essential idea
The continued survival of living organisms including humans depends on sustainable communities
Nature of science
Looking for patterns, trends and discrepancies-plants and algae are mostly autrophic but some are not
understandings
4.1.1 Species are groups of organisms that can potentially interbreed to produce fertile offspring
4.1.2 Members of a species may be reproductively isolated in separate populations
4.1.3 Species have either an autotrophic or heterotrophic method of nutrition ( a few species have both methods)
4.1.4 Consumers are heterotrophs that feed on living organisms by ingestion
4.1.5 Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion
4.1.6 Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion
4.1.7 A community is formed by populations of different species living together and interacting with each other
4.1.8 A community forms an ecosystem by its interactions with the abiotic environment
4.1.9 Autotrophs obtain inorganic nutrients from the abiotic environment
4.1.10 The supply of inorganic nutrients is maintained by nutrient cycling
4.1.11 Ecosystem have the potential to be sustainable over long periods of time
4.1.2 Members of a species may be reproductively isolated in separate populations
4.1.3 Species have either an autotrophic or heterotrophic method of nutrition ( a few species have both methods)
4.1.4 Consumers are heterotrophs that feed on living organisms by ingestion
4.1.5 Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion
4.1.6 Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion
4.1.7 A community is formed by populations of different species living together and interacting with each other
4.1.8 A community forms an ecosystem by its interactions with the abiotic environment
4.1.9 Autotrophs obtain inorganic nutrients from the abiotic environment
4.1.10 The supply of inorganic nutrients is maintained by nutrient cycling
4.1.11 Ecosystem have the potential to be sustainable over long periods of time
applications and skills
4.1.12S: Classifying species as autotrophs, consumers, detritivores or saprotroph from a knowledge of their mode of nutrition
4.1.13S: Setting up sealed mesocosms to try to establish sustainability
4.1.4S: Skill: Testing for association between two species using the chi-squared test with data obtained by quadrat sampling
4.1.15S: Recognizing and interpreting statistical significance
4.1.13S: Setting up sealed mesocosms to try to establish sustainability
4.1.4S: Skill: Testing for association between two species using the chi-squared test with data obtained by quadrat sampling
4.1.15S: Recognizing and interpreting statistical significance
guidance / international mindedness/ theory of knowledge
Looking for patterns, trends and discrepancies: plants and algae are mostly autotrophic but some are not
species
Species are groups of organisms that can potentially interbreed to produce fertile offspring
- Birds of paradise inhabit Papua New Guinea and other Australasian islands
- In the breeding season the males do elaborate and distinctive courtships dances, repeatedly carrying out a series of movements to display their exotic plumage
- This is to show to a female that they are fit and would be a suitable partner and that they are the same type of bird of paradise as the female
- Each of the 45 different types of bird of paradise reproduces with others of its type and hybrids between the different types are rarely produced . Therefore, each of this bird of paradise remains distinct
- When two members of the same species mate and produce offspring they are interbreeding
- Most of the times different species breed together,is called cross-breeding, it happens with birds of paradise
- The offspring that is produced by cross-breeding between species are always infertile, which prevents the genes of two species becoming mixed
- To briefly summarize, a species is a group of organisms that interbreed to produce fertile offspring
populations
A group of organisms of the same species which live in the same area at the same time
- If two populations live in different areas they are unlikely to interbreed with each other, it doesn't mean that they are different species
- If they could interbreed, they are still members of the same species
- if two populations of a species never interbreed then they may develop differences in their characters
- Even if there are recognizable differences, they are considered to be the same species until they cannot interbreed and produce fertile offspring
autotrophs
Organisms that are capable of making their own organic molecules as a food source
- Autotrophs synthesize their organic molecules from simple inorganic substances, this involves using photosynthesis
- They can take light energy from the Sun, combine it with inorganic substances and obtain chemical energy in the form of organic compounds
- Autotrophs are producers
Examples of Autotrophs ----^
heterotrophs
Cannot make their own food from inorganic matter and must obtain organic molecules from other organisms
- They get their chemical energy from the autotrophs or from other heterotrophs
- They rely on others for food
- They are referred to as consumers
- They ingest organic matter that is living or has been recently killed
Examples of Heterotrophs ----^
detritivores
Are heterotrophs that obtain organic nutrients from detritus by internal digestion
Organisms discard large quantities of organic matter, for example:
Organisms discard large quantities of organic matter, for example:
- Dead leaves and other parts of plants
- Feathers, hairs and other dead parts of animal bodies
- Feces from animals
SAProtrophs
- An organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion
- They are known as decomposers because they break down carbon compounds in dead organic matter and release elements such as nitrogen into the ecosystem so that they can be used again by other organisms
DETRITIVORES
SAPROTROPHS
COMMUNITIES
- A group of populations living and interacting with each other in an area
- An Important part of ecology is research into relationships between organisms
- Relationships are complex and varied
- In some cases the interaction between two species is of benefit to one species and harms the other, for example, the relationship between a parasite and its host
- In some cases, both species benefit, as when a hummingbird feeds on nectar from a flower and helps the plant by pollinating it
- All species are dependent on relationships with other species for their long-term survival
- A population of one species can never live in isolation
- Groups of population live together
- A group of population living together in an area and interacting with each other is known in ecology as a community
- Typical communities consists of hundreds and thousands of species living together in an area
ecosystems
A community and its abiotic environment
- A community is composed of all organisms living in an area
- These organisms could not live in isolation- they depend on their non-living surroundings of air, water, soil or rock
- Ecologists refer to these surroundings as the abiotic environment
- In some cases the abiotic environment exerts a powerful influence over the organisms
- There are cases in which living organisms influence the abiotic environment. Sand dunes are an example of this
- So, not only are there complex interactions within communities, there are also many interactions between organisms and the abiotic environment
- The community of organism in an area and their non-living environment can therefore be considered to be a single highly complex interacting system, known as an ecosystem
- Ecologists study both the components of ecosystems and the interactions between them
Inorganic nutrients
Autotrophs and heterotrophs obtain inorganic nutrients from the abiotic environment
Living organisms need a supply of chemical elements:
Living organisms need a supply of chemical elements:
- Carbon, hydrogen and oxygen are needed to make carbohydrates, lipids and other carbon compounds on which life is based
- Nitrogen and phosphorus are also needed to make many of these compounds
- A proximately fifteen other elements are needed by living organisms
- Autotrophs obtain all of the elements that they need as inorganic nutrients from the abiotic environment
- Heterotrophs on the other hand obtain these two elements and others as part of the carbon compounds in their food
nutrient cycles
The supply of inorganic nutrients is maintained by nutrient cycling
- There are limited supplies on Earth of chemical elements
- Although living organisms have been using the supplies for three billion years, they have not run out
- Chemical elements can be endlessly recycled
- Organisms absorb the elements that they require as inorganic nutrients from the abiotic environment, use them and then return them to the environment with the atoms unchanged
- The carbon cycle is different form the nitrogen cycle
sustainability of ecosystems
Ecosystems have the potential to be sustainable over long periods of time
- The concept of sustainability has risen to prominence recently because it is clear that some current human uses of resources are unsustainable
- Something is unsustainable if it can continue indefinitely
- Natural ecosystems can teach us how to live in a sustainable way, so that our children and grandchildren can live as we do
- There are three requirements for sustainability in ecosystems:
- Nutrient availability
- Detoxification of waste products
- Energy availability
Sources: Chapter 4 Ecology notes