Cellular Transport: Passive vs Active
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Questions and Answers

What is the primary characteristic of passive transport?

  • Involves active transport proteins
  • Moves molecules from low to high concentration
  • Requires energy to move molecules
  • Moves molecules from high to low concentration without using energy (correct)

Dynamic equilibrium occurs when there is no movement of particles.

False (B)

Name one type of passive transport.

Diffusion

In diffusion, particles move from an area of ______ concentration to an area of ______ concentration.

<p>high, low</p> Signup and view all the answers

Match the factors affecting the rate of diffusion with their effects:

<p>Temperature = Directly proportional to rate Size of molecules = Inversely proportional to rate Pressure = Can increase movement Concentration gradient = Higher difference increases rate</p> Signup and view all the answers

Which of the following is true about dynamic equilibrium?

<p>There is continuous movement but no overall change (C)</p> Signup and view all the answers

Higher temperatures cause molecules to move slower, resulting in a decreased rate of diffusion.

<p>False (B)</p> Signup and view all the answers

Explain how the size of molecules affects their rate of diffusion.

<p>Smaller molecules diffuse faster than larger molecules.</p> Signup and view all the answers

What is the main purpose of exocytosis?

<p>To release substances like hormones (A)</p> Signup and view all the answers

Energy can be created in living organisms.

<p>False (B)</p> Signup and view all the answers

What is the formula for cellular respiration?

<p>C6H12O6 + 6O2 -&gt; 6CO2 + 6H2O + energy</p> Signup and view all the answers

In photosynthesis, light energy is converted into __________.

<p>chemical energy</p> Signup and view all the answers

Match the following metabolic pathways with their definitions:

<p>Catabolic pathway = Releases energy by breaking down large molecules Anabolic pathway = Uses energy to build larger molecules Cellular respiration = A specific catabolic pathway involving glucose Photosynthesis = A specific anabolic pathway that converts light energy into chemical energy</p> Signup and view all the answers

What type of energy is most directly captured by plants during photosynthesis?

<p>Light energy (C)</p> Signup and view all the answers

All living organisms are either autotrophs or heterotrophs.

<p>True (A)</p> Signup and view all the answers

What molecule is primarily responsible for carrying energy in cells?

<p>ATP</p> Signup and view all the answers

The breakdown of ATP to ADP releases energy when the _______ phosphate bond is broken.

<p>2nd and 3rd</p> Signup and view all the answers

Which of the following is a type of energy that is evident in cellular processes?

<p>Chemical energy (B)</p> Signup and view all the answers

Which process describes the diffusion of water across a semi-permeable membrane?

<p>Osmosis (C)</p> Signup and view all the answers

Concentration affects the rate of diffusion; a greater difference in concentration results in a slower rate of diffusion.

<p>False (B)</p> Signup and view all the answers

What is the purpose of the sodium-potassium pump?

<p>To transport sodium ions out of the cell and potassium ions into the cell against their concentration gradients.</p> Signup and view all the answers

In a __________ solution, the concentration of solute is lower than inside the cell, leading to water entering the cell.

<p>hypotonic</p> Signup and view all the answers

What is directly proportional to the rate of diffusion?

<p>Concentration difference (D)</p> Signup and view all the answers

Match the type of solution to its description.

<p>Hypotonic = Water flows into the cell, causing it to swell Isotonic = Equal concentrations inside and outside the cell Hypertonic = Water flows out of the cell, causing it to shrink Facilitated diffusion = Transport of molecules via transport proteins</p> Signup and view all the answers

Facilitated diffusion requires energy input from ATP.

<p>False (B)</p> Signup and view all the answers

What type of transport proteins change shape to allow molecule diffusion?

<p>Carrier proteins</p> Signup and view all the answers

Active transport moves substances from an area of __________ concentration to __________ concentration.

<p>low, high</p> Signup and view all the answers

Which of the following statements is true regarding hypertonic solutions?

<p>They cause cells to shrivel as water leaves the cell (A)</p> Signup and view all the answers

What is the first step of exocytosis?

<p>Vesicle transporting substances approaches the plasma membrane.</p> Signup and view all the answers

Osmosis involves the movement of solute molecules.

<p>False (B)</p> Signup and view all the answers

What is the main function of the sodium-potassium pump?

<p>To maintain the electrochemical gradient (C)</p> Signup and view all the answers

During the breakdown of ATP, it is converted to __________, releasing energy.

<p>ADP</p> Signup and view all the answers

Flashcards

Passive Transport

The movement of molecules across the plasma membrane from an area of high concentration to an area of low concentration without requiring energy.

Concentration Gradient

The difference in concentration of a substance between two areas.

Dynamic Equilibrium

The state where molecules are constantly moving, but the overall concentration remains the same.

Diffusion

Movement of particles from an area of high concentration to an area of low concentration until they are evenly distributed.

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Factors Affecting Diffusion

The rate at which diffusion occurs is affected by temperature, size, pressure, and concentration. Higher temperatures, smaller molecules, higher pressure, and higher concentration gradients lead to faster diffusion.

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Osmosis

Diffusion of water molecules across a selectively permeable membrane from an area of high water concentration to an area of low water concentration.

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Facilitated Diffusion

Movement of molecules across the plasma membrane with the help of transport proteins. It still follows the concentration gradient (high to low) and doesn't directly require energy.

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Active Transport

Cellular transport that requires energy to move molecules across the plasma membrane, often against their concentration gradient (from low to high).

