Active transport

• What is the main difference between diffusion and active transport?

  Active transport moves particles against the concentration gradient, while diffusion moves particles down the concentration gradient.
• What is a good source of iodine?

  Seaweeds are a really good source of iodine.
• Why do we need iodine in our diet?


  We need iodine in our diet to help us make some hormones.
• How do seaweeds obtain their iodine?

  Seaweeds get their iodine from the surrounding seawater.
• What is the concentration of iodine in some seaweeds compared to seawater?

  Some seaweeds contain iodine at concentrations many times higher than in seawater.
• Did iodine get into seaweeds by diffusion?

  No, iodine did not get there by diffusion because it is moved against the concentration gradient.
• What is active transport?

  Active transport is the movement of particles against the concentration gradient, which requires energy.
• What is required for active transport to occur?

  Active transport requires energy to move particles against the concentration gradient.
• Which process provides a cell with energy for active transport?

  Cellular respiration provides a cell with energy.
• What is active transport?

  Active transport is the active uptake of molecules against the concentration gradient using energy.
• What does movement against a concentration gradient mean?

  It means moving from low concentration to high concentration.
• How does active transport differ from diffusion and osmosis?

  Active transport requires energy and moves against the concentration gradient, while diffusion and osmosis do not require energy and move down the gradient.
• What is required for active transport to occur?

  Carrier proteins are needed to transport the molecules across the cell membrane.
• Give an example of active transport in plants.

  Root hair cells actively uptake mineral ions from the soil.
• How do humans utilize active transport in digestion?


  Humans absorb nutrients such as glucose from the gut into the blood.
• What effect does an increase in temperature have on active transport?

  As temperature increases, the energy provided by respiration increases, leading to an increase in the active transport rate.
• What happens to the active transport rate at temperatures above 37°C?


  The active transport rate reaches a peak and then drops steadily due to protein denaturation.
• Why does protein denaturation affect active transport?

  Denatured proteins can no longer provide active transport channels.
• What is the role of cyanide in relation to active transport?

  Cyanide is an inhibitor that blocks a membrane protein in the mitochondria, stopping respiration and energy release.
• Why is energy important for active transport?

  Active transport requires energy to move particles into or out of the cell against their concentration gradient.
• What is the relationship between respiration and active transport?

  Respiration releases energy, which is necessary for active transport to occur.
• What are four factors that affect the rate of diffusion across a partially permeable membrane?

  Concentration gradient, temperature, surface area, and the nature of the membrane
• How does concentration gradient affect the rate of diffusion?

  A higher concentration gradient increases the rate of diffusion as particles move from high to low concentration
• Why does the surface area to volume ratio decrease as size increases?

  As size increases, volume increases faster than surface area, leading to a lower ratio
• What is active transport in cells?

  • Movement of particles against a concentration gradient
  • Requires energy
  • Example: root hair cells absorbing nitrate ions
  • Example: kidneys reabsorbing glucose
• What is an example of active transport in plants?

  Root hair cells absorbing nitrate ions from the soil
• What is an example of active transport in animals?

  Reabsorption of glucose in the kidneys from kidney tubules
• Why do cells use energy for active transport?


  To absorb substances against their concentration gradient
• How does active transport occur in cells?

  • Involves special carrier proteins in the cell membrane
  • Proteins pick up particles from one side
  • Transport particles to the other side of the membrane
• What is the role of carrier proteins in active transport?


  They transport particles across the cell membrane
• What is the role of a carrier protein in a membrane?

  It facilitates the active transport of molecules across the membrane.
• What type of molecule is actively transported through a carrier protein?

  A sugar molecule.
• What is the source of energy for active transport?

  The energy comes from cell respiration.
• How can you test if a substance is being absorbed by an active process?

  By treating the cells with a poison that stops respiration.
• What effect does cyanide have on root hair cells regarding nitrate ion uptake?

  Cyanide stops the uptake of nitrate ions.
• How does cyanide affect diffusion and osmosis in root hair cells?

  Cyanide does not affect diffusion or osmosis.
• What is active transport?

  • The movement of molecules against their concentration gradient.
  • Requires energy, typically from ATP produced during cell respiration.
  • Involves carrier proteins in the cell membrane.
• Provide examples of active transport in plants and animals.

  • Plant example: Uptake of nitrate ions by root hair cells.
  • Animal example: Sodium-potassium pump in nerve cells.