Yeast

Question 1

What is fermentation?

Answer 1

When yeast cells respire anaerobically

Question 2

What is the equation for anaerobic respiration in yeast cells?

Answer 2

glucose —>ethanol + carb diox

Question 3

What is fermentation useful for?

Answer 3

1. Brewing and baking

2. Bread making

Question 4

How is fermentation useful in breadmaking?

Answer 4

1. Yeast respires using sugar in dough
2. Bubbles of co2 make bread rise.
3. Ethanol evaporates as bread is baked

Question 5

How do we investigate anaerobic respiration in yeast?

Answer 5

1. Boil glucose solution to sterilise and remove oxygen
2. Cool before adding yeast
3. Place layer of oil on top of solution to prevent oxygen entering
4. Yeast will respire anaerobically - products can be collected in limewater.

Question 6

Why do we use limewater when investigating anaerobic respiration?`

Answer 6

1. Turns cloudy in presence of co2

2. Used as evidence of respiration

Question 7

What factors might we change when investigating yeast?

Answer 7

1. Temperature - with water bath

2. substrate

Question 8

How is the volume of CO2 recorded?

Answer 8

Gas syringe

Question 9

How is the rate of anaerobic respiration in yeast measured?

Answer 9

rate (cm ^3/s) = volume of gas produced / time taken