Scientific Knowledge Flashcards

Which type of hypersensitivity reaction is mediated by IgE antibodies and mast cell degranulation?

Answer: Type I (immediate hypersensitivity)

Type I hypersensitivity involves IgE-mediated mast cell and basophil degranulation, releasing histamine and other mediators causing anaphylaxis, asthma, and allergic rhinitis.

What is the primary structural difference between gram-positive and gram-negative bacterial cell walls?

Answer: Gram-negative bacteria have an outer membrane containing lipopolysaccharide (LPS)

Gram-negative bacteria possess an outer membrane containing lipopolysaccharide (endotoxin), which gram-positive bacteria lack, accounting for different staining and pathogenicity patterns.

During glycolysis, which molecule serves as both a substrate and an allosteric activator of phosphofructokinase-1 (PFK-1)?

Answer: AMP

AMP allosterically activates PFK-1, signaling low cellular energy and promoting glycolysis, while high ATP inhibits PFK-1 to prevent excess glucose breakdown.

Which pulmonary function test finding is characteristic of obstructive lung disease such as COPD?

Answer: Decreased FEV1/FVC ratio (<0.70)

Obstructive disease is defined by a reduced FEV1/FVC ratio (<0.70 post-bronchodilator), reflecting impaired expiratory airflow due to airway obstruction.

Which hormone stimulates osteoclast activity, increases renal calcium reabsorption, and raises serum calcium levels?

Answer: Parathyroid hormone (PTH)

PTH raises serum calcium by stimulating osteoclast-mediated bone resorption, increasing renal calcium reabsorption, and promoting renal 1-alpha-hydroxylase activity to activate vitamin D.

Which statistical test is most appropriate for comparing means between three or more independent groups?

Answer: One-way ANOVA

One-way ANOVA compares means across three or more independent groups while controlling the type I error rate that would inflate with multiple t-tests.

DNA gyrase, the bacterial enzyme targeted by fluoroquinolone antibiotics, belongs to which class of enzymes?

Answer: Type II topoisomerase

DNA gyrase is a bacterial type II topoisomerase that introduces negative supercoils to relieve tension ahead of the replication fork; fluoroquinolones inhibit it by stabilizing the cleavage complex.