Biology Chapter 5: Homeostasis and Cell Transport

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Questions and Answers

What is required for substances to move across the cell membrane through passive transport?

Assistance from protein pumps

No energy input required (correct)

Energy input from the cell

Active involvement of the cell structure

What primarily drives the process of diffusion?

Electrical potential difference

Kinetic energy of molecules (correct)

Cell membrane structure

Concentration of solute

In osmosis, what determines the net direction of water movement?

Temperature and pressure conditions

Concentration of ions

Relative solute concentrations on either side of the membrane (correct)

Type of cells involved

Which of the following processes does NOT fall under passive transport?

Active transport Signup and view all the answers

What term describes the movement of molecules from an area of higher to lower concentration until equilibrium is reached?

Diffusion Signup and view all the answers

What is the definition of dynamic equilibrium in the context of diffusion?

Continuous movement with no net change in concentration Signup and view all the answers

Which type of transport specifically involves the movement of water across a semipermeable membrane?

Osmosis Signup and view all the answers

When a cell is placed in a hypertonic solution, what will happen to the water in the cell?

Water will diffuse out of the cell Signup and view all the answers

What is the primary function of the sodium-potassium pump in animal cells?

To maintain a higher concentration of Na+ outside the cell Signup and view all the answers

Which statement accurately describes the process of active transport?

It requires energy to transport molecules against their concentration gradient. Signup and view all the answers

During the sodium-potassium pump operation, how many potassium ions are moved into the cytosol for every three sodium ions transported out?

Two K+ ions Signup and view all the answers

What type of transport mechanism involves the engulfing of large particles or entire cells?

Phagocytosis Signup and view all the answers

What does the electrical gradient created by the sodium-potassium pump facilitate?

Conduction of electrical impulses along nerve cells Signup and view all the answers

What is the role of ATP in the sodium-potassium pump?

It provides energy for the pump's activity. Signup and view all the answers

What process allows cells to absorb external fluid and solutes?

Pinocytosis Signup and view all the answers

In endocytosis, what happens to the pouch formed around ingested materials?

It becomes a vesicle within the cell. Signup and view all the answers

What occurs when a cell is placed in a hypotonic solution?

The cell bursts due to water gain. Signup and view all the answers

Which of the following best describes an isotonic solution?

Equal solute concentrations inside and outside the cell. Signup and view all the answers

What is the primary function of contractile vacuoles in cells such as paramecia?

To regulate water levels. Signup and view all the answers

In facilitated diffusion, what role does the carrier protein play?

It binds a molecule and changes shape to transport it across the membrane. Signup and view all the answers

What typically happens to red blood cells (RBCs) in a hypertonic solution?

They lose water and shrink. Signup and view all the answers

What is plasmolysis in relation to cell transport?

The shrinking of the cell due to water loss. Signup and view all the answers

What do ion channels facilitate in the context of cellular transport?

The transport of specific ions across the cell membrane. Signup and view all the answers

Which statement accurately describes the outcome of osmosis?

Water moves from areas of low solute concentration to areas of high solute concentration. Signup and view all the answers

Signup and view all the answers

Study Notes

Chapter 5: Homeostasis and Cell Transport

This chapter covers homeostasis and cell transport, specifically passive and active transport mechanisms.

Section 1: Passive Transport

Objectives:
- Explain how equilibrium is established through diffusion.
- Differentiate between diffusion and osmosis.
- Detail how substances cross cell membranes through facilitated diffusion.
- Explain the role of ion channels in ion diffusion across cell membranes.
Passive Transport:
- Molecules move across the cell membrane without energy input from the cell.
- Examples of substances that move passively include water, lipids, and lipid-soluble substances.
- No energy required.
Types of Passive Transport:
- Diffusion
- Osmosis
- Facilitated Diffusion
- Filtration

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.
Driven by the kinetic energy of the molecules.
Continues until a dynamic equilibrium is reached.
Equilibrium is when there is no net change in concentration across space. It is influenced by random movement of particles (Brownian motion).

Osmosis

Specific type of diffusion.
Movement of water across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.
Direction of Osmosis:
- Determined by relative solute concentrations on either side of the membrane.
- Hypertonic: Higher solute concentration outside the cell; water moves out of the cell (plasmolysis).
- Hypotonic: Lower solute concentration outside the cell; water moves into the cell (cytolysis).
- Isotonic: Equal solute concentrations inside and outside the cell; no net water movement.
How Cells Deal with Osmosis:
- Cells in multicellular organisms often use mechanisms to regulate water levels, including pumping solutes out or using contractile vacuoles.
- Red blood cells (RBCs) cannot pump solutes to regulate water.

Facilitated Diffusion

Movement of molecules across a membrane that aren't lipid-soluble or are too large to pass through membrane pores.
Molecules bind to carrier proteins on one side of the membrane.
The carrier protein changes shape, transporting the molecule down its concentration gradient to the other side of the membrane.

Diffusion Through Ion Channels

Ion channels are proteins (or groups of proteins) that create small passageways across the cell membrane.
Special channels allow particular ions to diffuse across the membrane, crucial for cellular function.
Important ions include sodium, potassium, calcium, and chloride.

Section 2: Active Transport

Objectives:
- Compare and Contrast passive and active transport.
- Explain how the sodium-potassium pump functions.
- Contrast endocytosis and exocytosis processes.
Active Transport: Movement of molecules across the membrane from an area of lower concentration to an area of higher concentration.
Energy is required for this process in order to move against the concentration gradient.
Example: Sodium-Potassium Pump
Sodium-Potassium Pump:
- Moves 3 sodium ions (Na+) out of the cell and 2 potassium ions (K+) into the cell.
- Uses ATP (energy) for its process.
- Creates an electrical gradient across the membrane (outside becomes positively charged, inside becomes negative).
- Essential for nerve cell function and other cellular processes.
Movement in Vesicles:
- Endocytosis: Cells take in external fluids, molecules, and large particles by folding their membranes to form pouches that pinches off (becoming vesicles).
  - Pinocytosis: Liquid.
  - Phagocytosis: large particles or whole cells.
  - Receptor-mediated endocytosis: Molecules bind to receptors, resulting in vesicles forming in coated pits (proteins).
- Exocytosis: Vesicles fuse with the cell membrane, releasing their contents into the external environment. Used to release proteins, waste products, or toxins that could be harmful if released within the cell.

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Description

This quiz focuses on Chapter 5, which explores the concepts of homeostasis and cell transport mechanisms. It covers the details of passive transport, including diffusion, osmosis, and facilitated diffusion, highlighting how substances cross cell membranes without energy. Test your understanding of these essential biological processes!