Download Respiration - King`s General Science

Introduction to Respiration
IGCSE Biology
How is digested food used by the
body?
The body needs a constant supply of energy which comes from
digested food.
Glucose, from digested carbohydrates, is an important substance that contains
stored chemical energy. This is released when it reacts with oxygen in cells.
The energy is used in many ways, such as for:
 enabling muscles to contract
 keeping warm in mammals and birds
 building new molecules, cells and tissues.
Some examples of the use
of energy in organisms
muscle
contraction
Respiration
supplies
the energy for
germination
chemical changes in cells
cell division
Energy use in muscle contraction
shoulder blade
The blood stream brings food
and oxygen to the muscle
cells. Respiration occurs in
the cells and releases energy
which……
upper arm
bone
lower arm bones
…….makes the muscle contract
and pull the lower
arm up
food store
embryo
shoot
shoot
embryo
root
(a)
(b)
(a) is a section cut through the
length of a maize seedling. Areas
of rapid respiration are stained pink.
(b) and (c) are drawings of the seed
and the seedling that grows from it.
Can you suggest reasons why
respiration should be so rapid in the
stained regions?
(c)
root
root
What is respiration?
Respiration is the process that the body uses to release energy from digested food
(glucose).
glucose
from the
digestive system
+
oxygen
from the
respiratory
system

carbon
dioxide
waste product
(exhaled)
+
water
(
+ energy)
waste product
(exhaled)
This type of respiration is called aerobic respiration because energy is released in the
presence of oxygen.
How do the glucose and oxygen needed for aerobic respiration get to the all the
body’s cells?
What do you notice about these two
equations?
Plants respire too!
glucose + oxygen
Reactants
Water + carbon dioxide (+ energy)
Products
• Aerobic respiration (uses oxygen)
• Happens all the time
• Overall plants produce more oxygen by photosynthesis than they use by
respiration
YouTube - Plant Physiology: Respiration (Britannica.com)
How can we prove respiration is taking
place?
• Limewater
-tests for the presence of carbon
dioxide
-how does it change when it is present?
• Cobalt chloride paper
-tests for the presence of water
-how does it change when water is
present?