Importance of Active and Passive Transport

Cell Transport

the movement of substances across the cell membrane either into or out of the cell

Active Transport

• Movement of particles from an area of low concentration to an area of high concentration using energy

• large and small particles can travel through the membrane

• movement of ions against a concentration gradient using energy.

• against a concentration gradient

Passive Transport

• requires no energy input by the cell

• movement of particles down a concentration gradient

Diffusion

• movement of particles from an area of high concentration to an area of low concentration

• occurs at the cell membrane (controls what enters and leaves the cell)

Osmosis

• specific type of diffusion

• involves the movement of water molecules across a semi-permeable membrane.

• high concentration → low concentration

• water moves in or out until its concentration is the same on both sides of the membrane

Examples of Passive and Active Transport in Plants and Animals

✅ Simple Diffusion

• Animals:

  • Oxygen diffuses from alveoli (lungs) into blood capillaries.

  • Carbon dioxide diffuses out of cells into the bloodstream.

• Plants:

  • Carbon dioxide diffuses into leaf cells for photosynthesis.

  • Oxygen diffuses out during photosynthesis.

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✅ Osmosis

• Animals:

  • Water moves into red blood cells when placed in a dilute solution (can cause swelling or bursting).

  • Kidney cells reabsorb water via osmosis.

• Plants:

  • Water enters root hair cells from the soil by osmosis.

  • Helps maintain turgor pressure in plant cells, keeping the plant upright.

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✅ Active Transport

• Animals:

  • In the small intestine, glucose is absorbed from the gut into the blood, even when the concentration is higher in the blood.

  • In nerve cells, sodium and potassium ions are pumped across membranes to create nerve impulses.

• Plants:

  • Mineral ions (e.g., nitrates, magnesium) are absorbed from the soil into root hair cells, even when their concentration is lower in the soil.