• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The effect of inhibitors on the germination and growth of cress seeds

Extracts from this document...


The effect of inhibitors on the germination and growth of cress seeds Introduction Germination process Before seeds can mature into plants, they need to germinate. When the seed's internal and external conditions are favourable (specific for different seed species), their natural dormancy period brakes and germination begins. The limiting factors for germination are: Temperature (within a specific range limit) Light (Some seeds e.g. lettuce require differing wavelengths of light to germinate; others require specific intensities) Oxygen Water (An adequate supply) When given the right conditions, imbibition occurs as seeds take in water through the testa via osmosis and they enlarge in size. Water dissolves the hormone gibbellerinic acid in the cotyledon which diffuses across the aleurone layer and activates the gene coding for amylase. Amylase is then synthesised by the aleurone layer and diffuses into the endosperm and hydrolyses the starch store present which produces maltose. This is then hydrolysed to glucose which diffuses into the embryo and used in aerobic respiration. When the seed is fully turgid, the testa ruptures and splits allowing oxygen to penetrate the seed for respiration to occur. When seeds begin to respire and utilise glucose, they begin to lose mass until leaves are developed and photosynthesis occurs; they then increase in mass. ...read more.


Weighing dish Thermostatically controlled oven Glass dish Large conical flask Large metal spoon Dessiccator Method * Scoop pulp from half of tomatoes, sieve to discard seeds and place in clean processor. Discard remaining flesh. * Measure 250 ml of propanone and add to pulp. Process for 3 minutes. Pour mixture into glass dish and cover to prevent evaporation. * Repeat above procedure for remaining tomatoes and add mixture to glass dish. Mix thoroughly with large spoon. * Filter the mixture using the funnel lined with filter paper and pour extracts into the conical flask. * Label 1 syringe 'water' and 1 syringe 'extract' to avoid successive contamination of extracts and control. * Label 6 tests tubes in holder : 1) Control 2) 20% 3) 40% 4) 60% 5) 80% 6) 100% * Using the 'water' syringe, add 10 ml distilled water to tube 1. Using the 'extract' syringe add 2 ml of extract tube 2, 4 ml of extract to tube 3, 6 ml of extract to tube 4, 8 ml of extract to tube 5 and 10 ml of extract to tube 6. Seal the tubes. * Line each petri dish with cotton wool of equal amounts and depth. ...read more.


Mass loss of 15 seeds (g) % mass loss or gain of 15 seeds 3 4 5 6 7 8 9 Plot a graph of % mass loss or gain (y-axis) against days for each extract. By calculating the gradient of each graph you can discover the rate of change of mass (g day -�). Comparing each rate from each graph you will be able to see which concentration of inhibitor had the most inhibitory effect on growth. The smallest rate should correspond with the 100% concentration. Using day 2 and 3 percentage germination data calculate mean % germination and plot a graph of extract (x-axis) against mean % germination (y-axis). From this you should be able to see a negative correlation between the variables. This will tell you there is a direct inhibitory effect on germination by the extracts. Graphs could also be drawn to display rate of germination. Extract Mean % germination Control (0%) 20% 40% 60% 80% 100% Risk assessment and safety Propanone is an irritant to eyes skin and lungs and is highly flammable. * Extracts should be produced and used in the fume cupboard/ if unavailable wear a mouth mask. * Extracts should be kept away from flames and dishes and bottles covered * Wipe away spillages with paper towels * Wear safety goggles and gloves * Handle the scalpel and blade carefully ?? ?? ?? ?? ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Genetics, Evolution & Biodiversity section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Genetics, Evolution & Biodiversity essays

  1. Peer reviewed

    An Investigation into the effect of caffeine on reaction times

    5 star(s)

    I will then compare the results with caffeine to the results without. This will give me an idea as to whether my range of doses is sufficient to give conclusive results, or whether the caffeine does not have enough of an effect to measure.

  2. Peer reviewed

    Is there a relationship between the girth of a tree trunk and the percentage ...

    4 star(s)

    A sample size of twenty five is likely to give a more reliable and valid result, however. The larger the sample, the more reliable and valid the results will be. Results The raw data collected at the site: Tree Girth of the trunk / m Percentage cover of lichens on

  1. patterns of growth and development

    32 weeks 2.0 kg (4 1/2 lb) 36 weeks 2.6 kg (5 3/4 lb) 40 weeks 3.5 kg (7 1/2 lb) This is a table of the average weight for girls and boys. It goes up to 13 years but in this unit only the first 8 years are important.

  2. Investigation as to whether the aspect of a wall affects the growth of lichens

    The number of squares occupied by lichens will be counted and recorded in a tabular sheet against the light intensity of the area within the quadrat. Care should be taken to ensure that the photometer is never directly in the way of sunlight.

  1. HSC maintaining a balance notes

    increased the number of birth defects 4. f) Variations Supports Darwin's Theory Variation in a population comes from: - Random pairing of gametes in sexual reproduction - Crossing over during meiosis - Random assortment of chromosome pairs in meiosis - Mutations of chromosomes and genes Sexual reproduction ensures individuals in any population differ.

  2. Investigating the effect of trampling on salt marsh

    In both the areas, the square point quadrat was randomly put down at 30 places between the ranging poles and the species cover was recorded accordingly. The results gained could be then used to find species diversity and also the types of species found in both areas.

  1. An Investigation into the effect of flow rate on the size of Gammarus pulex

    They are primary consumers. They expend large amounts of energy using active transport to replace the mineral ions lost through diffusion12. They also take in water at the gills and absorb the ions in their digestive systems. They hatch from eggs fully developed therefore have no larval stage like many other freshwater invertebrates.

  2. Investigating what effect varying the concentration of copper sulphate has on the enzyme Catalase ...

    What affects the activity of an enzyme? Enzyme activity is affected by many factors. The most obvious ones would be the concentration of the Enzyme and the concentration of the substrate. So, as an example, as the enzyme concentration increases the rate of reaction will increase so long there is a plentiful supply of substrate for it to work with.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work