The correct answer is C) There is not enough oxygen in the culture medium. This is because of alcoholic fermentation, and anaerobic process where the yeast transform sugar (glucose) in ethylic alcohol (ethanol) and carbon dioxide. Glucose is decomposed into pyruvic acid which then after turns into CO2 and ethanol. The bubbles described, are produced by the carbon dioxide.
The yeast, as well as some bacteria, use the glucose molecule through "glycolysis" to obtain a 3-carbon molecule called pyruvates. Glycolysis consists of 10 coupled reactions, in the end, from one glucose (6 carbons) the yeast will obtain two pyruvates (3 carbons each).
Pyruvate can follow three main routes to obtain ATP, end up as lactate, as carbon dioxide (CO2) and water or as ethanol (alcohol) and CO2. Regarding yeast, it can only be used to obtain Ethanol plus CO2 or to obtain CO2 plus water.
The path that follows from here depends on the reaction medium. The cell gets much more energy (38 molecules of ATP) by converting pyruvate into water + CO2 than by turning it into ethanol + CO2 (2 molecules of ATP). Then, whenever possible, the yeast will follow the CO2 + water path. To support this route the cell needs oxygen. In this case, the cell obtains its energy by breathing when there is no oxygen available, the yeast has a way that allows it to gain much less energy but allows it to survive, the alcoholic fermentation, previously mentioned.
Therefore, A, B, and D answers are wrong for the reasons mentioned above.
To determine whether a cell is a eukaryotic or
prokaryotic cell, one can observe certain features.
If the cell in the question possesses a well-defined
or definite nucleus and have membrane-bound
organelles such as mitochondria, chloroplasts,
Golgi apparatus, endoplasmic reticulum, the cell is
eukaryotic. If the cell has nucleoid or indefinite
nucleus and without membrane-bound cell
organelles, the cell is prokaryotic. If ribosomes in
a cell are the 80S (S=Svedberg units) type, the cell
is eukaryotic and if ribosomes are 70S type then it
is prokaryotic.
vaccines are weakened viruses or bacteria that prompt the body to develop antibodies to foght against disease
