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

Measuring rate of water uptake by a leafy shoot

Extracts from this document...

Introduction

Measuring rate of water uptake by a leafy shoot. The water uptake can be measured easily and because very high proportion of the water taken up by a stem is lost in transpiration, it enables the rate of transpiration to be measured. Key Factors to be kept Constant: - * Temperature - room temperature (approximately 25�C) * Wind speed - No artificial wind was produced to affect results * Light intensity - Extra light was not used * Humidity - it was not humid on the day experiments were conducted The water uptake for the control Experiment. Time (minutes) Initial meniscus position of the air bubble (cm) Final meniscus position of the air bubble (cm) Water uptake (Distance moved) (cm) Total water uptake (cm) 1 10.0 10.7 0.7 0.7 2 10.7 11.5 0.8 1.5 3 11.5 12.3 0.8 2.3 4 12.3 13.0 0.7 3.0 5 13.0 14.0 1.0 4.0 6 14.0 14.8 0.8 4.8 The water uptake when Vaseline is applied on the top surface of the leaves. Time (minutes) Initial meniscus position of the air bubble (cm) Final meniscus position of the air bubble (cm) Water uptake (Distance moved) (cm) Total water uptake (cm) 1 6.0 6.6 0.6 0.6 2 6.6 7.2 0.6 1.2 3 7.2 7.9 0.7 1.9 4 7.9 8.5 0.6 2.5 5 8.5 9.2 0.7 3.2 6 9.2 9.7 0.5 3.7 Time (minutes) ...read more.

Middle

Stomata are pores surrounded by specialized cells (guard cells). These pores allow water to escape by diffusion into the air. As the water evaporates from the leaf by water evaporating from the surface of the parenchyma and escaping out through the stomata into the atmosphere, water from the xylem in the leaf replaces it. As water leaves the xylem, more is sucked up from below. A negative gradient in hydrostatic pressure forms, causing a column of water to rise up the plant. This is known as the transpiration pull. This means that transpiration directly affects the rate of water uptake. If this did not occur, the plant will wilt, and if water loss continues without being replaced, it will suffer plasmolysis. (Biology 1 text book and 'Biology - AS in a week). When both surfaces were covered with Vaseline, the Vaseline was applied over the stomata as well. By covering the stomata it meant that this would prevent water from escaping by diffusion, so this will reduce transpiration, which then led to a decrease in water uptake. The fact that both sides were now preventing any water from evaporating from the leaves of the plant means that this experiment had to have a lower water uptake, which it did. ...read more.

Conclusion

For all three T-tests, the pattern that is similar is that the probabilities are all below the critical value, which is 0.05. This means that I can reject the "null" hypothesis that there is no difference between the means for each T-test and that the results only occurred by chance. I can assume that there is a significant difference between the means and the difference is real. There is not a big difference between each individual reading either which means that my results must be quite accurate. From the tests I can also see that the mean for the control test is greatest (0.8000), then the mean for the experiment with Vaseline on top (0.6167) and the lowest mean was for the experiment with Vaseline on both sides (0.4500). The standard deviation also shows this trend 0.1095 for the control, 0.0753 for the Vaseline on top, and 0.0548 for the one with Vaseline on both surfaces. The variance also supported this, 0.0120 for the control experiment, 0.0057 for the Vaseline on top, and 0.0030 for the one with Vaseline on both sides. The results from the T-tests support the trend showed by the graph, and this is supported by the background information. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Green Plants as Organisms 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 GCSE Green Plants as Organisms essays

  1. Three separate experiments which are to be carried out to investigate a plant's unique ...

    I currently have a range of 4 inclusive. If I had a range of 2 or 3 inclusive, I would have carried out the talk successfully. Also, I wish that I had collected more results, even if they were from leaf. I carried out the experiment 6 times; whereas I believe that I should have carried it out

  2. Free essay

    Transport in flowering plants- Dye Experiment 2. Aim: To find (a) the tissue ...

    Therefore, the number of stain will decrease when the distance from the cut end of the stem increase.

  1. Factors affecting the rate of transpiration

    Temperature, humidity, air movement and light can affect the rate of transpiration. If the air is still, water vapour diffusing out of the leaf will tend to accumulate around the stomata pores. This reduces the water potential gradient and slows down the rate of transpiration.

  2. Experiment to Compare Stomata Density in Different Dicotyledonous

    ? This plant likes shade and thus would suggest relatively high stomata density as the leaves are out of the sun. However, it's original ecosystem is quite hot and this would lower the stomata density, bringing down to around the average stomata density, as set by the previous investigation..

  1. Investigation of the factors affecting the rate of transpiration from a shoot of Privet.

    The stomatal density on the leaves - Transpiration happens in the stomata, so more stomata means more transpiration. The species of plant - Some plants photosynthesise faster than others, and so need more carbon dioxide, so have more stomata, and lose more water through transpiration.

  2. Investigate factors affecting rate of transpiration in a leafy shoot.

    The test tube labelled controlled should show the least decrease in water level. Scientific knowledge: The external factor, which has the greatest effect on transpiration, is temperature. The higher the temperature, the greater the rate of evaporation of water from mesophyll cells and the greater the saturation of the leaf atmosphere with water vapour.

  1. Design and Carry out an investigation to see what effect light intensity has on ...

    increased as the source (lamp) moves closer. The intensity of the light will be measured using a luxmeter, this will be kept at a stationary position and angle on the plant, so that any discrepancies will be nullified i.e. if the angle of the luxmeter is not optimal to obtain the current reading, then it

  2. How temperature affects the rate of photosynthesis.

    Comparing the accuracy of the two graphs, it can be said that both of them are similar in accuracy because both the anomalous results are only present at 25 oC and both the anomalies lie above the line of best fit.

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