Topic 4 Flashcards
List the organelles that are only found in a plant cell?
- cellulose cell wall
- middle lamella
- plasmodesmata
- pit
- amyloplast
- tonoplast, vacuolar membrane
- vacuole
- chloroplast
What is the function of a chloroplast
Site of photosynthesis
What is the function of amyoplasts?
Storage vacuoles containing starch
What is cellulose made of?
Beta glucose monomers joined by 1,4 glycosidic bonds in a condensation reaction
Describe microfibrils
- make up the cell wall
- made of cellulose chains joined by hydrogen bonds between side groups
- arranged at angles, in net shape, for strength
- laid parallel for flexibility
- microfibrils are held together by hemicellulose and calcium pectate (pectins)
Describe plasmodesmata
Narrow cytoplasm filled channels that cross cell walls
What is the difference between a pit and plasmodesmata?
A pit has a thin cell wall, plasmodesmata don’t
Is cellulose a branched molecule/
No
What is secondary thickening?
When lignin is added to the cell wall
What is found in a vascular bundle/
- xylem vessel
- phloem sieve tubes
- sclerenchyma fibres
- cambium - unspecialised stem cells
Describe the xylem structure
- lignified, lignin found in spirals and strings for strength and flexibility, water proofs the cell, secondary strengthening
- have absent cell walls
- have pits, allows lateral movement of water
- hollow, no cytoplasm
What does xylem transport
Water and mineral ions
- via transpiration ONE WAY
Describe autolysis
Cell organelles are broken down by the action of enzymes, leaves dead empty cells that form a tube
Describe the 5 stages of transpiration
- water vapour diffuses out through the stoma down a diffusion gradient
- water evaporates from the surface of cells lining the substomatal cavity, water moves by osmosis across the leaf, from cell to cell
- water replaced by Dan’s of capillary action within the cell walls
- water is drawn out of the xylem
- a continuous column of water is drawn up through the xylem
Define the transpiration stream
Unbroken chain of water molecules
Describe cohesion
- attraction between like molecules
- hydrogen bonds between the water molecules
Describe adhesion
- attraction between unlike molecules
- hydrogen bonds form between water molecules and the OH groups of the cellulose cell wall
Describe cohesion-tension theory
Water is linked by cohesion and is pulled up under tension
Water moves thorugh the xylem tube by ___________.
Mass flow system
Describe the phloem
- comprised of sieve tubes and companion cells
- a sieve tube element is a section of phloem with sieve plats at the end
- is alive
- TWO WAY
The phloem transports ________ via __________
- sucrose and water
- translocation
describe the movement of sucrose in a plant
- sugars are produced at source
- transfer cells actively pump sucrose into phloem against concentration gradient
- water is drawn into phloem via osmosis due to increased solute concentration, increasing hydrostatic pressure
- diffusion- down a conc.gradient by mass transport
- sucrose is then actively unloaded into transfer cell then sink
- water osmoses back into xylem
The plant stem relies on ________, fully ____________ parenchyma cells to maintain its shape and keep it upright
- tightly packed
- turgid
What is the plant stem comprised of?
- parenchyma- provide support
- vascular bundles
- epidermis
- collenchyma tissue- strength
What are calcium ions used for?
- calcium pectate in cell wall
- middles lamella
What are magnesium ions used for?
- chlorophyll
- nucleic acid synthesis
What are nitrate ions used for?
- making amino acids
- chlorophyll, nucleic acids, atp, growth hormones
What are phosphate ions used for?
- nucleic acid
- ATP
- phospholipids
- NADP- co enzyme
Why do phloem have companion cells/
Provide metabolic support
What can starch from seeds be used for/
- stiffening agents
- thickening agents
- super absorbants
- starch foam
Define sustainable
-a resource that can be renewed and will not run out for future generations
Plants are renewable as the can be _________
Regrown
Plants _________ so wont contribute to _________
Biodegrade/decompase
Landfill
How do bacteria reproduce?
Binary fission
- asexual reproduction resulting in identical cells
What are the conditions required for growth?
- optimum temperature
- optimum pH
- optimum oxygen (if needed)
- optimum concentration of glucose
- moisture/water- for hydrolysis
- no build up of waste products
Describe the phases of bacterial growth
Lag phase
- no increase in cell number as cells adjust to conditions
Log/exponential phase
- cell number increases exponentially at the fastest rate possible
Stationary phase
- no change n cell number, when cell formation=cell death
Death phase
- cell number decreases as cells die due to change conditions of run out (of space)
Define antimicrobial
The ability to kill microorganisms
Define generation time
Hw long it takes between new cells forming and cell division
What did William withering do?
- found foxglove/ digitalis
- did no test on healthy volunteers
- did not have placebo or double blind
What happens in pre-clinical testing
- tissue cultures and animal testing
- assess safety and efficiency
- several years
Describe phase one of clinical trials
- small group of healthy volunteers
- safer y and doses
Describe phase II clinical trials
- on volunteer patients
- 100-300
- look at effectivnss
Describe phase 3 clinical trials
- patients in two groups
- 1000-3000
- placebo and double blind used
- control group for comparison
- efficacy
Describe phase 4
- after licensing
- trial continue of wider public
Define placebo
An inactive compound or the original drug
Define double blind trial
When neither the doctor of the patient know if the drug is being taken or if the placebo is
