Biology 1A Mid-Term Exam Study Guide
Chapter 1 Main Concepts

Characteristics of Living Things
o What is homeostasis? Explain the idea of a feedback mechanism in multicellular organisms. Give an example.
Homeostasis is the process of maintain an internal conditions. Homeostasis often involves internal feedback
mechanisms that work in much the same way as a thermostat. Just as a thermostat in your home turns on the heat
when room temperature drops below a certain point, you have an internal thermostat that makes your body
shiver if your internal temperature drops too low.
o What are the differences between single-celled and multicellular organisms? Single-celled organisms are called
unicellular; many of them are prokaryotic cells. Multicellular organisms are made of many cells combined together
to form more levels of organization. Multicellular organisms are usually eukaryotes and very complex.
o What are the differences between asexual and sexual reproduction? What advantage does sexual reproduction
have over asexual reproduction? Asexual reproduction involves one parent making a copy of itself . Sexual
reproduction involves 2 parents and a recombination of their genes to create a whole new organism. Sexual
reproduction is advantageous because of the recombining of the genes, it allows an organism to possibly inherit
the best traits from each parent
o All living things require _Energy__ to live.

Levels of Organization
o What are the levels of organization from smallest  largest? In a complex organism. Organelles, Cells, tissues,
organs, organ systems and organisms.

Steps of the Scientific Method and Keys to Good Experimental Design
o What are the parts of a controlled experiment? The controlled variable and the manipulated variable.
o What is the difference between an experimental group and a control group? The experimental group is the one
being tested; it is exposed to the independent variable. A control group is separate from the rest of the experiment
where the independent variable being tested cannot affect it.
o What is an observation? Give an example. Gathering information about the events or processes in a careful,
orderly way. An example would be “During the experiment, it was observed that once the liquids were mixed they
changed colors and a strong odor was present.”
o Why should sample sizes be large? A sample size should be large because it allows less room for error and give
more accurate results.
o What is data? The information gathered from an observation. Can be number results (Quantitative) or descriptive
words (Qualitative)
Chapter 3 Main Concepts

Types of Organisms
o Know definitions and examples of the following: Autotroph (Producer), Heterotroph (Consumer), Herbivore,
Carnivore, Decomposer.
Autotroph- Organisms that can produce their own food from inorganic compounds.
Heterotroph- Organisms that must obtain energy by consuming
Herbivore – Organism that eats only plants
Carnivore - Organism that eats only meat or other organisms
Decomposer – Organisms that feed on dead or decaying organic matter.

Energy Flow
o Food Chains vs. Food Webs – What types of organisms always start a food chain? Autotrophs (Producers)
o What ultimately ends a food chain? Decomposers
o How are primary consumers different from secondary consumers? Primary consumers are first and plant eaters,
Secondary are second and meat eaters.
o
o
o
o

If one organism is removed from an ecosystem, how will it affect the other organisms? It will disrupt the food
chain, and therefore the ecosystem. It could cause the loss of another organism or at least cause a lack of
resources, lower a population’s carrying capacity.
Energy/Biomass/Numbers Pyramids – In any stable ecosystem, the pyramid is always _Large __ with the producers
(at the base) and _Small_ with the top of the food chain (at the top). If a pyramid is misshapen, the ecosystem is
unstable.
Energy flows in one direction through an ecosystem. How much energy is lost from one trophic level to the next?
About 90% is lost, mostly in the form of heat.
The _Sun_ is ultimately the source of all life on Earth. Producers absorb this in the chloroplasts of their cells and
make food in the form of glucose (a carbohydrate).
Nutrient Recycling
o Matter is _Recycled_ throughout an ecosystem.
o The Hydrologic (Water) Cycle – what are the steps involved? Evaporation and Transpiration, Condensation,
Precipitation and repeat.
o The Carbon Cycle – How is carbon stored in the ecosystem? In the air as Carbon Dioxide, underground as fossil
fuels and dissolved into the ocean waters as Carbon Dioxide.
o What releases carbon dioxide into the atmosphere? Respiration, Decomposition, Human activity (burning fossil
fuels), and Volcanoes
o How is carbon removed from the atmosphere? Photosynthesis
o The Nitrogen Cycle – How is nitrogen moved from the atmosphere to the soil and back again? Through Nitrogen
Fixation in the roots of Legumes it’s a process done by Bacteria. Then a different type of Bacteria does
Denitrification a process to return nitrogen back into the atmosphere.
o Where would you expect to find N2, nitrates, and ammonia?N2 would be found in the atmosphere as a gas,
nitrates and ammonia would be found in the soil.
o What are legumes and why are they important? Legumes are a special kind of plant that contains a bacteria in its
roots, the bacteria is what does nitrogen fixation and denitrification.
Chapter 4 Main Concepts


What is a niche? A niche is the full range of physical and biological conditions in which an organism lives and the way in
which the organism uses those conditions.
o What defines a species niche? The combination of biotic and abiotic factors in an ecosystem. For example the type
of food they eat, and the physical conditions it requires to survive, it could also include how it reproduces.
Community Interactions
o What is symbiosis? Any relationship in which 2 species live closely together.
o Describe the following relationships and give an example of each of the following:
 Predation (Predator vs. Prey) an interaction in which one organism captures and feeds on another
organism. An example - Wolf eating a Moose
 Parasitism (Parasite vs. Host) one organism lives on or inside of another organism and harms it. An
example – A tick sucking the blood of a giraffe.
 Mutualism both species benefit from the relationship. An example – a humming bird and a flower.
 Commensalism One organism benefits while the other is not helped nor harmed. An example – a clown
fish and a sea anemone (Finding Nemo)