Plant vascular system

Question 1

What is transported in the phloem and what is it made up of?

Answer 1

• The phloem carries sucrose down to the roots for growth or for storage and may later carry it back up again
• Made of living cells and perforated end plates to allow stuff to flow through.
• They transport food made in leaves to other parts of the plant in both directions
• They carry sugars, fat, proteins etc. to growing regions in shoot tips and root tips and to/from storage parts in the roots

Question 2

What is transported in the xylem and what is it made up of?

Answer 2

• Xylem carries water and minerals (which are taken in by the roots) up to the leaves
• Made of dead cells joined end to end with no end walls between them.
• Side walls are strong and stiff, containing lignin which helps provide plants support.
• Carry water and minerals from the roots up to the leaves in the transpiration stream

Question 3

Give the definitions of translocation and transpiration.

Answer 3

TRANSLOCATION - the movement of food (sucrose and amino acids) from regions of production or storage (source) to regions of usage, respiration, growth or storage (sink)

TRANSPIRATION - The loss of water to the atmosphere, mainly through the leaves

Question 4

Show how these adaptations of root hair cells help.

Increase surface area, Lots of mitochondria, Transport proteins

Answer 4

Increase surface area- To absorb water and minerals
Lots of mitochondria - Energy for active transport of minerals
Transport proteins - Pumps ions in against a diffusion gradient

Question 5

Show how these adaptations of xylem.
No end plate, Transports water and minerals, Side walls reinforced with lignin, Transports water from roots to the leaves.

Answer 5

No end plate - Helps for the flow of water
Transports water and minerals - Water for photosynthesis, minerals for growth
Side walls reinforced with lignin - Makes it strong and gives the plant support
Transports water from roots to leaves - Helps in transpiration

Question 6

Explain what causes transpiration and what are its benefits.

Answer 6

• It is caused by evaporation of water from inside the leaves
• This creates a slight shortage of water in the leaf which draws more water up from the rest of the plant which in turn draws more up from the roots. The whole column of water is pulled along bcz of the water’s property of cohesion

BENEFITS :

1) water for photosynthesis
2) transports minerals from soil
3) cools down the plant

Question 7

What are the factors affecting transpiration?

Answer 7

• Amount of light (when there is light stomata are open and vice versa)
• Temperature (increases evaporation)
• Amount of air movement (decreases humidity)
• Humidity of the surrounding air (higher water potential gradient)

Question 8

What are systemic pesticides and what are contact pesticides?

Answer 8

SYSTEMIC PESTICIDES
Can be translocated in the phloem from the site of application to the site of action. It is more effective as it absorbed in the phloem and enters the pests’ body when they feed on the plant.

CONTACT PESTICIDES
Need to be absorbed through the surface of the pests. Not as effective as it needs to be in contact with the pests’ body.