Practical 9 biology - preliminary research on the effect of temperature on yeast respiration PDF

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Summary

preliminary research on the effect of temperature on yeast respiration...

Description

Practical 9: the effect of a named variable on the rate of respiration of cultures of singlecelled organisms Aim  to investigate how temperature ca effect the yeast’s anaerobic respiration and to procede to observe the bubbles produced

background  yeast is a single-celled organism the respires both anaerobically and aerobically.  During respiration the electrons are transferred in order to synthesizes ATP  Yeast respiration can be measured using redox indicator dye for example methylene blue which undergoes a color change form blue to colorless once it accepts the electrons.

Equipment list -

Yeast and glucose in a buffered solution Water bath Thermometer ( as my variable is temperature ) Test tubes Timer Beaker

Independent variables -

Temperature

Dependent variables -

The change of colors

Controlled variables -

Ph solution, buffer the solution Stirring Volume of yeast Volume of water Volume of dye

-

The kind of yeast The time

Methodology

1. Set up a water bath at 35°C. 2. Add 5cm3 of the yeast and glucose solution to three test tubes. Place test tubes in the water bath and leave them, for the solution to equilibrate for 10 minutes. 3. Add 2cm3 of methylene blue to the test tubes and start the timer. Shake for 10 seconds and place test tube back in water bath. Record how long it takes for the methylene blue to turn colourless for each test tube. 4. Repeat the experiment using temperatures of 40°C, 50°C, 60°C and 70°C. 5. Find the mean of the results for each temperature and use to calculate the average rate of respiration. Rate of respiration = 1/ mean time

Predictions I’m hoping that as temperature increases the rate of respiration so the time that takes for the solution to turn colorless will reduce However it can also be expected due to very high temperatures the yeast is put in the enzymes might be denatured and at for example 70 c there is a high probability that the solution will not turn colorless.

Data collection With the information I collect I plan on plotting a results in a line graph of temperature against time

Risk assessment risk Control High temperatures can burn glass material can break

Methylene dye

Use of gloves for protection when dealing with the water Careful use of the materials

Use protective clothing and eye gear (googles) as well as gloves also avoid using powdered dyes

Action Ice pack on burns ask for help when using the water Make sure not to touch it and in case of a injury utilize first aid carefully clean up the glass If its in the eye, should flood the eye with tap water while waiting for the medic If spilt on skin contaminated clothing should be removed skin should be washed off which soap and a lot of water

Table of results Temperature (°C)

Time it took to get colorless (s)

Rate of respiration (s^-1)

30 40 50 60 70

References hazards http://science.cleapss.org.uk/resource/SSS070Dyes-and-indicators.pdf method https://www.savemyexams.co.uk/notes/a-levelbiology-aqa/5-energy-transfers-in-betweenorganisms/5-2-respiration/5-2-9-investigating-therate-of-respiration/ https://pmt.physicsandmathstutor.com/download/Bi ology/A-level/Notes/AQA/Practical-Skills/RP %2009%20-%20Respiration%20in%20Single %20Celled%20Organisms.pdf

https://www.studocu.com/en-gb/document/sixthform-uk/biology-a2/the-effect-of-temperature-onthe-rate-of-respiration-in-yeast/9600084...