Plant Nutrition and transportChapter 32

Real Quiz!

• Closed book, 10 minutes, 10 points

Draw a GENERAL diagram that describes how a plant undergoes alternation of generations. In your diagram include all the different phases that the plants go through and the processes that lead from one phase to another. Indicate which phases have the full chromosome number, and which have half the chromosome number.

Objectives

• Identify the needs of plants and the entry points of materials

Fig 32.1A

Uptake and transport of plant nutrients

• Co2 enters plants through the leaves• Water, minerals and some O2 enters

through from the soil through the roots• All other materials are produced through

mixtures of these• Energy is obtained from the respiration of

sugars. Leaves produce O2 for this , roots absorb it from the soil

Solute uptake in the roots

Fig 32.2B

Solute uptake in the roots• Roots have large surface area• Mycorrhizal fungal interactions supply

nutrients and water to the plant• Substances enter roots both

intracellularlly and extracellularly, control over substances occurs at the cell membrane

• Intracellular (root hair membrane-plasmodesmata-cortex cells, endodermal cells- xylem)

• Extracellular (porous cell walls,around casparian strips, to xylem

Properties of waterWater molecules stick to one Another (cohesion) and other s(adhesion)

Water is a polar molecule

Fig 2.9

Fig 2.10

Transpiration

Fig 32.3

Transpiration

• Water – cohesion, diffusion, osmosis• How do plants lift water from the roots to

the leaves• Root cell membranes pump solutes into the

xylem, then water follows• Transpiration – adhesion-cohesion

– Evaporation of water from leaves thru stomata– Cohesion of water molecules in the xylem– Adhesion of water to cellulose

Fig 32.4Transpiration is controlled by stom

Sugar transport

Fig 32.5B

Sugar transport

• Sugars are made at “sugar sources”• Sugars travel to and are used at

“sugar sinks”• Osmosis is responsible for

generating pressure differences that move the sugar.

• Proof ! –Aphids!

Sugar sink

Aphids

Fig 32.6B

Fig 32.8

Pop Quiz •What part of the leaf releases gasses and water vapor?•What are the two pathways by which water enters roots?