To show experimentally that carbon dioxide is given out during respiration Video Lecture - Class 10

role of carbon dioxide during
respiration
respiration is the process through which
energy stored in organic molecules is
released for growth and other life
processes during respiration organic
food breaks down into simpler substances
and liberates carbon dioxide and energy
respiration that requires oxygen is
called aerobic respiration aerobic
respiration takes place inside the
mitochondria the respiration that does
not require molecular oxygen is called
anaerobic respiration this process
occurs in the cytoplasm of the cells in
this experiment we shall look at the
release of carbon dioxide gas during
aerobic respiration by plants and human
beings respiration in plants to do the
experiment we require a test tube a
beaker containing distilled water
germinating seeds of bean a cork with a
hole a conical flask measuring cylinder
freshly prepared potassium hydroxide
solution petroleum jelly thread and the
glass delivery tube with two bends at
right angles procedure
using a spatula place about 30
germinating bean seeds in a conical
flask for 4 ml of potassium hydroxide
solution into a measuring cylinder
transfer the potassium hydroxide
solution from the measuring cylinder
into a small test tube tie a cotton
thread around the neck of the test tube
suspend the test tube in the conical
flask above the germinating seeds close
the mouth of the conical flask with a
cork insert one end of the delivery tube
into the conical flask through the cork
and dip the other in a beaker containing
water observe the position of the water
level in the delivery tube this is the
initial reading of the water level in
the delivery tube use your finger to
take some petroleum jelly then apply the
petroleum jelly on the cork to make the
apparatus airtight keep the apparatus
undisturbed for 2 hours after 2 hours
you will see that the level of water has
risen in the delivery tube at the end
dipped in the beaker of water note this
level as the final level the germinating
seeds in the conical flask release
carbon dioxide during respiration which
is absorbed by the potassium hydroxide
solution kept in the small test tube
this creates a partial vacuum in the
flask and it forces the water up the
delivery tube thus it proves the
germinating seeds produce carbon dioxide
during respiration precautions ensure
all connections are airtight the freshly
prepared concentrated solution of
potassium hydroxide solution should not
be kept for later use respiration in
humans to do the experiment we require
freshly prepared lime water a cork with
two holes two glass tubes bent at right
angles and a boiling tube procedure
poor freshly-prepared line water into
the boiling tube so that it is 3/4 full
take a cork with two holes and fix it
into the mouth of the boiling tube
insert the glass tubes let us name them
a and B into the boiling tube through
the cork so that the end of glass tube a
dips in the lime water breathe out air
with full force by putting your mouth at
the end of tube a continue doing this
vigorously for at least 1 minute
the bubbles of the air breathed out
gradually turn the lime water milky the
only gas that can turn lime water milky
is carbon dioxide when carbon dioxide
reacts with lime water it forms calcium
carbonate thus giving lime water the
milky appearance so we can conclude that
both plants and human beings produce
carbon dioxide during respiration
precautions
use freshly-prepared limewater breathe
out air for at least one minute