Describe double circulation of blood in human beings. Why is it necessary?
Mammals like human beings, monkeys etc. have a double circulatory system and they include four chambered hearts (two auricles and two ventricles). Heart’s internal structure consists of auricles, ventricles, blood vessels, apertures and valves (contains various parts). As the blood passes through the heart twice during one cycle, this is known as double circulation of blood. Auricles act as the collecting chamber for the blood returning to the heart. They have to force the blood into the ventricles because of the thin wall of auricles; and ventricles act as the distributing chambers of the blood reaching the atria. Process of double circulation involves two parts – pulmonary and systemic circulation.
In pulmonary circulation, the exchange of blood takes place between heart and lungs. The deoxygenated blood from the right ventricle is pumped into the lungs through the pulmonary artery and from lungs oxygenated blood goes to the left auricle through the pulmonary vein; and from the left auricle the blood is pumped into the left ventricle.
In systemic circulation, the exchange of blood takes place between heart and body. The oxygenated blood from left ventricle is pumped into the aorta for further transportation of blood in the body and the deoxygenated blood from the body enters the right auricle through vena cava; and from right auricle the blood is pumped into the right ventricle of the heart by the body tissues.
Both pulmonary circulation and systemic circulation take place simultaneously.
This double circulation is necessary for the regulation and the maintenance of the body temperature.
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 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?
What is the role of decomposers in the ecosystem?
What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Which of the following constitute a food-chain?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
Why does the sky appear dark instead of blue to an astronaut?
Give an example of characteristics being used to determine how close two species are in evolutionary terms.
A concave mirror produces three times magnified (enlarged) real image of an object placed at 10 cm in front of it. Where is the image located?
List the properties of magnetic field lines.
Why does a compass needle get deflected when brought near a bar magnet?
Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?
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?