Double science - investigating the effect of Osmosis on potatoes
Hypothesis/Introduction
If a plant is deprived of water, it wilts. If bacteria are placed in a high concentrated solution of salt water, they "collapse" and die. Human red blood cells, if placed in distilled water, expand and burst. These are all examples of osmosis and its effects.
The aim is to see the change in mass, length, and density of 21/2 cm potatoes in solutions of 1%, 10% and saturated (approximately 85-90% salt).
Osmosis is the movement of water molecules from a high-solution of water molecules to a low-solution of water molecules via a semi-permeable membrane.
(Fig 1)
Water Salt-solution
KEY TO DIAGRAM
Water molecule
Salt molecule
Net movement of water molecules
The diagram above shows how the process of osmosis occurs. The water molecules move through the semi-permeable until it is equalled. However, the sugar molecules cannot move through the semi-permeable membrane, as they are too big to. This can explain why proteins, fats and carbohydrates are broken down into smaller soluble molecules to pass through the villi.
Plants also use osmosis to keep themselves upright too. The cells draw in water; this allows the cells to become turgid. The "cell-content" pushes against the cell wall and thereby gives support to the plant tissues. This pressure is called turgor pressure.
Hypothesis/Introduction
If a plant is deprived of water, it wilts. If bacteria are placed in a high concentrated solution of salt water, they "collapse" and die. Human red blood cells, if placed in distilled water, expand and burst. These are all examples of osmosis and its effects.
The aim is to see the change in mass, length, and density of 21/2 cm potatoes in solutions of 1%, 10% and saturated (approximately 85-90% salt).
Osmosis is the movement of water molecules from a high-solution of water molecules to a low-solution of water molecules via a semi-permeable membrane.
(Fig 1)
Water Salt-solution
KEY TO DIAGRAM
Water molecule
Salt molecule
Net movement of water molecules
The diagram above shows how the process of osmosis occurs. The water molecules move through the semi-permeable until it is equalled. However, the sugar molecules cannot move through the semi-permeable membrane, as they are too big to. This can explain why proteins, fats and carbohydrates are broken down into smaller soluble molecules to pass through the villi.
Plants also use osmosis to keep themselves upright too. The cells draw in water; this allows the cells to become turgid. The "cell-content" pushes against the cell wall and thereby gives support to the plant tissues. This pressure is called turgor pressure.
