Within an ecosystem, which of the following best explains why organisms from higher trophic levels typically account for less biomass than those from lower trophic levels?

In a population of flowering plants, there are two alleles for flower color. One is dominant and is represented A, one is recessive and is represented a.  The allele frequency of A is 0.7. What is the allele frequency of a?

In a population of 1000 flowering plants, there are two possible alleles for flower color, one dominant and one recessive. 400 plants are homozygous dominant, 200 plants are heterozygous, and 400 plants are homozygous recessive. How many total alleles are in the gene pool?

  Male red-winged blackbirds defend high-quality territories using vocal displays and bright plumage. Females actively observe these displays to select a mate, as the best territories provide superior protection for their offspring. This process, where the female chooses a partner based on the quality of his territory and physical signals, is an example of:

The orca, or “killer whale” is actually part of the dolphin family, called Delphinidae, and is referred to by the scientific name Orcinus orca. What is the name of the genus?

Which of the following is NOT a source of water vapor in the atmosphere?

In order for natural selection to occur, what must be present?

Barriers that prevent mating between species before fertilization are called ______.

Some people store their newborn baby’s umbilical cord blood in a cryobank because umbilical cord blood contains high levels of stem cells. The specific types of stem cells found in umbilical cord blood are hematopoietic progenitor cells (HPCs) and may develop into certain types of blood cells. Which statement is a compelling scientific argument in support of banking umbilical cord blood?

Arctic foxes typically have a white coat in the winter. In summer, when there is no snow on the ground, the foxes typically have a darker coat. Which of the following is most likely responsible for the seasonal change in coat color?