Introduction to Sponges and Cell Types

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Questions and Answers

What is the primary function of choanocytes in sponges?

To form the external lining of the sponge

To filter water through their collar (correct)

To provide structural support

To produce nutrients for the sponge

Which type of cell is known for moving through the mesohyl and is totipotent?

Choanocytes

Archeocytes (correct)

Pinacocytes

Sclerocytes

Which secretory cells are responsible for producing mineral spicules?

Choanocytes

Sclerocytes (correct)

Spongocytes

Collencytes

What is the main role of pinacocytes in sponges?

To form a protective outer layer Signup and view all the answers

Which cell type is primarily involved in forming channels for water flow in some sponges?

Porocytes Signup and view all the answers

What do spongocytes primarily produce in sponges?

Spongin spicules Signup and view all the answers

Which cell type gives rise to all other cell types in a sponge?

Archeocytes Signup and view all the answers

What structural role do collagen spicules play in sponges?

They contribute to shape and support Signup and view all the answers

What type of cells provide a filtering mechanism by pulling water through?

Choanocytes Signup and view all the answers

In what cellular arrangement do porocytes exist within the sponge structure?

Along the pinacoderm Signup and view all the answers

Which of the following statements accurately describes autotrophs?

They use photosynthesis or chemosynthesis to produce their own food. Signup and view all the answers

What distinguishes osmotrophs from phagotrophs?

Osmotrophs absorb soluble food while phagotrophs ingest visible particles. Signup and view all the answers

Euglena viridis is capable of changing its nutritional mode. What condition triggers this change?

Absence of light. Signup and view all the answers

During classic amoeboid phagocytosis, what is formed when the plasma membrane encloses a food particle?

Food vacuole. Signup and view all the answers

What role does the Golgi body play in the feeding process of amoeboid forms?

It helps in the fusion of the food vacuole with the lysosome. Signup and view all the answers

What mechanism do Didinium use to capture its prey?

Cytopharynx to engulf prey. Signup and view all the answers

How does the structure of Stentor contribute to its feeding mechanism?

It transforms into a horn-like shape to generate a feeding current. Signup and view all the answers

What type of nutrition involves the ingestion of solid particles?

Holozoic. Signup and view all the answers

Which type of nutrition is characterized by the absorption of soluble food?

Osmotrophy. Signup and view all the answers

What function does the lysosome perform during digestion in unicellular eukaryotes?

It releases enzymes to break down the food vacuole contents. Signup and view all the answers

What mechanism do suctorians use to obtain food?

Tentacles to snag protozoans and suck cytoplasm Signup and view all the answers

Which organelle is responsible for osmoregulation in freshwater unicellular eukaryotes?

Contractile vacuoles Signup and view all the answers

What is the primary active transport mechanism identified in osmoregulation?

Proton pump (H+-ATPase) Signup and view all the answers

During exocytosis, what occurs to eliminate undigested material?

Fusion with the cell surface Signup and view all the answers

In the context of osmoregulation, how does freshwater differ from the internal environment of unicellular eukaryotes?

Freshwater is more dilute than the internal environment Signup and view all the answers

What is a characteristic of the cytoproct?

It is a permanent excretory pore Signup and view all the answers

How does environmental size impact the filling and expulsion rates of contractile vacuoles?

Filling and expulsion rates depend on organism size Signup and view all the answers

What type of feeding mechanism do sponges practice?

Filter feeding using a system of canals Signup and view all the answers

What role does cytoplasmic carbonic anhydrase play in osmoregulation?

It generates H+ and HCO3- for transport Signup and view all the answers

Which of the following statements about metabolic waste diffusion is correct?

Metabolic wastes like ammonia readily diffuse across the cell membrane Signup and view all the answers

Study Notes

Introduction

Sessile and multicellular animals without organs
Functionally distinct cell types
Filter feeders
Water is pumped through the body via a system of canals
Food particles are collected from the water

Cell Types

Choanocytes
- Ovoid cells lining the canal system and chambers
- Have a collar forming a filtering device at the exposed end
- Flagella motion pulls water through the filter
- Embedded end in the mesohyl
Archeocytes
- Amoeboid cells moving through the gelatinous matrix (mesohyl) within the sponge
- Receive food particles from choanocytes
- Digest food particles
- Totipotent (can differentiate into all other cell types in sponge)
Secretory Cells
- Produce spicules
  - Mineral (calcium)
  - Protein (collagen, spongin)
- 3 subtypes
  - Sclerocytes: produce mineral spicules
  - Spongocytes: produce spongin spicules
  - Collencytes: produce collagen spicules
Pinacocytes
- Form the pinacoderm, a protective lining facing the external environment
- Also line some internal canals where choanocytes are not present
Porocytes
- Found only in some sponges (Asconoid)
- Form channels in the pinacoderm through which water flows into the sponge (ostia)

General Arrangement of Cell Types

Porocytes make up the ostia
Pinacocytes form the pinacoderm, which is the outer layer of cells
Archeocytes are found in the mesohyl, which is the gelatinous matrix within the sponge
Sclerocytes are found in the mesohyl and produce spicules
Choanocytes make up the choanoderm, which lines the internal canals of the sponge

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Description

Explore the fascinating world of sponges, multicellular organisms that play a crucial role in aquatic ecosystems. This quiz covers their unique cell types, including choanocytes and archeocytes, and explains their filtering mechanisms and functions. Test your knowledge on how sponges thrive as filter feeders in their environments.