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 the components of the transport system in highly organised plants?
What are outside raw materials used for by an organism?
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?
Which of the following terms does not represent electrical power in a circuit?
(a) I2R (b) IR2 (c) VI (d) V2/R
How are the modes for reproduction different in unicellular and multicellular organisms?
Find out about the traditional systems of water harvesting/management in your region.
Compare the power used in the 2 Ω resistor in each of the following circuits:
(i) a 6 V battery in series with 1 Ω and 2 Ω resistors, and (ii) a 4 V battery in parallel with 12 Ω and 2 Ω resistors.
How can three resistors of resistances 2 Ω, 3 Ω, and 6 Ω be connected to give a total resistance of (a) 4 Ω, (b) 1 Ω?
Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
We saw in this chapter that there are four main stakeholders when it comes to forests and wildlife. Which among these should have the authority to decide the management of forest produce? Why do you think so?
Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?
What is (a) the highest, (b) the lowest total resistance that can be secured by combinations of four coils of resistance 4 Ω, 8 Ω, 12 Ω, 24 Ω?
Explain the following in terms of gain or loss of oxygen with two examples each.
(a) Oxidation
(b) Reduction