Answer:
Natural selection causes change in allele frequencies within a population.
So option A is correct one.
Explanation:
Natural selection generally work on an organism’s phenotype, or observable features. Phenotype is often largely a product of genotype (the alleles, or gene versions, the organism carries). When a phenotype produced by certain alleles helps organisms survive and reproduce better than their peers, natural selection can increase the frequency of the helpful alleles from one generation to the next – that is, it can cause microevolution.
Answer:
<em>6</em><em> </em><em>minutes</em>
EXPLANATION:
The brain can survive for up to about six minutes after the heart stops. The reason to learn cardiopulmonary resuscitation (CPR) is that if CPR is started within six minutes of cardiac arrest, the brain may survive the lack of oxygen. After about six minutes without CPR, however, the brain begins to die.
In fact, there are bacteria that grow in all kinds of pH, from the most acidic to the bad alkaline. Depending on the pH at which they live, bacteria can be classified as neutrophil, acidophilic and alkalineophilic.
But in general, when we talk about bacteria that are present in foods, they tend to grow in a pH range between 5 and 9, so they are considered as <u>neutrophil</u>. This can vary by species and other factors such as temperature and available nutrients.
An eon is 1.05 billion years and an era is 350 million years
