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1. Question
The Internal Compartments of the Human Body
A human body consists of trillions of cells organized in a way that maintains distinct internal compartments. These compartments keep body cells separated from external environmental threats and keep the cells moist and nourished. They also separate internal body fluids from the countless microorganisms that grow on body surfaces, including the lining of certain tracts, or passageways. The intestinal tract, for example, is home to even more bacteria cells than the total of all human cells in the body, yet these bacteria are outside the body and cannot be allowed to circulate freely inside the body. Cells, for example, have a cell membrane (also referred to as the plasma membrane) that keeps the intracellular environment—the fluids and organelles—separate from the extracellular environment. Blood vessels keep blood inside a closed circulatory system, and nerves and muscles are wrapped in connective tissue sheaths that separate them from surrounding structures. In the chest and abdomen, a variety of internal membranes keep major organs such as the lungs, heart, and kidneys separate from others.
Q. Which of the following is NOT true about the internal compartments of the body?
a. They are kept separate because of the way that the trillions of cells within the human body are organized
b. These compartments not only nourish cells but they keep microorganisms on the exterior away from our bodily fluids
c. They do allow certain bacteria cells to enter and circulate the body as needed
d. The membrane on cells and blood vessels that keep blood in a closed system contribute to keeping these compartments distinct
2. Question
Dorothy Hodgkin
Because the wavelengths of X-rays (10-10,000 picometers [pm]) are comparable to the size of atoms, X-rays can be used to determine the structure of molecules. When a beam of X-rays is passed through molecules packed together in a crystal, the X-rays collide with the electrons and scatter. Constructive and destructive interference of these scattered X-rays creates a specific diffraction pattern. Calculating backward from this pattern, the positions of each of the atoms in the molecule can be determined very precisely. One of the pioneers who helped create this technology was Dorothy Crowfoot Hodgkin.
She was born in Cairo, Egypt, in 1910, where her British parents were studying archeology. Even as a young girl, she was fascinated with minerals and crystals. When she was a student at Oxford University, she began researching how X-ray crystallography could be used to determine the structure of biomolecules. She invented new techniques that allowed her and her students to determine the structures of vitamin B12, penicillin, and many other important molecules. Diabetes, a disease that affects 382 million people worldwide, involves the hormone insulin. Hodgkin began studying the structure of insulin in 1934, but it required several decades of advances in the field before she finally reported the structure in 1969. Understanding the structure has led to better understanding of the disease and treatment options.
Q. According to paragraph 1, all of the following are true except …
a. X-ray wavelengths are similar in size to particles and are, thus, how scientists figure out the structure of molecules
b. The result of the collision of x-rays and electrons is a diffraction pattern
c. The pattern that results from the colliding of electrons and x-rays allows for the position of each atom to be accurately determined
d. Dorothy Hodgkin is considered a pioneer of this technology