In first period biology class we learned that the ecosystem is a fragile and sensitive thing.

Vvnici prece di evidence would best support teason #to the history of using animals for research extends asfar back as 322 bce, when early greek physician-scientists, such as aristotle and erasistratus,performed various experiments on living animals.0 animal research played an essential role in thedevelopment of herceptin and tamoxifen, twomedications that have already saved the lives ofthousands of women who have been diagnosed withbreast cancer.even those who believe in testing on animals when it isnecessary for vital medical research practice what isknown as "the 3 rs"-reduction, refinement, andreplacement to reduce the number of animals usedfor testingbiologists believe that chimpanzees share at least 98.4percent of the same dna as humans and gorillas shareat least 97 percent, making primates a popular andlikely choice for the testing of products intended for humans

In figure 4 of the telephone components what do the labels lettered a to e

Biologists recognize five levels of cell organization. the lowest and simplest is the cellular level. organisms here are either unicellular organisms, like protozoa, or colonial organisms. colonial organisms are composed of single-celled individuals that stay together to sustain the life of the whole colony. next on the scale of complexity is the level occupied by tissue. a tissue is a group of similar cells which perform a similar activity. tissues that are organized around a common function together make up an organ, the third level of complexity. the fourth level of organization is the system, formed by a group of organs which together perform a specific bodily process. the fifth and highest level is the organism level, in which body systems work together in a structure capable of independent life. main idea: