In familial hypercholesterolemia, individuals homozygous for the allele causing the disorder completely lack receptors on liver cells that take up cholesterol from the blood stream. heterozygotes have one-half the number of receptors while individuals homozygous for the normal allele are phenotypically normal. this is an example of

a) epistasis
b) incomplete dominance
c) complete dominance
d)codominance

The correct answer is option B, incomplete dominance

In the case of incomplete dominance, the allels of the two individuals that are cross do not produce either of their traits but results into a new individual with a different genotype and phenotype. For example if red and white flowers are crossed, pink offspring’s are produced.  

Here in this  case the heterozygotic parent cell has 50% of allel expressing the presence of receptors while homozygous lack receptor on liver cells that take up cholesterol from the blood stream and a cross between them produces homozygous , phenotypically normal individuals.  

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.