Ques: Q: Active and passive forms of what enable the body to resist damage from pathogens? Read this paragraph and choose the correct option from the provided answers: Active versus Passive Immunity Immunity to pathogens, and the ability to control pathogen growth so that damage to the tissues of the body is limited, can be acquired by (1) the active development of an immune response in the infected individual or (2) the passive transfer of immune components from an immune individual to a nonimmune one. Both active and passive immunity have examples in the natural world and as part of medicine. Active immunity is the resistance to pathogens acquired during an adaptive immune response within an individual (Table 21.6). Naturally acquired active immunity, the response to a pathogen, is the focus of this chapter. Artificially acquired active immunity involves the use of vaccines. A vaccine is a killed or weakened pathogen or its components that, when administered to a healthy individual, leads to the development of immunological memory (a weakened primary immune response) without causing much in the way of symptoms. Thus, with the use of vaccines, one can avoid the damage from disease that results from the first exposure to the pathogen, yet reap the benefits of protection from immunological memory. The advent of vaccines was one of the major medical advances of the twentieth century and led to the eradication of smallpox and the control of many infectious diseases, including polio, measles, and whooping cough. Choices: - potential - stem cells - autonomy - immunity A:
Ans: immunity

Ques: Q: For any given species, what term means the maximum population that can be supported by the environment? Read this paragraph and choose the correct option from the provided answers: A population can't keep growing bigger and bigger forever. Sooner or later, it will run out of things it needs. For a given species, there is a maximum population that can be supported by the environment. This maximum is called the carrying capacity . When a population gets close to the carrying capacity, it usually grows more slowly ( Figure below ). When the population reaches the carrying capacity, it stops growing. Choices: - zero population growth - mass extinction - tipping point - carrying capacity A:
Ans: carrying capacity

Ques: Q: Increasing voltage with a higher-volt battery does what to the current? Read this paragraph and choose the correct option from the provided answers: Ohm's law may be easier to understand with an analogy. Current flowing through a wire is like water flowing through a hose. Increasing voltage with a higher-volt battery increases the current. This is like opening the tap wider so more water flows through the hose. Increasing resistance reduces the current. This is like stepping on the hose so less water can flow through it. If you still aren't sure about the relationships among current, voltage, and resistance, watch the video at this URL: http://www. youtube. com/watch?v=KvVTh3ak5dQ. Choices: - blocks it - stops it - decreases it - increases it A:
Ans: increases it

Ques: Q: Memory t cells are long-lived and can even persist for how long? Read this paragraph and choose the correct option from the provided answers: The Cellular Basis of Immunological Memory As already discussed, one of the major features of an adaptive immune response is the development of immunological memory. During a primary adaptive immune response, both memory T cells and effector T cells are generated. Memory T cells are long-lived and can even persist for a lifetime. Memory cells are primed to act rapidly. Thus, any subsequent exposure to the pathogen will elicit a very rapid T cell response. This rapid, secondary adaptive response generates large numbers of effector T cells so fast that the pathogen is often overwhelmed before it can cause any symptoms of disease. This is what is meant by immunity to a disease. The same pattern of primary and secondary immune responses occurs in B cells and the antibody response, as will be discussed later in the chapter. Choices: - eons - days - minutes - lifetime A:
Ans:
lifetime