How is the small intestine designed to absorb digested food?
Small intestine is a narrow tube, 6m long in the adults, is the longest part of the alimentary canal and comprises of three parts duodenum, jejunum and ileum. Duodenum is C- shaped, 25 cm long and extended from the stomach. It receives the hepatopancreatic duct formed by the combination of bile duct and pancreatic duct. Jejunum is the middle portion of the small intestine extends from duodenum and 2.4 cm long. Ileum forms the lower part of the small intestine and 3.6 m long and opens up into the large intestine.
The mucosa in the small intestinal part is raised into millions of tiny microscopic finger - like projection called villi. Villi contains blood vessels and the lacteals, they receives the product of digestion after the absorption. The free surface of the cells which covers the villi bear numerous microvilli. They both villi and microvilli increases the absorptive surface for the digestion of food.
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
How is the amount of urine produced regulated?
What criteria do we use to decide whether something is alive?
What are the different ways in which glucose is oxidised to provide energy in various organisms?
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 outside raw materials used for by an organism?
What would be the consequences of a deficiency of haemoglobin in our bodies?
What are the components of the transport system in highly organised plants?
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?
Compare and contrast bio-mass and hydro electricity as sources of energy.
Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H2SO4.
State Fleming’s left-hand rule.
Why do you think that there should be equitable distribution of resources? What forces would be working against an equitable distribution of our resources?
Identify the substances that are oxidised and the substance that are reduced in the following reactions.
(i) 4Na(s) + O2(g) → 2Na2O(s)
(ii) CuO(s) + H2(g) → Cu(s) + H2O(l)
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?
Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V.
What is ozone and how does it affect any ecosystem?
What are the functions performed by the testis in human beings?
What is a neutralisation reaction? Give two examples.