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Respiration of plant seeds
Science Background
BIOLOGY
Plant
Physiology
Cellular respiration
Plants as animals need energy to live. When plants use sugars stored in their leaves or
seeds they undergo cellular respiration.
The cellular respiration harvests energy stored in a glucose molecule by oxidizing the
sugar and reducing O2 to H2O. Cellular respiration releases chemical energy.
C6H12O6 + 6H20 + 6 O2  6 CO2 + 12 H20
Sugar + Oxygen  Carbon dioxide + Water + Energy (ATP)
In this way cellular respiration converts the energy stored in food into a form of energy that
plant cells use to carry out their life processes. During the respiration process, the plant
uses oxygen and release carbon dioxide and water.
Germinating seeds
After a seed drops from a plant it usually goes into a resting period called dormancy.
During dormancy the seed waits until conditions are right to germinate. Some seeds have
to wait for years before they are able to germinate. During this time, seeds cannot
photosynthesize as they lack leaves! Therefore, a seed needs to use stored energy
reserves and undergo cellular respiration in order to stay alive or grow.
Have you ever wondered why seeds and nuts have so many calories? The seed will use
those calories to survive during dormancy and to begin germinating.
Germination of a seed starts with water uptake by the seed. This is an essential step
for the seed to germinate. The total water take up is about 2-3 times the weight of the
seed. Whether or not a viable seed will germinate depends on a number of factors.
The chemical environment of the seed must be right. Water must be available, oxygen
has to be present since the seed must respire and no dangerous chemicals should be
present. The physical environment must also be favorable. The temperature must be
suitable as well as the light quality and quantity. A person may wonder why seeds are
often buried underground. The reason is that this helps guarantee the seeds receive
the correct amount of light for germination. Full sunlight can often prevent a seed from
germinating.
Respiration of germinating seeds
As the seeds respire, they take up oxygen and respiring carbon dioxide. If you place
germinating seeds in a closed system, it is possible to measure oxygen consumption
and carbon dioxide production. The oxygen concentration level can be monitored by
the O2 gas sensor and the carbon dioxide concentration level can be monitored by the
Respiration of plant seeds – Science Background
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CO2 gas sensor. Using both oxygen and carbon dioxide concentration levels,
respiration of plant seeds can be determined.
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