biology paper 2 + practicals Flashcards | Knowt (2024)

Practical 1 : Using a Light microscope to examine blood smears

Practical 2 : Dissection of a mammalian heart

Practical 3 : Dissection of a stem STEP 1

1. use a scalpel to cut a cross-section of the stem (transverse or longitudinal) as thinly as possible

Practical 3 : Dissection of a stem STEP 2

2. use tweezers to gently place the cut sections in water

Practical 3 : Dissection of a stem STEP 3

3. transfer each section to a stain toluidine blue o, stains the ligning in xylem walls blue-green, identify xylem structure

Practical 3 : Dissection of a stem STEP 4

4.rinse off the sections(so the pigment does not obstruct the speciment0 and mount onto a slide to view under the microscope

Practical 6: The effect of substrate/enzyme concentration on enzyme controlled reaction *catalase

Practical 7: Investigating the effect of temperature on amylase activity

*Practical 8: The effect of temperature on membrane permeability (beetroot experiment)

Practical 9: Determining glucose concentration

Method 1: Test strips and then compare to a chart

Practical 10: Using a potometer (Factors affecting transpiration rates)

Practical 11: The effect of antibiotics on bacterial growth

1. dip discs in antibiotics
2. place on bacterial culture
3. measure inhibition zone

Practical 12: Dilution plating to determine the density of microbes in liquid culture. **biotechnology and bacterial culture. (Factors affecting the growth of microorganisms)

Practical 13: Water potential of potato (The effect of solutions of different water potentials on plant/animal cells)

Practical 14: Osmosis in an artificial cell

like a potato but with different water potential in artificial cell and in surrounding solutions and no need to dry the

Practical 15: Rate of diffusion through a membrane (Factors aff ecting diffusion in model cells)

Practical 16: Qualitative testing for proteins

1. add a few drop sodium hydroxide solution
2. add equal volume of biuret solution
if protein is present the solution will turn from blue to purple

Practical 17: qualitative testing for lipids )Emulsion test

Practical 18: Qualitative testing for sugars (reducing and non-reducing)

Practical 19: Test for starch

1. add iodine
2. if starch is present it will turn from browny-orange to blue-black colour

Investigation into phototropism

1. Take nine wheat shoots. The shoots should be planted in individual pots in the same type of soil. The shoot should be roughly equal in height.
2. Cover the tips of the three shots with foil cap. Leave three shoots without foil. Wrap the base of the ifnal three shoots with foil, leaving only the tip expose
3. set up the shoots in front of the light source and leave them for two days. The shoots should all be the same distance from the lights source and experience the same intensity of light. All other variables including temperature and exposure to moisture, should be controlled.
4.By the end of the experiment you should be able to observe how the plans have changed in response to the light. The shoots with exposed tips should have grown towards the light source (positive tropism). Covering the tip with a foil cap prevents growth towards the light, it's the tip that's most sensitive to light and because it's covered the shoot should have continued to grow straight up. Covering the base of the shoot with foil should still allow the tip to grow towards the light.
5. Recording the amount of growth (in mm) , as well as the direction of growth, will give you quatitative results.

Investigations into Geotropism too

1. Line three Petri dishes with moist cotton wool.
You should use the same volume of water and the same amount of cotton wool in each dish
2. Space 10 cress seeds on the surface of the cotton wool in each dish, then push each one into the wool.
3. Tape a lid onto each dish and wrap each one in foil (this will prevent any light reaching the seeds and affecting your results).
4. Choose somewhere you can leave this dishes where the temperature is likely to be warmish and pretty constant e.g. cupboard.
5. Prop one dish. upright , at a 90 angle - label it and mark which way is 'up' (or down) . Place another dish on a slope at a 45 angle. Place the third dish on a flat, horizontal surface. You need to label the dishes carefully so you know which way up each one was when you come to unwrap the dishes at the end of the experiment.
6.Leave the seeds for 4 days. Then take a look at their shoot and root growth.
7. You should find that whatever the angle the dishes were placed at, the shoots have all grown away from gravity (negative geotropism) and the roots have grown towards gravity (positive geotropism).
8. To get quantitative results, measure the amount of growth of the shoots and root and the angle of growth.

