Question

cycle through systems. In 'perfect' systems, the amount of a nutrient remains relatively constant as it moves through soil/water and then feeding relationships.

The carbon cycle starts with  that is tied up in the air in CO2.

This carbon is trapped by producers that do  - the carbon ends up in organic compounds such as  . The carbon passes through consumers through feeding relationships and is returned to the air during cellular  in either living organisms, or as released by  breaking down dead organic material.

The carbon cycle is not stable due to excess carbon release by burning fossil fuels (and other sources) and this is leading to the environmental problem of  .

The nitrogen cycle starts with  gas in the atmosphere. This nitrogen can be 'fixed' by lightning, or by special bacteria that form a relationship with the roots of legumes. The nitrogen can then be taken up by the plants, trapped in their tissues and passed through living organisms through feeding relationships. Waste releases ammonia into the soil that can be converted to usable nitrogen by certain  in the soil. There are also bacteria that do denitrification - converting nitrites and nitrates to atmospheric nitrogen.

Flag this Question

Question 21 pts

Populations will show  growth if they are in an optimum situation.

J curve growth cannot continue indefinitely though. Biotic potential is what causes the initial growth -  is the potential to increase in numbers without constraint.

What happens with healthy populations is a leveling off into an  .

This leveling is caused by  (or limiting factors). Environmental resistance (limiting factors) cause deaths, or prevent population increases.

Limiting factors can be density-dependent which means the resistance increases as the  increases - competition for food or space, predation, spread of disease are all density-dependent limiting factors.

Density-independent factors limit growth without regard to population density. Factors such as floods, volcanoes, tornadoes are density-independent.

The leveling of the curve indicates the population has reached  - the maximum number of individuals that an area can support without causing damage.

Answer 1

Ans 1: In 'perfect' systems, the amount of a nutrient remains relatively constant as it moves through soil/water and then between species (food chain) through feeding relationships.

• The carbon cycle starts with the use of atmospheric carbon that is tied up in the air in CO2.
• This carbon is trapped by producers that do photosynthesis
• The carbon ends up in organic compounds such as Protein, carbohydrate, lipid and nucleic acid
• The carbon passes through consumers through feeding relationships and is returned to the air during cellular respiration as CO2 in either living organisms, or is released by decomposers by breaking down dead organic material.
• The carbon cycle is not stable due to excess carbon released by burning fossil fuels (and other sources) and this is leading to the environmental problem of global warming.