♦ Give an an activity to show that "anaerobic respiration in yeast." (with diagram)
♦ Give an activity to show that "respiration produces heat energy".
♦ give an activity to show "visual counting of pulse rate by pulse metre."
❌ wrong answer will be reported ❌
Answers
1.) "To show , Anaerobic respiration in yeast".
Take a conical flask. Add some lukewarm water in which a teaspoon of sugar has been dissolved. Add a few granules of dry yeast to the solution. (Dry yeast is available in bakery shops). Seal the conical flask with a cork, keep it at room room temperature and observed this setup after 3-4 days.
What do you observe ? Bubbles are observed in the solution that move up to the surface to form a froth. An alcoholic smell comes from the flask when you remove the cork. If a lighted matchstick is brought close to the mouth of the flask, it will get extinguished showing the gas present in the flask is carbon dioxide. The yeast spores, introduced in the flask, have multiplied and are respiring anaerobically.
(⭐ REMEMBER : The flask is sealed and oxygen content in it is limited. )
2.) "To show, Respiration produces heat energy".
Soak one gram seeds in water overnight. Allow then to germinate on moist cotton for 3-4 days. Deactivate half of the seeds by placing them in a boiling water for 2-3 minutes. Place the live germinating seed in one flask (experimental), and the 'dead seeds' in another (control) flask. Insert thermometer into each flask. Record the temperature and seal the flasks with cotton wool. Record the temperature daily over the next five days. You'll observe that there is no temperature change in the flask contain boiled, dead seeds. However, in the other flask, there is a steady rise in temperature each day.
We, thus, find that only the living, and respiring, seeds cause a rise in temperature. We can, therefore, conclude that respiration produces heat.
3.) "To show, Visual counting of pulse by 'pulse metre'."
You'll need : A stopwatch, a drinking straw, modelling clay / some plastic putty.
Producer :
Hold the inside of your left wrist towards you. Place the index and middle finger of your right hand on the inner side of your left wrist (on the thumb side). Feel the pulse. Now, place a small piece of putty / modelling clay, where you feel the pulse. Press a straw, into the putty so that it sticks the upper right from your wrist. Lay the back of your left hand on the table and observe.
Every time the pulse passes, the straw Rock slightly. Count the number of times the straw moves in one minute. This is your pulse rate.
