What is the role of saliva in the digestion of food?
Human digestive system includes various glands and salivary gland is one of them. Saliva is secreted by salivary gland located under the tongue which helps in the digestion of food and it contains water, salts, mucin and some enzymes salivary amylase or ptyalin. PH is neutral i.e, 6.7. about 1.5 litres saliva and mucus are secreted in every 24 hours in the buccal cavity. Salivation activation depends on the smell, idea and imagination of food.
Role of saliva:
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
How is the amount of urine produced regulated?
What are the different ways in which glucose is oxidised to provide energy in various organisms?
What criteria do we use to decide whether something is alive?
The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm. (c) chloroplast.
(b) mitochondria. (d) nucleus.
What are the differences between autotrophic nutrition and heterotrophic nutrition?
What are the components of the transport system in highly organised plants?
What would be the consequences of a deficiency of haemoglobin in our bodies?
What are outside raw materials used for by an organism?
What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
What is a good source of energy?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the difference between a reflex action and walking?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
Why does dry HCl gas not change the colour of the dry litmus paper?
Do basic solutions also have H+(aq) ions? If yes, then why are these basic?
Plaster of Paris should be stored in a moisture-proof container. Explain why?
While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?
No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be
(a) only plane.
(b) only concave.
(c) only convex.
(d) either plane or convex.
Compare and contrast the arrangement of elements in Mendeléev’s Periodic Table and the Modern Periodic Table.
The anther contains
(a) sepals.
(b) ovules.
(c) pistil.
(d) pollen grains.
Draw the structure for the following compounds.
(i) Ethanoic acid (ii) Bromopentane*
(iii) Butanone (iv) Hexanal.
*Are structural isomers possible for bromopentane?
Why is sodium kept immersed in kerosene oil?
You have two solutions, A and B. The pH of solution A is 6 and pH of solution B is 8. Which solution has more hydrogen ion concentration? Which of this is acidic and which one is basic?