Biology Cell Structure & Function Flashcards
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Read the first 7 Biology Cell Structure & Function flashcards as text
A cell placed in a hypertonic solution will most likely:
Answer: Shrink due to water loss by osmosis
In a hypertonic solution, the solute concentration outside is higher than inside the cell, so water moves out by osmosis, causing the cell to shrink (crenation in animal cells).
Which of the following best describes the fluid mosaic model of the plasma membrane?
Answer: A dynamic phospholipid bilayer with mobile embedded proteins and cholesterol
The fluid mosaic model describes the membrane as a flexible phospholipid bilayer in which proteins, cholesterol, and glycolipids can move laterally.
What happens to a plant cell in a hypotonic solution?
Answer: It becomes turgid as water enters but is restrained by the cell wall
Water enters the plant cell by osmosis, increasing internal pressure (turgor pressure), but the rigid cell wall prevents lysis, making the cell turgid.
Which protein channel facilitates the passive transport of water across the cell membrane?
Answer: Aquaporins
Aquaporins are specialized channel proteins that allow rapid, selective transport of water molecules across the plasma membrane without energy expenditure.
During endocytosis, a cell engulfs a large solid particle by extending pseudopods around it. This specific process is called:
Answer: Phagocytosis
Phagocytosis ('cell eating') involves the engulfment of large particles or microorganisms by extending pseudopods that fuse to form a phagosome.
The sodium-potassium pump maintains the resting membrane potential by:
Answer: Moving 3 Na⁺ out and 2 K⁺ in per cycle using ATP
The Na⁺/K⁺-ATPase uses one ATP to pump 3 sodium ions out of the cell and 2 potassium ions in, generating an electrochemical gradient.
Gap junctions in animal cells primarily allow:
Answer: Direct cytoplasmic communication between neighboring cells
Gap junctions are channels formed by connexin proteins that connect the cytoplasm of adjacent cells, allowing ions and small molecules to pass directly between them.