3-3 Microfilaments Which of the following types of cells contain more microfilaments? 1. Epithelial cell in the outer layer of the skin (withstands tension) 2. Intestinal absorptive cells (with microvilli). 3. Respiratory epithelium (with cilia). 4. Muscle cell (contractile) 2& 3 1& 2 2& 4 3& 4 1& 3

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3-3 Microfilaments Which of the following types of cells contain more microfilaments? 1. Epithelial cell in the outer layer of the skin (withstands tension) 2. Intestinal absorptive cells (with microvilli). 3. Respiratory epithelium (with cilia). 4. Muscle cell (contractile) 2& 3 1& 2 2& 4 3& 4 1& 3

Answer 1

The correct answer is **2 & 4**. Here's why:* **Microvilli:** Intestinal absorptive cells have abundant microvilli, which are finger-like projections of the plasma membrane that increase surface area for absorption. Microvilli are supported by a core of microfilaments (actin filaments).* **Muscle Contraction:** Muscle cells rely heavily on microfilaments (actin) and myosin for contraction. The interaction between these two proteins generates the force needed for muscle movement.Let's look at why the other options are incorrect:* **Epithelial cells in the outer layer of the skin:** While these cells experience tension and contain intermediate filaments (keratin) for strength, they don't have a particularly high concentration of microfilaments compared to muscle cells or cells with microvilli.* **Respiratory epithelium with cilia:** Cilia are primarily composed of microtubules, not microfilaments. While microfilaments play a role in cilia anchoring and some aspects of their movement, the main structural component is microtubules.

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