Practical 21: Investigation into plant hormones (Auxin)

1. Plant 30 plants that are similar age, height and weight in pots
2. Count and record the number of side shoots growing from the main stem of each plant.
3. For 10 plants, remove the tip of the shoot and apply a paste without auxins to the top of the stem.
4. For another 10 plants, remove the tip of the shoot and apply a paste with auxins to the top of the stem
5. Leave the final 10 plants as they are - these are your controls. They are needed so you know that any effects observed is caused by the application of plant hormone auxin.
6. Let each group now grow for six days. You need to keep all the plants in the same conditions- the same, light intensity, water, temperature, etc. This ensures any variable that may affect your results are controlled, which makes your experiment more valid.
7.After six days, count the number of sides shoots growing from the main stem of each of your plants.
8. The results in the table show that removing the tips of shoots caused extra side shoots to grow, but removing tips and applying auxins prevented extra side shoots from growing.
9. the results suggest auxins inhibit the growth of side shoots- suggesting that auxins are involved in apical dominance.

Practical 21: Investigation into plant hormones (Gibberlins)

1. Plant 40 plants that are similar age, height and weight in pots
2. Leave 20 plants as they are to grow, watering them all in the same way and keeping them all in the same conditions - these are your controls.
3. Leave the other 20 plants to grow in the same conditions except a dilute solution of gibberlin.
4. Let the plants grow for about 28 days and measure the lengths of all the stems once each week.
5. You light get results a bit like these:
6. The results in the table show that stems grow more when watered with a dilute solution of gibberlin
7. The results suggest gibberlin stimulate stem elongation.
8.May have to calculate the rate of growth such as cm/day

Investigating the rate of respiration of yeast under aerobic and anaerobic conditions

Practical 22: Investigation into the respiration rate of yeast (Factors affecting the rate of respiration) ***respirometer

1. Set up the apparatus like on the diagram
2. Each tube contains potassium hydroxide solution (or soda lime) to absorb the carbon dioxide produced.
3.The control tube is set up in the exactly the same as the test tube, but without the woodlice, this is to make sure that any results observed are only due to the woodlice respiring. The control will usually contain some beads that are the same mass as the woodlice.
4. coloured fluid is then added to the manometer by dipping the end of the capillary tube into a beaker of fluid. Capillary action will make the fluid move into the tube. The syringe is then used to set the fluid to a know level.
5. The apparatus is left for a set period of time
6.During that time there'll be a devrease in the volume of air in the test tube due to the oxygen consumption of the woodlice ( all the Co2 produced is absorbed by the potassium hydroxide)
7. The decrease in the volume of air will reduce the pressure in the tube and cause the coloured liquid in the manometer t move towards the test tube
8. The distance moved by the liquid in a given time is measured. This value can then be used to calculate the volume of oxygen taken in by the woodlice per minute.
* remember you need to know the diameter of the capillary to do this.
9. Any variables that could affect results are controlled e.g. temperature, volume of potassium hydroxide solution in the test tube.
10. To produce more precise results, the experiment is repeated and mean volume of O2 is calculated.

Practical 23: Investigation into the rate of oxygen production in pondweed (photosynthesis). light intensity (Factors affecting the rate of photosynthesis)

Paper/Thin-Layer Chromatography

1. Grind up several leaves with anhydrous sodium sulfate and propanone.
2. Transfer the liquid to test tube, add some petroleum ether and gently shake the tube. Two distinct layers form in the liquid, the top layer is the pigments mixed in with the petroleum ether.
3. Transfer some of the liquid from the top layer into a second test tube with some anhydrous sodium sulfate.
4. Draw a horizontal pencil line near the bottom of a chromatography plate (silica plate). Build up a single concentrated spot of the liquid on the line by applying several drops and ensuring each one is dry before the next one is added. This is the point of oriigin.
5.Once the point of origin is completely dry, put the plate into a glass beaker with some prepared solvent ( eg. a mixture of propanone, cyclohexane, and petroleum ether. Lower is just enough so that the point of origin is slightly above the solvent. Put a lid on the beaker and leave the plate to develop. As the solvent spreads up the plate, the different pigments move with it, but at different rates - so they separate.
6.When the solvent has nearly reached the top, take the plate out and mark the solvent front (the furthest point the solvent has reached) with a pencil before it evaporates and leave the plate to dry in a well-ventilated place.
7. There should be several new coloured spots on the chromatography plate between the point of origin and the solvent front. These are the separated pigments. You can calculate the rF values and look them up in a data base to identify the pigments.

