Structure & Function of Plants
Photosynthesis
important biological process
Theories, Hypotheses & Models
Theories
a well-substantiated & comprehensive set of ideas explaining a phenomenon in nature
based on large amounts of data & observations collected over time
Hypotheses
Models
an inferred explanation of an observation or research finding
more exploratory in nature than theories --> based on existing scientific knowledge
hypothesis becomes a model after testing
some only valid in specific instances
Transpiration-Cohesion-Tension theory
movement of water from soil, through xylem & into air by evaporation
water molecules are cohesive --> attracted to other water molecules
transpiration pull --> pulls water from roots to leaves, to replace evaporated water
xylem vessel walls
producing collectively huge total SA
water molecules attracted to surfaces & carry other molecules upwards with them
tension --> xylem vessels consist of fused cells
create continuous tube for unimpeded flow of molecules
how plants produce own food/energy
need sunlight, carbon dioxide & water to survive
produces oxygen and glucose
(late 1770s) scientist Ingenhousz
experiments w/ submerged plants in both sunlight & shade
noticed small bubbles produced by plants in sunlight, but not by plants in shade
conclusion: plants use light to produce oxygen
carbon dioxide + water --sunlight / chlorophyll--> glucose + oxygen
leaves have stomata
allow exchange of gases in/out of leaves
guard cells control opening/closing of stomates
Source to Sink theory
sugars produced at source cells are actively transported into phloem
creates high concentration of solutes within sieve tubes
movement of glucose, proteins, and nutrients in phloem
photosynthesis products
Structure
plant body
stems, roots & leaves
transport water, minerals & sugars produced by photosynthesis
Scientists
investigate & build upon each other's discoveries
perform experiments to find out what & how things happen
investigations by scientists
began w/ experiments in 17th century --> Van Helmont
Priestley & Ingenhousz built upon Van Helmont
theory has been developed by investigations from scientists over many years
John Joly
Henry Horatio Dixon
Stephen Hales
Eugen Askenasy
Steven Jansen
H/ Jochen Schenk
Jean Senebier
Nicolas-Theodore de Saussure
F.F. Blackman
Cornelis van Niel
Samuel Ruben
Martin Kamen
Melvin Calvin
consist of cellulose each with own surface