Transport in Plants
Food and water in plants have to move very long distances. However, on the contrary they
also move short distances, such as Intracellular and Intercellular (via Plasmodesmata)
SHORT DISTANCE TRANSPORT
• Intercellular transport occurs passively by diffusion or facilitated diffusion or actively by
Pumps, Channels and Transporters etc.
• Diffusion occurs randomly, independent of the living tissue and requires no energy
• Diffusion is the only means of gaseous transport in plants
Factors affecting rate of diffusion
• Size of molecules
• Solubility or Lipids
• Concentration Gradient
• Facilitated transport/diffusion of hydrophilic substances occurs without energy requirement
via Transport Proteins
• Facilitated diffusion is maximum when all Transport Proteins are saturated
• Highly sensitive to side Protein Chains that inhibit the transport
• Some Protein Channels are always open while some open up with the expenditure of
energy
• Porins is a protein that forms pores in the outer membrane of several organelles such as
Plastids and Mitochondria
• When a molecule attaches to its surface, the Porins protein rotates completely, allowing the
molecule the enter the protoplasm
Based on types of substances, their ways of transport is altered
Uniport
When only one molecule is there, it gets transported via the protein
Antiport
When two different molecules are present on the different sides, they get transported, in
antagonistic directions to each other
Symport
When two different molecules are present on the same side, they are transported together
Water entering a solid increases its size
Imbibition
Special reversible movement where water moves along the concentration gradient
Food and water in plants have to move very long distances. However, on the contrary they
also move short distances, such as Intracellular and Intercellular (via Plasmodesmata)
SHORT DISTANCE TRANSPORT
• Intercellular transport occurs passively by diffusion or facilitated diffusion or actively by
Pumps, Channels and Transporters etc.
• Diffusion occurs randomly, independent of the living tissue and requires no energy
• Diffusion is the only means of gaseous transport in plants
Factors affecting rate of diffusion
• Size of molecules
• Solubility or Lipids
• Concentration Gradient
• Facilitated transport/diffusion of hydrophilic substances occurs without energy requirement
via Transport Proteins
• Facilitated diffusion is maximum when all Transport Proteins are saturated
• Highly sensitive to side Protein Chains that inhibit the transport
• Some Protein Channels are always open while some open up with the expenditure of
energy
• Porins is a protein that forms pores in the outer membrane of several organelles such as
Plastids and Mitochondria
• When a molecule attaches to its surface, the Porins protein rotates completely, allowing the
molecule the enter the protoplasm
Based on types of substances, their ways of transport is altered
Uniport
When only one molecule is there, it gets transported via the protein
Antiport
When two different molecules are present on the different sides, they get transported, in
antagonistic directions to each other
Symport
When two different molecules are present on the same side, they are transported together
Water entering a solid increases its size
Imbibition
Special reversible movement where water moves along the concentration gradient
