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 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 outside raw materials used for by an organism?
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 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?
How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R′, then the ratio R/R′ is –
(a) 1/25 (b) 1/5 (c) 5 (d) 25
The human eye can focus on objects at different distances by adjusting the focal length of the eye lens. This is due to
(a) presbyopia.
(b) accommodation.
(c) near-sightedness.
(d) far-sightedness.
What is hydrogenation? What is its industrial application?
What are the functions performed by the testis in human beings?
Which one of the following materials cannot be used to make a lens?
(a) Water (b) Glass (c) Plastic (d) Clay
Which of the following correctly describes the magnetic field near a long straight wire?
(a) The field consists of straight lines perpendicular to the wire.
(b) The field consists of straight lines parallel to the wire.
(c) The field consists of radial lines originating from the wire.
(d) The field consists of concentric circles centred on the wire.
An example of homologous organs is
(a) our arm and a dog’s fore-leg.
(b) our teeth and an elephant’s tusks.
(c) potato and runners of grass.
(d) all of the above.
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
(a) calcium
(b) carbon
(c) silicon
(d) iron.
What are the different methods of contraception?