All Hard Questions Flashcards
What are polymers
Long chains of molecules that are made up of identical, smaller monomers
How to show polymer repeated unit
- Lines must cross brackets
- n to show long number
- carbon must have single bonds (usually have double tho)
Why is high melting and boiling point of polymers
- large amount of covalent bonds that requires energy to break
- however despite having weak intermolecular forces, due to the large number of them, energy also used to break those
that’s why they also solid at room temp
Thermosoftening
- Thermosoftneing melt when heated
- due to weak intermolecular can break bonds and reshape to cool
- can go back into solid
Thermosetting
- do not melt when heated
- due to strong cross links between molecules, do not break due to high temperatures
What can nanoparticles be used for
-catalysts (high sa:v)
- medicine (small enough to deliver to body cells)
- used in electric components
- surgical equipment (can reduce chance of infection/sterilise)
Dangers of nanotechnology
- relatively new/ recent discovery = haven’t learnt/ understood effect on body
- they are so small = could be breathed in, absorbed by skin
- due to high sa:v toxic substances can stick and be absorbed in body
Why is alveoli good exchange surface
- high sa, larger rate of diffusion of oxygen and co2 in and out of blood
- thin walls - decreases the distance of travel and faster rate
- good supply of oxygen - increasing the concentration gradient
- permeable = to allow gases to dissolve
How is villi adapted
Increase sa of intestines = easily absorb nutrients such as glucose and amino acids
How to destarch plant
Place in boiling water to kill plant
Place in boiling ethanol (with water bath) to get rid of all chlorophyll
If iodine present will turn blu/black otherwise yellow/orange
How to test for chlorophyll
Place variegated (with chlorophyll only in some areas) and destarched
Place in sunlight
Places with chlorophyll will only photosynthesise and therefore will change colour
How to test light needed for photosynthesise
Take plant and cover a bit
Due to lack of light intensity, plant will not photosynthesise
Test for starch whereby covered = will remain yellow
Normal will be blu/black
How is co2 needed for photosynthesis
Place plant in covered area
Pit of soda lime with plant
This will absorb all co2 and water vapour
As reactants not available, photosynthesis will not occur
Will test for starch and will remain yellow
How is oxygen released in photosynthesis
Place an upturned plant in water with cut part facing up
Place with varying distances away from light source
Will collect different amounts of oxygen in gas cylinder
Can place glowing splint that will relight in presence of oxygen
How are hormones used to increase egg production
FSH given to stimulate egg production and mature eggs on ovaries
Also stimulates oestrogen - build up uterus lining to prepare for implantations
LH also given to trigger ovulation and carry eggs to uterus
What was mendels experiment and what did that prove
Crossed one tall plant with short - found all offspring was tall
Crossed one tall with another tall - found 75% was tall and 25% is short
- showed some characteristics in pea plants are determined by separate ‘inherited factors’ passed on from parents - genes
- can be dominant or recessive
How to observe specimens
- Place lowest objective lens
- Place lowest stage positions
- Place specimens on stage
- Use coarse focus to lift into highest resolution
- Use coarse focus to lower and make image clearer
- Use fine focus to make more detailed
- Use higher objective magnification and repeat
Why does water expand in solid state
When freezes, hydrogen bonds form
This creates lattice structure
Prevents water molecules to be packed together
Is less dense and takes up more space
Taking more results or average…
Reduces effect of random error on experiment so gives more precise results
Resistance in parallel/simple
Simple - resistance increases
Parallel - decreases as adds more loops
Staining cells
Methylene blue - easier to see animal nuclei
Iodine - easier to see plant cell wall and nuclei
Crystal violet - can see bacterial cell wall
Testing…
Benedict’s - used to test for sugars AND HEAT SOLUTION = is blue and turns red if +
Iodine - test for starch = is yellow and turns blue/black if +
Beirut - test for protein = mix with Na(OH) then test is blue and turns purple if +
Emulsion - test for lipids = mis with ethanol then pour into water if + will be very cloudy
How are radio waves created and transmitted
An oscillating potential difference makes electrons move back and forth
This creates a changing electric and magnetic field
When field in other metal, electrons move producing signal
EM waves form as radio waves and also in atoms
Light intensity equation
Light intensity = k/ distance (m) ^2
Why is it difficult to do brain activity
