Download Mineral Ions in Plants

Mineral Ions in Plants
Ion
Absorbed as
Magnesium
Magnesium ions
Iron
Iron ions
Nitrogen
Role
Needed to make
chlorophyll
Nitrates
Amino acids
Proteins
Growth
Deficiency
Less photosynthesis,
Small leaves,
Yellow leaves,
Weak stem
Poor growth
Small leaves
Weak stems
How do minerals get into the plants?
-
Through root hair cells
Minerals are dissolved in soil water and so, move in as soluble ions with water
Minerals ions move in initially by diffusion – down a concentration gradient
Minerals diffusing into
root hair cell
High
concentration of
minerals outside
cell
Low
concentration of
minerals inside
cell
Soil particles
If an equilibrium is reached, diffusion stops. To continue getting ions into the plant, active
transport is required.
Active transport
transporting minerals into
root hair cell
Low
concentration of
minerals outside
cell
Soil particles
High
concentration of
minerals inside
cell
Plant Cells
The cytoplasm of a plant cell and the cell sap in its vacuole contain salts, sugars and
proteins, which effectively reduce the concentration of free water inside the cell. The cell
wall is freely permeable to water and dissolved substances but the cell membrane of the
cytoplasm is partially permeable.
If a plant cell is surrounded by water a solution more dilute than its contents, water will pass
into it via osmosis. The vacuole will expand and press outwards on the cell wall and
cytoplasm. The cell wall of a mature plant cell cannot be stretched so the water stops
coming in when the cell wall is stretched the most.
A normal cell
A turgid cell
A plant cell with the vacuole pushing out onto the cell wall is said to be turgid and the
vacuole is exerting a turgor pressure. If all cells are turgid, the stem and leaves will be
straight. If vacuoles lose water, they become flaccid. A leaf with flaccid cells is wilted.