Why do some bread recipes suggest letting the dough rise in a warm place after kneading?

Question

A.  Warming the bread slightly before cooking it in a hot oven stretches out the gluten.
B.  The metabolic rate of yeast speeds up at warmer temperatures, so more carbon dioxide is released and the dough rises more quickly.
C.  The metabolic rate of yeast slows down at warmer temperatures, so more sugar is maintained and the bread is sweeter. 
D.  Yeast cannot carry out fermentation at room temperature.

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

Gather Content
What do you already know about yeast? What other information is related to the question?

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

B.  The metabolic rate of yeast speeds up at warmer temperatures, so more carbon dioxide is released and the dough rises more quickly.

Clarify Question
What is the key concept addressed by the question?
        · This question is asking about the benefit of a warm temperature to the rising of bread dough.
What type of thinking is required?
        · Apply level:
            o You are being asked to take what you already know and use, or apply, it to the consequences of an increased temperature on the outcome of rising bread dough.

Gather Content
What do you already know about yeast? What other information is related to the question?
        · Living yeast, a one-celled fungus, is a necessary component of bread dough if the dough is to rise.
        · Yeast feed on the sugar in bread dough.
        · As the yeast ingest the sugar, they carry out glycolysis and then alcoholic fermentation on the sugar.
        · Glycolysis and fermentation are enzyme-driven processes.
        · As long as the temperature is not so high that it is damaging to the structure of the enzyme, enzyme activity tends to increase with temperature to a certain point.
        · Fermentation produces carbon dioxide, which is released as a gas.
        · The gas bubbles of carbon dioxide cause bread dough to rise.

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · Yeast can ferment at room temperature, but the rate is much slower than it is at warmer temperatures.
        · Metabolism does not decrease with increased temperature unless the temperature is so high that it becomes damaging to enzymes.
        · If the yeast is kept warm, its enzymes will metabolize the sugar in the bread dough faster, which will cause the bread dough to rise faster.

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        · Apply level:
            o Answering this question correctly depended on your ability to use the action of yeast in a new situation. If you got an incorrect answer, did you remember that yeast metabolize the sugar in bread dough, or that temperature and the rate of activity for metabolic enzymes increase together? Did you have trouble extending the nature of yeast to determine the correct answer?