Answer:
Option (A).
Explanation:
Lac operon system in bacteria explains the lactose metabolism in the cell. The first operon system was discovered by Jacob and Monod. Operon may be defined as the cluster of genes that are transcribed as a single RNA unit.
The bacteria uses glucose if glucose and lactose are present in the media. The bacterial cell can recognize the glucose presence as CAP-cAMP complex are required for the process of transcription and the complex level is low in the presence of glucose. This way bacteria turns off transcription for lactose genes even when the lactose is present.
Thus, the correct answer is option (A).
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The body temperature of the mammal will be higher than that of the reptile. this is because the mammal body temperature does not depend on its environmental temperature while a reptile does not have a stable body temperature and depend on the temperature of its environment.
Biotic and living are the same thing, abiotic would be non-living
Answer:
The correct answer is: upper esophageal sphincter.
Explanation:
The alimentary canal is a very long tract responsible for the digestion of the food. It is composed of several organs with many different and important functions. The alimentary canal also has a few sphincters, which are muscular valves that open and close when needed for the food to pass or be retained.
The first sphincter is the upper esophageal sphincter. One particularity of this sphincter is that is one of the few sphincters in the body that opens and closes under our conscious control, which happens when we decide to swallow our food.
From the first to the last, the order of the sphincters in the gastrointestinal tract is: upper esophageal sphincter, lower esophageal sphincter or gastroesophageal sphincter, pyloric sphincter, ileocecal sphincter, and anus.
