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BIOLOGY 1M03 Final: Complete and Comprehensive 68 Page Final Exam Study Guide Fall 2015Premium

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Jon Stone
Study Guide

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BIOLOGY 1M03– Biodiversity,
Evolution and Humanity
Final Exam Study Guide
McMaster University – Fall 2015

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BIOLOGY 1M03 - Lecture 3 - The Tree of Life
Key Concepts of Life:
The main concept of life is that organisms are ‘alive’, meaning they display the
ability to grow, metabolize, reproduce, respond to the environment by processing
information, and, collectively as populations, evolve.
The cell theory, another concept of life, involves the idea that all organisms
comprise cells and that all cells derive from preexisting cells.
The theory of evolution by natural selection involves the idea that species change
through time because individuals with particular heritable traits survive and
produce offspring more effectively than do other individuals, continuing to pass
on those traits from generation to generation.
A phylogenetic tree is a diagram that may be interpreted as representing
evolutionary relationships, concluded from research, among species.
Phylogenics (translates into ‘tribe sources’) can be established by
analyzing similarities and differences in traits. Species sharing
distinctive traits are situated in close proximity on phylogenetic
Scientific Theories in Biology:
Biologists, and scientists in general, ask questions, generate hypotheses to
answer them, and design experiments or make observations that test the
predictions made by competing hypotheses, creating scientific theories.
Scientific theories are made of two components: patterns observed in the
natural world, and mechanisms or processes identified that produce
A hypothesis is a proposal; a prediction is something that can be
measured and must be correct if a hypothesis is valid.
Louis Pasteur, a French chemist and microbiologist, demonstrated
experimentally that cells arise from cells and not by spontaneous
Pasteur’s experimental setup was effective because the two
groups he involved differed in only the one factor being tested:
exposure to preexisting cells.
For his experiment, Pasteur simply placed nutrient broth in a
straight-necked flask with a nearby opening to the outside of the
glassware, exposing the living organisms within the broth to the
outside, and vice versa. He boiled the flask, killing any living cells,
and preexisting cells from the outside simply made their way in
through the opening, and repopulated.
Pasteur then repeated the experiment, with only a swan-
necked flask with the opening stretching far from the broth.

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As he boiled this flask, all organisms within died, and
because none could enter from the outside, the flask
remained empty. Consequently, it was determined that
cells do not spontaneously appear.
Elaborating on the Cell Theory:
In the late 1660’s, Robert Hooke and Anton van Leeuwenhoek were the first
scientists to observe cells.
The two scientists contributed in concluding that a cell is a highly
organized compartment bounded by a plasma membrane that contains
concentrated chemicals in an aqueous solution.
Robert Hooke is credited for the term ‘cells’
The complete cell theory states that all organisms are made of cells and all cells
come from preexisting cells; as a result, all individuals of single-celled organisms
are related by common ancestry.
In a multicellular organism, all of the cells present descend from
preexisting cells and are connected by common ancestry.
Origins of Life:
Current ideas for the origin of life include models where cell-based life emerged
from abiotic matter (such as molecules), perhaps aboard meteors and delivered
to Earth by meteorites.
In 1858, Darwin and Wallace proposed that all species are related by common
ancestry. The two scientists also proposed that the characteristics can be
modified from generation to generation; in other words, evolution occurs.
Evolution and Populations:
Evolution entails that species are related to one another and can change through
time. Natural selection is a process that explains how evolution works.
Fitness is conceptualized as the ability of a typical individual (generally
within a group) to survive (to reproductive maturity) and produce offspring.
Adaptation (at the microevolutionary scale) refers to a trait that increases
the fitness of a typical individual in a particular environment.
A population, by definition, is a group of individuals of the same species living in
the same area.
Natural selection acts on individuals, but evolutionary change occurs in
Natural selection occurs whenever two conditions are met:
Individuals within a population vary among themselves in characteristics
that are heritable
In an environment, particular versions of these heritable traits help
individuals survive better or reproduce more than the other versions do.
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