Active Transport

• Substances are absorbed by active transport, which moves substances from a more dilute solution to a more concentrated solution, against the concentration gradient, requiring energy from respiration.
• Examples of active transport in animals and plants include the cells lining the human small intestine, which absorb molecules produced when foods digested, such as sugars like glucose.
• The concentration of sugars in the lumen of the small intestine is lower than the concentration inside the cell, preventing sugars from diffusing into the cell and instead, these sugars are carried in by active transport.
• Once inside the cell, sugars can then be transported into the blood and carried around the body.
• The cells lining the human small intestine, known as enterocytes, have lots of mitochondria to provide the energy for active transport.
• Another example of active transport is found in root hair cells, which transport ions such as magnesium into the plant from the soil.
• Plants need magnesium to make chlorophyll in the leaves, and the concentration of ions in the soil is lower than the concentration inside the root hair cell, so active transport is used to move the ions into the cell.
• These ions are then transported to the xylem vessels and moved to the leaf.
• Root hair cells have lots of mitochondria to provide the energy for active transport.