Transcript Importance Of Plants

Importance Of Plants
D. Crowley, 2008
Importance Of Plants
To know why plants are useful to animals
Plants Crosswords

Complete the plants crossword
Plants Crosswords
Atmosphere
How do plants produce their own food?

Photosynthesis
light + chlorophyll
carbon dioxide + water → glucose + oxygen
Why is oxygen important?
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Respiration
oxygen + glucose → carbon dioxide + water
Respiration

Respiration is the release of energy (from glucose) in our cells
(requires oxygen)
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Animals and plants respire!
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In the light plants respire, but produce the oxygen for this to
occur via photosynthesis

In the dark plants still respire, however they do not produce any
oxygen (as no photosynthesis takes place) meaning they also
need to use the atmospheric oxygen
Food

As well as providing the oxygen needed for respiration by animal
and plant cells, plants also store the food they make from
photosynthesis as starch

Plants provide food in many different forms, including from the:  Leaf
 Stem
 Roots
 Seeds
 Fruit
Food

Your task is to look at a variety of foods from a plant, and decide
from which part of the plant it is – record your results
Starch Test
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As a class we are going to test each of the parts of the plant for
the presence of starch
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Iodine goes from orange / brown → dark blue / black if starch is
present
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Boil the plant tissue, and place in some ethanol (leave for 5
minutes, then rinse off the ethanol). Take a dropping pipette and
add some iodine to the part of the plant, noting what happens
Starch Test
Food Store

Glucose is turned into starch, and is stored in roots, stems
and leaves
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Why is this done?!

It is stored in these areas so the plant cells can still respire,
even if photosynthesis does not occur (starch is insoluble)

Some glucose is turned into lipids for storing in seeds

Some plants also store a large amount of starch in their
roots over winter, allowing new plants to grow the following
spring (e.g. potato and carrot plants)

Fruits also contain glucose to encourage animals to eat the
fruit (helping disperse the seeds)
Benefit

Plants store their food not for the benefit of animals, but for the
benefit of themselves
Food is stored: 
So it can be used when photosynthesis cannot take place
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As an energy store for harsher times

As an energy store for the seeds when they germinate
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As a bribe to attract animals (helping with seed dispersal)
Plants & Photosynthesis
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Using the sheet, cut out the
key points and stick them
in your book, making a
revision page about
photosynthesis