This document provides an overview of the Year 12 HSC Geography unit on ecosystems at risk. It defines key terms like ecology, ecosystems, biotic and abiotic factors. It explains how ecosystems vary naturally or through human intervention. It also describes ecosystem productivity, energy flows through food chains and nutrient cycling. Nutrient cycling involves elements like carbon, oxygen, water, phosphorus and nitrogen passing between living and non-living aspects of the environment. The document also notes how bioaccumulation can occur as toxic substances collect in animal tissues at higher rates than they are lost.

1. YEAR 12 HSC GEOGRAPHY
UNIT 1:Ecosystems at Risk
1: Biophysical interactions which lead to diverse ecosystems and their functioning
Mr Shipp

2. MAIN SYLLABUS

3. • Ecology is the science that examines the interactions between living
(biotic) and non-living (abiotic) environment
• Ecosystems are dynamic and adaptive systems through solar energy is
captured and channelled through a variety of lifeforms
Ecosystems and their Functioning

5. • Vary naturally or through
human intervention
• Ecosystems have changed
due to global climate and
sea level (10,000 years
ago)
• Ecosystems can be
classified due to their
dominant feature, physical
features or vegetation
• Ecosystems can be
categorised by terrestrial or
aquatic
Variations in Ecosystems

7. Hint: The Biosphere is the aggregate of all ecosystems on the
planet

8. INTERDEPENCE
LEVEL 2: DEFINITIONS
TERRESTRIAL

9. Hint: For the HSC paper, you will need to know two different types of ecosystems.
It is important to know different types away from your excursion
• Ecosystem productivity can involve:
• The amount of biomass produced in an area (per metres
squared)
• Energy flows of nutrients and matter through the ecosystem
Productivity of Ecosystems

11. • Producers, consumers and decomposers form a
chain that facilitates the energy from the sun
through plants to animals in the ecosystem
• Through the food chain nutrients are cycled through
the different tropic levels
Energy Flows

14. • The sun is the primary source
of energy which plants use
to photosynthesise
• Nutrient cycles pass from the
non-living (Atmo, Litho and
Hydro) to living (Bio)
environment
• Nutrients and energy is lost
which results in fewer tertiary
consumers than primary

15. • Energy enters the biological
system as light energy, then
transformed into chemical
energy in organic molecules by
cellular processes including
photosynthesis and respiration
• This energy is dissipated,
meaning it is lost to the system
as heat; once it is lost it cannot
be recycled.
• Thus the earth is an open
system with respect to energy.

17. • Most of the available food or nutrients for any ecosystem are found in the
top layer of soil and leaf litter.
• The biomass (total dry weight of all organisms at each level) of food
available is in the lowest trophic levels.
• Nutrients can be passed through oxygen, carbon, water, phosphorus and
nitrogen cycles
Nutrient Cycling

18. • The consequence of the loss of energy between trophic
levels that contaminants collect in animal tissues
• This occurs when an organism absorbs a toxic substance
at a rate greater than that at which the substance is lost.
Bioaccumulation

20. AUTOTROPHIC
LEVEL 2: DEFINITIONS
HETEROTROPHIC

22. HSC EAR ESSAYS
2018
2019?
2017
2016
2015

23. DESCRIBING AFFECTS OF NUTRIENT CYCLING
LEVEL 4: PAST PAPER QUESTION