Biology, the Study of Life study guide

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Biology, the Study of Life study guide

Chapter 1 Biology, the Study of Life

Chapter Outline

I. Fire Ants Have a Good Defense

A. Fire ants can be used as an interesting example of the complexity of life.
B. Fire ants can be used to describe all of the levels of biological organization.
C. Fire ants exhibit interactions with the environment and other organisms.
D. Chemical nutrients and energy are required for fire ants to survive.
E. Behaviors are present and designed to enhance survival.
F. Use the fire ants example to make connections between biological concepts.

II. Organisms Are Characterized by Diversity and Unity
-The diversity of life contains unity in the presence of common characteristics of life.
-Critical concepts include: levels of organization and unifying characteristics.

1.1 Life is diverse
A. Life on Earth is abundant and varied.
B. Life on Earth often behaves and functions in strange ways.
Ex.: Fetal sand sharks kill/eat their siblings in the womb.
Ex.: Some Ophrys orchids mimic female bees, tricking the males into mating.
C. Individual living things are called organisms, which range from single-celled to multi-cellular individuals.

1.2 Life has many levels of organization
A. All forms of life are organized similarly.
B. There are eleven levels of biological organization.
1. Atoms: – Smallest unit of an element containing electrons, protons, neutrons
2. Molecules – Union of two or more atoms.
3. Cells – Basic unit of structure and function of all living things.
4. Tissues – Group of cells with a common structural function.
5. Organs – Structure composed of tissues with similar function.
6. Organ Systems – Composed of several organs working together.
7. Organisms –– An individual.
8. Populations –– All organisms of one species that live in a particular area.
9. Communities – Interacting populations in a particular area.
10. Ecosystems –A community and the physical environment around it.
11. Biosphere: –The sum of all of Earth’s ecosystems, the most complex level.
C. Complexity increases with each level from atom to biosphere.
D. Each increase in complexity is associated with the establishment of properties beyond those of the previous level. This is known as emergent properties.

1.3 Organisms share the same characteristics of life
A. All living things share seven characteristics.
1. Order:
a) An organism is highly ordered with cells, tissues, organs, etc.
b) The biosphere is highly ordered in terms of the lower levels.
c) Individual structures, like compound eyes, show distinct organization.
2. Response to Stimuli:
a) Interaction with the environment and other living organisms.
b) Responses help ensure survival.
c) Activities in response to stimuli are termed behaviors.
3. Regulation of Internal Environment:
a) Organisms must maintain a state of biological balance.
b) Homeostasis is the balance maintained regarding temperature, moisture, acidity, and other physiological factors.
c) Organisms have feedback and control mechanisms that do not require conscious activity.
d) Through behavior, organisms can also maintain homeostasis.
4. Acquisition of Materials and Energy:
a) Living organisms require an outside source of nutrients and energy.
b) Energy is the capacity to do work. It can be gained from food intake.
c) Metabolism is the sum of all chemical reactions that occur in a cell.
d) Energy is required to ensure that metabolism can occur.
e) The sun is the ultimate source of all energy on Earth.
f) Photosynthesis transforms solar energy into chemical energy in the form of organic molecules in plants.
g) All life acquires energy by metabolizing the products of photosynthesis.
5. Reproduction and Development:
a) Life comes only from life.
b) An organism can reproduce or make more organisms like it.
6. Genetic Inheritance
a) The blueprint for an organism is encoded in the genes of DNA.
b) Genes contain specific information for how the organism is to be
ordered.
c) DNA (deoxyribonucleic acid) is the genetic code in all living things.
7. Evolutionary Adaptations:
a) Adaptations are modifications that make organisms suited to their life.
b) Adaptations come about through evolution.
c) Evolution is the process by which a species changes over time.
d) A species is a group of similar organisms that can interbreed.
e) Modifications occur over time as organisms reproduce.
f) Natural selection, proposed by Charles Darwin, explains how species change over time when a new variation arises that allows certain members to be more competitive and thus survive and reproduce better.
g) The theory of evolution can explain the diversity of life.

III. Classification Helps Us Understand Diversity
-Classification explains the relationships between organisms both present and past.
-Critical concepts include: classification categories.

