Short Answers - EAR

Question 1

🌟 How is an ecosystem you have studied both vulnerable and resilient to natural stress? (4 marks)

Answer 1

Vulnerable

• Washovers (storm waves, rainfall) flood dunes, drowning vegetation which destabilises the dunes as there is nothing holding the sand together
• Also disconnected (not a discontinuous pattern) so species cannot easily move to another ecosystem
• Primary species (quite specialised) - if they are impacted, dunes are destabilised (impacts plants in further zonation levels)

Resilient

• Primary species able to build the dune back up through strong root systems, ability to grow very quickly and how it’s tolerant
• Supports further zonation levels - succession (increases the biodiversity of dunes)
• Sandbars form during storm events

Question 2

Identify 9 natural causes of ecosystem stress.

Answer 2

Fire, flood, landslide
Volcanic eruption, earthquake, drought
Disease, cyclone, change in stream course

Question 3

🌟 Using an example, describe how nutrient cycling affects ecosystems. (4 marks)

Answer 3

Nutrients are chemical elements or compounds taken in by an organism to survive, and its cycling is often facilitated through food chains and an ecosystem’s abiotic and biotic components so that ecosystems can restore and maintain their dynamic equilibrium. The carbon cycle plays a critical role in ocean functioning. As inorganic carbon dioxide gas is captured from the atmosphere, some organisms (e.g. phytoplankton) use this along with sunlight to photosynthesise and make their shells. Many marine animals consume phytoplankton and use the carbon for energy and growing new cells, and ultimately through respiration, this carbon dioxide is released back into the atmosphere. Unconsumed detritus and dead phytoplankton settle to the bottom of the ocean where it is stored as biomass carbon amongst sediment. Over time, carbon-rich sediments on the ocean floor compact under pressure to form sedimentary rocks such as limestone and shale, which ultimately alters the shape of the ocean floor.

Question 4

🌟 With specific reference to both diagrams, explain the biophysical interactions responsible for the functioning of ecosystems. (6 marks)

Answer 4

Spheres, food webs, energy transfer (producers → consumers → decomposers, loss of energy further up food chain) and range of nutrient cycles (including carbon, nitrogen, phosphate cycles)

Question 5

Identify 9 human-induced modifications to ecosystems.

Answer 5

Deforestation, fire, mining
Overgrazing, pesticide application, water & air pollution
Excessive tourism, overhunting/overfishing, introduction of exotic species

Question 6

Why is it important to protect and manage ecosystems? (6 marks)

Answer 6

• Define ecosystems at risk and why they are so important
• Maintenance of genetic diversity (explanation and Acropora millepora)
• Utility values (medical GBR, tourism)
• Intrinsic & heritage values (Blacksmiths Beach Awabakal Tribe - mythological stories, e.g. moon man’s tears, Belmont Lagoon - site of celebration/annual corroboree, birthing sites, midden sites = need to protect for current and future Indigenous generations)

Question 7

Explaining importance of genetic diversity (short answer)

Answer 7

The greater the genetic diversity in an ecosystem, the more likely it is that individuals in a population will possess the differentiated genes which are needed to evolve, adapt and breed successfully in an environment, thus also decreasing its vulnerability by making it less susceptible to natural stress and reducing its chances of extinction. Successful traits can also be passed down to future generations and a species will adapt over time to change. The importance of the maintenance of genetic diversity is further proved through a situation where if one variation of a particular species died out, there would still be other variations of the species to fill the vacuum in the ecosystem. This ensures that the ecosystem and other organisms function normally with minimal change, and allows the ecosystem to continue to flourish.