Transport in animals and plants

Why do plants need transport systems ?

1. low surface area to volume ratio

2. diffusion is too slow to meet their metabolic needs

3. substances need to be moved over longer distances

Materials plants exchange and transport (5)

Carbon dioxide

Oxygen

Water

Organic nutrients

Inorganic ions

Carbon is used for…

Photosynthesis

Oxygen is used for…

aerobic respiration

Water is used for…

photosynthesis and transpiration

Inorganic ions are used for…

Chlorophyll production

Organic ions are used for…

Improves soil quality and allows for the slow release of nutrients…

Plant processes (3)

Photosynthesis

Respiration

Active transport

Photosynthesis - PGTS

plants produce glucose through sunlight

Respiration - PSE

plants supplying energy

Active transport

energy required to move and transport substances

Transpiration :

movement of water molecules and dissolved mineral ions

• happens in the xylem vessels

• passive process

Translocation :

movement of sucrose and amino acids

• happens in the phloem cells - sieve and companion cells

• active process

vascular bundle in the roots

• provide a drill like structure

• enables the plant to push down into the roots

• xylem tissues is the strongest so is in the centre - X structure

• Phloem in 4 separate sections

Vascular bundle in the stem

• Xylem located in the inside in non wooded plants

• this provides additional support to the stem

• cambium layer contains meristem cells

Young root vascular distribution

endodermis - surrounds the vascular bundle

pericycle - meristem cells

Stem vascular tissue distribution

• vascular bundles around the edge of the stem

• cambium - meristem cells

Vascular bundle in the leaf

• xylem is located on top of the phloem

• Only in dicotyledonous plants

Structure of xylem vessels

• hollow tubes (no cytoplasm)

• spirals of lignin around the tube

• thick lignified wall - non lignified pit

• lignin helps reinforce the xylem so that it does not collapse under the force of the transpiration pull

Structure of phloem vessel

• sieve plate element, sieve plate and companion cell

• thin layer of cytoplasm in the sieve tube element

• dense cytoplasm of companion cells

• plasmodesma linking cytoplasm of companion cell and sieve plate element

• large nucleus

• mitochondria

spread of disease in plants (indirect)

1. soil contamination

2. wind

3. water

4. animals

5. humans

spread of disease in plants (direct)

contact between leaves

4 factors affecting transmission of disease in plants

1. susceptibility of disease

2. overcrowding ( density of plants )

3. climatic conditions ( damp, heat )

4. climate change

5 ways to prevent spread of disease in plants

1. leave plenty of room between plants

2. rotate crops

3. strict hygiene practices

4. control insect vectors

5. clear fields as thoroughly as possible

physical plant defences

• waxy cuticle

• cell wall

• production of callose

what is callose?

polysaccharide deposited between the cell wall and cell surface membrane to make it harder for pathogens to enter the cell

chemical defences

• insect repellants

• insecticides

• antibacterial substances

• toxins