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Biological Sciences

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Specialized Eukaryotic Cells and Tissues

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Arteries are constantly expanding and contracting due to the force of blood pumped from the heart, the “blood pressure”. One would expect the walls of arteries to be composed largely of:

A Cartilage.
B Connective tissue containing mainly collagen fibers.
C Connective tissue containing mainly elastin fibers.
D Muscular tissue.
Ans. C

Elastin fibers allow stretching, which clearly must take place in the walls of the arteries. Collagen confers strength and is not stretchable; cartilage is even harder and more unyielding. While a small amount muscle tissue may exist in the walls of arteries, it is not significant with regard to the question.

Specialized Eukaryotic Cells and Tissues Flashcard List

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Cancer is a disease in which cells begin to divide when they shouldn’t, producing masses of cells called tumors. Cancerous tumors are called “malignant” ones because of their ability to grow aggressively, invade surrounding healthy tissue, and “metastasize”, or spread to different locations in the body as tumor cells break off, travel through the blood or lymph, and establish new tumors. Cancer is generally caused by environmental agents known as “carcinogens”, which include chemicals (such as those found in cigarette smoke) and radiation (like the UV rays of sunlight) that mutate cells, causing them to become cancerous. Tumors that originate from epithelial cells are generally known as carcinomas, and it is estimated that about 90% of all human cancers are carcinomas. Tumors that originate from muscle tissue are called “sarcomas”, and tumors can also originate from nervous and connective tissues. Epithelial tissue exists in various locations in the body, including the skin, the mucous membranes lining the lungs and gastrointestinal tract, and the linings surrounding major organs. A lab worker in Alaska develops a carcinoma of the skin. This particular worker is very dedicated, and almost never leaves the lab. The tumor is most likely the result of:A Excessive cigarette smoking by coworkers.B Excessive ingestion of toxic chemicals.C Exposure to radiation from phosphorus-32, a radioactive isotope the worker routinely uses.D Exposure to ultraviolet rays of sunlight.