How are the lungs designed in human beings to maximise the area for exchange of gases?
Lungs are the two pairs of organ lies in the thoracic cavity on the sides of the heart. The trachea divides into two tubes- major or primary bronchi. Major bronchus enters the right lung and second one enter into the left lung. Then bronchus divides into secondary bronchi further extends into three lobes of right lung and subdivides into small tertiary bronchi and finally they divided into smaller bronchioles (wall consists of epithelium). Then, these terminal bronchioles divided into alveolar ducts enters into alveolar sacs. This respiratory pathway within the lungs are known as respiratory tree.
Alveoli are pouch like structure present on the each nerve ending and possess network of blood capillaries or covers very huge amount of surface of the human body, which increases the surface area for the exchange of gases. That is how, the lungs are designed in human beings to maximise the area for exchange of gases- uptake of oxygen by blood and release of carbon dioxide by blood.
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?
What are the advantages of sexual reproduction over asexual reproduction?
Name the sodium compound which is used for softening hard water.
The radius of curvature of a spherical mirror is 20 cm. What is its focal length?
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.
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
Name two energy sources that you would consider to be renewable. Give reasons for your choices.
Explain why the planets do not twinkle.
State two ways to prevent the rusting of iron.
Why do we prefer a convex mirror as a rear-view mirror in vehicles?
(a) What property do all elements in the same column of the Periodic Table as boron have in common?
(b) What property do all elements in the same column of the Periodic Table as fluorine have in common?