OpenLibri

Open Education For

Everyone

Home / Library / Collections / Sciences / Biology / Fundamentals of Biology /

Chapter 01: Them es of Bio logy

Chapter 01: Themes of Biology

Biology is defined simply as the study of life. It is a very broad term that encompasses a wide

array of much more specific studies. There are marine biologists, microbiologists, zoologists,

ecologists, and dozens of other types of biologists. Even with so many different areas of

study, all biologists need to understand the basics, which is the fundamental purpose of this

book.

Key Topics: Biological Order, Cell Theory, Properties of Life, Evolution & Natural Selection,

Studying Biology

Biological Order

All the different types of biologists study very different types of living things. Some work on a

microscopic scale and look at the individual components of living organisms, while others look at

the broader picture, and focus on how different types of organisms interact with one another.

These different levels of life can be categorized into a Biological Order. This scale starts very

large, and encompasses all the life on the planet, but can be broken down to something as tiny as

INTRODUCTION

the study of a single atom. The entire scale is

depicted in the diagram.

The theory of biological order is a simple one,

start from the outside and work your way in.

Because this is an introductory series, we will

only extensively cover information about Cells,

Organelles, Molecules, and Atoms – the four

lowest levels of Biological Order on which all

the rest of life is based. These topics will

provide the foundation for your continued

education in Biology.

It is also important to remember that biological

systems are far more complicated than their

single components. Just because you

understand how an atom works does not

mean you understand how a molecule works.

As you progress through this text, you should constantly be questioning how different things will

interact with one another, and what could happen if one of the components in a system fails.

Cell Theory & History

The Cell Theory states that cells are the basic fundamental units of life, and that cells originate

from other cells.

The first recorded observation of cells occurred in 1665, when Robert Hooke, an early English

scientist, looked at a thin cork sample placed under a basic magnifying lens. What he saw was

the thick cell walls between the cork cells. He illustrated his findings and is credited as being the

first to discover cells.

The next major milestone in cell observation occurred in the late

17 and early 18 centuries, when Anton van Leeuwenhoek

began building his own microscopes. He achieved an

impressive magnification of 300x, and was the first to use

microscopes to view living cells. His other major

accomplishments include being the first to observe bacteria,

cell vacuoles, and red blood cells. Although his discoveries

were well documented, he did not fully document how he went

about making his microscopes. This slowed major progress on the study of cells for nearly a

century, as microscopes were not readily available to scientists.

Theodor Schwann and Matthias Schleiden were scientists in Germany during the early 1800s.

Through collaboration, they established the first portion of the cell theory, stating that all living

things are made up of cells. Another German scientist, Rudolf Virchow, helped revise the theory to

include a statement about cell reproduction. His portion of the theory stated that cells come from

preexisting cells.

General Cell Properties & Types

In addition to the two basic components of the cell theory, it is also important to note that all cells

are enclosed by a cell membrane, and that all cells contain DNA (genetic material) at some point

in their lifespan. Cells will be discussed in greater detail later.

It is also important to know that cells are classified into two general categories, Prokaryotic and

Eukaryotic. They each are very different and are easily distinguishable from one another.

Prokaryotic cells (pictured in the diagram to the left) are small compared to Eukaryotic cells,

are missing many of the organelles found in Eukaryotic cells, and they do not have a nucleus.

Prokaryotic cells have existed on Earth much longer than Eukaryotic cells and therefore are much

more simple and primitive. In a sense, Eukaryotic cells can be viewed as an evolution of

Prokaryotic cells.

th th

Unlike Prokaryotic cells, Eukaryotic cells contain many different organelles ("tiny" organs), each

with specialized functions. Additionally, their organelles follow the rules of

compartmentalization, meaning that their organelles are arranged into specific areas of the

cell. They also contain DNA, their genetic material, within their nucleus. You can easily tell that the

right cell in the diagram below is Eukaryotic because of its many complex internal structures.

The Properties of Life

How do you prove whether or not something is living? What traits are universally common

across all different forms of life? These types of questions led the scientific community to

develop a list of seven Properties of Life, which are characteristics that all living organisms

exhibit. An overview of these properties is shown below.

Cell Theory: All Living Things are made up of Cells

Biological Order: Life follows Biological Order, in that all the characteristics of an organism

are the result of the many cells, tissues, and organs making it up.

Homeostasis: All living things must be able to regulate their internal environment (body

temperature, etc.)

Metabolism: All organisms must be able to perform metabolic reactions, which allow

organisms to obtain and use energy.

Development: All living organisms must Grow, Develope and Reproduce.

Response: Organisms must be able to Respond to Changing Conditions in the Environment,

like birds migrating in winter.

Evolutionary Adaptation: All organisms must Adapt to the Environment over time, through

evolution.

Form Follows Function: The shapes of biological structures (cells, organelles, organs,

etc.) are correlated with the individual function of the structure. Flowers aren’t beautiful just

for the sake of being beautiful. Every stem, leaf, and petal serves a function.

