What hormone secreted during the stress response reduces the body's inflammatory response?

Rationale:

A. Sickle cell anemia is a monogenic disorder caused by a mutation in the HBB gene, which leads to abnormal hemoglobin S production. It follows a Mendelian autosomal recessive inheritance pattern, meaning a person must inherit two defective alleles (one from each parent) to express the disease. Environmental factors have little influence on whether the disease occurs, although they can affect disease severity.

B. Cystic fibrosis is caused by mutations in the CFTR gene and is also a single-gene autosomal recessive disorder. Disease expression is largely determined by genetics, although certain environmental factors, like respiratory infections, may influence symptoms and progression. It is not considered multifactorial because a single gene mutation is sufficient to cause the disorder.

C. Hemophilia A is an X-linked recessive disorder caused by a mutation in the factor VIII gene. Males are predominantly affected because they have only one X chromosome. This disorder follows a single-gene inheritance pattern, and while environmental factors can influence bleeding risk, the underlying cause is genetic alone.

D. Cleft palate is a classic example of a multifactorial disorder. It results from the interaction of multiple genes and environmental factors. Genetic predisposition may increase risk, but environmental influences—such as maternal smoking, alcohol use, certain medications, or nutritional deficiencies during pregnancy—can trigger or exacerbate the condition. Unlike single-gene disorders, multifactorial conditions do not follow simple Mendelian inheritance and often appear sporadically within families, though they may recur more frequently among relatives.

Rationale:

A. Artificial active immunity occurs when a person produces their own antibodies in response to a vaccine or other immunization. This is not how a fetus gains immunity from maternal antibodies.

B. Natural passive immunity occurs when antibodies are transferred from one person to another naturally, without vaccination or direct exposure. In the case of a fetus, IgG antibodies cross the placenta from mother to fetus, providing temporary protection against infections the mother is immune to. This immunity is short-term, lasting only a few months after birth, until the infant’s immune system can produce its own antibodies.

C. Artificial passive immunity occurs when pre-formed antibodies are injected into an individual, such as immunoglobulin therapy after exposure to hepatitis B or rabies. This is not the natural transfer from mother to fetus.

D. Natural active immunity occurs when a person produces their own antibodies after natural infection with a pathogen. The fetus is not exposed to the infection, so immunity is not active.