Fungi: Yeast - Conditions for growth

Question 1

What is yeast?

3

Answer 1

A unicellular fungi

Yeast causes food spoilage

Can also be used in the manufacture of food stuffs e.g. bread and beer.

Question 2

What foods does yeast feed on?

Answer 2

They feed on high-carbohydrate foods

Question 3

Does yeast need oxygen to grow?

Answer 3

Yeast is facultative which means it can grow with or without oxygen

Question 4

At what temperature do yeasts grow?

Answer 4

They are mesophilic and have an optimum temperature of 25-30 degrees Celsius

Question 5

What temperatures destroy a yeast cell?

Answer 5

Temperatures above 60 degrees Celsius

Question 6

What temperatures inactivate yeast cells?

Answer 6

Freezing temperatures

Question 7

What temperatures slow yeast growth?

Answer 7

Temperatures below 15 degrees Celsisu

Question 8

What aw level does yeast need to grow?

Answer 8

An aw level of 0.85 or above

Question 9

What type of pH environment do yeast cells need to grow?

2

Answer 9

A slightly acidic environment (4-6)

Extremely acidic or alkaline environments inhibit growth

Question 10

Is yeast saprophytic or parasitic?

Answer 10

They are saprophytic so they feed on non-living matter