Computer modelling and data logging

DNA extraction

Phases of a population growth curve

Lag, log, stationary

Limiting factor

Environmental resource or constraint that limits population growth

Reasons for slight increases and decreases in the stationary phase

Fluctuations in limiting factors

Examples of limiting factors

Interspecific competition, disease, temperature, light, pH, availability of water, humidity, predators

Types of limiting factor

Biotic, abiotic

Examples of biotic factors

Predators, disease, competition

Examples of abiotic factors

Temperature, light, pH, availability of water or oxygen, humidity

Carrying capacity

Maximum population size that an environment can support

Examples of density independent factors

Earthquakes, volcanic eruptions, fires, storms

Examples of interactions between populations

Predator-prey, interspecific competition, infraspecific competition

Competitive exclusion principle

When two species compete for the limited resources, the one that uses the resources most effectively will eliminate the other

Example of interspecific competition

Red and grey squirrels, grey squirrels can eat a larger variety of food and is larger so can store more fat

Stages of infraspecific competition

Resource is plentiful so population size increases, too many individuals so resources are limited, population decreases in size, less competition so population size increases, repeats

Predation

When one organism kills and eats another organism

Stages in a predator-prey relationship

Increase in prey population means more food for predators so more (than) survive, more predators so more predation so death rate of prey population increases, too small prey population so infraspecific competition in predators increases, predator population decreases in size, fewer prey killed, prey population increases

Limitations to the predator-prey relationship

Populations also affected by availability of other foods or other predators or abiotic factors

Conservation

Maintenance of species, genetic and habitat diversity through human action or management

Preservation

Protection of an area by restricting or banning human interference so the ecosystem is kept in its original stage

Economic reasons for conservation

To provide resources that humans need to survive, to provide an income for people through selling medicines or drugs or clothes or food

Social reasons for conservation

People enjoy natural beauty, means of relaxation and exercise through bird watching or walking or cycling or climbing

Ethical reasons for conservation

All organisms have a right to exist, some play important roles within their ecosystem, we should not have the right to choose which organisms survive, moral responsibility to future generations

Sustainable resource

A renewable resource that is being economically exploited in a way that will not diminish it or cause it to run out

Examples of resources being used in a sustainable way

Timber production, fishing

Methods of sustainable timber production

Coppicing, pollarding, clear-felling, selective cutting

Coppicing

Tree trunk is cut close to the ground, new shoots form from the cut surface, shoots cut eventually, more produced in their place, done rotationally

Benefits of rotational coppicing

Trees never grow enough to block out light, succession stopped, more species can survive

Pollarding

Coppicing but higher up

Why is pollarding done?

So larger mammals can't eat the new shoots as they appear

Clear felling

Areas of a forest are cleared and replanted

Selective cutting

Individual trees are selected and cut down

Methods of sustainable fishing

Quotas set by the Common Fisheries Policy, nets with large mesh sizes, only allowing commercial and recreational fishing at certain times of the year

Example of an ecosystem being used to balance the conflict between conservation and human needs

Masai Mara region in Kenya, Terai Region in Nepal, peat bogs

Main problems for the land in the Masai Mara

Intensive herding and tourism putting strain on soil, endemic vegetation and wildlife

How is conservation being done in the Masai Mara?

Big cat project tries to secure future of big cats, elephant project tracks movements of elephants to understand movements and provides anti-poaching education, lion project tries to understand exact movements of lions in time and space so local people can be advised on where and where to not graze their livestock

How is the conflict between human needs and conservation being resolved in the Masai Mara?

From the conservation there are employment possibilities, locals benefit from water conservation and access to renewable energy, education programs, female empowerment

Main problems in the Terai Region of Nepal

Natural resources at risk of being overused, clearing of large areas of forest exacerbates effects of monsoon flooding, soil erosion, loss of tourism, loss of biodiversity, illegal logging

How is conservation being done in the Terai Region of Nepal?

