movement of substances

What is diffusion?

The net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient, without requiring energy.

How does diffusion assist in nutrition uptake in the small intestine?

Glycerol and fatty acids diffuse into the epithelium, while glucose and amino acids are absorbed by diffusion into the blood capillaries of the villi.

What role does diffusion play in gaseous exchange in the lungs?

Oxygen diffuses through the wall of the alveolus and the wall of blood capillaries into the RBC, while carbon dioxide diffuses from the blood into the alveolar air.

What is osmosis?

The net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane, without requiring energy.

What happens to a plant cell in a solution with higher water potential?

The plant cell swells and becomes turgid due to the vacuole increasing in size and pushing the cytoplasm against the cell wall.

What is plasmolysis in plant cells?

Plasmolysis is the shrinking of cytoplasm and cell membrane from the cell wall when plant cells are in a solution with lower water potential.

What is active transport?

A process in which energy is used to move particles of a substance across a membrane against its concentration gradient from a region of lower concentration to a region of higher concentration.

How do root hair cells utilize active transport?

Ions move into root hair cells via active transport if the ion concentration in the soil is higher than in the cell.

How does active transport function in the villi of the small intestine?

Glucose and amino acids move into blood capillaries in the villi via active transport if their concentration in the blood capillaries is higher than in the small intestine.