Directional selection is where one phenotype is favored, so an example would be "a population of madagascar hissing cockroaches suffers heavy predation from lizards. Because their heads are small, the lizards are unable to eat the very largest adult cockroaches, and instead prey upon small and medium sized adults, so as a result the large cockroaches are favored and live".
Meanwhile, disruptive selection is where both extreme phenotypes are favored, an example would be "a population of rabbits can have black fur, white fur or grey fur. This population of rabbits lives in an area of white rocks. When a local volcano erupts, black volcanic rock now dots the landscape amongst the white rocks. Now the black and white rabbits live longer because the black and white spots on the landscape camoflauge them. The two extreme phenotypes are being favored."
Genetic drift occurs when there is no random mating across a population. This causes a change in allelic frequency due to a random sampling of the population.
As the aboriginal population explored the earth, a small part of the population became geographically isolated either due to continental drift and climate changes. As the isolated population grew bigger, they established their own gene pool. This resulted a change in genotypic frequencies from that of the aboriginal population.
Answer:
The thyroid gland increase in size.
Explanation:
Iodine plays an important role in the generation of thyroid hormones and is mainly found in the soil in coastal areas and in seawater. In the developing nations, the individuals who live at high elevations or inland are generally deficient in iodine and can develop a condition known as goiters.
In the condition, the thyroid gland increases in size in an attempt to get more iodine. However, in the countries where iodine is added routinely to foods and table salt, the lack of dietary iodine is not the typical reason of goiters.
Answer:
Explanation:
Two Types of Cellular Processes . Cellular respiration can be aerobic (meaning "with oxygen") or anaerobic ("without oxygen"). Which route the cells take to create the ATP depends solely on whether or not there is enough oxygen present to undergo aerobic respiration.
Answer:
The correct answer is - per gram, the marathon runner's muscles would contain more myoglobin than the sprinter's muscles.
Explanation:
Marathon runners have smaller leg muscles and thinner quads and calves as marathon runners require slow-twitch muscles while in sprinters the fast-twitch muscle requires. Slow-twitch muscles of marathon runners have more amount of myoglobin, per gram than fast-twitch muscles.
Myoglobin acts as local oxygen storage that provides oxygen to the muscles in case of less oxygen supply than required temporarily and a marathon race is an intense exercise or activity that requires more oxygen.
