reproduction in plants.
The term ‘flower’ is much misused and will need to be redefined here, as will the term ‘weed’.
Many students would not consider grass to be a flowering plant. The difference between flowering and non-flowering plants will have to be explained. The connection between some everyday fruit, ‘vegetables’, and seeds may have to be pointed out.
It may be useful to plan ahead for teaching this topic, to ensure a variety of
plants are in flower. Plants with large, visible, easily dissected flowers that
bloom in spring and are usually fairly easily availably are tulips (but no sepals!) and daffodils. Comparison by observation, description and dissection of various flowers will serve the learning process, particularly for the visual and kinaesthetic learners. Investigating the life cycle by growing plants from seed is ideal. Larger seeds, e.g. butter beans and peas, are ideal for dissection to see the embryo, but can be slow to germinate. Smaller seeds,
e.g. mustard, cress, alfalfa and
quinoa grow rapidly once damp but
can be difficult to see. A happy
medium is the mung bean (the bean sprouts used in oriental cuisine!). It germinates without a medium, provided it is rinsed daily, and grows very quickly.
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JSSS Teacher material
Common growing media are damp cotton wool, newspaper, or compost. Gelatine, a cheap alternative to agar, can be ideal as it is transparent, supplies water and can have nutrients added. Investigation
This topic lends itself to a wide variety of investigation, with the simplest of material. A webcam or digital camera could be used to good effect – recording the growth of germinating seeds over
time. Some seeds grow very quickly even within a day, students cannot be there to watch – but
the camera can!
One problem encountered at this level in studying germination is the exclusion of oxygen from germinating seeds under investigation. There are two techniques that work well – covering the
seeds with oil, or leaving no room at the top of a closed jar of gelatine.
Seeds under oil Seeds on top of
on left have no gelatine have almost
access to O2no access to O2
There are many areas of the syllabus with which to link this topic.
; 1C1 Living things, particuarly OB40
; 1C3 Plant structure, particularly OB45
; 1C5 Photosynthesis, particulary OB50. The seeedlings grown in germination
investigations can be used as the starting point for photo- and geotropism investigation.
; 1C7 Ecology, particularly OB60, living things respoding to changes in the
environment, and OB62, adaptation
; 1B4 Human reproduction, particulary OB33 fertilisation
; 1A4 Aerobic respiration, particularly OB10 – germinating seeds make excellent
subjects for respiration investigation
Did you know?
; Pure saffron, the red or yellow spice used in cooking, is made from the dried stamen of
the crocus flower. It was once worth it weight in gold, and is still the most expensive
spice in the world. See http://www.thefoodclub.org.uk/saffron.htm
; The world’s smallest flower is called Wolffia, a tiny duckweed less than 1mm in
diameter. See http://waynesword.palomar.edu/plmar96.htm
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JSSS Teacher material
th Century saw tha price of one tupil rise to over thirty ; Tulip mania in Europe in the 17
times the annual wage of a skilled craftsman! See
; The world’s largest flower is Rafflesia, the three foot wide relative of the violet, growing
in the rainforest of SE Asia. See
; The Dead-Horse Arum, a plant that grows in uninhabited areas of Sardinia and Corsica,
smells and looks like a dead carcass. It attracts blowflies, and traps them inside for up to
three days to ensure pollination. See
; It has been reported that seeda of the arctic lupin that were found in a frozen lemming
burrow along with animal remains in the Yukon were at least 10,000 years old.
Amazingly, these seeds germinated within 48 hours. See
The following can be downloaded from www.juniorscience.ie or from the Round 5 CD.
; PowerPoint slides outlining flower structure and flowering cycle
; PowerPoint slides of Irish flowers from various habitats
; Web page with rollover images of flower structure
; Short movie on germinating peas
; Short movie on germinating beans on gelatine
; Students exercise on flower structure and function
; Students exercise on every day fruit
; Advice sheet on sprouting seeds
; Advice sheet on using gelatin as a growing medium
; List of plant reproduction topics covered in the primary syllabus
; A map showing links to other areas of the syllabus
Links to useful websites are to be found on www.juniorscience.ie
Local florists or supermarket will often have flowers past their sell by date, but still in good enough condition for class dissection
The most cost effective source of seeds is the supermarket or local health food store.
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