The actual sites of gas exchange within the lungs are the

Alveoli

Explanation:

Gaseous exchange takes place in the alveoli of the lung.

As deoxygenated blood travels through the alveoli, excretory product in the form of carbon dioxide diffuses out through the capillaries and oxygen diffuses in the opposite direction. The now oxygenated blood travels form the lung to the left side of the heart where it is pumped to the rest of the body.

the diploid number of chromosomes is sometimes represented by the symbol 2n. for the fruit fly, the diploid number is 8, which can be written as 2n = 8, where n represents twice the number of chromosomes in a sperm or egg cell.

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.