When a population is at hardy-weinberg equilibrium which one of the following is true?

a. genotypic frequencies change generation after generation.
b. allele frequencies change generation after generation.
c. the population is a sink for immigrants.
d. one can calculate the recessive allele frequency directly from the homozygous recessive genotype.
individuals of like genotype are most likely to mate.

The correct answer will be option-D

Explanation:

The Hardy-Weinberg principle was given by two different scientists Godfrey Hardy and the Wilhelm Weinberg which worked on understanding the population genetics.

The Hardy- Weinberg equilibrium is based on certain assumptions like population should have no mutations, no emigration, no selective pressure, no migration and the population should be infinite.

Since the Hardy- Weinberg equilibrium is widely used to determine the allelic frequency from the genotype therefore option-D is the correct answer.

the transfer of energy between two molecules spaced just nanometers apart plays a key role in many technologies, including photovoltaics, quantum information systems, lighting, and sensors, as well as in biophysics to measure nanometer distances and in photosynthesis. but an open question in this area is what effect, if any, the surrounding photonic environment has on this nanoscale energy transfer. by designing and performing a carefully controlled experiment to answer this question, scientists have settled the debate and found clues to improving the efficiency of many of the technologies that rely on this process.

explanation:

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.