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Exocytosis

The release of substances from a cell's interior to the outside, often through the plasma membrane, using vesicles.

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Thermodynamics

The study of energy flow and transformation in living organisms and their surroundings.

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First Law of Thermodynamics

The principle that energy cannot be created or destroyed, only converted from one form to another.

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Second Law of Thermodynamics

The principle that during energy conversion, some energy is lost as heat, and no process can be 100% efficient.

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Autotrophs

Organisms that make their own food using energy from sunlight or inorganic chemicals, like plants.

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Heterotrophs

Organisms that cannot produce their own food and obtain energy by consuming other organisms.

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Metabolism

The sum of all chemical reactions occurring within a living organism.

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Metabolic Pathway

A series of chemical reactions where the product of one reaction becomes the reactant of the next.

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Catabolic Pathway

A type of metabolic pathway that breaks down large molecules into smaller ones, releasing energy.

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Anabolic Pathway

A type of metabolic pathway that uses energy to build larger molecules from smaller ones.

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Pressure and Diffusion

The pressure exerted by a gas or liquid, which can affect the rate of diffusion. Diffusion usually happens faster in gases than liquids.

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Hypotonic Solution

A solution with a lower concentration of solute (like sugar) than the inside of the cell. Water moves into the cell.

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Hypertonic Solution

A solution with a higher concentration of solute (like sugar) than the inside of the cell. Water moves out of the cell.

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Isotonic Solution

A solution with the same concentration of solute as the inside of the cell. There is no net movement of water.

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Channel Protein

A type of transport protein that forms a channel through the membrane, allowing molecules to pass.

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Carrier Protein

A type of transport protein that changes shape to bind to a molecule and move it across the membrane.

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Sodium-Potassium Pump

A type of active transport that pumps sodium ions out of the cell and potassium ions into the cell, using ATP as energy.

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Study Notes

Cellular Transport

  • Cellular transport is categorized into passive and active transport.

Passive Transport

  • Definition: Movement of molecules across the cell membrane from high to low concentration without energy input.
  • Direction: High concentration to low concentration.
  • Energy Requirement: No energy required.
  • Movement: Down the concentration gradient.
  • Types: Diffusion, osmosis, and facilitated diffusion.

Diffusion

  • Definition: Movement of particles from high to low concentration until dynamic equilibrium is reached.
  • Dynamic Equilibrium: Continuous movement of particles, but no overall change in concentration across a barrier.
  • Example: Red and blue particles moving randomly until equal distribution across sides.
  • Factors Affecting Rate: Temperature (directly proportional), size (inversely proportional), pressure (directly proportional), concentration (directly proportional).

Osmosis

  • Definition: Diffusion of water across a semi-permeable membrane from high to low water concentration.
  • Water Concentration: Inverse relationship with solute concentration.
  • Example: Water moving from a region with high water concentration (low solute) to a region with low water concentration (high solute)

Facilitated Diffusion

  • Definition: Movement of molecules across the membrane with transport proteins.
  • Transport Proteins: Channel proteins and carrier proteins.
  • Channel Proteins: Open and close to allow diffusion.
  • Carrier Proteins: Change shape to facilitate diffusion.

Solutions

  • Hypotonic: Lower solute concentration outside the cell than inside. Water diffuses into the cell, potentially causing cell swelling/bursting (except in plant cells).

  • Isotonic: Equal solute concentration inside and outside the cell. Water movement is balanced, no net change in cell size.

  • Hypertonic: Higher solute concentration outside the cell than inside. Water diffuses out of the cell, causing cell shrinking/wilting.

Active Transport

  • Definition: Movement of molecules across the membrane from low to high concentration, requiring energy input..
  • Direction: Low concentration to high concentration.
  • Energy Requirement: Requires energy (ATP).
  • Movement: Against the concentration gradient.
  • Process: Uses transport proteins powered by ATP hydrolysis.
  • Types: Sodium-potassium pump, exocytosis, and endocytosis.

Sodium-Potassium Pump

  • Function: Maintains sodium and potassium ion concentrations via transport proteins.
  • Process: Uses ATP to move sodium out and potassium in against their concentration gradients.
  • Cycle: Sodium binds, ATP hydrolyzes, protein shape changes, sodium released, potassium binds, phosphate released, protein returns to original shape, potassium released.

Exocytosis

  • Function: Removing substances from the cell.
  • Process: Vesicles containing substances fuse with the cell membrane and release contents outside.

Endocytosis

  • Function: Bringing substances into the cell.
  • Process: Cell membrane surrounds substance, forming a vesicle that is internalized.

Energy for Life

  • Energy is required for all cellular activities.
  • Energy comes from the sun, either directly or indirectly. Autotrophs capture light energy, while heterotrophs obtain energy by consuming other organisms.
  • All chemical reactions in a cell are categorized as metabolism.
  • Metabolic pathways: Catabolic (breaking down molecules) and anabolic (building molecules).

ATP

  • Definition: Adenosine triphosphate, the primary energy currency of the cell.
  • Structure: Adenine, ribose, and phosphate groups.
  • Function: Releases energy when a phosphate bond is broken (forming ADP), driving cellular processes. The ATP -->ADP process is catabolic and ADP-->ATP is anabolic.
  • ATP plays a crucial role in most biochemical reactions.

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Description

Explore the concepts of cellular transport, focusing on passive transport mechanisms such as diffusion and osmosis. This quiz covers definitions, examples, and factors affecting the rate of diffusion. Test your understanding of how substances move across cell membranes.

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