HESI Biology
Biology is the study of living organisms and to understand anatomy and
physiology, a nurse must first grasp the science of biology. While you may not
use your knowledge of biology directly every day, biology serves as a
prerequisite before moving on to other sciences such as anatomy, physiology,
and microbiology.
Here are some key concepts you should understand in order to do well on the
Biology section of the HESI exam:
Classification of Organisms
Early biologists faced difficulty in devising a method for discerning living
organisms from nonliving things. After developing rules to differentiate life
from nonlife, scientists then faced the struggle of organizing and classifying
life. Taxonomy, or the science of classifying, resulted from these early
struggles. Many years of classification have occurred since, and because of
advancements in biotechnology, scientists can now categorize life based on
similarities and differences at the genetic level. Scientists utilize a
hierarchical system for classifying organisms. Six Kingdoms contain the
taxonomic breakdown of life. These Kingdoms are further divided into Phyla,
then Class, Order, Family, Genus, and Species. A common mnemonic for
remembering this hierarchy is, “King Phillip Came Over For Great Spaghetti,”
where the first letter of every word indicates the corresponding taxonomic
class. Over the years, the taxonomic classification schemes have changed
and will continue to change as we further our understanding of genetics.
Currently, scientists use Six Kingdoms to subdivide life: Bacteria, Protozoa,
Chromista, Plantae, Fungi, and Animalia make up these Six Kingdoms.
Scientists categorize organisms within one of these Kingdoms by
investigating the organisms’ cellular composition, methods for obtaining and
using energy, genotypic similarities, and other techniques.
The Scientific Method
The Scientific Method is a way of devising and performing experiments
that yield meaningful results. It involves a procedural approach to gaining
information about the physical world that begins with a formulated
question and ends with the rejection of a hypothesis and the reevaluation
of the experiment.
The Scientific Method can be summarized as the following:
, Question ― A curiosity about a phenomenon arises and, in response, a
question is formulated. Early thinkers looked at the sky and wondered why it
was blue or looked at the grass and wondered why it was green.
Research ― After formulating a question, a scientist looks for any relevant
research or data already discovered and provided for the phenomenon in
question. This helps give some direction in how to set up or approach the
question.
Hypothesis ― The scientist then generates a hypothesis, or an educated
guess, as to what could be causing the phenomenon. This step helps narrow
down the possible options for experimentation.
Experiment ― Using available measuring tools and technology, an experiment
is designed to provide valuable data for the scientist to investigate.
Evaluation ― The data will then be analyzed and assessed for its
validity. Do the observations made support the hypothesis, or do they
support a different hypothesis?
Conclusion ― Finally, the scientist will decide if the hypothesis is
confirmed, in which case other scientists will then recreate the same
experiment to confirm that the results hold true in a different time or place
using the same methods. If the hypothesis is not confirmed, the scientist
may choose to adjust some of the experimental methods or devise a new
hypothesis.
Overall, the Scientific Method provides a methodical approach for
investigating experiments, data, and drawn conclusions. It is worthwhile to
know that developments in scientific research do not arise from haphazard
guessing and checking, but rather through logical design and reasoning.
Even a basic familiarity with the method will prove useful when making
sense of scientific experiments.
Cells, Tissues, and Organs
The most fundamental unit of life is the cell. Organisms that exist as a
single cell, like bacterium, are called prokaryotes and those that are
multicellular, like humans, are called eukaryotes. The major difference
between these two groups is that eukaryotes possess a nucleus and
membrane bound organelles while prokaryotes do not.
Beginning with an understanding of the cell, its form and function, we can
start to make sense of how life operates, and what cellular features enable
this operation. Learning the components of the cell is not a difficult task, but
it can be tedious.
Biology is the study of living organisms and to understand anatomy and
physiology, a nurse must first grasp the science of biology. While you may not
use your knowledge of biology directly every day, biology serves as a
prerequisite before moving on to other sciences such as anatomy, physiology,
and microbiology.
Here are some key concepts you should understand in order to do well on the
Biology section of the HESI exam:
Classification of Organisms
Early biologists faced difficulty in devising a method for discerning living
organisms from nonliving things. After developing rules to differentiate life
from nonlife, scientists then faced the struggle of organizing and classifying
life. Taxonomy, or the science of classifying, resulted from these early
struggles. Many years of classification have occurred since, and because of
advancements in biotechnology, scientists can now categorize life based on
similarities and differences at the genetic level. Scientists utilize a
hierarchical system for classifying organisms. Six Kingdoms contain the
taxonomic breakdown of life. These Kingdoms are further divided into Phyla,
then Class, Order, Family, Genus, and Species. A common mnemonic for
remembering this hierarchy is, “King Phillip Came Over For Great Spaghetti,”
where the first letter of every word indicates the corresponding taxonomic
class. Over the years, the taxonomic classification schemes have changed
and will continue to change as we further our understanding of genetics.
Currently, scientists use Six Kingdoms to subdivide life: Bacteria, Protozoa,
Chromista, Plantae, Fungi, and Animalia make up these Six Kingdoms.
Scientists categorize organisms within one of these Kingdoms by
investigating the organisms’ cellular composition, methods for obtaining and
using energy, genotypic similarities, and other techniques.
The Scientific Method
The Scientific Method is a way of devising and performing experiments
that yield meaningful results. It involves a procedural approach to gaining
information about the physical world that begins with a formulated
question and ends with the rejection of a hypothesis and the reevaluation
of the experiment.
The Scientific Method can be summarized as the following:
, Question ― A curiosity about a phenomenon arises and, in response, a
question is formulated. Early thinkers looked at the sky and wondered why it
was blue or looked at the grass and wondered why it was green.
Research ― After formulating a question, a scientist looks for any relevant
research or data already discovered and provided for the phenomenon in
question. This helps give some direction in how to set up or approach the
question.
Hypothesis ― The scientist then generates a hypothesis, or an educated
guess, as to what could be causing the phenomenon. This step helps narrow
down the possible options for experimentation.
Experiment ― Using available measuring tools and technology, an experiment
is designed to provide valuable data for the scientist to investigate.
Evaluation ― The data will then be analyzed and assessed for its
validity. Do the observations made support the hypothesis, or do they
support a different hypothesis?
Conclusion ― Finally, the scientist will decide if the hypothesis is
confirmed, in which case other scientists will then recreate the same
experiment to confirm that the results hold true in a different time or place
using the same methods. If the hypothesis is not confirmed, the scientist
may choose to adjust some of the experimental methods or devise a new
hypothesis.
Overall, the Scientific Method provides a methodical approach for
investigating experiments, data, and drawn conclusions. It is worthwhile to
know that developments in scientific research do not arise from haphazard
guessing and checking, but rather through logical design and reasoning.
Even a basic familiarity with the method will prove useful when making
sense of scientific experiments.
Cells, Tissues, and Organs
The most fundamental unit of life is the cell. Organisms that exist as a
single cell, like bacterium, are called prokaryotes and those that are
multicellular, like humans, are called eukaryotes. The major difference
between these two groups is that eukaryotes possess a nucleus and
membrane bound organelles while prokaryotes do not.
Beginning with an understanding of the cell, its form and function, we can
start to make sense of how life operates, and what cellular features enable
this operation. Learning the components of the cell is not a difficult task, but
it can be tedious.
