biology: growth of leaf yeast using starch agar

abundance of leaf yeast

greater during teh symmer months due to more suitable temperatures and more leaves on trees

factors that harm leaf yeast growht

air pollution

asepsis

free from pathogens

sterility

free from all microorgansims

aseptic techniques

wash hands with dettol

swab bench with disinfectant before and after use

seal petri dishes with tape and keep all containers closed

sterile techniques

sterilise all equipment before and after by autoclaving at 120 degrees for 15 min and immersing in dettol

flame equipment used during equipment by heating in teh flkame of a bunsen burner and allowing to cool

nutrient agar plates and their purpose

dishes with adatives

provide medium for growth

what is nutrient medium

supplies food for growth

agar

material derived from seaweed, solid growth medium allowing microorganisms to grow

experiment account: collecting leaves

pick leaves from an ash tree

place leaves in a container to avoid contamination and to prevent leaves from being shaken or crushed

account of experiment: treatment of leaves on return to lab

wash hands with dettol to reduce riskof contamination and swab worktop with disinfectant

obtain 2 sterile starch agar petri-dishes, one for control and another for test

experiment test dish

flame forceps using bunsen burner, once cooled use it to pick up leaf

apply small spot of petroleum jelly to uper surface of the leaf and attack the upper surface of the leaf to the inside of the lid

lower surface of leaf should face the agar plate

seal petri dish with tape to prevent accidental openning

purpose of control plate

control is used to show that teh eyast cells came from the leaf and not from the agar

experiment control plate

reflame forceps and use it to pick up the seconf ash leaf and wash both upper and lowers sides of the leaf with dettol

attack the leaf to the lid of the second plate teh same way as the test plate, seal the plate with tape

incubation

incubate both dishes in teh oven at 25 degrees as leaf yeast grows faster at higher temp, initially allow dishes to stand upright for 24 hrs so spores are disperssed into teh agar

petri disges should be placed upside down to prevent condensation on the lid

results

test plate: pink colonies

control plate no growth visable

disposal of agar plates

autoclave at 120 degrees for 15 minutes

immerse in dettol