Problem 1 - Biology

Question

Which of the following statements is false? a. Choanocytes have flagella that propel water through the body. b. Pinacocytes can transform into any cell type. c. Lophocytes secrete collagen. d. Porocytes control the flow of water through pores in the sponge body.

Step-by-Step Solution

Answer

b. Pinacocytes can transform into any cell type.

Step 1: Identify Cell Functions

Read each statement carefully and identify the specific function attributed to each cell type mentioned in the options.

Step 2: Verify Choanocytes Functionality

Choanocytes have flagella that propel water through the sponge’s body. This statement is true because choanocytes are known to create water currents necessary for filter feeding.

Step 3: Verify Pinacocytes Functionality

Pinacocytes form the outer layer of the sponge and provide protection. They do not transform into other cell types. Therefore, the statement that pinacocytes can transform into any cell type is false.

Step 4: Verify Lophocytes Functionality

Lophocytes are responsible for secreting collagen fibers, which provide structural support. This statement is true.

Step 5: Verify Porocytes Functionality

Porocytes control the flow of water through the pores of the sponge body, allowing water to enter the sponge. This statement is true.

Key Concepts

Choanocytes

Choanocytes play a crucial role in the life of a sponge. They are specialized cells equipped with flagella, which are hair-like structures that can move. The main function of choanocytes is to create water currents by flapping their flagella. This water movement is essential for the sponge's filter-feeding mechanism.
As water flows through the sponge's body, choanocytes trap food particles on their collars, tiny structures around the base of the flagella. This is how sponges obtain nutrients from their environment. Additionally, choanocytes also aid in gas exchange and waste removal, ensuring the efficient functioning of the sponge's internal system.

Pinacocytes

Pinacocytes form the outermost layer of a sponge, providing a protective barrier against external elements. These cells are flat and can cover the entire surface of the sponge. Their main function is to protect the sponge and regulate its shape.
Unlike some other cells in the sponge, pinacocytes do not have the ability to transform into other cell types. This is an important distinction. Pinacocytes are integral in maintaining the structural integrity and overall stability of the sponge's body. They also play a role in controlling the expansion and contraction of the sponge, helping it respond to environmental changes.

Lophocytes

Lophocytes are another type of specialized cell found in sponges. Their primary function is to secrete collagen, a protein that forms a fibrous network within the sponge's tissues. This collagen matrix provides structural support and maintains the sponge's resilience.
By producing collagen, lophocytes help in the repair and regeneration of sponge tissues. Collagen acts like a scaffold within the sponge, helping it retain its shape and withstand various physical stresses. Without the activity of lophocytes, sponges would lack the necessary structure and durability to thrive in their underwater environments.

Porocytes

Porocytes are cells that control the flow of water through the sponge's pores. These tubular cells form channels called ostia, through which water enters the sponge's body. The function of porocytes is crucial for the sponge's filter-feeding process.
Porocytes can open and close these channels to regulate water flow, ensuring that the sponge can effectively filter nutrients and oxygen from the water. This ability to control water entry also helps the sponge manage waste removal. By adjusting the size of the pores, porocytes play a key role in maintaining the sponge's internal balance and overall health.