10. (a) (i) Is leaf yeast a unicellular or a multicellular organism? (ii) Name the type of asexual reproduction in yeast - Leaving Cert Biology - Question 10 - 2021

The type of asexual reproduction in yeast is budding.

The purpose of malt in these plates is to provide the necessary nutrients for the growth of yeast organisms. Malt contains sugars and other nutrients that are essential for the metabolism of yeast, promoting their growth in the agar medium.

The underside of the leaf was facing the agar because the leaf yeast primarily grows on the underside surface, where it can obtain moisture and nutrients more effectively. This orientation maximizes the exposure of yeast cells to the nutrient-rich agar.

The purpose of plate A is to act as a control in the experiment. It is used to compare with the results obtained from plates B and C, helping to determine the effect of the leaf discs on yeast growth.

The colour of the leaf yeast colonies on plate B is typically pink or red.

One reason for the difference in results between plates B and C could be due to pollution in the urban area where the leaf discs from plate C were collected. Higher levels of smoke, sulfur dioxide, and other harmful chemicals in urban settings can adversely affect yeast growth compared to the quieter, rural setting of plate B.

1. Disinfecting surfaces: Prior to the experiment, surfaces, such as benches and equipment, were wiped with a disinfectant to eliminate any potential contaminants.
2. Sterilization of equipment: Petri dishes were either soaked in disinfectant or autoclaved at a high pressure and temperature to sterilize them before use, ensuring that no other microbes could interfere with the results.

The plates should be soaked in disinfectant for a period of time before being disposed of, or they can be placed in a biohazard bag for proper disposal.