How many genes make up the human genome? a. four: adenine, thymine, guanine, and cytosine b. 23 pairs of genes c. 20,000-25,000 genes d. 3 billion genes

The correct answer is- C. 20,000-25,000.

Human genome can be described as the whole genetic makeup/material of human beings (that is determined by DNA, deoxyribonucleic acid).

There are approximately 20,000-25,000 genes (which have been estimated to code for particular protein) that are present in the human genome.

Genes are considered as the unit of hereditary as they carry genetic instruction (in the form of DNA sequence), which is transmitted from one generation to the next generation.

answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.