SCIE 3001
1 - Nature of Living Things
1.4 Human Organ Systems and Health
4 - Cycles and Seasons
5 -Structure of the Earth, and Earth Movements

Unit 3: Ecosystems

7 Mater Energy and Life

The following processes takes material from the non-living (AKA - abiotic or mineral or inorganic) world to be recycled in the living (AKA - biotic or organic).

  1. nutrition
  2. growth
  3. reproduction

They are then returned to the abiotic world by

  1. excretion
  2. death
  3. decay

Consolidating and constantly reorganizing atoms

  1. first into plants as sugars and starches through the process of photosynthesis
    1. Carbon dioxide and water (abiotic) are converted to sugar and starches (biotic materials) with the help of chlorophyll in plants and sunlight as energy for the process and releases abiotic oxygen.
  2. then into biotic, (living or organic matter) as plant tissues (proteins, etc.) through plant growth and reproduction
    1. minerals (abiotic) - most important carbon, nitrogen, phosphorous and sulphur as well as some metals like calcium, magnesium, sodium, potassium
  3. then converted into animal tissues through food chains by herbivores
  4. recycled in the biotic word by omnivores and carnivores through food chains and webs
  5. or released back to the abiotic world by the process of
    1. respiration in plants and animals where energy is obtained for the living process of cells by breaking the sugars back into carbon dioxide and water
    2. excretion in plants (not limited to oxygen, carbon dioxide and water - remember the function of the vacuole?) and animals from complex life process as for example urea in animals.
    3. Death and then decay by organisms like the detrivores (scavengers earthworms, maggots, woodlice - to break down into smaller bits) and decomposers (fungi and bacteria that break down organic material (biotic) into minerals (abiotic) like nitrates)
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Four spheres

Everything in Earth's system can be placed into one of four major subsystems: land, water, living things, or air. These four subsystems are called spheres.

  1. Geoshpere - land (AKA lithosphere)
  2. Hydrosphere - water
  3. Atmosphere - air
  4. Biosphere - living things

Living things have six key elements which are essential in the tissues which make up living things (the biotic world):

  1. Carbon
  2. Hydrogen
  3. Oxygen
  4. Nitrogen
  5. Sulphur
  6. Phosphorus

Almost all the energy in the biosphere comes from the Sun as plants convert sunlight to the chemical energy found in living things.

Fig. 1 Four Spheres  

Energy Changes in Organisms

All organic molecules contain:

  1. high levels of chemical energy.
  2. require energy to be produced.
  3. release energy when broken down.

Producers take the abiotic material and change them into high level energy biotic materials

Consumers release this energy for living process by respiration.


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Producers and Photosynthesis

carbon dioxide
glucose (sugar)

The glucose produced has three functions:

  1. changed to the organic molecules necessary for forming parts of the plant like roots, stem, branches, leaves, flowers. etc.
  2. to provide energy for the cells to perform their functions
  3. may be converted to starches or fats and oils for storage.
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Respiration provides energy for the Cells

glucose (sugar)
carbon dioxide
Fig 2 Cycle of materials  
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Energy Flow

  • Energy enters the cycle from the Abiotic when green plants use sunlight (Electromagnetic Radiation Energy A.K.A. Light) to make glucose (Chemical Energy).
  • Energy is lost at every trophic level as heat when living things release the chemical energy by respiration.
  • All the Light energy eventually becomes heat which is dissipated in the atmosphere.
  • Energy, therefore flows from the producers through the consumers to the decomposers, some being lost as heat to the atmosphere when it moves to a higher trophic level.
  • A constant supply of sunlight is needed.

Nutrient Cycle

  • Nutrients cycles between the Abiotic (Inorganic mineral) and the Biotic (Organic) worlds.
  • Producers turn Abiotic (Inorganic mineral) into the Biotic (Organic) by the process of photosynthesis.
  • All living things return carbon dioxide and water from the glucose of the Biotic to the Abiotic world by respiration.
  • Decomposers return minerals (carbon, hydrogen, oxygen, nitrogen, sulphur,phosphorus, etc.) in organic materials of the Biotic to the Abiotic world.

Energy FLOWS but Nutrients CYCLE between the Abiotic and Biotic.


