Multiple Choice
In the context of eukaryotic cell architecture, which organelle is commonly described as the cell’s control center because it houses most of the genetic material and regulates gene expression?
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1. Overview of Cell Biology
Eukaryotic Cell Architecture
Multiple Choice
In a eukaryotic cell, which organelle is primarily responsible for pumping out excess water to maintain osmotic balance (especially in freshwater protists)?
A
Central vacuole
B
Lysosome
C
Smooth endoplasmic reticulum
D
Contractile vacuole
Verified step by step guidance1
Understand the problem context: The question asks which organelle in a eukaryotic cell pumps out excess water to maintain osmotic balance, particularly in freshwater protists.
Recall the function of each organelle listed: The central vacuole mainly stores water and nutrients in plant cells, lysosomes digest cellular waste, and the smooth endoplasmic reticulum is involved in lipid synthesis and detoxification.
Identify the organelle specialized for expelling excess water: Freshwater protists live in hypotonic environments where water tends to enter the cell by osmosis, so they need a mechanism to remove this excess water to prevent bursting.
Recognize that the contractile vacuole is a specialized organelle that collects excess water from the cytoplasm and periodically expels it outside the cell, thus maintaining osmotic balance.
Conclude that the contractile vacuole is the organelle responsible for pumping out excess water in freshwater protists, ensuring cell survival in hypotonic environments.
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