transport in plants Flashcards

Question

What happens in phloem unloading?

Answer 1

1. Sucrose diffuse from phloem to sinks because it has a low sugar concentration 2. Sucrose is moved to other cells or converted to other forms - maintains concentration gradient between cells and phloem 3. Loss of assimilates increases WP of STE * H2O moves out into cells by osmosis or enters xylem's transpiration stream

Answer 2

Large surface area due to shape - increases water uptake for osmosis Permanent vacuole containing cell sap, which is more concentrated than soil water - ensures a high water potential gradient is maintained

Answer 3

Plants with adaptations to reduce water loss and are therefore found in locations with limited water, for example, the desert * Marram grass is found on sand dunes, which despite being next to the ocean, there is limited water due to sand beiing so porrous

Answer 4

* Curled leaves to trap moisture to increase local humidity * Hairs to trap moisture to increase local humidity * Sunken stomata to trap moisture to incease local humidity * Thicker cuticle to reduce evaporation * Large root network to reach more water

Answer 5

Plants which live in or on water, so require adaptations to survive in an excess of water * Water lillies grow on the surface of water

Answer 6

Ensures no additional water us retained in the plant and efficient water loss: * Short roots * Very thin to no waxy cuticle * Stomata permenantly open and in the top surface of lead Ensures light is still absorbed for photosynthesis: * Leaves being large, wide and on the surface of leaf

Answer 7

* As water moves into the roots by osmosis it increases the volume of liquid inside the root and therefore the pressure inside the root increases. This is known as root pressure * This increase in pressure in the roots forces water above it upwards (positive pressure)

Answer 8

1. The sucrose in the STE has decreased the water potential 2. Water moves to STE which creates high hydrostatic pressure 3. Water acts as as medium to transport he assimilates from an areas of high hydrostatic pressure to low 4. Once it reaches an area of low HSP the sucrose is used by cells and surroounding tissures 5. Sucrose diffuses from the STE to surrounding tissues which decreases its WP 6. Water moves from STE to surrounding tissues by osmosis down a WP gradient

Answer 9

In between xylem and phloem Layer of meristem cells that divide to produce new xylem and phloem

Answer 10

1. Water enters the leaf through the xylem and moves by osmosis into the cells of. the spongy mesophyll 2. Evaporates from the cells walls of the spongy meosphyll 3. Water vapour moves by diffusion out of the leaf through the open stomata due to water vapour potential gradient

Answer 11

Part of the plant that loads materials into the transport system E.g leaves photosynthesise and the sugaars made are moved to others part of the plant

Answer 12

Part of the plant where materials are removed from the transport system

Answer 13

1. Minerals actively transported into xylem from root which lowers the water potential and water enters by osmosis 2. Cohesion of water molecules enables water to move by mass flow, pulled upwards by tension from above 3. Movement of water out of xylem into leaves creates low hydrostatic pressure thus tension 4. Osmosis moves water across the leaf and water evporates from cell surface 5. Diffusion of water vapour out leaf