Resources from plants - Topic 4B

Measuring tensile strength of pant fibres

- Attach the fibre to a clamp stand and hang a weight from the other end. - Keep adding weights one at a time until the fibre breaks. - Repeat with diff samples of the same fibre and calculate mean of results which reduces effect of ransom error ^ precision of results. - Fibres being tested should always be same length unless testing effect of length on TS. - All other variables like temp and humidity must be kept constant. - Safety - wear goggles and leave area where weights will fall free. - Could investigate different thicknesses, age or length.

Conditions for bacterial growth

- Bacteria need a source of nutrients so they can respire and grow. - If they rely on aerobic respiration so they'll need oxygen. - Temp + pH are important, if too high or low it will effect enzyme activity so metabolic processes can't take place normally.

Human use plant fibres

- Because they're strong - use for useful items like rope or fabrics like hemp. - Made up of long tubes of plant cells e.g. sclerenchyma fibres. - 2 main reasons - the arrangement of cellulose microfibrils in the cell wall and the secondary thickening of cell walls.

Plasmodesmata

- Channels in the cell walls that link adjacent cells together. - Allow transport of substances and communicate between cells.

Starch contribution to sustainability

- Found in all plants - potatoes and corn are particularly rich in starch. - Plastics usually made from oils but can be made from plant based materials like starch - bioplastics. - More sustainable than oil because less fossil fuel is used up and crops from which the starch came from can be regrown. - Vehicle fule is also usually oil but can make it from starch - bioethanol for eg. - More sustainable as less fossil fuels are used up and same as above.

Xylem vessels

- Function is to transport water + mineral ions up the plant and provide support. - They're v long tube like structures formed from dead cells joined end to end. The tubes are found together in bundles. - The cells are longer than they are wide, they have hollow lumen + no cytoplasm and have no end walls. - This makes an uninterrupted tube allowing water + mineral ions to pass through the middle easily. - Their walls are thickened with a woody substance lignin which helps support the plant. - Water and mineral ions move into and out of the vessels through pits in the walls where there is n lignin.

Calcium ions for plant deficiency

- Important components in plant cell walls. They're required for plant growth.

Placebos

- In p2 patients are split into 2 groups. One is given drug other gets a placebo, an inactive substance that looks exactly like the drug. Patients often show a placebo effect where they show some improvement because they believe they're receiving treatment. Allows scientists to see if drug actually works - compare to placebo.

Testing drugs used to be trial and error

- In past drug testing was lot less scientific than modern clinical trials: - William Withering (digitalis soup0 was a scientist in the 1700s. Discovered that an extract of foxgloves could be used to treat dropsy (swelling brought about by heart failure). This extract contain drug digitalis. - Made a chance observation - patient suffering from dropsy made a good recovery after being treated with a traditional remedy containing foxgloves. He knew foxgloves were poisonous so started testing different versions w/ diff conc of digitalis = digitalis soup. - Too much digitalis poisoned his patients, too little had no effect. - It was through this crude method of trial and error that he discovered the right amount to give a patient.

Starch

- Main energy storage in plants. - Cells get energy from glucose. Plants store excess glucose as starch when a plant needs more glucose for energy it breaks down starch to release the glucose. - Starch is a mixture of 2 polysaccharides of alpha glucose - amylose and amylopectin. - Amylose - long unbranched chain of a-glucose. Angles of glycosidic bonds = coiled structure like a cylinder. This makes it compact so its good for storage because you can fit more in a small space. - Amylopectin - long branched chain of a-glucose. Side branches allow enzymes that break it down to easily access glycosidic bonds = released quickly. - Starch is insoluble in water so it doesn't cause H2O to enter cells via osmosis = swelling = good for storage.

Cellulose

- Major component for cell walls in plants. - Cellulose is made of long unbranched chains of B-glucose joined by 1-4 glycosidic bonds. - Glycosidic bonds are straight so cellulose chains are straight. - Between 50 - 80 cellulose chains lined together by large number of hydrogen bonds to form strong threads = microfibrils. The strong thread = cellulose used for structural support for cells.

Tensile strength

- Maximum load it can take before it breaks. - Knowing it is important especially for uses like rope for rock climbing.

Plants need water and inorganic ions to grow

- Need water and minerals for diff functions, absorbed through roots and travel through xylem. If there isn't enough minerals there will be deficiency syndromes.

Plants antimicrobial properties ex

- On sheet - remember to use glass beads to spread bacteria and keep in 20-30 degrees not 37 as this humans. Photo on phone.

Double blind experiment

- P2 + 3 are usually double blind, where neither patients nor doctors know who's been given the new drug and placebo or old drug. Reduces bias in results as attitudes towards patients and doctors won't effect results, s/a thinking someone may have improved more as they took the drug but they haven't.

Aseptic techniques to prevent contamination

- Prevents contamination of unwanted microorganisms. Important as contamination can affect the growth of the microorganisms + avoid human pathogens. - Use the following aseptic techniques: - Close windows and doors to prevent draughts disturbing air. - Regularly disinfect work surfaces to minimise contamination. - Work near a bunsen flame - hot air rises so any microbes in air should be drawn away. - Sterilise wire inoculation loop before and after each use by passing it though hot bunsen flame for 5s. - Briefly flame neck of glass container of broth just after its opened and before its closed causing air to move out of the container preventing unwanted organisms falling in. - Sterilise glass wear before and after use in autoclave (steams equipment at high pressure).

Modern drug testing is more rigorous

- Protocols are much more controlled, computers and models are used and carried out on human tissues in lab then tested on live animals before clinical trials on humans.

