ATI LPN
Hematologic System Questions Questions
Question 1 of 5
Individuals with a genetic deficiency of C6 have
Correct Answer: D
Rationale: The correct answer is D: decreased resistance to Neisseria bacteremia. This is because C6 is a component of the complement system, which plays a crucial role in the immune response against Neisseria bacteria. A deficiency in C6 would impair the ability to effectively combat Neisseria infections. Choice A is incorrect because the deficiency of C6 does not directly affect resistance to viral infections. Choice B is incorrect as hypersensitivity reactions are not specifically linked to C6 deficiency. Choice C is incorrect because there is no direct correlation between C6 deficiency and an increased frequency of cancer.
Question 2 of 5
Which one of the following is NOT true of class I MHC antigens?
Correct Answer: D
Rationale: The correct answer, D, is not true because class I MHC antigens are primarily found on all nucleated cells, not just B cells, macrophages, and activated T cells. These antigens present endogenous antigens to CD8+ T cells. Choice A is incorrect because class I MHC antigens are not typically assayed using antibody and complement; instead, they are recognized by CD8+ T cells. Choice B is incorrect because identifying class I MHC antigens in the lab usually requires more than a few hours due to the complexity of the process. Choice C is incorrect because class I MHC antigens are controlled by a single gene locus in the major histocompatibility complex.
Question 3 of 5
Which one of the following does NOT contain C3b?
Correct Answer: C
Rationale: The correct answer is C because classic-pathway C3 convertase does not contain C3b. In the classical pathway, C3 convertase is formed by the cleavage of C4bC2a, which does not involve C3b. A: classic-pathway C5 convertase contains C3b as it is formed by the binding of C4b2a3b complex to C5. B: alternative-pathway C5 convertase contains C3b as it is formed by the binding of C3bBb3b complex to C5. D: alternative-pathway C3 convertase contains C3b as it is formed by the binding of C3bBb complex to C3.
Question 4 of 5
An Rh-negative woman married to a heterozygous Rh-positive man has three children. The probability that all three of their children are Rh-positive is
Correct Answer: C
Rationale: Certainly! The Rh factor follows Mendelian inheritance. The Rh-negative woman is homozygous Rh-negative (rr) and the Rh-positive man is heterozygous (Rr). The Punnett square for their offspring shows a 1/2 chance of each child being Rh-positive (Rr). Therefore, the probability of all three children being Rh-positive is (1/2)^3 = 1/8, making choice C the correct answer. Choices A, B, and D are incorrect because they do not consider the specific genetic inheritance pattern of the Rh factor in this scenario.
Question 5 of 5
An individual who is heterozygous for Gm allotypes contains two allelic forms of IgG in serum, but individual lymphocytes produce only one of the two forms. This phenomenon, known as 'allelic exclusion,' is consistent with
Correct Answer: A
Rationale: The correct answer is A because allelic exclusion in this context refers to the phenomenon where only one allelic form of a gene is expressed in a particular cell. In this case, the individual is heterozygous for Gm allotypes, meaning they have two different allelic forms of IgG. Since the individual lymphocytes produce only one of the two forms, it suggests that the heavy-chain gene on one chromosome has undergone rearrangement, leading to the expression of a single form of IgG. This supports choice A. Choices B, C, and D are incorrect because they involve either both chromosomes or light-chain genes, which are not relevant to the scenario described.