37. What is the difference b/w endocrine and exocrine glands?
38. Discuss about alimentary canal of earthworm?
39. Difference between prokaryotic cells and Eukaryotic Cells along with diagrams?
Answers
Answer:
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Explanation:
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It is a straight tube that is present from the 1st segment to the last segment of an earthworm’s body. The anterior part of the body has the mouth that leads to a buccal cavity. This, in turn, leads to the muscular pharynx, after which is present the oesophagus and the muscular gizzard.
The muscular gizzard is a structure that helps in the grinding of the soil particles that are mixed with the organic matter and other decayed leaf particles. The gizzard leads to the stomach, which is present from 9th to 14th segments. In the stomach calciferous glands are present. They neutralize the humic acid that is present in the humus. (Humus is the organic matter of the soil that is formed due to the decomposition of leaves and other plant material)
The stomach leads to the intestine which begins from the 15th segment and continues till the last segment of the earthworm’s body. On the 26th segment, there is a pair of short and conical intestinal caecae. After the 26th segment, there is an internal median fold of dorsal wall called typhlosole, which is a characteristic feature. Typhlosole helps in increasing the area of absorption.
The anus is the small aperture through which the alimentary canal opens out. The food ingested by the earthworm passes through the alimentary canal, where the food is digested and broken down into simpler substances and absorbed through the intestinal membranes. Any insoluble and undigested food particles along with the soil particles are thrown out of the anus and are called as worm castings
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ANSWERS BIOLOGY A LEVEL
What is the difference between an endocrine and exocrine gland?
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An endocrine gland secretes its products, for example hormones, directly into the blood. An example of an endocrine gland is the adrenal gland which secretes adenaline made in the adrenal medulla directly into the blood.
An exocrine gland secretes its products for example enzymes, into ducts that lead to the target tissue. For example the salivary gland secretes saliva into the collecting duct which leads to the mouth.
It's important to note that the pancreas performs both endocrine and exocrine functions. It releases insulin and glucagon directly into the blood (endocrine) and also secretes pancreatic fluid into the pacreatic duct which leads to the duodenum (exocrine).
