The answer to the given question will be that the muscles that guard the entrances and exits of the internal passage are known as sphincter (circular muscles).
Due to their structure and controllability, skeletal circular muscles differ from their smooth muscle counterparts.
The muscularis mucosa, which is mostly found in the stomach, is composed of smooth muscle.
The longitudinal layer shortens the tract while the circular muscle layer in the muscularis externa prevents food from moving backward.The human body contains at least 50 or 60 different types of sphincters.
Some are quite small, like the many precapillary sphincters that line the circulatory system's blood vessels.
Lower esophageal sphincter (LES), pyloric sphincter (PS), ileocecal sphincter (ICS), and internal sphincter are the four different smooth muscle sphincters found in the GI system (IAS).
Hence, the answer is that the muscles that guard the entrances and exits of the internal passage are known as sphincter (circular muscles).
a) seedless (bryophytes) vs. seed condition (all others)
Explanation:
Theyproduce enclosed gametangia( sexual) and sporangia(asexual), but they do not produce flowers or seeds. Reproduction proceeds through sexual and an asexual phase. They produce spores.
Because the definition of parasitism is living as a parasite on or in another organism and in this case the Aphids are living on the underside of the leaves. So i would go with Parasitism. If im wrong please forgive me :)