Pits

- Regions of the cell wall where the wall is very thin. They're arranged in pairs - the pit in one cell is lined up with a pit in another. - Allow transport of substances between cells.

Cell wall

- Rigid structure that surrounds plant cells - made mainly of the carb cellulose. - Supports plant cells.

Plant fibres contribution to sustainability

- Ropes and fabrics can be made of plastic from oil, but can also be made from plant fibres. - More sustainable from plants as less fossil fuel is used up and crops regrown to maintain the supply for future. - Products made from plant fibres are biodegradable and can be broken down by microbes unlike most oil-based p. - Plants are easier to grow and process than extracting and processing oil. This makes them cheaper and its easier to do in developing counties as less tech and expertise needed.

Chloroplast

- Small flattened structure surrounded by a double membrane and has membranes inside called thylakoid membranes. These are stacked up in some parts of the chloroplast to form grana - linked together by lamellae, thin flattened pieces of thylakoid membrane. - The site where photosynthesis takes place. Some parts of photosynthesis happen in the grana, and others in the stroma (thick fluid found in chloroplasts.)

Amyloplast

- Small organelle enclosed by a membrane. They contain starch granules. - Storage of starch grains - they also convert starch back to glucose for release when the plant requires it.

The arrangement of the cellulose microfibrils in the cell wall

- The cell wall contains cellulose microfibrils in a net-like arrangement. - The strength of the microfibrils and their arrangement in the cell wall gives plant fibres strength.

Sclerenchyma fibres

- The function of S fibres is to provide support, they are not involved in transport. - Like xylem vessels, they're also made of bundles of dead cells that run vertically up the stem. - The cells are longer than they are wide ad have a hollow lumen but unlike xylem vessels they have end walls. - Their cell walls are also thickened with lignin but they don't contain pits, they have more cellulose than other plant cells too.

Phloem tissue

- The function of the phloem tissue is to transport solutes (mainly sugars like sucrose) from where they're made in the plat to where they're needed - translocation. - Like xylem, phloem is formed from cells arranged in tubes. But unlike xylem, its purely transport tissue - it isn't used for support as well. - Phloem tissue contains diff types of cells including sieve tube elements and companion cells. - Sieve parts are the end walls which have lots of holes in them to allow solutes to pass through. - Unusually for living cells, sieve tube elements have no nucleus, v thin layer of cytoplasm and few organelles. The cytoplasm of adjacent cells is connected through holes in sieve plates. - Lack of nucleus and other organelles means sieve tube elements can't survive on their own, so theres a companion cell for every sieve tube element. - Companion cells carry out other living functions for example both themselves and their sieve cells. For example they provide the energy for active transport of solutes.

Primary lamella

- The outermost layer of the cell. - This layer acts as an adhesive, sticking adjacent plant cells together + gives stability.

Dissecting plants

- Use scalpel to cut cross section as thinly as possible + use tweezers to gently place in water to prevent drying out. - Transfer to dish containing stain e.g. TOB and leave for 1 min - stains lignin blue-green to see xylem and sclerenchyma and phloem cells + rest should = pinkish. - Rinse off sections in water and mount to slide.

Sustainable practices dont deplete recourses

- Using recourses in a way that meets the needs of the present generation without messing up for future generations. - Use renewable resources = sustainable. - RR = something we can use indefinitely without running out - plants are renewable recourses as they're harvested and regrown. Fossil fuels are not. - Example of sustainable practice - replacing trees after logging, when ones cut down plant a new one. - Unsustainable practices can't continue indefinitely - they will eventually run out - oil-based plastics like polythene via fossil fuels.

Vacuole and tonoplast

- Vacuole is a compartment surrounded by a membrane called a tonoplast. - The vacuole contains the cell sap, which is made up of water, enzymes, minerals and waste products. Vacuoles keep the cells turgid - this stops plants wilting. They're also involved in the break down and isolation of unwanted chemicals in the cell. Tonoplast controls what enters and leaves the vacuole.

The secondary thickening of cell walls

- When some structural plant cells (lie sclerenchyma and xylem) have finished growing, they produce a secondary cell wall between the normal cell wall and the cell membrane. - The secondary cell wall is thicker than the normal cell wall and usually has more of a woody substance called lignin. - The growth of a secondary cell wall is called its secondary thickening. - Secondary thickening makes plant fibres even stronger.

Vascular bundles

- Xylem and phloem are found here. - In the stem, the xylem vessels group together with phloem tissue to form vascular bundles. Sclerenchyma fibres are usually associated with VB. - Transverse cross section + longitudinal cross section (see photos on phone).

3 stages of clinical testing

1 - Involves testing a new drug n a small group of healthy individuals. Its done to find out things like safe dosage, if there are any side effects, and how the body reacts. 2 - If drug passes 1 then it will be tested on a larger group of people (patients) to see how well the drug actually works. 3 - During this phase the drug is compared to existing treatments. It involves testing the drug on hundreds or thousands of patients. Using a large sample size = reliable results. Patients are randomly split into two groups. One receives the new treatment and other recipes existing to see if new = better.

Water for plant deficiency

Needed for photosynthesis, to transport minerals, to maintain rigidity when water exerts pressure on the cell vacuole and regulate temp when water evaporated from leaves to cool plants down.

Nitrate ions for plant deficiency

Needed for production of DNA, proteins (+enzymes) and chlorophyll. They're required for plant growth, fruit production and seed production.

Magnesium ions for plant deficiency

Needed for production of chlorophyll - pigment needed for photosynthesis.

Investigating plant mineral deficiencies

on sheet