1.4 Taxonomists categorize organisms according to evolutionary relationships
A. A classification system groups organisms into categories.
B. Taxonomy is the disciple of identifying and classifying organisms based on
evolutionary history and relationships.
C. Basic classification categories (taxa) are arranged from least to most inclusive:
SpeciesàGenusàFamilyàOrderàClassàPhylumàKingdomàDomain
D. As the classification increases in inclusiveness, it contains more organisms.
E. Organisms placed in each grouping share characteristics.
F. Domains:
1. Largest classification category.
2. Three domains: Bacteria, Archaea, Eukarya.
3. Prokaryotes are unicellular organisms that lack a membrane bound        nucleus and make up the domains Bacteria and Archaea.
4. Eukaryote cells have a membrane bound nucleus and make up the domain      Eukarya.
G. Kingdoms:
1. Archaea and Bacteria are still in flux regarding further classification.
2. Eukarya contains four kingdoms:
a) Kingdom Protista (protests) includes multicellular and unicellular
forms that vary in metabolic processes as well as complexity.
b) Kingdom Fungi (fungi) includes molds, mushrooms and decomposers.
c) Kingdom Plantae (plants) – Multicellular photosynthetic members.
d) Kingdom Animalia (animals) – Multicellular organisms that must ingest and process their food.
H. Scientific Names:
1. Binomial nomenclature is used to assign two-part scientific names.
2. The genus is the first word of the name.
3. The species is the second word of the name.
4. Scientific names are in Latin and are universally used to avoid confusion.

IV. The Biosphere is Organized
-The biosphere is the largest of the biological organizations.
-Critical concepts include: organization, chemical cycles, and energy flow.

1.5 The biosphere is divided into ecosystems
A. The biosphere, which consists of all of Earth’s ecosystems including the air
above and the ground below, is further classified into more specific categories.
B. The ecosystems include the presence of a community and the physical
environment (including the soil, atmosphere, and chemicals).

Ex.: A grassland ecosystem.

C. Communities include all of the populations of organisms in the same area.

Ex.: Rabbits, mice, snakes, hawks, grasses, and forbs present.

D. Populations encompass all of the individuals of one species in a given area.

Ex.: Rabbits that live in the area.

E. All ecosystems undergo chemical cycling and energy flow due to
interactions within the communities of the ecosystem.
F. A typical chemical cycle may flow as follows:
1. Inorganic nutrients are taken up from the soil and atmosphere by plants.
2. Rabbits and mice feed on the plants and seeds, taking in nutrients.
3. A snake may eat mice and a hawk may eat the snake or rabbit.
4. Chemicals are passed from organism to organism.
5. Ultimately the hawk may die and decompose, returning the chemical      nutrients to the soil where they are available to plants.
G. The basic pathway of energy flow is as follows:
1. Solar energy from the sun is absorbed by photosynthetic organisms      including plants, algae, and some bacteria.
2. Plant transform the energy into chemical energy stored in organic      molecules synthesize using nutrients from the environment.
3. Rabbits and mice gain energy from the plant material consumed.
4. Other predators gain energy from the molecules in the rabbits/mice.
5. Energy is lost and returned to the environment as heat during each transfer      step.
6. Upon death the molecules are broken down releasing energy back to the      environment as heat which can leave the system.
H. The energy flows through the ecosystem and does not cycle.
I. Energy flow depends on a constant input from the sun.
J. Nearly all life depends on the presence of photosynthetic organisms to harvest solar energy from the sun.

1.6 Most of the biosphere’s ecosystems are now threatened
A. Humans modify existing ecosystems for their own purposes.
Ex.: Clearing forests for farmland. Developing coastal areas with homes.
B. Human modifications decrease the area of ecosystems.
C. Human modifications change the balance of chemical nutrients and energy flow by disrupting the communities that previously existed in an area.
D. Tropical rainforests and coral reefs are especially sensitive to human activity.
E. Rainforests and reefs have significant diversity and human influence decreases that diversity through the loss of habitat.
F. Disruptive human activity includes pollution, overfishing, clear-cutting, etc.
G. Scientists study the environment to determine how to preserve ecosystems.

V. Scientists Observe, Hypothesize, and Test
-The process of gathering information and using is transcends all scientific disciplines.
-Biologists use the scientific method to advance their understanding of life.
-Critical concepts include: the scientific method, scientific theories, and experimentation.

