New species develop naturally through the process of natural selection . Due to natural selection, organisms with traits that better enable them to adapt to their environment will tend to survive and reproduce in greater numbers. Natural selection causes beneficial heritable traits to become more common in a population and unfavorable heritable traits to become less common. For example, a giraffe's neck is beneficial because it allows the giraffe to reach leaves high in trees. Natural selection caused this beneficial trait to become more common than short necks. A large group of bears lives in a forest. Over time the climate of the forest changes and becomes very cold. Some of the bears have thicker fur while some of the others have thinner fur. Due to the cold weather the bears with thinner fur die earlier. Also the bears with thicker fur have an easier time finding mates. Because of this the bears with thick fur have their traits passed on more often and bears with thin fur appear less and less in the population Will the number of bears with thin fur increase or decrease if the climate of the forest becomes hot?
Ans: increase

As for the public health or food safety concern, organic foods are intended to be healthy, free of contaminations and free from agents that could cause human diseases. Organic milk is meant to have no chemical residues to consumers, and the restrictions on the use of antibiotics and chemicals in organic food production has the purpose to accomplish this goal. Although dairy cows in both organic and conventional farming practices can be exposed to pathogens, it has been shown that, because antibiotics are not permitted as a preventative measure in organic practices, there are far fewer antibiotic resistant pathogens on organic farms. This dramatically increases the efficacy of antibiotics when/if they are necessary. Two farmers sold their produce and milk on a large nearby market. John practiced organic farming and also produced organic milk, while Danny sold non-organic produce and milk. Which farmer sold more healthy and safe foods?
Ans: John

Another obvious change that occurs during puberty is rapid growth. This is called the adolescent growth spurt . In boys, it is controlled by testosterone. The rate of growth usually starts to increase relatively early in puberty. At its peak rate, growth in height is about 10 centimeters (almost 4 inches) per year in the average male. Growth generally remains rapid for several years. Growth and development of muscles occur toward the end of the growth spurt in height. Muscles may continue to develop and gain strength after growth in height is finished. Two researches studied adolescents during puberty. Tim studied males, while Dan studied females. Which researcher didn't observe that growth in height is about 10 centimeters (almost 4 inches) per year in the average male?
Ans: Dan

Klinefelter's syndrome is caused by the presence of one or more extra copies of the X chromosome in a male's cells. Extra genetic material from the X chromosome interferes with male sexual development, preventing the testicles from functioning normally and reducing the levels of testosterone. Triple X syndrome (trisomy X) results from an extra copy of the X chromosome in each of a female's cells. Females with trisomy X have a lower IQ than their siblings. Turner syndrome results when each of a female's cells has one normal X chromosome and the other sex chromosome is missing or altered. The missing genetic material affects development and causes the characteristic features of the condition, including short stature and infertility. David is a physician with the children's hospital. He is seeing four patients, patient A, patient B, patient C, and patient D. Patient A is a male with Klinefelter's syndrome. Patient B is female with Turner syndrome. Patient C is a male and does not have any of these illnesses. Patient D is a female and she too does not have any of these illnesses. Would patient C have higher or lower level of testosterone than patient A?
Ans: higher