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

Factors affecting the rate of transpiration

Extracts from this document...

Introduction

Biology Lab Design Factors affecting the rate of transpiration Elric Balrog Introduction There are several factors which can affect the rate transpiration of plants; these could either increase the rate of water uptake or decrease the rate of water uptake. These factors could be internal or external. In this investigation we will be looking at the external factors which affect the rate of respiration, such as temperature, light intensity... etc. Transpiration is known as the loss of water vapour through the stomata of the leaves. It is needed to keep the cells of the spongy and palisade mesophyll cells moist as this allows carbon dioxide to dissolve before diffusing into the cells for photosynthesis. A suction force is created on the column of water below it in the xylem when water is evaporated. The upwards force on the column of water created by transpiration and the downwards force due to gravity created a tension in the column of water. As there is a difference in the upwards pull, which is greater than the downwards pull, the column of water moves up the xylem. As the cohesion tension theory explains it, water molecules are polar, meaning that they stick to one another. ...read more.

Middle

thermometer 1 x 1 Balsam leafy shoot 1 x 1 beaker 1 x 1 candle 1 x 1 match box 1 x 1 30 cm ruler 1 x 2 syringe with needle 50 ml DCPIP 1 x 1 black polythene bag 1 x 1 rubber bung Method 1. The apparatus was set up as shown on the protocol diagram. 2. The conical filter flask was filled with water. 3. The leafy shoot was transferred from the water filled beaker to the sink and a slanting cut was made few centimeters above the last cut in water. 4. The shoot was fit into the bung of the flask under water and pushed in to make a tight fit. 5. The end of the rubber bung with wax was sealed using a candle and matches. 6. DCPIP, the indictor, was inserted into one end of the graduated capillary tube using a syringe. 7. The shoot was left to equilibrate for 5 minutes as it adjusts to its external conditions whilst regularly replacing the water taken up. 8. The time taken for the water to move 30 cm along the capillary tubes were measured every 2 minutes. ...read more.

Conclusion

The experiment took roughly about 3 hours 30 minutes to complete as the set up of the equipment took a lot of time as well as the preparation of the shoot and adjustments which had to be made to limit air loss from the rubber bung. An unbalance in the pressure between the potometer and the graduated capillary tube would disrupt cohesion tension in the shoot. Seeing as only 3 environmental conditions were tested, a broader understanding of the effect of external factors on the rate of water uptake by a leafy shoot would be possible if other conditions were tested for, such as humidity, increased light intensity and vaselining the upper and lower epidermises of the leaves. More readings over a longer period of time could have been taking to obtain more accurate average. Moreover, an estimate of the water loss per unit in leaf area could have been derived by measuring the volume of water lost and then removing all the leaves in order to determine the surface area. Overall, I would have preferred looking at more factors which could have influenced the rate of water uptake by the Balsam leafy shoot, but because of time restraints I could not do so. It was interesting to see how external factors affect the rate of transpiration in plants. ?? ?? ?? ?? IB Biology Lab Design Page 9 of 9 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Biology 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 International Baccalaureate Biology essays

  1. Biology HL IA - Transpiration lab report

    more equal to zero. The method of investigation might be discussed as having some limitations and weaknesses. First, the anomalous results of water having been absorbed even when the plant had no more leaves at all may not occur if the leaves would have been not cut (which might cause air bubbles getting into xylem)

  2. internal assessment rate of transpiration

    � 0.01 Mass of entire apparatus, Newton (N) � 0.05 High speed of wind (under fan) Low speed of wind (normal room condition) Trial 1 Trial 2 Trial 1 Trial 2 0 0.85 0.96 0.80 0.88 15 0.82 0.94 0.80 0.88 30 0.80 0.94 0.80 0.87 45 0.80 0.92 0.79 0.86 Table 1; the mass of entire apparatus

  1. Environmental Factors affecting plant growth

    The points will be pretty much very close to each other. Apparatus For the experiment I required twenty five tubes for five treatments; there were about five replicates for each treatment so that our results did not contain any complications.

  2. Testing the effect of characteristics of leaves on the transpiration rate of * ...

    During this, water evaporates as well. When there is lot of water in plant, guard cells are widely open to transpire. If the plant lacks H2O, it closes guard cells for no more loss of water. Transpired water should be replaced by more water from soil through the roots, stem and xylem (Transpiration, 2009).

  1. Comparing the Sexy Sons Hypothesis and the Pathogen Avoidance Models Effects on Sexual Selection

    In this experiment, darcin, a protein found in mouse urine, was used as a measure the degree to which the mice were sick. As these secondary sex traits are known to be honest signals of quality, meaning lower quality mice (sick)

  2. Examine the correlation between soil moisture at different heights up the slope and the ...

    There should thus be 7 readings taken for the longest leaf. 4) Our independent Variable, soil moisture, should be measured after the longest leaf of a Bracken Fern has been found, but before the next reading of the longest Fern leaf, 5 metres along the transect.

  1. Sleep is a normal part of human life. Investigate the neurobiological basis of normal ...

    There is a big difference between getting at least 8 hours of sleep and less than 8 hours of sleep, you are able to function properly with adequate sleep and live your life to the best of your quality. A solution to this problem would be to definitely reduce the

  2. Measuring the effects of wind and light on the transpiration rate in a leaf

    Wind can blow water vapor away faster than it would escape normally, and light can increase the plant?s temperature and thus increase evaporation from the leaves. Tartachnyk and Blanke (2007) showed that increased sunlight increases transpiration, thus seeming to confirm our hypothesis.

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