Question

Name the end product of anaerobic metabolism in muscle cells.
a. Mitochondria
b. Cytoplasm
c. Pyruvate
d. Lactic acid
e. Glucose

Answer 1

Anaerobic respiration is the type of respiration where oxygen is not used and can be defined as the process in which energy is created through the combustion of carbohydrates in the absence of oxygen is anaerobic metabolism. This type of respiration is mostly seen in lower animals.

Complete answer:
Anaerobic respiration is fermentation including a process using electron acceptor other than oxygen for metabolism reactions which convert $NADH \to NAD^{+}$.Anaerobic respiration takes place in the cytoplasm of the cell. Some prokaryotes depend on the anaerobic respiration for the production of energy.

On the basis of electron acceptor, anaerobic respiration is two type:-

Alcoholic fermentation: - Alcoholic fermentation is done by the cytoplasmic enzyme which is pyruvate decarboxylase with coenzyme thiamine pyrophosphate produces ethanol as a product.
$\text{Pyruvic acid} \to CO_{2} + \text{acetaldehyde} + NADH \to \text{ethanol} + NAD^{+}$

Lactic acid fermentation: - The lactic acid fermentation is common in muscle cells that have run out the oxygen and this fermentation method is used by eukaryotes and some bacteria. During the lactic acid fermentation, glucose is converted into 3 carbon compound pyruvate through glycolysis and in the absence of oxygen in muscles pyruvate is converted into lactate through fermentation. As a result of glycolysis, 2ATP is formed. $\text{Pyruvic acid} +NADH \to \text{lactic acid } + NAD^{+}$.

Hence, the correct answer is option (D). Since Lactic acid is the end product of anaerobic respiration.

Note: When the muscle cell performs the high activities in gym and other workouts and there is less supply of oxygen so the cell performs anaerobic type of respiration and the lactic acid formed produces painful cramps in the body.