Evolution & Natural Selection

Evolution is an accepted scientific theory stating that different kinds of organisms have

developed from earlier, often simpler, forms of life in order to adapt to changes in their

environment. Evolution occurs as the result of Natural Selection. Natural Selection is the idea

that a small number of organisms within a population will be born with a random genetic

modification. If this genetic modification proves useful to the survival of the organism, then the

organism is more likely to reproduce, and its mutated trait is more likely to pass on. Likewise, if

the organism is given a gene that proves to be a hindrance to its survival, then the organism is

more likely to die before reaching reproductive age, and will not pass on the unwanted gene.

A good, but sad example of observable natural selection has occurred over the past few decades

in Africa amongst Elephants, who are ferociously pursued by poachers for their ivory tusks. At

random, a genetic mutation has allowed some elephants to be born without tusks. Traditionally,

this would prove to be a hindrance on their survival, because elephants need tusks to ward off

attackers. Now, in some areas, it has almost become a necessity for survival, because poachers

will not waste their time killing a tuskless elephant.

Although some examples of natural selection can be visibly seen occurring, most are not. Most

evolutionary adaptations result after hundreds of thousands, if not millions of years of natural

selection. Birds did not evolve their bones to be light and somewhat hollow over the course of just

a couple of years to enable them to fly. It took millions of years, and countless amounts of genetic

modifications to give them the unique traits they have today.

Studying Biology With Experiments

Biologists, like all other scientists, have to follow a certain set of rules and proceedures as they

progress through experiments. This set of rules is known as the Scientific Method. It contains

five steps. It is especially important that you know and understand all the steps of the scientific

method, because it is highly likely that you will have to use it if you ever attend a labratory class (in

any science field).

The fist step to the scientific method is to Ask a Question about something unknown based on

observations you are experiencing, or have experienced. This is also known as making an inquiry

about the unknown. This step is essential, because asking questions and then attempting to

answer those questions is the basis of any type of scientific study.

Once a question has been formed, scientists move on to produce a hypothesis. A hypothesis is

a possible solution to the question being asked. Hypotheses are based on other relevant scientific

findings, and should make logical sense. It is also important that the hypothesis is testable. In

other words, there must be some way to prove the hypothesis to be true or false.

After a proper hypothesis has been formed, the scientist can go about performing a controlled

experiment. Controlled experiments are methodical tests designed to answer a hypothesis. At

their most simplest level, controlled experiments contain two types of variables. Variables are

anything that can change based on things that the experimenter does, and can affect the outcome

of an experiment. Variables can be almost anything. Temperature, acid levels, moisture, and

lighting amounts are just some examples of variables that can be manipulated in experiments.

Only one variable should be manipulated at a time during an experiment. This variable is known as

the maniuplated variable. For example, if you wanted to test the effects of adding acid to a fish

embryo you would manipulate the acidity levels. You would not change the temperature of the

embryos, the amount of sunlight the embryos are typically exposed to, or the hardness of the

water. You would only change the acidity levels. All the variables that do not change are referred to

as constants , because they must remain constant, or the same throughout the entire

experiment.

Controlled experiments should contain two

different types of groups – a control group

and a variable group. This helps to ensure

the validity, reliability, and accuracy of an

experiment. The subjects being tested are

divided into one of these two groups at

random. The control group is the group

that remains the same throughout the entire

experiment – they are not affected by

whatever variable is being manipulated. The

variable group is the group where the

manipulated variable is modified. Returning

to the example of acidity levels in fish

embryos, one group of embryos would be

left alone, and a second group would

receive the acid treatment. The constants

would still remain the same between the two groups. Having a control group is very important,

because it gives the experimenter something to compare the effects of the manipulated variable

to. For example, if changing acidity levels in the variable group of fish embryos to a higher

concentration results in the embryos dying, and the control group of embryos are still alive, then

the scientist can safely conclude that the acid is what resulted in the embryo deaths. If however,

the scientist raises the acidity levels in the variable group, and then both the control group and the

variable group of embryos die, the scientist cannot conclude that it was the acidity levels that

resulted in the deaths. In this case, one of the constant controlled variables resulted in the deaths

of the embryos. The experimenter would have to figure out what caused the embryos to die, and

then they would have to perform the experiment over again with new, corrected control variables

that ensure that the control group does not die during the duration of the experiment.

It is also possible for the scientist to test more than one level of acidity in the experiment at the

same time. If a scientist wanted to determine what levels of acidity resulted in embryo deaths,

they would use one control group, and multiple variable groups at varying acidity levels. Note that

the manipulated variable – the acidity- remains the same. No other variables are changed. The

scientist could then observe the results. They might find in the end that the control group, and the

variable group with the lowest amount of acidity stay alive, and that the remaining groups with

higher acidity levels die. The scientist would record this information as data. Data is the

information that is collected from experiments. In this case, the scientist would collect two types of

data – the acidity levels, and the state of the embryos. It might look something like the table below.

