Wild hogs introduced to Texas from Europe became feral after the hogs escaped from the ranches where they lived. Feral hogs are omnivores that feed on native plants, crops, and small animals. Feral hogs can damage an ecosystem by rooting through the soil to look for food and trampling small plants. Which types of native organisms do feral hogs most likely compete with for food sources?

Giant salvinia is an aquatic plant that floats on water and reproduces rapidly. When these plants die, decomposition by bacteria affects oxygen levels in the water. As more plants die, less oxygen is available in the water. Students observe a pond covered by giant salvinia. Which statement is the best prediction the students can make about the immediate future of the pond?"

Researchers are studying lichens growing on trees in a forest ecosystem. At the beginning of the study, the researchers identified twelve lichen species in the forest. Later, a forest fire happened in the study area. The researchers returned to the area and found only six lichen species. Which inference is best supported from the researchers’ observations?

An environmental change drastically reduced the population of milkweed plants in an area. The milkweed plants provided the only source of food for a nearby population of monarch butterfly caterpillars. Which statement describes the most likely effect of this environmental change on this population of monarch butterflies?

A student observes several species of plants growing in a drainage ditch. Some species have short roots, while others have long roots. During periods of heavy rain, the ditch fills with fast-moving water, which uproots more plants that have short roots than long roots. Which short-term effect will most likely result from a year with more heavy rain than normal?

Which of these human activities is most likely to cause the excessive growth of phytoplankton in the world’s oceans?

A coastal area that once supported a thriving fishing industry is overfished. The number of species found living in the marine ecosystem decreases. Which of these activities is most likely to increase the natural biodiversity in the area?

Which is a way that human activities on land can affect ocean systems

Black walnut trees produce a nontoxic chemical that becomes highly toxic when it is exposed to air or soil. How does this chemical help black walnut trees compete with plants growing nearby?