Scientific information refers to the classification, collection, dissemination, and retrieval of recorded knowledge treated both as a pure and as an applied science. The two features of a scientific information source, which may suggest that the information is not reliable are:
1. The information is based on data that are not peer-reviewed, that is, the information has not been reviewed by the experts in the field, or is not encouraged by an accord of experts in the field.
2. The references are not cited, that is, it not clear or not known that from where the information originated.
The skin is an example of a non-specific defense.
For example, bacteria or diseases have trouble entering a healthy person's skin because it is formed by closely packed cells with multiple layers and a substance called keratin that protects is.
On the other hand, the immune system is a specific defense mechanism.
When bacteria is able to enter the body in cases of fever for example, the immune system is activate and sends out protector cells such as the white blood cells to combat infection.
Answer:
The correct answer is 4: "The exception to Mendelian laws of inheritance that best explains the mentioned symptoms is codominance".
Explanation:
In codominance, both alleles can be expressed. In these cases, heterozygote individuals<em> instead</em> of showing an <em>intermediate phenotype</em>, express both of the alleles. Their phenotype is an additive expression of their parents' genes.
In cystic fibrosis, there is a gene responsible for coding for a protein named "cystic fibrosis transmembrane conductance regulator, CFTR".
-Most of the people have two copies of the normal allele and produce the functional CFTR protein form.
-Patients with cystic fibrosis have two copies of the mutated allele and so produce the mutated and dysfunctional form for this protein.
-Heterozygote people possess only one normal CFTR allele and a mutated form for the same allele and produce a normal protein and a mutated protein.
In the last case, both alleles are codominant and they express in heterozygote individuals. Given the fact that the normal allele produces enough functional CFTR protein, these individuals do not have any adverse effect and the mutated allele is recessive at a physiological level.
Natural selection occur to give the best survival chance to the organisms. Hence, they bring about biological evolution through future generations thereby increasing the variety of living things. This survival reflects on their ability to produce more offspring. The offspring must continue to survive by competing with the resources found in nature.
