Identifying the Incorrect Immunoglobulin Statement
The question asks to identify the statement about Human Immunoglobulins that is not correct. Let's analyze each option:
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Option 1: IgG comprises about 85% of the total serum immunoglobulins
This statement is approximately correct but not precise. IgG is the most abundant immunoglobulin, typically constituting around 70-75% of serum immunoglobulins, though figures can vary slightly.
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Option 2: IgG and IgM can both cross the placenta
This statement is incorrect. Only IgG can efficiently cross the placental barrier, transferring passive immunity from mother to fetus. IgM, being a larger molecule (pentameric), cannot cross the placenta.
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Option 3: The half life of IgM is about 10 days
This statement is correct. The serum half-life of IgM is relatively short, typically around 5 to 10 days.
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Option 4: IgA comprises 15% of the total serum immunoglobulins and is mainly found in the body secretions
This statement is largely correct. While IgA is the second most abundant immunoglobulin in serum (around 5-15%), its primary role is in mucosal immunity, where it is the predominant immunoglobulin found in secretions like saliva, mucus, and breast milk.
Reasoning for Incorrect Statement
The key fact is the ability of immunoglobulins to cross the placenta. This passive immunity is crucial for newborns. Only the smallest immunoglobulin class, IgG, possesses this capability. Larger classes like IgM are excluded. Therefore, the assertion that both IgG and IgM can cross the placenta is factually wrong.
Based on this analysis, the incorrect statement is Option 2.
Important Questions from Preventive Medicine
In primary immune response, how much more antigenic dose is required to induce IgG antibodies as against the induction of IgM antibodies?
Consider the following statement :
"The people should seek to preserve their traditional eating patterns and life-styles associated with low levels of Coronary Heart Disease (CHD)."
Which level of prevention is implied in this statement?
- Which of the following will be target population for screening of diabetes?
1. Women who have had a baby weighing more than 4.5 kg
2. People over 40 years of age
3. People with family history of diabetes
Select the correct answer using the code given below. - Which of the following criteria must be met by a disease before it is to be considered suitable for a screening programme?
1. The natural history of the disease should be adequately understood.
2. No effective treatment should exist for the disease.
3. The disease should not have a recognizable latent or asymptomatic stage.
4. There should be a test that can detect the disease prior to onset of signs and symptoms.
Select the correct answer using the code given below. - Determination of alpha-fetoprotein levels in maternal serum is a useful screening tool for