As nerve fibres are very close together, it is difficult to repair or follow one without affecting or damaging all. Also, activity and research on brain has ethical issues as it could result in permanent damage to the brain
What are stem cells
Stem cells are undifferentiated cells that are able to become differentiated and specialised to carry out specific jobs and roles
How do guard cells control rate of transpiration
Photosynthesis occurs in guard cells whereby it receives water and carbon dioxide to produce oxygen and glucose. However as it receives water, the guard cells through osmosis will go from high to low water potential, water moves into guard cells. The cells swell up and turgid which restricts the movement and diffusion of water from the stomata. Controls the amount of water lost by leaves and therefore the rate of transpiration
Why do scientists test for reproducibility/repeatability
To get similar results and make sure it is safe
How is glucose stored in a plant
- glucose used in respiration
- build up the cell wall with cellulose
- starch store
- fats and lipids for food store and growth
- sucrose and fructose (natural sugars of fruit)
- proteins for growth and repair
Plant cell structure
- waxy cuticle which acts as a hydrophobic layer to stop water (borne) fungi from direct contact and spreading disease to epidermal cells. Also barrier to prevent uncontrolled water loss
- epidermal cells are transparent to maximise light intentisty for photosynthesis on palisade cells
- palisade cells are full of chloroplasts and in a rectangular structure to maximise rate of photosynthesis
- spongy mesophyll with cavities to ensure gas exchange takes place
- guard cells which become turgid to alter shape of stomata and control water loss
- vascular bundle to provide support and structure to plants roots and stem
- xylem for transpiration and mineral ions and phloem for translocation and movement of sugars
Why should you recycle materials
- conserve raw materials and energy sources
- reduce release harmful substances in environment
- reduce waste
What factors influence material recycling
- how easily waste can be collected and stored
- amount and any byproducts released
- cost
- amount of energy used at each stage
What materials recycled
Metal - melted by heating and molten poured into moulds to create ingots
Paper - mixed with water, cleaned and rolled and heated to dry
Glass - melted and moulded into new objects
Polymers - melted and formed and moulded
How to reduce greenhouse emissions
- reduction of burning of fossil fuels
- use of renewables like solar, wind, geothermal
- carbon capture
Fresh water treatment
- water enters metal bar screen to get rid of large objects
- settlement talk to allow heavy sand and soil out
- aluminium sulphate and lime added to clump tog particles of dirt and removed as mud at landfill site
- water passes through another filter of fine sand to get rid of smaller particles
- water is clean but chlorine added to get rid of bacteria dissolved
- pH checked to neutral and pumped to schools, homes and offices
Solder process
Tin - 232
Copper - 1085
Solder composite - 227
Molten fills up gaps and cools quickly allowing to conduct electricity
Silver corrosion
Corrodes in H2S - hydrogen sulphide gas produced by bacteria but also with oxygen and water creating Ag2S
What are ceramics and it’s typical properties
Hard, non-metallic materials such as brick, China, glass and porcelain
- high mp
- hard and stiff but brittle
- poor conductors of heat and electricity
What is metabolic rate
The rate/ speed at which chemical reactions in cells transfer energy from it’s chemical store in food
Extraction of DNA from fruit
- mash up fruit with detergent and salt = detergent breaks down the cell membrane freeing DNA and salt makes DNA clump together
- drain and filter to get rid of insoluble debris of cells
- add ice-cold ethanol causing the DNA to precipitate = come out of the solution
- the white insoluble precipitate can be removed with a glass rod
Why do scientists peer review
- check if it is valid and correct
- suggest improvements
What does accurate mean
When measurements are close to the true value
What does precise mean
Giving similar results if you are repeating it
- gained with high resolution instruments
Why do scientists publish results
- gain recognition for work
- allow advancements in studies
How to alter concentration of CO2 in atmosphere for experiment
Use potassium hydrogen carbonate powder
Mass of atoms
Entities = mol * avo constant
Why is a heat sink used
- Absorbes heat and light intensity, which maintains and keeps temperature constant
- do not want to change temperature which would spoil experiment and only want to measure light intensity
How to prepare coverslip
- take slide and add sample
- add few drops of stain
- add cover slip 45 degrees on
- press and tap down to get rid of air bubbles
How to make sure microscopy is clean
- wear gloves
- do not leave sample out for long
- sterilise working surface
- wash hands if contaminated