Fig 2b Cycle of materials and Flow of Energy between living and non-living  
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Fig. 3 Plants are producers  

Consumers need energy and nutrients for:

  1. movement - whole body and internal organ movement.
  2. growth, maintenance and repair of body tissues
  3. reproduction
  4. The get their energy and nutrients by feeding on other organisms.
  5. They digest starches, fats and proteins by breaking them down into simpler substances to be absorbed and taken to the cells where they are used.
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Herbivore is an animal that gets its energy from eating only plants

  • have special digestive systems that let them digest all kinds of plants (may have multiple stomachs)
  • mechanical adaptations of body parts like specialized teeth and the crop in birds (no teeth)
  • biochemical adaptations like enzymes to combat plant poisons
  • behavioral adaptation like eating only young leaves to avoid tannins
  • storing plant poisons to be used in their own defense e.g. monarch butterfly stores poisons from milkweed
  • Symbiosis - animals have gut with bacteria and fungi to digest plant material
  • Usually have eyes on the side of the head for wider field of vision to avoid predators
Fig. 4 Herbivore 
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Carnivores eat mostly meat, or the flesh of animals

  • some carnivores like cats cannot cannot digest food from plants
  • cold-blooded predators like snakes have slow-moving digestive systems that allow them to go days or even months between kills
  • carnivorous mammals such as wolves have strong jaws and long, sharp teeth that help them grab and rip apart their prey
  • cats have sharp claws that they use to hunt and birds such as hawks and owls also hunt with their claws, called talons
  • many carnivorous birds, called raptors, have curved beaks that they use to tear apart their prey
  • some carnivores like snakes attack their prey with a bite or a sting that injects toxic venom into the victim
  • many carnivores are scavengers eating the meat of dead animals, or carrion
  • certain plants are also carnivorous. The Venus flytrap has leaves modified to act as snap traps
Fig. 5 Carnivores  
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Omnivores consume both meat and plant matter

  • they have a digestive system very similar to carnivores
  • they are able to consume a wide diet
  • survive well in many environments
Fig. 5 Omnivores  


What did you eat today?

  • most humans eat meat and plants.
  • human teeth are designed to eat both meat and plants
  • the front teeth help us rip into meat and bite into fruits and vegetables
  • molars help us grind up meat and chew fruits and vegetables.

Humans are omnivores in all relevant anatomical traits.


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Detritus: Feeders and Decomposers

Detritus is made up of

  • mainly plant material from leaves and woody material with animal waste.
  • digested by fungi an bacteria called decomposers
  • Decomposers change biotic (organic) into abiotic (inorganic) material which can be used by plants
  • Decomposers produce heat.
Fig. 6 Importance of decomposers
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Fig 7. Food Chain
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Fig. 8 Food Web

Ecosystem Types

  • Coasts and oceans
  • Farmlands Forests
  • Fresh waters
  • Grasslands and shrub lands
  • Urban and suburban areas

Some important terms:

  • Populations: number of individuals that make up the interbreeding, reproducing group
  • Biotic communities: grouping or assemblage of plants, animals, and microbes
  • Species: different kinds of plants, animals, and microbes in the community
  • Associations: how a biotic community fits into the landscape
  • Ecosystem: a grouping of plants, animals, and microbes occupying an explicit unit of space and interacting with each other and their environment

How Ecosystems Are Formed

Abiotics determine plants

  • moisture - greatest moisture - forest
  • temperature- forest type

Plants determine animals

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Trophic Levels: Pyramid of Biomass

Which level is occupied by:

  • producers?
  • primary consumers?
  • secondary consumers?
  • third-order consumers?
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Trophic Levels: Pyramid of Energy

Which level is occupied by:

  • producers?
  • primary consumers?
  • secondary consumers?
  • third-order consumers?

Living Together

  • – and – = Competition. Both species are adversely affected by the interaction.
  • + and – = Predation, Parasitism, And Disease. One species benefits from the interaction and the other is adversely affected.
  • + and 0 = Commensalism. One species benefits from the interaction and the other is unaffected: remora fish and shark.
  • + and + = Mutualism. Both species benefit by the interaction between the two species: cow and bacteria in gut
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  • adaptation that allows animals to blend in with certain aspects of their environment
  • increases an organism's chance of survival by hiding it from predators
  • also used by some predators as a tool for hunting

Chemical Warfare

  • animals that use chemicals as a defense rarely use camouflage
  • these animals are usually brightly and distinctively colored to stand out.
  • these markings are called warning coloration and are bright or distinctive markings that serve as a warning to would-be predators.


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  • some harmless species have developed similar coloration to mimic dangerous animals
  • the coral snake has a mimic
  • many types of butterflies also practice mimicry
  • there are cases where two or more dangerous or unpalatable species all resemble one another eg, the viceroy and monarch butterflies.
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  1. Evaporation / Transpiration (called Evapotranspiration) - Water vapour evaporates using the energy from the Sun. Water is also released by plants through the process of transpiration. This water rises with hot air.
  2. Condensation - As air rises, it cools and the vapour may change into ice or liquid water.
  3. Precipitation - When water droplets or ice gets to heavy to be supported in the atmosphere, it falls to the ground as rain, snow, hail, etc.
  4. Surface Runoff When rain falls it may runoff on the surface to rivers, etc.
  5. Percolation - water may enter the ground and reaming underground in aquifers. It may emerge in springs and rejoin surface runoff to restart the cycle.


Concept by Kishore Lal. Programmed by Kishore Lal... Copyright © 2015 Kishore Lal. All rights reserved.