Which of the following statements best describes trace elements?
A. Trace elements are found in very small quantities in cells but still play a critical role in the functioning of living organisms.
B. Trace elements are only found in some living organisms, but not all of them.
C. Trace elements are present in living organisms in small amounts and have no special role in the fuciton of cells.
D. Trace elements are elements that are found in small quantities in nature and living orgamisms uptake them to improve the condition of the environment.
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Living matter is made up of many different elements, but 96% of all living matter is comprised of just a few. Which element below is part of this 96%?
A. iodine
B. phosphorus
C. iron
D. nitrogen
1.4 Based upon the structure of the cell membrane, which description of molecules describes those that would most easily pass through a cell membrane?
A. large and hydrophilic
B. hydrophobic and small
C. covalently bonded
D. ring structures with amine groups
1.4 The immune system is part of the body's specific defense system. When the body is exposed to a foreigh protein (antigen) that stimulates an immune response, cells known as macrophages engulf and digest the foreign protein. The macrophages then engage in what is known as antigen presentation, a process in which the macrophage displays the antigen on its cell membrane's surface. Which of the following statements below correctly describes the process of antigen presentation?
A. The macrophage's smooth ER packages the antigen proteins in a vesicle and transports the vesicle to the macrophage's cell membrane surface.
B. The macrophage's lysosomes will fuse with the vesicle containing the antigen, digesting it. The vesicle will then migrate to the macrophage cell membrane and expel the antigen proteins to the membrane surface.
C. The rough ER will envelop the antigen in a vesicle, and the golgi body will package the antigen inside the vesicle so that is can be moved to the macrophage's cell membrane.
D. The mitochondria will help the lysosomes digest the antigen and then the golgi body will package up the digested antigen proteins for transport to the macrophage cell membrane.
1.3 Individuals with a genetic disorder Tay-Sachs disease have a mutant HEXA gene. This gene codes for an enzyme (HEXA) that metabolizes a specific type of lipid called a ganglioside glycolipid. When HEXA is mutant, this glycolipid cannot be degraded and accumulates in the bloodstream, causing irreparable brain damage. Which of the following cellular organelles is most directly involved in the disease process?
A. lysosome
B. smooth ER
C. ribosome
D. rough ER
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