Cycles in Ecosystems, Limiting Factors, and Population Sizes

Cycles in Ecosystems … Energy FLOWS (it travels ONE way – due to heat loss, and it must always be replenished by the sun) Matter (water, CO 2, O 2, nitrogen, carbon, etc.) CYCLES – it moves from one part to the next and changes form, but it does NOT have to be replaced/ replenished Energy FLOWS through and Ecosystem and Matter (nutrients) CYCLE

Biological Processes Cycle Nutrients Photosynthesis: Light energy + 6 CO H 2 O → C 6 H 12 O O 2 Cellular respiration (the process in living cells like yours – in the mitochondria – that makes energy): C 6 H 12 O O 2 → 6 CO H 2 O + energy (ATP)

The carbon cycle is an important cycle in the biosphere Carbon is in all the major molecules of all living organisms Producers “produce” glucose with carbon from CO 2 in the atmosphere (photosynthesis) Consumers release carbon through cellular respiration and during decomposition Decomposers break down dead plants and animals making carbon available in the soil/ water to producers Carbon ends up in oceans, soil, rocks, the atmosphere and more producers (making glucose) The Carbon Cycle

Nitrogen is also an important element in molecules of living organisms (DNA and proteins) The atmosphere is 78% nitrogen Bacteria that live in the soil and on the roots of some plants “fix” the nitrogen so plants can use it Consumers eat the producers and eventually deposit nitrogen back into the soil (aka: poop/ pee or die) Nitrogen in the soil is released back into the atmosphere (bacteria) or absorbed by plants The Nitrogen Cycle

Explain how each of the following can occur in the ecosystem shown. Nitrogen is absorbed Carbon is released by a consumerinto the atmosphere Carbon entersNitrogen is “fixed” the soil

C and N cycles Draw a simple C cycle and a N cycle for each video. Include plants, animals, air, soil, and water. Carbon cycle: c_pKg c_pKg Nitrogen cycle:

Factors in the environment that control the ability of an organism to survive and, therefore, limit the size of the population What are some abiotic factors that could limit the population of yellow-legged frogs in Yosemite National Park? Biotic factors? What are Limiting Factors?

Biotic Factors: Competition for food Availability of food Parasitism/Disease Predation Abiotic Factors: Water Oxygen Space Light Temperature Soil Pollution Examples of Limiting Factors

Time (Days) # of yeast 1.Yeast feed on sugar and require O 2. What could have allowed the yeast population to grow so quickly? 2.What could have caused the yeast population to decline so rapidly? Population Growth of Yeast

Limiting Factors Identify 4 factors that limit the snail population in a freshwater ecosystem. Include biotic and abiotic factors.

Population growth is based on limiting factors and population interactions in each ecosystem. These limits set the carrying capacity (k) of the ecosystem. The carrying capacity is the maximum number of organisms a given area can support. What determines Population Size?

Populations continue to grow until one or more limiting factors limit the growth. Within an ecosystem, population size usually hovers around a certain number, which is the carrying capacity, depending on how the limiting factors allow organisms to grow, reproduce and survive. Population Growth

Interpret the graph of Deer Population What is the carrying capacity before 1925? What is the carrying capacity after 1925? Describe the change in deer population before 1925 and suggest a reason for this. Suggest a reason the deer population changes as it does from 1925 to Change in Deer Population from

When a population exceeds the carrying capacity, a strain upon resources could result in a sharp decline in the population. Human Carrying Capacity for Earth

Changes in Limiting Factors affect Populations In the early 1950’s the people in Borneo suffered from malaria transmitted by mosquitoes. The World Health Organization used DDT to kill the mosquitoes to reduce people infected with malaria. What impact did the DDT have on the ecosystem?

How did adding DDT change …? Mosquito population Wasp population Caterpillar population Gecko population Cat population Rat population Describe overall affects of DDT usage.

Bozeman Science Paul Anderson Ecosystems Video TYfRA TYfRA