1.7 The natural world is studied by using scientific methods
A. Biology is the scientific study of life.
B. Biology uses the scientific method to investigate what life is and how it
works.
C. The scientific method consists of four parts: Observation, Hypothesis, Testing, and Conclusion.
D. Observation and Hypothesis:
1. Observations are noticeable details of the natural world using our senses.
2. Observations also include the integration of previous data.
3. Observations can result in the development of questions.
4. A hypothesis is developed following observations and is a possible      explanation for a natural event.
5. A good hypothesis is testable.
E. Testing and Conclusion:
1. Testing a hypothesis can involve either an experiment or further observation.
2. Deductive reasoning is used to test a hypothesis and uses “if, then” logic.
Ex.: If an organism is made of cells, then any part of the organism will be    made of cells.
3. Making a prediction helps the scientist to know what to do next.
4. Data are the results of an experiment.
5. A conclusion describes if a hypothesis is supported or rejected based on data.
6. Hypotheses are never proven “true” since information is always increasing.
7. A hypothesis is considered false if the data do not support it.
8. False hypotheses help direct the scientist to new hypotheses.
F. Scientific Theories:
1. A scientific theory is one supported by a broad range of observations,      experiments, and data from a variety of disciplines.
2. This contrasts with the typical definition of a theory as a speculative idea.
3. Five basic theories are present in biology:
a) The Cell Theory: all organisms are made of cells, and new cells come from preexisting cells.
b) The Gene Theory: organisms contain coded information that dictates their form, function, and behavior.
c) The Evolution Theory: all living things have a common ancestor, but each is adapted to a particular way of life.
d) The Homeostasis Theory: the internal environment of an organism stays relatively constant within a range protective of life.
e) The Ecosystem Theory: organisms are members of populations that interact with each other and with the physical environment within a particular locale.

1.8 Control groups allow for the comparison of results
A. In a typical scientific investigation, the scientist will work is a series of steps.
B. Design an Experiment that can be any method designed to test a hypothesis.
1. Experimental variables represent the environmental aspect being      investigated.
2. All other environmental variables need to be kept the same (i.e. temp.).
3. A control group represents a group within the test that is not exposed to      the experimental variable and should be included in the experiment.
4. The control group shows that changes are due to the experimental variable      and not some other outside influence.
5. Test groups consisting of experimental and control groups should be as large as feasibly possible.
C. Analysis of the Results:
1. Measurements are made of the experimental and control groups.
2. Possible measurements include biomass, height, weight, or behavior.
3. The results are combined and interpreted to present a conclusion.
4. The conclusion can either support or disprove the hypothesis.
5. The conclusion will provide new information for the next experiment.
D. Perform a Follow-Up Experiment based on the previously obtained results.
1. A new hypothesis is formed and acted upon with a new experiment.
2. This experiment may continue to pursue the original idea or it may expand.
     -Ex.: Change the amount of time the experiment is performed.
E. Analyze the Results of the new experiment to determine the next step.
1. Careful interpretation of the results is performed.
2. Based on the data the hypothesis can be supported or rejected.
3. Continued analysis provides more in-depth explanations of life’s complexity.
F. An example of an experiment can be seen below:
1. Observation: Chemical fertilizer added to soil can be lost to water while                         organic nitrogen deposited by legume plants is retained in the soil.
2. Hypothesis: Planting a non-legume crop followed by a legume crop will                          improve soil fertility and decrease loss of nitrogen from the soil.
3. Experimental Groups: Plant non-legume plants in pots with varying                                levels of chemical fertilizer and in pots that previously contained legumes.
4. Control Group: Non-legume plants in a pot without any additions.
5. Results: Non-legume plants did not grow as well in pots that previously                           contained legume plants.
6. Conclusion: The results reject the hypothesis.
7. New Hypothesis: Prolonged rotations of legumes with non-legumes will                           eventually increase non-legume growth.
8. Experimental Groups: Same experimental design as before except now                            extended for four years.
9. Control Group: Same as before.
10. Results: Improved growth was seen after four years in the rotating                                           pots.
11. Conclusion: The results support the hypothesis.

G. The impact of the experiment should always be reflected on.
H. Experiments can provide information that has ecological importance.
I. Scientific contribution is made with experiments at all levels of organization.

How Biology Impacts Our Lives:
1.9 DNA barcoding of life may become a reality
A. Advances in science give rise to new technologies.
B. Technologies enhance the lives of both the scientist and nonscientist.
C. The development of using DNA to barcode life is an example of a technology.
D. DNA provides a unique identifying tag for each species on Earth, like
barcodes.
E. A sample of an organism would be used to determine the code, identifying it.
F. The identification would rely on the presence of vast databases with genetic
information from every species on Earth.
G. Currently the Consortium of the Barcode of Life (CBOL) is working on this
task.

VI. Connecting the Concepts

A. Use this chapter to preview all of the major concepts of biology.
B. These concepts are primers and will be covered in more detail in other
chapters.
C. The scientific method explained here is the basis for the detailed information
expanded on in the other chapters.
D. Ultimately it is biology’s goal to understand life in terms of theories.
E. This text is organized around the major theories of biology previously
described.
F. The theory of evolution is a unifying concept because it pertains to all of the
different aspects of living things.
G. Emphasize that science does not make ethical or moral decisions.
H. Ethics/morals are the province of the public and so it is the goal of this text to
provide a basis for the public to make educated decisions.
I. Overall, this text is designed to introduce you to the scientific process and to
help you learn the basic concepts of general biology.

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