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

Biology lab - transpiration

Extracts from this document...

Introduction

AP Biology Lab 9: Transpiration Introduction Most of the water a plant absorbs is not used for a plant's daily functioning. It is instead lost through transpiration, the evaporation of water through the leaf surface and stomata, and through guttation, which is the loss of water from the vascular tissues in the margins of leaves. There are three levels of transport in plants: uptake and release of water and solutes by individual cells, short distance cell to cell transport at tissue and organ levels, and long distance transport of sap by xylem and phloem at the whole plant level. The transport of water is controlled by water potential. Water will always move from an area of high water potential to an area with low water potential. This water potential is affected by pressure, gravity, and solute concentration. Water moves into the plant through osmosis and creates a hydrostatic root pressure that forces the water upward for a short distance, however, the main force in moving water is the upward pull due to transpiration. This pull is increased by water's natural properties such as adhesion and cohesion. Transpiration decreases the water potential in the stele causing water to move in and pull upward into the leaves and other areas of low water potential. ...read more.

Middle

The slice was placed in the 50% ethanol. The slices were left in the ethanol for five minutes. Using the forceps, the slices were moved to a dish of the toluidine blue O stain and left for one minute. The sections were rinsed in distilled water. The section was mounted on the slide with a drop of 50% glycerin. A cover slip was placed over the slide. The cross section was observed under a light microscope and drawn. Results Table 9.1: Individual Potometer Readings Time (min) Beginning (0) 3 6 9 12 15 18 21 24 27 30 Reading (mL) .02 .03 .04 .05 .06 .07 .09 .10 .11 .13 .13 Class Potometer Readings Time (min) Beginning (0) 3 6 9 12 15 18 21 24 27 30 Room .53 .54 .55 .56 .57 .58 .59 .60 .61 .62 .63 Mist .34 .36 .38 .40 .42 .43 .43 .44 .45 .45 .46 Light .67 .68 .69 .70 .71 .72 .73 .74 .75 .77 .79 Fan .02 .03 .04 .05 .06 .07 .09 .10 .11 .13 .13 Mass of leaves = 1.1 g Leaf Surface Area = 0.0044 m2 Table 9.2: Individual Water Loss in mL/m2 Time Interval (minutes) 0-3 3-6 6-9 9-12 12-15 15-18 18-21 21-24 24-27 27-30 Water Loss (mL) ...read more.

Conclusion

Error Analysis This lab had many opportunities for error. The potometer set up was a complicated procedure. If any air bubbles were present in the plastic tubing, it could cause drastic error to occur. Any miscalculations or inaccurate weighing could also account for error. Conclusion Transpiration in plants is controlled by water potential. This change in water potential in leaves causes a gradient by which water can be moved upward. When the water potential of the air was increased by the mist and plastic bag, less water evaporated from the leaves, decreasing the water potential gradient between the root and stem. This decreased the transpiration pull. The fan and floodlight simulated environmental conditions such as wind, heat, and intense light. These conditions increase the amount of water transpired by plants. This in turn increased the water potential gradient causing more water to be pulled through the stem. The control plant should have had normal rates of transpiration. The stem must have specialized cells for support and transport. The epidermis is the outermost layer of the stem. The xylem is a transport tube for water, and the phloem transports food and minerals through the plant. Parenchyma are non-specialized cells and are located in the interior. The tougher sclerenchyma and collenchyma make up the structural outer support of the epidermis and the transport tubes of phloem and xylem. ...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

Here's what a teacher thought of this essay

5 star(s)

A very good A level standard practical write up, investigating transpiration in plants, and what factors can have an effect on it. The background information is well researched and
presented. The results are clear and well analysed. A few additions such as labelled diagrams would reinforce some of the text. But overall very good. 5 stars.

Marked by teacher Louise Star 09/04/2013

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. Marked by a teacher

    transpiration lab

    3 star(s)

    The reason that an increase in temperature will cause an increase in transpiration rate is because an increase in temperature will cause more water to evaporate from the cell walls inside the leaf. This will increase the water potential gradient between the leaf interior and the outside air causing water

  2. Peer reviewed

    An Investigation into the Effects that Different Light Intensities have on the Speed of ...

    5 star(s)

    i Woodlice, Stephen Sutton, 1972 ii www.geocities.com/~gregmck/woodlice iii http://www.cambridge.org/catalogue/catalogue An Investigation into the Effects that Different Light Intensities have on the Speed of Woodlice: Abstract: The aim of this investigation was to find out the effects that different light intensities had on the speed of movement of woodlice.

  1. Does Leaf Surface Area Affect the Rate of Transpiration in a Plant?

    of the leaf because the more surface area there is the more stomata there is. The more stomata there are then the more opportunity for the loss of water making the rate of transpiration faster. Photosynthesis also affects the rate of transpiration because during the day photosynthesis takes place much faster and it requires more water and more gases.

  2. The effect of wind speed on the rate of transpiration.

    The small diameter would mean that the wind will not get to all the leaves. I intend to place the plant at 20, 40, 60, 80 and 100cm away from the fan thus decrease the wind by five times. Later I will measure using an anemometer the relationship between these distances and the wind speed.

  1. The effects of osmosis in plant tissues

    Each dish was labeled with the appropriate sugar concentration so that they could be easily identified. The cucumber plant was then sliced using the machine cutter to obtain thin even slices. This helps to ensure fair testing because surface area might affect osmosis.

  2. Determination of the water potential of potato tissue by a gravimetric method.

    also since water would be used as a sort of support medium i.e. to remain turgidity, the gained water would mean the cells would be turgid so means that there would be a larger cellular volume therefore the discs/chips would be bigger.

  1. How Does Water Depth Affect Wavespeed?

    This shows my results support my prediction. If the results are plotted on a graph (see the next page) the line of best fit runs through most of the points, showing there is a strong relationship between the water depth and wavespeed.

  2. Factors Affecting Infiltration Rates

    A number of factors are responsible for this phenomena, including: (1) The filling of fine soil pores with water reduces capillary forces. (2) As the soil moistens, clay particles swell and reduce the size of pores. (3) Raindrop impact breaks up soil clumps, splashing fine particles into pores.

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