Biology Unit 1 Study Guide: Ecology And Scientific Method

Biology Unit 1 Study Guide: Ecology And Scientific Method


BIOLOGY is the study of living things.   To distinguish something as living, it must have all of the following characteristics of life:

  1. made of cells
  2. obtain and use materials and energy (metabolism)
  3. all reproduce
  4. maintain internal balance (homeostasis)
  5. have genetic code (DNA/RNA)
  6. respond to environment
  7. grow and develop
  8. as a group, change over time (evolve)


What is the difference between homeostasis and responding to the environment?

homeostasis is maintenance of internal conditions, not through conscious thought (ex. sweating when hot, liver storing sugar, etc.)      

response to environment is changes to the organism caused by changes in the environment (ex. plant growing because of sunlight, lizard sitting on rock to keep warm, etc.)

What is the SMALLEST unit that is still considered living?

A cell

Out of the following words, circle all those that are BIOTIC factors:

feather, turkey, wind, egg, rock, acorn, humidity, water

Answers: feather, turkey, acorn, egg



A branch of biology, ECOLOGY is the study of living things and their interactions with the environment.

What is the difference between a biome and ecosystem?

 an ecosystem includes where all biotic and abiotic factors in one area  

a biome is a group of ecosystems with same climate and dominant communities

What is the difference between a niche and a habitat?

a habitat is where an organism lives

a niche is not only where it lives but how it lives and uses the resources around it

Give a definition and example of each of the following relationships: parasitism, commensalism, mutualism

  parasitism commensalism mutualism
definition one organism harms the other one organism benefits, the other is neither helped nor harmed both organisms benefit
example tapeworms, fleas sucking blood from host barnacles on whale bird that eats bugs off cows

The grasses and bushes are examples of producers, also known as autotrophs.  This is because they have the ability to convert energy from the sun into a chemical form of energy, glucose, using CO2 from the air.  Anything that must eat something else for energy is called a consumer, also known as a heterotroph.  The prairie dogs feed off the grass, making them primary consumers.   If the grass had 750 joules of energy, the prairie dog would only get 75 joules of energy because only 10% of energy is conserved as it moves to the next trophic level.

What is the relationship between metabolism and the loss of energy as it moves up a food chain?  What happens to the energy that is “lost”?

When glucose is broken down for energy (metabolism) within an organism, about 90% of that energy is converted into heat.  Only the energy trapped in the biomass of an organism gets passed onto the next trophic level.



The San Francisco Bay plays many important roles in our ecosystem.  Because it receives both salt water and fresh water, the SF Bay is an estuary, which means it’s very important to many animals that depend on a specific salinity level. Biodiversity is the sum of all variety of living organisms.  While biodiversity is important for genetic diversity, research and resources, there are many threats to biodiversity.  Complete the following table (refer to 6-3 and History of SF bay lecture notes if needed):

Threats to Biodiversity Examples from SF Bay
habitat fragmentation loss of marshland due to urbanization
demand for wildlife products/ overhunting sea otters hunted by man until they were endangered
pollution DDT, mercury in fish
invasive species Chinese mitten crab, non-native grasses

The Bay gets its fresh water from creeks and rivers that run from the mountains.  The mountains and valley create a watershed, which collects water run-off.  The meeting of the San Joaquin and Sacramento River forms a maze of land and water called the delta, creating great fertile land for agriculture. Pollutants contributed by residents can be carried from the creek to the Bay because of substances that are disposed of through the storm drain instead of the sewage system, or being properly recycled.  This type of pollution is called non-point pollution because it comes from many sources and therefore is more difficult to control. One way to assess the health of a creek is to study the biodiversity of organisms called macroinvertebrates.  A healthy stream contains a mix of tolerant, intolerant, and facultative macroinvertebrates.

Things that affect creek health How it affects the health of the creek
Turbidity, loss of trees Chlorine, ammonia Nitrates, phosphates Temperature pH Blocks vision of fish, decrease O2 levels Toxic to organisms Increases algae growth, dead algae attract bacteria, decreases dissolved oxygen levels Increased temp decreases O2 levels Must be in neutral range for organisms to live



Water follows a cycle and can regenerate, therefore it is a renewable resource.  However, only 3% of water available to us is fresh water and can be used for drinking and farming. Explain how water gets to your kitchen sink and where it goes from there. Water from rainfall in the Sierra Nevada mountains and our local watershed runs into rivers and is contained in reservoirs and aquifers (groundwater).  From here it is brought goes to the water treatment plant through aqueducts and then taken to homes through smaller pipes.  Water from the kitchen sink will be taken to a wastewater treatment plant where most of the cleaned water will go to the Bay (some can be used as recycled water for landscape irrigation). Carbon also follows a cycle.  However, since the Industrial Revolution began in the 1750s, carbon levels in the atmosphere have actually been increasing at a rapid rate.  This increase can be attributed to human actions such as deforestation and burning fossil fuels.

Processes that release CO2 Processes that absorb CO2
decomposition of dead matter cellular respiration (breathing out) burning fossil fuels or trees release of CO2 from ocean volcanic eruptions weathering of limestone rocks plants doing photosynthesis incorporation of CO2 into the ocean dead material that does not decompose becomes fossil fuels incorporated into limestone

The greenhouse effect is:

the trapping of heat from the sun by gasses such as water vapor, carbon dioxide, and methane.  This keeps the Earth’s surface warm enough to sustain life, but too many greenhouse gases could increase temperature too much – causing global warming.

Globe On Moss In Forest - Environment Concept


A population study was done to see under what conditions a population of bacteria would grow best in a petri dish.  A researcher started a population of bacteria on three different dishes and placed them in three different temperatures (10 C, 30 C, and 50 C).  Every day he took out the dishes and counted how many colonies of bacteria were on each dish.  The dish at 30 C eventually became completely covered with bacteria and there was no more room for growth.

What is the dependent variable?  # of bacteria colonies

What is the independent variable?  days (time)

Thanks for reading, hope this helps, and have a wonderful day!

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9 replies »

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