Answer the following question given this paragraph: Evasion of the Immune System by Pathogens It is important to keep in mind that although the immune system has evolved to be able to control many pathogens, pathogens themselves have evolved ways to evade the immune response. An example already mentioned is in Mycobactrium tuberculosis, which has evolved a complex cell wall that is resistant to the digestive enzymes of the macrophages that ingest them, and thus persists in the host, causing the chronic disease tuberculosis. This section briefly summarizes other ways in which pathogens can "outwit" immune responses. But keep in mind, although it seems as if pathogens have a will of their own, they do not. All of these evasive "strategies" arose strictly by evolution, driven by selection. Bacteria sometimes evade immune responses because they exist in multiple strains, such as different groups of Staphylococcus aureus. aureus is commonly found in minor skin infections, such as boils, and some healthy people harbor it in their nose. One small group of strains of this bacterium, however, called methicillin-resistant Staphylococcus aureus, has become resistant to multiple antibiotics and is essentially untreatable. Different bacterial strains differ in the antigens on their surfaces. The immune response against one strain (antigen) does not affect the other; thus, the species survives. Another method of immune evasion is mutation. Because viruses' surface molecules mutate continuously, viruses like influenza change enough each year that the flu vaccine for one year may not protect against the flu common to the next. New vaccine formulations must be derived for each flu season. Genetic recombinationthe combining of gene segments from two different pathogensis an efficient form of immune evasion. For example, the influenza virus contains gene segments that can recombine when two different viruses infect the same cell. Recombination between human and pig influenza viruses led to the 2010 H1N1 swine flu outbreak. Pathogens can produce immunosuppressive molecules that... Q: Bacteria may become untreatable if they develop what in response to multiple antibiotics? Choices: - affinity - weakness - acceptance - resistance A:
resistance
Answer the following question given this paragraph: Major exchange pools of carbon include organisms and the atmosphere. Carbon cycles more quickly between these components of the carbon cycle. Q: Major exchange pools of carbon include organisms and what else? Choices: - location - duration - the intensity - the atmosphere A:
the atmosphere
Q: Answer the following question given this paragraph: Male Reproductive System Erectile dysfunction (ED) is a condition in which a man has difficulty either initiating or maintaining an erection. The combined prevalence of minimal, moderate, and complete ED is approximately 40 percent in men at age 40, and reaches nearly 70 percent by 70 years of age. In addition to aging, ED is associated with diabetes, vascular disease, psychiatric disorders, prostate disorders, the use of some drugs such as certain antidepressants, and problems with the testes resulting in low testosterone concentrations. These physical and emotional conditions can lead to interruptions in the vasodilation pathway and result in an inability to achieve an erection. Recall that the release of NO induces relaxation of the smooth muscles that surround the penile arteries, leading to the vasodilation necessary to achieve an erection. To reverse the process of vasodilation, an enzyme called phosphodiesterase (PDE) degrades a key component of the NO signaling pathway called cGMP. There are several different forms of this enzyme, and PDE type 5 is the type of PDE found in the tissues of the penis. Scientists discovered that inhibiting PDE5 increases blood flow, and allows vasodilation of the penis to occur. PDEs and the vasodilation signaling pathway are found in the vasculature in other parts of the body. In the 1990s, clinical trials of a PDE5 inhibitor called sildenafil were initiated to treat hypertension and angina pectoris (chest pain caused by poor blood flow through the heart). The trial showed that the drug was not effective at treating heart conditions, but many men experienced erection and priapism (erection lasting longer than 4 hours). Because of this, a clinical trial was started to investigate the ability of sildenafil to promote erections in men suffering from ED. In 1998, the FDA approved the drug, marketed as Viagra®️. Since approval of the drug, sildenafil and similar PDE inhibitors now generate over a billion dollars a year in sales, and are reported to be effective in treating... Q: What percentage of men suffer from some form of erectile dysfunction by age 40? Choices: - approximately 60 percent - approximately 10 percent - approximately 80 percent - approximately 40 percent A:
A: approximately 40 percent
Question: Answer the following question given this paragraph: During active transport, specialized integral membrane proteins recognize the substance and allows it access. Essentially this process is forcing a ion or molecule to cross the membrane when normally it would not. Moving a substance against its concentration gradient is known as primary active transport , and the proteins involved in it as "pumps". This process uses the energy of ATP. In secondary active transport , energy from an electrochemical gradient is used to transport substances. This process involves pore-forming proteins that form channels through the cell membrane. Q: What phenomenon involves the forcing of a substance into a cell against its concentration gradient? Choices: - active absorption - osmosis - secondary transport - primary active transport A:
Answer: primary active transport
*Question*
Answer the following question given this paragraph: Hydrogen bonds cause water to have a relatively high boiling point of 100C (212F). Because of its high boiling point, most water on Earth is in a liquid state rather than in a gaseous state. Water in its liquid state is needed by all living things. Hydrogen bonds also cause water to expand when it freezes. This, in turn, causes ice to have a lower density (mass/volume) than liquid water. The lower density of ice means that it floats on water. For example, in cold climates, ice floats on top of the water in lakes. This allows lake animals such as fish to survive the winter by staying in the water under the ice. Q: What bonds cause water to have a high boiling point, leaving most water on earth in a liquid state rather than in a gaseous state? Choices: - potassium bonds - carbon bonds - helium bonds - hydrogen bonds A:
**Answer**
hydrogen bonds
Answer the following question given this paragraph: Food provides building materials for the body. The body needs building materials for growth and repair. Q: What provides building materials for the body? Choices: - energy - heat - water - food A:
food