Transmission electron microscopes (TEM) focus a beam of electrons through an object and can magnify an image up to two million times with a very clear image ("high resolution").
Scanning electron microscopes (SEM) (Figure below) allow scientists to map the surfaces of extremely small objects. These microscopes slide a beam of electrons across the surface of specimen, producing detailed maps of the shapes of objects.
Scanning acoustic microscopes use sound waves to scan a specimen. These microscopes are useful in biology and medical research.
Figure 1.21
A scanning electron microscope.
Other Life Science Tools
What other kinds of tools and instruments would you expect to find in a biologist’s laboratory or field station? Other than computers and lab notebooks, biologists use very different instruments and tools for the wide range of life science specialties. For example, a medical research laboratory and a marine biology field station might not use any of the same tools. Tools such as a radiotelemetry device (Figure below), or a thermocycler (Figure below) and even a fume hood (Figure below) are all biological equipment.
Figure 1.22
A radiotelemetry device used to track the movement of seals in the wild.
Figure 1.23
A thermocycler used for molecular biological and genetic studies.
Figure 1.24
A laboratory fume hood. This laboratory hood sucks dangerous fumes out of a lab and allows researchers to work with dangerous chemicals without breathing them.
Using Maps and Other Models
You use models for many purposes. A volcano model, is not the same as a volcano, but it is useful for thinking about real volcanoes. We use street maps to represent where streets are in relation to each other. A model of planets may show the relationship between the positions of planets in space. Biologists use many different kinds of models to simulate real events and processes. Models are often useful to explain observations and to make scientific predictions.
Some models are used to show the relationship between different variables. For example, the model in Figure below says that when there are few coyotes, there are lots of rabbits (left side of the graph) and when there are only a few rabbits, there are lots of coyotes (right side of the graph). You could make a prediction, based on this model, that removing all the coyotes from this system would result in an increase in rabbits. That's a prediction that can be tested.
Figure 1.25
This graph shows a model of a relationship between a population of coyotes (the predators) and a population of rabbit, which the coyotes are known to eat (the prey).
Lesson Summary
From the time that the first microscope was built, over four hundred years ago, microscopes have been used to make major discoveries.
Life science is a vast field; different kinds of research usually require very different tools.
Scientists use maps and models to understand how features of real events or processes work.
Review Questions
What did van Leeuwenhoek discover when he looked at plaque from his own teeth under the microscope?
What does the symbol 10X on the side of a microscope mean?
What is a scientific model?
Look at the predator/prey (coyote/rabbit) model again. What does the model predict would happen to the rabbit population if you took away all the coyotes?
How long ago were the first microscopes invented?
What tool would you use to keep track of where a wolf travels?
What is the relationship between basic and applied research?
Vocabulary
electron microscopes
Used to create high magnification (magnified many times) and high resolution (very clear) images.
microscopes
A set of lenses used to look at things too small to be seen by the unaided eye.
microscopy
All the methods for studying things using microscopes.
optical (light) microscopes
A microscope that focuses light, usually through a glass lens; used by biologists to visualize small details of biological specimens.
scanning acoustic microscopes
A microscope that focuses sound waves instead of light.
scanning electron microscopes
A microscope that scans the surfaces of objects with a beam of electrons to produce detailed images of the surfaces of tiny things.
Points to Consider
What could be some hazards that biologists may face in the laboratory?
What could be risks of doing field research?
So what do you think biologists do to protect themselves?
Lesson 1.4: Safety in Scientific Research
Lesson Objectives
Recognize how the kind of hazards that a scientist faces depends on the kind of research they do.
Identify some potential risks associated with scientific research.
Identify who and what safety regulations are designed to protect.
Check Your Understanding
What is the scientific method?
