| ultrastructure of plant cells | cell wall
chloroplasts
amyloplasts
vacuole
tonoplasts
plasmodesmata
pits
middle lamellae
nucleus |
| cell wall in plant cells | made of cellulose
made up of middle lamellae which is made of calcium pectate
provides structure, support and shape to the plant cell |
| chloroplasts | site of photosynthesis
contain stacks of thylakoid called grana which contain chlorophyll |
| amyloplasts | organelles surrounded by a double membrane which contain amylopectin
stores starch |
| vacuole | contains cell sap
surrounded by a tonoplast (single membrane)
provides structure and support to the cell
also helps maintain water balance |
| tonoplasts | cytoplasmic membrane that surrounds the vacuole
regulates the movement of substances around the cell
isolates harmful material |
| plasmodesmata | extension of the cytoplasm between adjacent cell walls
it is involved in the transport of substances between cells |
| pits | depressions (holes) in the cell wall
act as channels for water and mineral transport between adjacent cells |
| middle lamellae | layer that cements two neighbouring plant cells together
made up of calcium and magnesium pectates |
| how does the structure of starch relate to its function? | insoluble - no osmotic effect
branched - can be easily broken down
compact - so can be stored in large amounts |
| features and function of cellulose | main structural component of plant cell walls
high tensile strength
made up of beta glucose
only contains 1-4 glycosidic bonds
forms microfibrils which are joined by hydrogen bonds (occurs between OH groups)
alternating pattern of inverted glucose molecules
straight and unbranched |
| why are plant fibres useful to humans? | sustainable renewable resource
biodegradable
they are very strong - make ropes and fabrics
cheaper than oil-based products
starch can be used to make bioplastics and bioethanol |
| sclerenchyma fibres | lignified
made of dead cells
has a hollow lumen and end walls
provides structural support to the plant |
| xylem vessels | transport water and minerals
provide structural support to the plant
lignified
made of dead tissue |
| phloem vessels | transport nutrients and food substances
involved in translocation
made of living cells
made up of sieve tube elements and companion cells |
| importance of nitrate ions in plants | makes up amino acids which make proteins
also make up DNA and RNA nucleotides |
| importance of calcium ions in plants | make up the plant cell wall
form calcium pectate |
| importance of magnesium ions in plants | involved in chlorophyll production
activate some plant enzymes |
| importance of water in plants | important for photosynthesis
maintains plant structure
transports substances
thermoregulation |
| investigate plant mineral deficiencies | plant seedlings - same age, same source
nutrient broths each lacking a mineral
cover test tube with foil to prevent light entering
experiment occurs over a week so some change is observed
same temperature, same light intensity, same volume of nutrient broth used |
| lack of nitrate ions | stunted growth, yellow leaves, dead leaves |
| lack of calcium ions | stunted growth, yellow crinkly leaves, dead leaves |
| lack of magnesium ions | slowed growth, yellow leaves |
| determine the tensile strength of plant fibres | source of fibre should be soaked to allow easy extraction of the fibres
attach fibre to clamp and hook to other end of fibre
add weights to the hook gradually until fibre breaks
record weight fibre broke at
repeat this for different fibres obtained many times to find the mean averages |
| describe William Withering's drug test | potential substance identified but not as a single active ingredient
trial on small group of patients with the disease
large group of patients trial also with the disease
dosage refined and method of extraction improved
general use |
| differences between modern drug testing and Withering's testing | preclinical trials
use of animals
placebo used
double blind trial
more ethical
proper approval of use of drug
healthy volunteers used |
| investigate the antimicrobial properties of plants including aseptic techniques | grind some garlic or mint in a mortat and pestle
squeeze out the juice with muslin
soak small paper disk into the garlic/mint solution for 20 mins
heat forceps on a bunsen burner to get rid of excess bacteria
use forceps to place a garlic/mint disk into agar plate of e.coli
use disk soaked in distilled water for control
incubate e.coli at 25 degrees for a few days
measure the diameter of each clear zone
repeat to calculate mean |
| conservation | preventing the extinction of critically endangered organisms |
| genetic diversity | the total number of genetic characteristics in the genetic makeup of a species |
| role of zoos | conservation
research
education |
| methods used for conservation | studbooks
captive breeding programme
seedbanks
reintroduction into the wild |
| captive breeding programme | endangered animals are captured and taken into zoos
zoos encourage breeding between species of captured animals to increase the population
once the population is sufficient animals are reintroduced back into the wild
risk of genetic drift |
| genetic drift | when in a small population allele frequency changes due to a chance event |
| why is genetic drift bad? | reduces genetic diversity
weaker organism so more likely to die
population reduces as a result |
| seed banks | seeds placed in low temp, dry conditions to stop growth
periodically tested for viability
conserves genetic diverstiy |