Scroll horizontally to view the whole table

GroupControl

(7.0)

6.5 (Low

Acid) 5 (Med Acid) 3 (High Acid)

Embryo

StateAlive Alive Dead Dead

The scientist would likely use more incrementing levels of acidity than in the example above, but

you get the idea. As acidity increases the embryos begin to die.

Once the scientist finished performing the experiment, they analyze the data and form a

conclusion. In the embryo example, the scientist would look at the data and determine that the

embryos will die when exposed to highly acidic environments. This allows them to form

a conclusion about their experiment, which states whether or not their original hypothesis was

correct or not. If the hypothesis stated that “rising acidity levels in fish embryos has no effect on

their health” them the experimenter’s hypothesis would have been proven untrue by the

experiment. If, on the other hand, the scientist stated in their hypothesis that “high acidity levels in

fish environments results in embrio deaths,” then their hypothesis would have been correct.

Once the scientist has drawn their conclusion, they share their results with the rest of the

scientific community. Generally, this is done through scientific writing and experimental reports,

which are then published online in scientific journals.

Experimental Ethics & Forbidden Experiments

Although seeking out and understanding

knowledge is important to the evolution

of humanity, there are certain prices that

can never be justifiably paid in order to

obtain knowledge. For example, during

the Holocaust the Nazis killed millions of

Jews, but this is not all they did. Some

Nazi scientists were performing

inhumane experiments on the prisoners.

This gave them vital information which led to the advancements of some modern medical

sciences that people benefit from today. Even so, these advancements are the end result of a

horrifically tragic violation of human rights. Modern ethics and rules have been established to

ensure the safety of people who choose to partake in experiments.

When planning experiments, keep the following in mind:

If you are using human subjects, they must be consenting. If any risks are involved with the

experiment, they must be clearly stated. Written consent should be documented.

Human subjects must be voluntary. People must not be threatened or bribed to volunteer.

The names of your participants must remain confidential. They should be referred to as

"Subject A" and such when mentioned in research papers.

If you are using animal subjects, you must comply with very strict animal testing guidelines.

Scientific Writing

As a biology student, it is important to be able to write, analyze, and understand scientific writing.

Scientific writing is used to convey the results of experiments. Virtually every research article in

biology journals will follow a specific format, known as the IMRAD format. The term IMRAD is an

acronym, and stands for “Introduction, Methods, Results and Discussion.” Although these four

sections make up the general overview of how a scientific paper should look, there are, in total,

about nine portions to every piece of scientific writing.

Title Page

The title page is a separate sheet of paper at the beginning of a report that generally

contains the title of the experiment, the name of the experimenters, and the date the

experiment was performed.

Abstract

Abstracts are summaries of the report. They outline the rest of the lab paper, and are used

so readers can decide whether or not the report is relevant to their studies. It generally

makes sense to write the abstract after the rest of the report has been written.

Introduction

The introduction gives the reader enough information so they can better understand why the

experiment is being performed, what the experiment is building upon, and how the

experiment works.

Methods

The methods section contains all the information about the materials and tools needed to

set up the exam, the amounts of substances used, and the proceedures that went into

performing the experiment. It should be written in a way that enables other experimenters to

perform the experiment and confirm its results.

Results

The results section of the report is where the findings of the report can be found. The

results section generally contains a substantial amount of measurements and records in

the form of numerical data. It should be noted that the results section only contains the

results of the experiment, the experimenter does not explain or interpret these results until

the next section is reached.

Discussion

In this section, the data is interpreted and the meaning of the results is explained. This

section concludes whether or not the experiment was successful in testing what it set out

to test, and whether or not the hypothesis was correct or incorrect. It may also discuss how

results correlate with other studies, and discuss how the experiment may be able to be

improved upon in the future.

Literature Cited

Any citations that are used throughout the paper are found in this section. The manner in

which a citation is formated is dependent on the specifications of the university or scholarly

journal in which the report is published. If you are a student writing your own Scientific/Lab

report, you should ask your professor how he or she wants the literature cited entries

formatted.

Tables

This section contains the numerical data that the experimenter gained from the experiment.

These tables may have been referenced and used to explain things in other sections of the

report.

Figures & Graphs

In order to make data more visually appealing, and understanding by the reader, it is

generally formatted into graphs. These should be high quality graphs of data that are

referenced to explain concepts in other portions of the paper.

Review

Biology is the study of life. The different levels at which life can be studied is known as

Biological Order. Every living thing is made up of cells, and cells come from preexisting cells.

There are two types of cells – primitive prokaryotic cells and more complex eukaryotic cells.

There are seven properties that all forms of life share in common. Biology is studied through

the use of the scientific method, and experiments are explained through experimental reports

CHAPTER SUMMARY

Chapter 01: Themes of Biology

Biological Order

Cell Theory & History

General Cell Properties & Types

The Properties of Life

Evolution & Natural Selection

Studying Biology With Experiments

Experimental Ethics & Forbidden Experiments

Scientific Writing

Review

All Website Contents Copyright 2013 OpenLibri

in scientific journals.