TOPIC 4: Natural Resources Flashcards
What organelles present in animal cells aren’t in plant cells?
centrioles
lysosomes
What organelles do plant cells have that animal cells don’t?
cell wall; vacuole and tonoplast; chloroplasts; pits; plasmodesmata; amyloplasts; middle lamella
Describe the structure of chloroplasts
biconvex shape;
double membrane
Describe the function of chloroplasts
site of photosynthesis
What are amyloplasts?
starch storage inside chloroplasts
What’s the function of the vacuole?
waste, food and water storage;
turgor pressure supports plant
What’s the tonoplast?
vacuole membrane
What is the middle lamella made of?
pectin
What’s the function of the middle lamella?
layer between cell walls which keep cells together for stability
What are pits?
pores in cell walls that allow movement of fluid between cells
What is plasmodesmata?
channels of cytoplasm through cell walls which transport substances between cells
How are plasmodesmata formed?
ER trapped between newly divided cells at pits
How are cellulose chains made?
condensation reaction between -OH groups on the 1st & 4th carbon on B-glucose, forming 1,4-glycosidic bond
How do microfibrils form?
H bonds between -OH groups in neighbouring cellulose chains
How is tensile strength related to the arrangement of cellulose?
many cellulose molecules;
criss-cross arrangement provides strength in both directions;
embedded in pectin and hemicellulose, which act as a glue - prevents sliding over each other
What’s sclerenchyma?
ground tissue (dead cells) with rigid and thick lignified walls for plant support
What’s parenchyma?
packing tissue providing mechanical support
What’s phloem?
made of sieve tube elements & companion cells;
translocation of sugars and amino acids
What are sieve tube elements?
living cells with perforated ends (sieve plates);
bidirectional flow;
few organelles
What are companion cells?
has cytoplasms with solutes, providing substances for phloem & metabolic function;
pores for transport to phloem
Describe the structure of xylem vessels
dead hollow cells from autolysis;
perforated ends so water can pass;
lignified secondary cell walls as well as cellulose cell wall;
pits that allow lateral movement
What’s the function of xylem vessels?
transport of water and minerals
What causes transpiration?
evaporation due to the hydrostatic pressure gradient;
higher pressure at the bottom of the plant
Describe the process of transpiration
high WP in soil and low in root hair cell so water moves in by osmosis;
water travels up xylem (transpiration stream);
water diffuses out of stoma due to evaporation from sun;
water replaced by capillary action
Why doesn’t the transpiration stream break?
cohesion between water molecules due to dipole nature of water
How are root hair cells adapted?
large SA due to hair-like projections
Why is water important to plants?
transporting mineral ions (solvent properties);
providing water to keep cells turgid (stability);
photosynthesis;
cooling the leaves
What is nitrate used for in plants?
amino acids,
chlorophyll,
ATP
What are the signs of a nitrate deficiency?
stunted growth,
yellow leaves
What is magnesium used for in plants?
chlorophyll
What are the signs of a magnesium deficiency?
yellow leaves
What is phosphorus used for in plants?
DNA,
ATP
What are the signs of a phosphorus deficiency?
purple leaves,
stunted growth
What is calcium used for in plants?
cell wall;
membrane permeability
What are the signs of a calcium deficiency?
stunted growth, especially at leaf margins
Why can plant fibres be used for ropes and clothing?
long and thin,
flexible,
strong
How are plant fibres extracted?
mechanically pulling out fibres;
digesting surrounding tissue (hemicellulose) by bacterial enzymes
Why are biocomposites sustainable?
renewable - available for future generations;
biodegradable
What are the disadvantages of plant fibres?
replace food crops;
energy demanding in production and transport;
don’t always have the same desirable qualities
What are the antibacterial properties of garlic?
allicin interferes with lipid synthesis and RNA production, killing bacteria
Describe the stages of bacterial growth
- lag phase - cells adjust to conditions by enzyme synthesis
- log phase - cells divide exponentially
- stationary phase - growth limited by factors
- death phase - cell deaths > cells formed
What are the ideal conditions for bacterial growth?
sufficient nutrients; optimum temperature; optimum pH; no build up of toxins; sufficient O2 for aerobic bacteria
Describe Withering’s drug development
- potential substance identified
- trial on a small group of people and then large
- dosage refined due to near death
- publication of treatise
Describe the stages of modern drug development
- active ingredient identified to be manufactured synthetically
- pre-clinical testing in animals to assess safety
- PHASE 1 trials - small group of healthy volunteers to assess absorption, digestion and doses
- independent review of data
- PHASE II trials - small group of patients to assess efficacy
- PHASE III trials - large group of patients with placebo, random assignment and double blind trial
- licensing for use
What are the advantages of modern clinical trials?
fewer side effects, safer
What are the disadvantages of modern clinical trials?
expensive, time-consuming
What is a placebo and why is it used?
pill without the active ingredient;
control experiment to show that effect is due to the active ingredient
Why is double blind testing used?
doctor and patient don’t know who has the placebo;
avoids researcher from influencing outcome
Why is random assignment used?
removes bias in assigning to a particular group
What’s an endosperm?
starch and lipid storage
Which seeds are not endospermic?
dicotyledons - embryo absorbs stored nutrients and food is stored in the cotyledon
What is the testa?
seed coat protecting embryo;
lignified outer ovule layer
How do seeds germinate?
- water taken in through pore in testa
- metabolic changes triggered and plant growth substances are made
- amylase breaks starch down into glucose and then sucrose for transport to radicle and plumule
How is starch foam made?
- water evaporates when heated, steam causes pressure to rise
- seed explodes and starch gelatinises when it absorbs water
- water creates bubbles in jelly, creating 3D foam
What are the uses of starch?
paints, plasters, cloth treatment
How are super-absorbents made?
made with chemically cross-linked starch
