Transport, protection and regulation. And the three being transported are Gases, namely oxygen (O2) and carbon dioxide (CO2),
The answer is B, carbohydrates.
Carbohydrates are the first choice of the energy source of your body, they can be broken down into simple and soluble compounds such as glucose. These can be used by cells for respiration to generate energy for activities such as growth, movement, repair etc. Besides using for respiration, they are also capable of forming cell structures such as cellulose.
In immunology two types of immune response are described depending on whether there is prior contact with the antigen.
• At this first contact, only lymphocytes with receptors specific to the antigen in question are stimulated and lead to the production of antibodies capable of neutralizing it. The lymphocytes capable of recognizing a specific antigen are very few and the production of antibodies - of low intensity and limited duration - is detectable only after a period of latency of several days. This is called the primary response. The specificity of the resulting seropositivity, however, makes it possible to detect contamination (seroconversion).
• Upon re-contact with an antigen that has already triggered a primary response, specific antibody production is found to increase rapidly after a short latency period. The secretion of IgG then reaches levels much higher than those observed during the primary response, while that of IgM is of the same order. This early and intense response, called secondary response, most often results in the destruction of infectious agents before any clinical sign.
• Many centuries before the discovery of microbes, it was noted that people who developed a contagious disease without death were then specifically immunized against the disease, without being protected against others.
• The ability to react appropriately to an already received stimulus supposes the existence of a memory. The immune memory is based on the existence of memory B and T lymphocytes, resulting from the clonal expansion due to the first contact with the antigen. Their lifespan is significantly higher than that of other lymphocytes and their high reactivity gives its rapid and intense character to the secondary response.
Nails are made of iron because, iron is strong and sturdy; although nail rust when it undergoes oxidation when expose to water but it is not explosive.
Barium and phosphorus are not suitable for nail making because of their properties.
Barium is an element which reacts with virtually all non metals, forming poisonous products which are dangerous to health and to the environment. It also reacts explosively with water.
Phosphorus is not found in its pure form in nature, it conducts electricity and it is combustible in nature.<span />
Answer:
C. The evolution of many species from a single ancestor over a long period of time
