Matrix formed outside the plasma membrane is referred to as:

Correct Answer: B

Rationale: The correct answer is B: glycocalyx. The glycocalyx is a matrix formed outside the plasma membrane that consists of glycoproteins and glycolipids. It plays crucial roles in cell-cell recognition, protection, and immune response. Cytoplasm (A) is the gel-like substance inside the cell, not outside. Exoplasm (C) is not a recognized term in biology. Cell wall (D) is a rigid structure found in plant cells, not outside the plasma membrane in all cells.

Correct Answer: A

Rationale: The correct answer is A: Chrysophyta. Diatoms are classified under the division Chrysophyta due to their unique characteristics, such as possessing a cell wall made of silica (siliceous frustule) and containing chlorophyll a and c for photosynthesis. Chrysophyta includes golden-brown algae, which diatoms are a part of. Rhodophyta (B) includes red algae, Chlorophyta (C) includes green algae, and Phaeophyta (D) includes brown algae. These choices are incorrect as they do not align with the specific characteristics and classification of diatoms within the kingdom Protista.

Correct Answer: C

Rationale: The correct answer is C: beaded. In an agar slant, beaded colonies appear as separate or semiconfluent, forming small, round colonies with gaps between them. This term accurately describes the appearance of the colonies in this context. A: Filiform colonies are dense and opaque with smooth edges, not separate or semiconfluent. B: Echinulate colonies have spiny projections, not the characteristic of separate or semiconfluent growth. D: Effuse colonies spread out extensively and lack defined borders, unlike the distinct appearance of separate or semiconfluent colonies.

Correct Answer: D

Rationale: The correct answer is D: components of the gram-negative cell wall. Bacterial endotoxins are lipopolysaccharides found in the outer membrane of gram-negative bacteria. They are released upon bacterial cell lysis and can cause severe immune responses. A: Proteins in the cell wall - This is incorrect because endotoxins are not proteins but rather lipopolysaccharides. B: Secreted into the environment - Endotoxins are not actively secreted but are released upon cell death or lysis. C: Components of the gram-positive cell wall - Gram-positive bacteria do not have an outer membrane with lipopolysaccharides, so endotoxins are not found in the gram-positive cell wall.

Correct Answer: A

Rationale: The correct answer is A: HSV-1. Herpes simplex infections on lips and in the mouth are most commonly caused by HSV-1 due to its preference for infecting oral mucosa. HSV-2 typically causes genital herpes. HSV-6 and HSV-7 are less common and not typically associated with oral infections. Therefore, based on the typical presentation and epidemiology of herpes simplex infections, HSV-1 is the most likely cause in this scenario.