3.1 Exchange and Transport in Plants

Question 1

Define the following terms:
a) Meristem
b) Dicotyledon
c) Xerophyte

Answer 1

a) unspecialised cells in the plant that are capable of cell division
b) plants which grow to have more than one leaf
c) plants which live in arid areas and have adapted, therefore do need as much water as other plants

Question 2

What is meant by the term assimilates?

Answer 2

The process of absorption vitamins and other chemicals.

Question 3

What is transpiration and describe what happens during it?

Answer 3

Transpiration is the evaporation of water from plant leaves that draws water up the stem by cohesion. During transpiration water evaporates from mesophyll cells and exists through the stomata.

Question 4

Define the following:
a) Transpiration pull
b) Root pressure
c) Capillary action

Answer 4

a) the process of hydrogen bonds within the stomata being attracted to each other moving the water molecules out of the root and to the leaves.
b) force that helps to push fluids upwards into the xylem. Osmotic pressure is used to create this movement.
c) when water travels in the xylem due to forces of cohesion against the forces of gravity. It is used to bring water up the roots and stems towards the rest of the plant (leaves)

Question 5

Define the following:
a) Translocation
b) Sink
c) Source

Answer 5

a) the transport of assimilates around the plant
b) any part of the plant where substances are removed from the transport system
c) where materials are loaded into the transport system

Question 6

What is lignin?

Answer 6

A carbohydrate that is impermeable, meaning it prevents substances from passing through the cell wall.

Question 7

What are pits?

Answer 7

Regions in the cell that are free from lignin and allow water and dissolved substances to pass between vessels.

Question 8

Name the two pathways water moves in.

Answer 8

Symplast pathway and Apoplast pathway.