ECOSYSTEMS

1. Ecosystem Basics

   1. What is an ecosystem?

An ecosystem refers to all the interacting parts of a biological community (a large group of living organisms), including both biotic and abiotic factors. 

2. Give three examples of biotic factors and three of abiotic factors. 

Biotic: plants, animals, bacteria

Abiotic: water, rocks, sunlight

3. What are the three main types of biotic relationships? Explain each one. 

Predation: one organism eating another

Competition: organisms competing for limited resources

Symbiosis: multiple organisms living together, where at least one of them benefits 

4. What are the three types of symbiosis? Give an example of each. 

Mutualism: where both organisms benefit from the relationship

Parasitism: where one organism benefits while the other is harmed

Commensalism: where one organism benefits while the other is unaffected

5. What makes something “living”? 

Made up of cells, Responds to environment, Grows, Reproduces, Expends energy, Excretes waste, Needs nutrients

6. Why are viruses not considered living? 

Viruses are not cells, they cannot reproduce on their own (without a host), they do not eat or excrete. 

2. Earth’s Spheres

   1. What are the four “spheres” of the Earth? 

Biosphere, lithosphere, hydrosphere, atmosphere

2. What are the main nutrients that a living organism requires to survive?

Carbohydrates, proteins, fats, vitamins, minerals, water 

3. What are the four basic elements and compounds that are cycled through the Earth?

Water, nitrogen, carbon, phosphorus 

4. Sketch a rough diagram of the water cycle.

5. Briefly describe the carbon cycle. 

Animals eat carbon food and breathe out carbon dioxide. Plants breathe in carbon dioxide and turn it into carbon compounds that animals eat. All living things die and decompose, returning most of their carbon back to the environment. Burning fossil fuels (like oil, coal, and gas) releases carbon compounds into the atmosphere. Forests and oceans absorb large amounts of carbon gasses from the atmosphere. 

6. How does nitrogen from the air get into the biosphere?

Nitrogen-fixing bacteria in the soil are able to breathe nitrogen and turn it into solid nitrogen compounds which they release into the soil. Plants are able to absorb these nitrogen compounds from their roots. 

7. How does phosphorus get into the biosphere? 

From the breakdown of rocks. Plants absorb it from the soil.

3. The Biosphere 

   1. Where does essentially all of the biosphere’s energy come from? 

The sun!

2. Which process harnesses sunlight into usable energy? Where does this process occur? 

Photosynthesis! It occurs inside chloroplasts, in the leaves and green parts of plants. 

3. Which types of organisms can undergo this process?

Plants, algae, plankton, and photosynthetic bacteria. These are producers.

4. What is the name of the basic energy molecule for all living things?

ATP

5. What is the basic equation for cellular respiration? Where does this process occur? 

In mitochondria inside cells. The equation is:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

6. What is the difference between an autotroph and a heterotroph? Give an example of each. 

Autotrophs make their own energy and do not need to eat other living things. Heterotrophs are consumers that must eat other organisms to survive. A tree is an autotroph and a lion is a heterotroph. 

7. Sketch a trophic level pyramid, showing at least 3 levels and their names. 

8. What is the difference between biomagnification and bioaccumulation? 

Bioaccumulation is that living organisms tend to store toxins in their bodies. Biomagnification is that the concentration of toxins increases as you go up the food chain. 

4. Biodiversity & Environment 

   1. What is eutrophication? What causes it? 

Large amounts of fertilizer runoff from farms and end up in bodies of water. These fertilizers stimulate algae in the water, resulting in algal blooms that cover the water surface. This blocks sunlight from entering the water, resulting in the death of underwater sea weeds and a lack of oxygen in the body of water (hypoxia). The result is that all living things in the water die. 

2. What are greenhouse gasses? Where do they come from? How do they affect the environment? 

Greenhouse gases are released into the atmosphere from the burning of fossil fuels (coal, oil, gas). They trap heat in the atmosphere, resulting in a warming of the climate. 

3. What is the problem with large-scale deforestation? Give at least two reasons. 

One is the destruction of biodiverse habitats. Another is that trees are a “carbon sink” and absorb large amounts of carbon dioxide from the air. When they are chopped down, they can no longer absorb carbon dioxide, and also release carbon dioxide that they contain within them. 

4. What are four major threats to biodiversity and the environment? What are some practical solutions to these threats? 

Many to choose from, such as oil spills, deforestation, eutrophication (build up of fertilizers in bodies of water, causing blooms of algae that end up destroying the ecosystem), bycatch (animals caught and killed inadvertently during fishing). Bioremediation can be used to clean up oil spills by releasing microbes that can eat up the oil. A solution for deforestation is to replant trees, as well as vertical farming and building upwards instead of outwards. Ending fishing subsidies and enforcing quotas, as well as developing new fishing technologies can reduce bycatch. Indoor farming is a good solution for eutrophication as well.