ESS IB Final Exam Questions & Answers
2024/2025
1.1.1 Outline the concepts and characteristics of a system - ANSWERSStorages of matter or energy.
Flows- inputs into the system and outputs from the system.
Processes which transfer or transform energy or matter.
System- An assemblage of parts and the relationships between them which together constitutes an
entity or whole. They always must contain energy, matter, and information.
• Feedback mechanisms that maintain feedback and equilibrium
o Ex. Photosynthesis: Transforms carbon dioxide, water, and light into biomass and oxygen
o Ex. Respiration: Transforms Biomass into Carbon dioxide and water
o Ex. Diffusion: Allowing the movement of nutrients and water into the trees
o Ex. Consumption: Transferring tissue from one trophic level to another
1.1.2 Apply the systems concept on a range of scales - ANSWERS• Ecosystem: Biologic community of
interdependent organisms in the physical environment they inhabit
• Gaia hypothesis: The Earth is a single living organism in which feedback mechanisms maintain
equilibrium.
o Ex. Population/energy of a vegetable garden
o Ex. Population/energy of a tropical rainforest
o Ex. Feedback, waste, and population of Gaia as a whole
1.1.3 Define the terms open system, closed system and isolated system - ANSWERS• Open system:
Exchanges in matter and energy
o Ex. Forest, Most common
• Closed system: Exchanges energy but not matter with its surroundings
o Ex. Fish tank, the Earth
• An Isolated system: Exchanges neither energy or matter with its surroundings
o Ex: The Universe
,1.1.4 Describe how the first and second laws of thermodynamics are relevant to environmental systems -
ANSWERS• First Law: Energy is neither created or destroyed, but it can change forms
• Second Law: In any isolated system, Entropy tends to increase spontaneously
• Entropy: A measure of the amount of disorder, chaos, or randomness in a system. The greater the
disorder, the higher the level of entropy. #Energyisneededtocreateorder
1.1.5 Explain the nature of equilibriam - ANSWERS• Equilibrium: The tenancy of a system to return to an
original state following a disturbance. At equilibrium, a state of balance exists among the components of
a system. There may be fluctuations but no sudden changes.
• Steady State: continuous inputs and outputs, but the system remains constant.
o Ex. Body Mass
• Static State: There is no change over time. The static equilibrium can change
o Ex. The location of a rock
• Stable Equilibrium: Tends to return to the same state after a disturbance
• Unstable Equilibrium: Does not tend to return to the same state after a disturbance
1.1.6 Define and explain the principles of positive feedback and negative feedback - ANSWERS•
Negative: Self-regulating method of control leading to the maintenance of a steady state equilibrium.
o Ex. Thermostat
• Positive: Leads to an additional increasing change in a system. It accelerates deviation.
o Ex. Greenhouse gasses leading to higher temperatures, leading to melting of permafrost, leading to
more gasses
1.1.7 Describe transfer and transformation processes - ANSWERS• Transfer: Movement of matter or
energy through a system that does not involve a change of form or state.
• Transformation: Movement of matter or energy through a system that does involve a change of form
or state.
• Both types of movement use energy. Transfers require less energy and are more efficient than
transformations.
• Transfers normally flow through a system and involve a change in location.
,• Transformations either lead to an interaction within a system, the formation of a new end product, or
they involve a change of state.
o Ex. Transfers: Movement of material through living organisms, Movement of material in a nonliving
process, Movement of energy.
o Ex. Transformations: Matter Transformations, energy transformations, Energy to matter
transformations, Matter to energy transformations.
1.1.8 Distinguish between flows and storages in relation to systems - ANSWERS• Inputs and outputs
(flows) are arrows
• Storages are boxes
• Longer arrow = Larger flow (More resource movement)
1.1.10 Evaluate the strengths and limitations of models - ANSWERS• A model is a simplified description
designs to show the structure or workings of an object, system, or concept
• Advantages: Allow scientists to predict and simplify complex systems, Inputs can be changes and
outcomes examined without having to wait for real events, results can be shown to other scientists and
to the public
• Disadvantages: They may not be accurate, they rely on the expertise of the people making them,
different people may interpret them in different ways, vested interests may hijack them politically, any
model is only as good as the data that goes in, different models may show different effects using the
same data
2.1.1 Distinguish between biotic and Abiotic components of an ecosystem - ANSWERS• Abiotic:
Nonliving components of an ecosystem
o Ex. Light, temperature, humidity, water, landscape, and altitude
• Biotic: Living components of an ecosystem
o Ex. Plants, animals, decomposers
2.1.2 Define the term trophic level - ANSWERS• Position where an organism is found in a food chain
• "Feeding level"
, 2.1.4 Explain the principles of pyramids of numbers, pyramids of biomass, and pyramids of productivity
and construct such pyramids from given data. - ANSWERS• Numbers: Illustrates quantity of organisms
found at each trophic level. Represents energy stored at each level.
• Biomass: Illustrates how much energy is available in each trophic level. Represents energy stores at
each level. Units: dry weight, grams per meter squared, or Joules per meter squared.
• Productivity: Illustrates the rate at which energy flows through an ecosystem. Units: Joules per meter
squared per year.
2.1.5 Discuss how the pyramid structure affects the functioning of the ecosystem - ANSWERS• Energy is
lost through food chains, so top carnivores are at risk for disturbance the further down the food chain
• Biomagnification: concentration of the materials increases up the trophic levels or some toxins do not
degrade and become concentrated in the food chain, leaving the top level consumer the most vulnerable
o Ex. Eagles and DDT Pesticide
2.1.6 Define the terms species, population, habitat, niche, community, and ecosystems with reference to
local examples - ANSWERS• Species: A population or group of populations whose members have the
potential to interbreed and produce viable offspring
• Population: A group of organisms of the same species living in the same areas at the same time and
which are capable of interbreeding
• Habitat: Place or type of place where an organism or population normally lives
• Niche: A species' share of a habitat and the resources in it. Its "role" in the ecosystem.
• Community: A group of populations living and interacting with each other in a common habitat
• Ecosystem: communities of different species interacting with each other and their physical
environment
2.1.7 Describe and explain population interactions using examples of explained species - ANSWERS•
Competition: When two or more species compete over limited resources.
o Ex: Elks battling over mates or land.
• Herbivory: When an animal eats parts of a plant.
o Ex: Caterpillars eating leaves, deer grazing
• Predation: When one species kills and eats another.
o Ex: Bear eats salmon, cat eating bird
