Biology EOC Category 5 (Cont)

Matter Flow in Ecosystems

• B.12(D) describe the flow of matter

  through the carbon and nitrogen cycles and explain the consequences of disrupting these cycles

Carbon Cycle

• The recycling of carbon in the ecosystem

• Carbon sinks have the ability to hold large amounts of carbon (i.e. oceans, forests, and fossil fuels)

• ALL living things contain carbon

Multiple Choice

The diagram shows why the ocean is a large carbon sink.

An increase in the amount of carbon dioxide in the atmosphere can cause atmospheric temperatures to increase. Which statement best explains how this could affect the ocean as a carbon sink?

• Less atmospheric carbon dioxide would be available to phytoplankton

• Dissolved carbon dioxide gas in the ocean would increase because surface winds would cause a deeper circulation pattern, making more room for the gas

• Less carbon dioxide gas would be contained in the ocean because increasing precipitation would dilute the carbon entering the ocean

• Less carbon dioxide would be dissolved in the ocean because increasing atmospheric temperatures would cause the ocean temperature to increase

Multiple Choice

The carbon cycle includes processes that release carbon dioxide into the atmosphere and places that act as carbon reservoirs. The diagram in the image shows both major processes that release carbon and major carbon reservoirs.

Which of these disruptions would cause an excess output in the carbon cycle?

• The destruction of terrestrial biota

• Increases in marine biota

• A reduction in the use of fossil fuels

• A thickening of ocean sediments

Nitrogen Cycle

• The recycling of Nitrogen in the ecosystem

• Nitrogen fixation is the process in which bacteria convert atmospheric nitrogen into usable sources for plants

• Animals obtain their nitrogen from other organisms, primarily plants, from proteins

Multiple Choice

As a part of the nitrogen cycle, animals acquire some amino acids by doing which of the following?

• Breathing air

• Eating plants

• Drinking water

• Producing waste

Multiple Choice

The diagram in the image represents the nitrogen cycle in a student's aquarium. Ammonia, nitrites, and, to a lesser degree, nitrates can be harmful to fish. The student wants to keep the nitrogen in this aquarium cycling normally without having to continually change the water.

Which of the following should the student add more of to help remove the nitrates and improve the natural cycling of nitrogen in this aquarium?

• Fish

• Plants

• Nitrobacter

• Water

​Phosphorus Cycle

• Does not have a gaseous State

• ​an important building the backbone of DNA and RNA

Ecological Succession

• B.11(B) describe how events and processes that occur during ecological succession can change populations and species diversity

• B.11(A) summarize the role of microorganisms in both maintaining and disrupting the health of both organisms and ecosystems

Ecological Succession

• Succession - changes in the environment over time

• Pioneer Species - first species to appear in an area

• Climax Community - the resulting ecosystem following ecological succession where diversity is high and the ecosystem is relatively stable

Primary Succession

• Longer period of time to reach climax community

• Start with bare rock/nothing

• Pioneer species = lichen and mosses, which break down rock into soil, provide nutrients to the soil, and give way to larger more complex plant life

Multiple Choice

Enchanted Rock State Natural Area is located in central Texas. Enchanted Rock is a dome of granite. The area consists of four easily identifiable communities. The table describes the characteristics of each type of community in the area.

A student studying primary succession should focus on which of these communities?

• Open oak woodland

• Mesquite grassland

• Floodplain

• Granite rock

Secondary Succession

• Shorter process of succession to reach a climax community

• Pioneer species = small plants and grasses

• Generally follows after an environmental catastrophe such as a forest fire, flooding, or human destruction

Multiple Choice

The graph shows the basic changes in a forest community following a disturbance.

The information shown in the graph suggests that the changes in the forest community were caused by-

• tree-leaf replacement after a storm

• succession after a fire

• repeated habitat destruction

• decreased species diversity

Multiple Choice

During secondary succession, which of these best describes why decomposing pioneer plants give way to larger, more complex plant species, such as hardwood trees?

• Increased amounts of sunlight are able to reach the ground while the pioneer species are decomposing

• Increased soil temperatures from decomposing pioneer species help tree seeds germinate more quickly

• Increased amounts of decomposing pioneer species remove nutrients that tree seedlings need to grow and mature

• Increased amounts of soil from decomposing pioneer species allow plants with more extensive root systems to become established

Ecosystem Stability

• B.12(E) describe how environmental change can impact ecosystem stability

Carrying Capacity

• The total population of organisms that can be supported by an ecosystem

• Limiting factors - resources in the ecosystem (biotic & abiotic) that can limit the population of individuals (ex. Water, Space, Mates, Food)

• The environment will naturally stabilize the population

Human Impacts

• Pollution/runoff can add excess carbon and toxins into the ecosystem

• Overhunting/overfishing will reduce the population of animals which reduces the amount of food for organisms that rely on them

• Deforestation destroys the habitats of many organisms forcing them to move elsewhere

Multiple Choice

Roads are often built through forests for industrial purposes or as land developed for residential or commercial needs. How would road construction through a forest most likely affect the ecosystem?

• Non-native species would replace native species

• The number of primary consumers would increase

• The natural succession of vegetation would change

• All producers will be eliminated from the community

Multiple Choice

Dead zones are low-oxygen areas that develop on the sea floor. Scientists hypothesize that phytoplankton blooms cause the dead zones. Phytoplankton blooms occur when excess nutrients are introduced by pollution from fertilizers, sewage plants, and the burning of fossil fuels. Which of the following would most likely cause an increase in these contributors to dead zones?

• Rainfall patterns that increase freshwater runoff from terrestrial areas

• Replacing coal-fired power plants with windmills

• Farming practices that reduce nitrate and phosphate applications

• Constructing efficient water-recovery and treatment plants