1. fruit flies with curly wings cannot survive at high temperatures
2. the environment influences wing phenotype in these fruit flies
3. height temperatures increases the rate of mutations
4. wing length in these fruit flies is directly proportional to temperature

Correct Answer Number: 2

Explanation: The environment influences the expression of many genes. For example, identical twins, with identical DNA, may look different from each other because of the different environmental influences.

1. increasing need for new antibiotics
2. increasing number of individuals in the human population
3. decreasing number of new fossils discovered in undisturbed rock layers
4. decreasing activity of photosynthetic organisms due to warming of the atmosphere

Correct Answer Number: 1

Explanation: It is believed that certain pathogens have adapted to the antibodies that we have, becoming resistant. These species are actually evolving, or changing through time, to include the resistant gene for the antibiotics. Therefore the pathogens with the gene survive, and pass on the resistant gene, which causes it to increase.

1. nondisjunction
2. crossing-over
3. segregation
4. hybridization

Correct Answer Number: 1

Explanation: Nondisjunction is the result of the paired homologous chromosomes seperating unequally during meiosis. So instead of one of a particular chromosome going to each of the 4 resulting sex cells, one cell gets two chromosomes of that type. Then during fertilization that zygote gets three of that particular chromosome instead of the normal two, resulting in one extra chromosome. That zygote then undergoes mitosis, resulting in all of that organisms cells containing one extra chromosome.

1. contribute to new variations in organisms
2. are usually related to the environment in which they appear
3. are usually beneficial to the organism in which they appear
4. usually cause species of organisms to become extinct

Correct Answer Number: 1

Explanation: Mutations, which usually happen randomly, increase variety in the offspring. It is this variety that allows species to survive in a changing environment.