Which layer of the digestive tract controls digestive propulsion?

a. serosa
b. mucosa
c. submucosa
d. muscularis externa

D. muscularis externa

Explanation:

The gastrointestinal tract or digestive tract consist of four main layers:

•Mucosa- consists of the epithelium together with glandular tissue and the lamina propria  (connective tissue)

•Submuscosa- consists of fibrous connective tissue with larger blood vessels, lymphatics, nerves..

•Muscularis externa-smooth muscle layer that consists of three layers, responsible for movement (propulsion) and physical break down of the food

•Serosa-consists of connective tissue continuous with the peritoneum.

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.

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