Unit 7 Reflection

This unit was about ecology, or the "study of house." We started off the unit by looking at how big ideas in biology, homeostasis, equilibrium, and interdependence are shown in nature. Environments are in best condition when they are in balance, or in homeostasis. Interdependence is also key theme in ecology because  living things are very dependent on each other for survival. We learnt about habitats vs. niches.  A habitat is the location where the organism lives, and includes all aspects of that area (abiotic and biotic factors). A niche includes all factors that a species needs to survive. I think that this was a weak area for me, and I still don't completely understand the difference between a habitat and a niche, but I think looking at more examples of this in nature will help me. There are 6 levels of organization on the earth: organism, population, community, ecosystem, biome, biosphere.

In an ecosystem, there are both producers (autotrophs) and consumers (heterotrophs). There are 5 trophic levels in an ecosystem: primary producers, primary consumers, secondary consumers, tertiary consumers, and quaternary consumers. A food chain shows how the different organisms get their energy, but doesn't account for the fact that usually an organism eats more than one other organism. A food web is a more accurate depiction. In a ecosystem, the producers at the bottom of the food web have the highest biomass (a method of measuring energy in calories or Joules), and the top-level consumers have the lowest biomass. This is because, at each level, 90% of the energy is lost as waste, and only 10% is retained. This is known as the 10% rule. I felt that trophic levels and energy transfer was one of my strengths.

We also learnt about the factors that can affect a population's growth. These include immigration, emigration, births, deaths, disease, predators, limited supply of abiotic factors, and population density and dispersion. All populations reach a carrying capacity (K), which is the maximum population that an environment can support. I thought that I understood this topic well. 

After a disturbance in an ecosystem, such as a fire, something called ecological succession results, which is the sequence of ecosystem changes that follow a disturbance. If soil remains after the disturbance, the type of succession is known as secondary succession. If there is no soil, it is called primary succession. 

A diagram of secondary succession 

Loss of species has shown to be tightly correlated with human population growth. Therefore, many species have gone extinct because of humans' behavior. 4 major threats to species' extinction are: habitat loss, introduced species by humans, overexploitation, and climate change. 

During this unit, we watched Bag It!, which explained why plastic bags and bottles are having a very negative impact of the environment. This is an issue that interested me, and I would like to learn more about it. 

We also did a conservation biologist project, where we researched an ecosystem (The Great Barrier Reef) and found out some of the threats facing the ecosystem. As a group, we brainstormed possible solutions to these threats. I learnt a lot from doing this project. Our group was able to collaborate effectively because we listened to each other's ideas and divided up the workload. We created a vodcast in which we taught what the Great Barrier reef looks like in balance, and how it is threatened.