(a)Describe briefly the process involved in the conversion of food to chyme in the stomach...
(a)Describebriefly the process involved in the conversion of food to chyme in the stomach of a mammal.
(b)Complete the table below by statingone enzyme, digestive juice, food acted upon and
end-product in the corresponding spaces.
| One Enzyme | One juice | One food acted upon | One end-product |
Pepsin (i) ----------- Lipase | (ii)--------------- (iii)--------------- (iv)--------------- | (v) -------------------- (vi) ------------------- (vii) ------------------- | (viii)------------------- Maltose (ix)----------------------- |
(c) Describe an experiment to show that carbon dioxide is necessary for photosynthesis.
Explanation
(a) Process of conversion of food to chyme in the stomach of a mammal
The stomach is a large thick-walled muscular sac; made of three layers of muscles; that contracts in different directions when food enters into it; bringing about a twisting/squeezing/churning effect; enabling food to mix with digestive juice; and HCL; this movement then converts food to the semi-liquid called chyme.
(b)Table
| Enzyme | Juice | Food acted upon | end product |
Pepsin | ii. Gastric | v. Protein | viii. Peptone/ polypeptide |
| iii. Saliva/pancreatic juice | vi. Cooked starch/carbohydrate | Maltose |
Lipase | iv. Intestinal/Pancreatic juice | vii. Fats and Oil | ix. Fatty acid and glycerol |
(c) Experiment to show that carbon dioxide is necessary for photosynthesis
Two potted plants are de-starched by placing them in a dark cupboard for 24hours;
a leaf each from both plants are then tested for starch to ensure they have no starch/have been de-starched; the potted plants are placed on a board each; a beaker containing caustic soda is placed beside plant A; to absorb carbon dioxide; while a beaker containing water is placed beside plant B as control; they are both covered with bell jars labelled A and B respectively; the rim/edge is smeared with vaseline/petroleum jelly to make it air tight; the setup is exposed to sunlight/light for 4-6 hours; a leaf each from both plants are plucked and tested for starch.
Observation:It is observed that leaf from plant A is negative/does not contain starch/remains brown in colour while leaf from plant B is positive/contains starch/turns blue - black.
Conclusion: Carbon dioxide is necessary for photosynthesis.
OR
De-starch a well-watered potted plant by putting it in darkness for 48 hours; insert a leaf into a flask containing water which serves as a control experiment; and another leaf into another flask containing KOH/ potassium hydroxide/ caustic potash; ensure both flasks are air tight by smearing the split corks with Vaseline; leave the potted plant in a well-lit place for