Any visible movement such as walking, breathing, or growing is generally used to decide whether something is alive or not. However, a living organism can also have movements, which are not visible to the naked eye. Therefore, the presence of life processes is a fundamental criterion that can be used to decide whether something is alive or not.
Life processes such as nutrition, respiration, transportation, excretion, etc. are essential for maintaining life.
The xylem in plants are responsible for
(a) transport of water.
(b) transport of food.
(c) transport of amino acids.
(d) transport of oxygen.
Ans: (a) transport of water.
The autotrophic mode of nutrition requires
(a) carbon dioxide and water.
(d) all of the above.
Ans: (d) all of the above.
Blood flow through vein does not exert pressure on the walls of veins. Due to this, they do not need thick walls. Hence, veins have thin walls as compared to arteries.
Alveoli provide a surface for the exchange of gases. An extensive network of blood vessels is present in the wall of the alveoli. By lifting our ribs and flatten the diaphragm, the chest cavity becomes spacious. Air is sucked into the lungs and alveoli. The oxygen from the breath, diffuses into the blood and CO2 from the blood brought from the body, diffuses out into the air.