unit 2 cont. Flashcards
(23 cards)
morphology of plants
shoot and root systems
vascular tissues
shoot system
- consists of stems, leaves, and flowers with internal pipelines for conduction
- stems are frameworks for upright growth and display of flowers
leaves have photosynthetic cells
flowers are displayed to attract pollinators
roots functions
anchoring the plant
absorbing minerals and water
often storing organic nutrients
stomata
on underside of epidermis
small pores flanked by guard cells (open/close)
allow CO2 exchange between the air and the photosynthetic cells in a leaf
also lose water
epidermal tissue
stomata is found in epidermis
each stoma is made up of two guard cells that enclose a pore called a stomata pore
ground tissue
site of photosynthesis
vascular tissue
veins
xylem and phloem
supply mesophyll with water and nutrients
move sugars to rest of plant
steps of transport in plants
- roots absorb water and dissolved minerals from soil
- water and minerals are transported upward from roots to shoots as xylem sap
- transpiration, the loss of water from leaves (mostly from stomata)
- through stomata, leaves take in CO2 and expel O2. the CO2 provides carbon for photosynthesis. Some O2 produced by photosynthesis is used in cellular respiration
- sugars are produced by photosynthesis
- sugars are transported as phloem sap to roots and other parts of the plant
- roots exchange gases with the air spaces of soil, taking in O2 and discharging CO2.
osmosis
allows for uptake of water across cell membranes
proton pumps
create a hydrogen ion gradient that is a form of potential energy that can be harnessed to do work
contribute to a voltage known as membrane potential
how do proton pumps
plant cells use energy stored in the proton gradient and membrane potential to drive the transport of many different solutes
water potential
a measurement that combines the affects of solute concentration and pressure
- determines direction of water
water flows from regions of high water potential to regions of low water potential
how does solute affect water potential
addition of solutes reduces water potential
aquaporins
transport proteins in the cell membrane that allow the passage of water
increase rate of water movement
how does water travel up the roots
water enters plant through the epidermis of roots and flow through the xylem
- plants lose an enormous amount of water through transpiration, and transpired water must be replaced by water transported up from the roots
root pressure
upward push of xylem sap
stomata closing
potassium ions move out of the vacuole and out of the cells, and water potential in cell increases. Water moves out of the vacuoles, following potassium ions
the guard cells shrink in size and the stomata closes
stomata opening
potassium ions move into the vacuoles, water potential decreases. Water moves into the vacuoles, following potassium ions
the guard cells expand and the stomata opens
guard cells
cells that surround the stomata
^ open and close the stomata
allows CO2 to enter for photosynthesis and releases O2
How does K+ enter the cell and leave
using the proton pump
- guard cells pump protons out (when activated by light)
when H+ leaves out the cell, electrochemical gradient is created which drives K+ into the cell, where it accumulates
increase in internal K+ changes solute potential driving water in and increasing turn or
factors influencing guard cell
light - stomata generally closed at night, preventing unnecessary water loss when too dark for photosynthesis
- uptake of potassium ions - changes potassium ions
- Level of CO2 in leaf air space
Internal clock
how does level of CO2 in leaf air space affect guard cell movement
less CO2 opens the stomata
how does internal clock influence guard cell
daily rhythm due to regulation of cell preocesses in eukaryotic cells
