Because freezing will often burst the cell walls and destroy tissue. The crystals of ice are very sharp and hard to control AFAIK. Note what happens to a banana or many types of fruit after you dethaw — it becomes all mushy and not of the same structure, fiber and cell form as before, like a bad beam up in Star Trek.
Answer:
The metamorphic rock and sedimentary rock were already at this location and magma flowed into other rocks
<span>This can be used as an overall population guideline. The references can be used to make sure that everyone knows what the basic levels of nutrition should be for each group, and how each person or group can achieve those levels on a daily basis.</span>
Hippocrates is credited with being the first person to believe that diseases were caused naturally, not because of superstition and gods. Hippocrates was credited by the disciples of Pythagoras of allying philosophy and medicine. It was in anatomy that Herophilus made his greatest contribution to medical science, conducting important anatomical investigations of the brain, eye, nervous and vascular systems, and the genital organs. He also wrote on obstetrics and gynecology and held an elaborate quantitative theory of the pulse
The answer is stabilizing selection.
<span>Sickle-cell anemia is a recessive disorder caused by the presence of two recessive alleles "s", so genotype is "ss". This disorder is characterized by sickle hemoglobin. In an area with malaria, heterozygous individuals "Ss" (with one dominant allele and one recessive allele) have an advantage. These individuals will have both normal and sickle hemoglobin. But pathogen that causes malaria affect only normal hemoglobin, so heterozygous individuals will have half of the hemoglobin resistant to the pathogen and those individuals are resistant to malaria.</span>
Stabilizing selection favors heterozygotes Ss, disruptive selection favors dominant (SS) and recessive (ss) homozygotes, while directional selection favors dominant (SS) or recessive (ss) homozygote. Since in this example, people with genotype Ss (heterozygotes) are in advantage, then this is an example of stabilizing selection.