Development of local community forest groups, protection of endangered species, promote food production in the hills so it's not in the forest, improved irrigation for crops, rotational planting, nitrogen fixing crops

Benefits to the local people as a result of the conservation in the Terai Region of Nepal

Empowerment of women, employment, income, increased retail price for forest produce, more technical skills, sustainable flow of income to next generation

Main problems for peat bogs

Intensive land use, afforestation, peat extraction, land drainage, all dry out the bogs

Afforestation

The establishment of a forest or stand of trees in an area where there was no forest

How conservation of lowland bogs is being done

Ensuring that peat and vegetation is as undisturbed and wet as possible, surrounded by ditches to allow water run off to prevent flooding of nearby land, removal of seedling trees from the area as they take water from the bog, controlled grazing

Examples of environmentally sensitive ecosystems

Galapagos Islands, Antarctica, Snowdonia National Park, Lake District

Animals and plants in the Galapagos Islands

Giant tortoise, marine iguana, rock purslane, scalesia tree

Main problems in the Galapagos Islands

Fishing, twelvefold growth in tourism, introduced species which threaten native species, habitat destruction for buildings or roads, agriculture, increased pollution

Methods of conservation in the Galapagos Islands

Culling goats, cap tourism at 100000 people per year, price hikes

Animals and plants in Antarctica

Whales, seals, penguins, lichens, moss, algae

Main problems in Antarctica

Tourism, global warming, hunting of whales and seals, fishing, discharging of waste into the sea

Methods of conservation in Antarctica

Antarctic Treaty - scientific cooperation between nations, protection of the environment, conservation of plants and animals, designation and management of protected areas, management of tourism

Animals and plants in Snowdonia National Park

Coughs, cormorants, oystercatchers, pied flycatcher, wood warblers (Yay!), ospreys, buzzards, sparrowhawks, snowdon lily, oak, alder, wych elm

Main problems in Snowdonia National Park

Trampling of parks, overuse of cycling or walking parks, pollution due to waterspouts, mechanical equipment

Methods of conservation in Snowdonia National Park

Park Authority - Conserve natural beauty and wildlife and cultural heritage, promote opportunities for understanding and enjoyment of park, enhance economic and social wellbeing of community, Dinorwig power station is inside a mountain to preserve natural beauty

Animals and plants in the Lake District

Water voles, Natterjack Toads, bats, red deer, Golden eagle, osprey, red squirrels, vendace, purple saxifrage, dwarf juniper, dwarf willow, sundew

Main problems in the Lake District

Fewer native tree species, trampling of plants, overuse of cycling or walking paths

Methods of conservation in the Lake District

Park Authority - Conserve the region while enabling access for visitors, replanting native tree species

What is an ecosystem?

a group of living oranisms living in a certain area that is dynamic and affected by abiotic and biotic factors.

what is a producer?

converts light energy into chemical energy

what is a consumer?

any of the heterotrophic organisms in a food chain

what is a trophic level?

the level at which an organism feeds in a food chain

what is a decomposer?

living bacteria/fungi that feeds on decaying waste/organic matter into inorganic compounds and external secrete enzymes and are saprotrophic.

examples of biotic factors? (2)

- competition
- parasitism

examples of abiotic factors? (3)

- pH
- light intensity
- water

what is the difference between a population and a community?

equation of efficiency of energy transfer?

energy level after transfer/energy level before transferx 100

how is light energy lost in plants? (4)

- reflection (green colour)
- heat loss
- light strikes non-light synthetic structures (bark)
- energy losses during photosynthesis

what is GPP?

Gross Primary Production: the amount of chemical energy created from light energy in a given amount of time, transferred by plants into tissues

what is NPP?

Net Primary Production: the chemical energy stored in a plant biomass after respiratory losses to the environment have been taken into account

what will have the highest NPP? why?
Desert, Rainforest, Open Ocean, Coral Reef

Coral Reef- water's a more stable environment

what are the main losses of energy from food chains? (6)

- heat
- movement
- waste
- growth
- urine
- homeothermic (temperature control mechanisms)

how to maximise energy input in crop plants? and livestock?

crops: Optimum planting distances between crop plants or provide light for greenhouse crops on overcast days
livestock: provide good-quality feed

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