What is the role of the acid in our stomach?
Hydrochloric acid is present in the gastric juice secreted by the gastric gland which helps in the breakdown of the food. When the food enters in the stomach, contraction and expansion of muscles of the wall of stomach brings churning movement which leads to the mixing of the food with the help of gastric juice (mixture of hydrochloric acid, pepsinogen, prorennin, lipase and mucus) secreted by gastric glands.
Hydrochloric acid helps in to disinfect the food by killing of bacteria, stops the action of the salivary amylase. It converts the pepsinogen to pepsin in the active form and convert prorenin with the addition of HCL gives the end product Rennin. It produces appropriate, i.e, low hydrogen ion concentration for about 1- 2 acidic pH for the protein digestion and the food digestion. It moistens the food and helps in the breakdown of the larger food molecules; also denatures the many food proteins which increases the exposure of the peptide bond to the pepsin.
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?
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?
What is the difference between a reflex action and walking?
Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
The change in focal length of an eye lens is caused by the action of the
(a) pupil. (b) retina.
(c) ciliary muscles. (d) iris.
Explain the formation of scum when hard water is treated with soap.
What are the disadvantages of fossil fuels?
Besides gallium, which other elements have since been discovered that were left by Mendeléev in his Periodic Table? (any two)
Why should a magnesium ribbon be cleared before burning in air?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10–8 Ω m. What will be the length of this wire to make its resistance 10 Ω? How much does the resistance change if the diameter is doubled?