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.
I believe D because if the fertilizer had a concentrated source of nitrate (which plants do need) then when watering that can go into the ground water which is underground <span />
The second one probably because of the law of conservation of mass where mass is not created or destroyed, so the mass has to be the same.
IT'S D becuse none of the other awser choses make sense so ya
Answer:
by which large pieces of food are cut and crushed into
by which large pieces of food are cut and crushed intosmaller pieces is called:
d. mechanical digestion
5. The tube that connects the mouth to the stomach is the:
a. oesophagus
5. The hard, outer coating of the tooth is called:
b. enamel
- The building blocks of proteins are:
c. amino acids
5. Which of the following vitamins is made by the body?
a. vitamin D- b. vitamin A c. vitamin C
. Having too little of the mineral iron can cause:
b. goitre
The wavelike motion that moves food through the digestive tract is called:
d. peristalsis
Gastric juice contains all of the following except:
d. bile
The process by which large food molecules are broken down into smaller food
The process by which large food molecules are broken down into smaller foodmolecules is:
c. mechanical digestion
Fats are digested in the:
b. small intestine
Poor nutrition caused by an unbalanced diet is called:
c. malnutrition
The fingerlike projections on the lining of the small intestine are called:
b. villi
