4.1: Species, communities and ecosystems

Key Vocabulary

Retrieval practice and prior learning

U1: Species are groups of organisms that can potentially interbreed to produce fertile offspring.

U2: Members of a species may be reproductively isolated in separate populations.

U7: A community is formed by populations of different species living together and interacting with each other.

U8: A community forms an ecosystem by its interactions with the abiotic environment.

Exercise 1: Identify the key terms given in the assessment statements above. Define each of them.

Create a flow chart that links each one of them to the other levels of organisation you have learned: organelles, cells, tissues etc

Exercise 2: Complete the following exercises:

These are the same species

So are these

these aren't

Neither are these

1. Can you say why?

2. Which one of these organisms has a tree for a habitat?

3. Which two images represent a population?

4. Which image doesn't fit with the others? Why?

S1: Classifying species as autotrophs, consumers, detritivores or saprotrophs from a knowledge of their mode of nutrition.

Exercise 3: Complete the model ecosystems activity either by using the link 

http://www.mhhe.com/biosci/genbio/virtual_labs/BL_02/BL_02.html 

U3: Species have either an autotrophic or heterotrophic method of nutrition (a few species have both methods).

U4: Consumers are heterotrophs that feed on living organisms by ingestion.

U5: Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.

U6: Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion.

U9: Autotrophs obtain inorganic nutrients from the abiotic environment.

Exercise 4: Make flashcards for each of these new definitions 

1.    Put the terms in some kind of order that you choose 

2.    Group the terms in some way, keep similar terms together and explain why.

NoS: Looking for patterns, trends and discrepancies—plants and algae are mostly autotrophic but some are not. (3.1) 

Exercise 5: Can you research any plants that are not autotrophic? Does this mean that the classification of plants as multicellular organisms that can photosynthesize is incorrect?

S3: Testing for association between two species using the chi-squared test with data obtained by quadrat sampling.

S4: Recognizing and interpreting statistical significance.

Guidance from the syllabus: To obtain data for the chi-squared test, an ecosystem should be chosen in which one or more factors affecting the distribution of the chosen species varies. Sampling should be based on random numbers. In each quadrat the presence or absence of the chosen species should be recorded.

Essential idea: The continued survival of living organisms including humans depends on sustainable communities.

U10: The supply of inorganic nutrients is maintained by nutrient cycling.

U11: Ecosystems have the potential to be sustainable over long periods of time.

S2: Setting up sealed mesocosms to try to establish sustainability. (Practical 5)

Guidance from the syllabus: Mesocosms can be set up in open tanks, but sealed glass vessels are preferable because entry and exit of matter can be prevented but light can enter and heat can leave. Aquatic systems are likely to be more successful than terrestrial ones.