A species of dark-green trees is spread over a very large terrain. Over a long period of time,
mountains form in this area and the trees
become split by the new formation. Later, the
trees on the east side of the mountain are all
light-green.

Over time, the light-green and dark-green trees
spread to a new field that is not separated by the
mountains. Both types of trees are seen in the
same field. However, the trees cannot produce
any fertile offspring together. Which of the
following provides the BEST explanation as to
why the two populations of trees cannot produce
fertile offspring?
A. The trees on the west side of the mountain
retained their original phenotype that became
unique to their population.
B. The trees on the east side of the mountain
developed a new phenotype, which made them
unable to produce fertile offspring.
C. The trees on the east side of the mountain
experienced many genetic mutations and
recombinations unique to their population.
D. The trees on the west side of the mountain
could not adapt to the new barrier, which made
them unable to produce fertile offspring.

european union policies. the eu's long-term objective is to achieve levels of air quality that do not result in unacceptable impacts on, and risks to, human health and the environment. eu policies aim to reduce exposure to air pollution by reducing emissions and setting limits and target values for air quality.

the main environmental problems in western europe were: energy production/acid rain, nuclear power/waste, air pollution/climate, heavy metals, pesticides, water pollution, solid waste, and unforeseen accidents. many environmental problems are common to most european countries.

answer: a) a compound microscope has a greater magnification ability than a simple microscope.

explanation:

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.

meiosis is the first to occur after the nuclei of opposite of opposite mating types fuse