The amount of energy produced by primary producers is always

Over the last century, the population sizes of many animal and plant species have been rapidly declining due to human activities. Given this information, which evolutionary mechanism would most likely be affected by this change?

The pesticide DDT was widely used in the 1940s as a method of insect control. In the late 1950s the first DDT-resistant mosquitoes were discovered, and eventually DDT-resistant mosquitoes were found globally. When DDT is used now, the development of DDT resistance in mosquito populations occurs in months rather than years. Which of the following best explains the observations concerning DDT resistance in mosquitoes?

Based on this cladogram, which group of eukaryotes comprise a single clade? From the left, a horizontal line extends to the right and reaches a branch point. The upper branch extends to the right, leading to Metamonada. The lower branch extends to the right and reaches a second branch point. The upper branch extends to the right, leading to Loukozon. The lower branch extends to the right and reaches a third branch point. The upper branch extends to the right and reaches a fourth branch point. The upper branch extends to the right, leading to Euglenozoa. The lower branch extends to the right, leading to Percolozoa. From the third branch point, the lower branch extends to the right and reaches a fifth branch point. The upper branch extends to the right, leading to Rhizaria. The lower branch extends to the right and reaches a sixth branch point. The upper branch extends to the right and leads to a seventh branch point. The upper branch leads to Alveolata and the lower branch leads to Chromista. From the sixth branch point, the lower branch leads to Plantae. From the fifth branch point, the lower branch leads to an eighth branch point. The upper branch leads to Apusozoa and the lower branch leads to a ninth branch point. The upper branch leads to Amoebozoa and the lower branch leads to a tenth branch point. The upper branch leads to Fungi and the lower branch leads to an eleventh branch point. The upper branch leads to Choanozoa and the lower branch leads to Animalia.

While studying Darwin’s finches on the Galapagos Islands you observe two species of ground finch that appear to successfully coexist on one island. One species has a large beak, the other a small beak. What is the best explanation for their coexistence?

A census of birds nesting on a Galapagos Island revealed that 20 of them show a rare recessive condition that affected beak formation. The other 63 birds in this population show no beak defect. If this population is in Hardy-Weinberg equilibrium, what is the proportion of the dominant allele? 

Many chemical toxins introduced by humans can be incorporated into animals, most often in fat. These toxins pose a particular problem to ______.

In a study on seed germination of radish seeds, five beakers were set up containing equal numbers of seeds. The beakers were subjected to the conditions indicated in the table below. Germination of Radish Seeds Beaker 1 Beaker 2 Beaker 3 Beaker 4 Beaker 5 Incubation Temperature 22°C 22°C 22°C 22°C 5°C Treatment of Radish Seeds None Boiled None None None Addition of deoxygenated water Yes Yes No Yes Yes Addition of mineral oil to block oxygen diffusion No No Yes Yes No Comparing results from which of the following pairs of beakers would help determine if enzymes are necessary for germination?

Which statement about competition between two species is correct?

At the bottom is node 1. From node 1, two lines extend upward, one leading to node 2 on the left and one leading to node 3 on the right. From node 2, two lines extend upward, one leading to node 4 on the left and one leading to node 5 on the right. From node 3, two lines extend upward, one leading to node 6 on the left and one leading to node 7 on the right. From node 4, two lines extend upward to taxa A on the left and B on the right. From node 5, two lines extend upward to taxa C on the left and D on the right. From node 6, two lines extend upward to taxa E on the left and F on the right. From node 7, two lines extend upward to taxa G on the left and H on the right. Which species on this cladogram is/are the most recent in evolutionary time?