module 2 Flashcards
cellular respiration
- mitochondria
- glucose + oxygen → carbon dioxide + water + energy (ATP)
photosynthesis
chloroplasts
carbon dioxide + water → (in the presence of sunlight) oxygen + glucose
what do autotrophs need
carbon dioxide
- produce food themselves
what do heterotrophs need
oxygen for cellular respiration
root system
- absorbs water and nutrients for plant growth
types of roots
tap root and fibrous
root hairs
increases surface area for absorption
fine like hari structures
root nodules
- found on legumes
-Home for nitrogen fixing bacteria → found places with low nitrogen
root tip
- Protective cover for the root
Specialised cells → statocytes (enable plant to detect gravity → dense organelles that sink to the bottom and indicate which way gravity is pulling)
function of the stem
Support for leaves, flowers and fruits
Transport of fluids between root and leaves
Storage of nutrients
Production of new living tissue
vascular bundle
bundle made up of fluid and nutrient transport tissue –> xylem and phloem
xylem
- mineral ions and water
- dead cells arranged to produce a continuous hollow tube
walls strengthened with lignin - unidirectional
- occurs at root hairs –> moves up the stem –> photosynthesis in the leaves –> the rest exits through the stomata
- transpiration pull brings it up
TACT
- transpiration adhesion cohesion tension model
- explains the movement of water and dissolved mineral ions in plants
1. water and ions diffuse through the soil into root hairs
2. water moves up the stem due to the transpiration pull
mechanisms that support: - capillary action –> narrowness of xylem tubes
- cohesion –> hydrogen bonding of water molecules
- adhesion –> attraction between water molecules and the xylem wall
- potometer
transpirational pull
a force caused by water draining out of the stomata and needing tto replace water in the leaves
phloem
- Transports dissolved nutrients and sugars
- sieve tubes and plates
- companion cells
- bidirectional
sieve tubes
series of joined end to end with sieve plates –> transports sugars
companion cells
actively transports sugars in and out of the phloem
- has a nucleus
- Unloading and unloading of nutrients in and out of of the sieve elements
- pressure flow hypothesis
Pressure flow hypothesis:
- Process responsible for the movement of sugar through the phloem
- Allows dissolved nutrients and sugars to be translocated from the source (site of sugar production) to the sink (site of sugar removal/use)
- Energy comes from companion cells
- glucose is converted into sucrose
- sucrose is loaded into the sieve tubes
- water follows the sucrose and moves into the phloem tissue by osmosis
- due to the low concentration of water in phloem active transport - high water pressure at the source forces the phloem sap to move towards the sink –> roots –> moves from one sieve cell to another
- after it reaches the root the sucrose is unloaded into the root svia active transport
- water returns to the xylem due to high concentration in phloem and not xylem
external leaf structure
- petiole
- veins
- leaf blade
internal leaf structure
- upper epidermis
- palisade mesophyll
- spongy mesophyll
- lower epidermis
palisade mesophyll
Contains chloroplasts and elongated in shape
Photosynthesises and contains chlorophyll
Closer to the upper epidermis as it can catch more sunlight which increases the rate of photosynthesis
spongy mesophyll
Contains chloroplasts but not as much
Loosely packed and large air spaces around them
Oxygen and carbon dioxide can easily diffuse through
upper and lower epidermis
Tightly packed layer of cells
Reduces water loss
Has stomata
gas exchange in plants
simple: moss and alge
larger –> specialised gas exchange system
- oxygen leaves through mesophyll
- water vapours leave through xylem
and stomata
- lenti