Living Environment Section 1, 2, 3 Quiz

Questions and Answers

What is osmosis?

Special diffusion of water across a membrane.

What do you call a state that exists when the concentration of a substance is the same throughout a space?

Equilibrium

What is concentration?

The amount of a particular substance in a given volume.

What term describes a difference in the concentration of a substance across a distance?

Concentration gradient Signup and view all the answers

What is passive transport?

Movement of substances from an area of higher concentration to an area of lower concentration without the use of energy. Signup and view all the answers

What is the definition of diffusion?

The movement of particles from regions of higher density to regions of lower density. Signup and view all the answers

What is the process called when small nonpolar molecules pass through the lipid bilayer?

Simple diffusion Signup and view all the answers

What is facilitated diffusion?

The process by which transport proteins help ions and polar molecules diffuse through the cell membrane. Signup and view all the answers

What role do channel proteins play in cellular transport?

They serve as tunnels through the lipid bilayer for specific substances. Signup and view all the answers

What are carrier proteins?

Transport proteins that bind to specific substances and change shape to move them across the membrane. Signup and view all the answers

How does osmosis occur?

As free water molecules move down their concentration gradient across a selectively permeable membrane. Signup and view all the answers

What is the sodium-potassium pump?

A carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into a cell. Signup and view all the answers

What is endocytosis?

The movement of large substances into a cell by means of a vesicle. Signup and view all the answers

What is exocytosis?

The movement of material out of a cell by means of vesicles. Signup and view all the answers

What is homeostasis?

The maintenance of a stable internal environment regardless of external conditions. Signup and view all the answers

What are phospholipids?

Lipids that contain phosphorus and form the structural component of cell membranes. Signup and view all the answers

What do membrane proteins do?

Aid in various functions such as transport, signaling, and cell recognition. Signup and view all the answers

Study Notes

Osmosis and Diffusion

Osmosis is the special diffusion of water across a selectively permeable membrane.
Equilibrium occurs when substance concentrations are equal throughout a space.
Concentration refers to the quantity of a specific substance in a given volume.
A concentration gradient is the difference in concentration of a substance over a distance.

Transport Mechanisms

Passive transport occurs when substances move from high to low concentration without energy, facilitated by concentration gradients.
Diffusion is the movement of particles from regions of higher density to lower density.
Simple diffusion allows small nonpolar molecules like oxygen to move directly through the lipid bilayer.
Facilitated diffusion employs transport proteins for ions and polar molecules, as they struggle to breeze through the nonpolar lipid bilayer.

Types of Transport Proteins

Channel proteins act as pores in the membrane, enabling specific substances to diffuse based on their size and charge.
Carrier proteins bind to specific substances and change shape to transport them across the membrane.

Osmosis in Depth

In osmosis, water moves through a selectively permeable membrane, favoring areas of lower water concentration.
Water channels facilitate this osmosis for polar water molecules within the cellular environment.

Water Movement Predictions

Water movement is influenced by the solution's concentration relative to the cell:
- Hypertonic solutions (high solute concentration) lead to water exiting the cell, causing it to shrink.
- Hypotonic solutions (low solute concentration) result in water entering the cell, leading it to swell.
- Isotonic solutions have equal concentrations, maintaining cell size due to balanced water movement.

Cell Responses and Active Transport

If a cell is placed in a hypotonic solution without regulation, it may burst, while plant cells thrive in such environments.
Active transport moves substances against their concentration gradients and requires energy, often supplied by ATP.
The sodium-potassium pump is a prime example, actively transporting sodium ions out and potassium ions into the cell.

Vesicles and Bulk Transport

Substances too large for carrier proteins are transported via vesicles, which are membrane-bound sacs.
Endocytosis brings large substances into the cell, while exocytosis exports materials out.

Cell Membrane Composition and Function

All cells possess membranes that regulate substance movement and provide structural support.
Homeostasis involves maintaining a stable internal environment, facilitated by the selective permeability of the cell membrane.
The phospholipid bilayer consists of phosphate heads (polar) and fatty acid tails (nonpolar), creating a barrier for only certain substances.

Membrane Proteins and Their Roles

Membrane proteins play diverse roles, including cell surface markers for cell identification, receptor proteins for sensing the environment, enzymes for accelerating reactions, and transport proteins for aiding substance movement across the membrane.

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Description

This quiz covers essential concepts from Living Environment, including key terms like osmosis, equilibrium, and concentration. Test your understanding of these foundational principles in biology. Perfect for students preparing for exams or quizzes in environmental science.