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Investigate the effect of moisture content on wheat grain seeds respiration rate.

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Experiment to investigate the effect of moisture content on wheat grain seeds respiration rate AIM: The aim of this experiment is to find out the effect of moisture content on a wheat grain seed's respiration rate. HYPOTHESIS: There will be a positive correlation between moisture content of wheat grains and their respiration rate. Therefore as the moisture content (independent variable) increases so will the respiration rate (dependent variable). The rationale behind the hypothesis came from studying photosynthesis in plants. During the light-dependent reactions of photosynthesis, the photolysis of water (H2O) occurs inside photosystem II. The products of photolysis combine with NADP from photosystem I, to form reduced NADP. This reduced NADP passes to the light-independent reactions of photosynthesis, where it is utilised to make triose phosphate from glycerate 3 phosphate. Without water, photolysis would not occur and therefore the light-dependent and light-independent reactions would not take place at all. Therefore I would predict that the higher moisture content of wheat grain seeds the higher the respiration rate will be, this is because the seeds will be able to utilise more water than a wheat grain seed with low moisture content. ...read more.


These spores then will start to destroy other seeds close to it, as well as producing moisture to surrounding seeds, which will cause them to germinate as well. These in turn will die and provide ideal conditions for more fungal and bacterial spores to develop, thus causing a destructive cycle. This cycle will ruin the stored grain, which is in storage. Deterioration of stored grain is an economic problem for More Economically Developed Countries (MEDCs) and Less Economically Developed Countries (LEDCs). In both it will cause agriculture to lose profits, as well as loss in food for their animals. However it is a more serious problem for LEDCs because often they only produce one type of crop, which the surrounding villages rely on for their food. If the wheat seeds are spoilt, it may cause starvation of the villagers, even a famine if spoilage is a countrywide problem. Starvation will cause protein energy malnutrition such as kwashiorkor and marasmus. Starvation can also cause oedema, wasting and stunting, as well as death. This obviously causes huge economic problems for such countries. Therefore the proper storage of grain is important in maintaining a countries economic system. ...read more.


(3) Attach both the tubes to the bungs on the respirometer. Making sure they are secure and air tight to the surroundings. Record the readings of the manometer for the control and experimental test tubes. (4) After 2 hours, record the reading of the manometer on the respirometer. (5) Remove the experimental and control tubes from the respirometer. Take out the seeds from the experimental tube, and wipe any moisture from their surfaces. Then reweigh the mass of the seeds and record the result. (6) Remove both remaining solutions and glass gauze from the experimental tube and make sure the tube is cleaned. (7) Add 10cm3 of oxygen absorbing solution using a 1cm3 to the experimental tube, then add the glass gauze just above the solution once more. Then replace the twenty ORIGINAL seeds into the experimental tube along with 50cm3 of distilled water. (8) Then repeat stages 3-7 every two hours, making sure that the readings are taken at the two-hour mark each time. Continue recording the results for a two day period (48 Hours), this should give a total of 25 different results for the manometer and a further 25 results for mass of the seeds (this includes the results taken at the start of the experiment when the seeds have no moisture content!). ...read more.

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Here's what a teacher thought of this essay

**Plan only. Unfortunately the methodology for this experiment is fundamentally flawed and could never yield valid results as written. The candidate chose a method that removed oxygen from the respirometer and then was hoping to measure the rate of respiration. This would only measure anaerobic respiration. The seeds also seem to be submerged in water and therefore therefore would be prevented from taking in oxygen.
To improve:
The candidate needs to include more background research which is linked to the problem being researched and that helps inform the plan. The methodology for respirometer experiments of this nature could also be researched. A large amount of time was spent discussing photosynthesis which is a process that does not occur in seeds until after germination. No references have been included and there are often marks awarded for suitable background research and evaluation of the resources.
The consideration of the variables should be widened to include more of the key factors in this experiment. A thorough risk assessment should be included. A diagram would help to clarify the experimental set up. The candidate should plan to include replicates for the experiment to improve validity. The candidate needs to correct several errors in fundamental science. The experiment as it stands could never yield any results since the author is trying to measure respiration whilst removing all oxygen from the seeds.

Marked by teacher Stevie Fleming 15/10/2013

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