Choanoflagellates Are Single-Celled Eukaryotes That Feed on Bacteria

question 40

Multiple Choice

Choanoflagellates are single-celled eukaryotes that feed on bacteria. In the presence of their food bacteria, some choanoflagellates develop multicellular structures in which the individual choanoflagellate cells are attached to one another. Based on this observation, it may be assumed that:

• A)the bacterial cells, or a chemical released by the bacteria, bind to a receptor on the plasma membrane of the choanoflagellate cells.
• B)the choanoflagellate cells use cadherins to attach to each other.
• C)the choanoflagellates use integrins to attach to each other.
• D)choanoflagellates are complex multicellular organisms because they alternate between single cell and multicellular states.

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Definitions:

Muscle Fiber Type

Classification of muscle fibers based on their contraction speed and fatigue resistance, including Type I (slow-twitch) and Type II (fast-twitch).

Terminal Cisternae

Enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules in muscle cells, involved in calcium storage and release.

Sarcoplasmic Reticulum

A specialized type of smooth endoplasmic reticulum found in muscle cells, involved in the regulation of calcium ions.

H-band

A region within the sarcomere of striated muscle fibers that shortens during muscle contraction and is situated between the filaments of actin and myosin.