movement of water through plants

Question 1

How is a root hair cell adapted for efficient, uptake of water and why do plants need to take up water constantly?

Answer 1

large surface area to volume ratio
Thin, so short, diffusion distance

For cell structural support and photosynthesis

Question 2

explain how water enters a plant root from the soil and travels through to endodermis

Answer 2

water enters root hair cells
By osmosis
Because active uptake of mineral ions has created a water potential gradient
Water moves through cortex
By osmosis down water potential gradient
Symplastic pathway
Apple plastic pathway

Question 3

describe how water travels by the apoplastic pathway

Answer 3

water travels through cell walls (non living) due to cohesion, and until it reaches the endodermis

Question 4

describe the symplastic pathway of water

Answer 4

water passes through cytoplasm (living) via plasmodesmata due to osmosis down water potential gradient

Question 5

what is inside the Endo dermis and what does it cause?

Answer 5

Casperian strip which is water proof and blocks the apoplast halfway causing water to go into symplast path way

Question 6

why do endodermal cells actively transport ions into the xylem

Answer 6

decrease water potential which maintains water potential gradient

Question 7

what are the three mechanisms responsible for water movement up the xylem in the stem

Answer 7

Root pressure: active transport by Endo, dermis of ions into xylem, lowers water potential in the xylem, causing water to enter by osmosis

Cohesion tension theory : hydrogen bonds cause water to stick together, transpiration and evaporation in leaves, create tension, pulling water up

Capillarity : narrow, xylem, causes water to rise up due to adhesion