Introduction
There are some very serious safety risks in scientific research. Research can involve many different kinds of risks. Yet, if science were as dangerous as some horror movies make it look, not many people would become scientists. Since the life sciences deal with living organisms, some research may have risks not found in other fields. Safety practices are needed to work with any potentially hazardous situation, such as:
pathogenic (disease-causing) viruses, bacteria or fungi
parasites
wild animals
radioactive materials
pollutants in air, water, or soil
toxins
teratogens
carcinogens
radiation
The kinds of risks that scientists face depend on the kind of research they perform. For example, a bacteriologist working with bacteria in a laboratory faces different risks than a zoologist studying the behavior of lions in Africa. Think back to the deformed frogs discussed earlier, the ones in the pond with extra limbs or extra eyes. If there is something in the frogs' environment causing these deformities, could there be a risk to a researcher in that environment? A chemical in the pond that could cause such deformities is called a "teratogen." Or perhaps a disease is causing the deformities. Infectious agents such as viruses and bacteria are called biohazards (Figure below). Biohazards include any material such as medical waste that could possibly transmit an infectious disease. A used hypodermic needle or a vial of bacteria are both biohazards.
Figure 1.26
The Biohazard symbol.
Laboratory Safety
Most laboratories are safe places to visit. If you plan to work in a scientific laboratory, ask someone to tell you about the safety rules they are required to follow. Scientists must follow regulations set by federal, state, and private institutions. For example, scientists cannot work with hazardous materials or equipment without:
Getting approval to do the specific research.
Using safety equipment, such as hoods and fans (Figure below and Figure below).
Demonstrating that the staff are familiar with risks, know how to respond to problems, and can follow safety regulations.
Accepting laboratory inspections by safety officers at any time.
Figure 1.27
An example of a science laboratory workbench. A fume hood is on the left.
Figure 1.28
Scientists studying dangerous organisms such as , the cause of bubonic plague, use special equipment that helps keep the organism from escaping the lab.
Field Research Safety
Scientists who work in the outdoors, called "field scientists," are also required to follow safety regulations designed to prevent harm to themselves, other humans, to animals, and the environment.
Scientists are required to follow the same level of safety standards in the field as th
ey do in a laboratory. In fact, if scientists work outside the country, they are required to learn about and follow the laws and restrictions of the country in which they are doing research. For example, entomologists following monarch butterfly (Figure below) migrations between the United States and Mexico would have to follow regulations in both countries.
Figure 1.29
A Monarch Butterfly
Field scientists are also required to follow laws to protect the environment. Before biologists can study protected wildlife or plant species, they must apply for permission to do so, and obtain a research permit, if required.
Lesson Summary
Research of any kind may have safety risks. Because biologists study living organisms as diverse as bacteria and bears, they deal with risks that other scientists may never encounter.
The risks scientists face depend on the kind of research they are doing.
Scientists are required by federal, state, and local institutions to follow strict regulations designed to protect the safety of themselves, the public, and the environment.
Review Questions
What kinds of hazards might be found in biology laboratories, but not physics laboratories?
Who has more freedom to do whatever research they want? Laboratory scientists or field biologists?
What is a biohazard?
What is a research permit?
What are some of the precautions you might take if you were collecting frogs in water you think might be polluted?
Name some possible hazards to field biologists.
If a scientist does research in a foreign country, which research laws would the scientist need to follow: those of the homeland or the foreign country?
Further Reading / Supplemental Links
Biosafety in Microbiological and Biomedical Laboratories (National Research Council, 1999).
Chemical Classification Signs:
http://www.howe.k12.ok.us/~jimaskew/nfpa.htm
NFPA Chemical Hazard Labels:
http://www.atsdr.cdc.gov/NFPA/nfpa_label.html
Where to Find MSDS's on the Internet:
http://www.ilpi.com/msds/index.html
Cornell University MSDS:
http://msds.pdc.cornell.edu/msdssrch.asp
MSDS Power Point:
http://www.tenet.edu/teks/science/safety/pdf/hazcom/msds.ppt
http://www.research.northwestern.edu/ors/biosafe/index.htm
Vocabulary
biohazard
Is any biological material, such as infectious material that poses a potential to human health, animal health, or the environment.
pathogen
A disease causing agent.
Points to Consider
We are now moving into examining living things.
What do you think makes something “alive?”
What may be some things a blade of grass, a fly, and you have in common?
Chapter 2: Introduction to Living Organisms
Lesson 2.1: What are Living Things?
Lesson Objectives
List the defining characteristics of living things.
List the needs of all living things.
Check Your Understanding
How do life scientists study the natural world?
Are scientific theories just a "hunch" or a hypothesis?
Introduction
How would you define a living thing? In other words, what do mushrooms, daisies, cats, and bacteria have in common? (The series of pictures in the Figure below are additional representations.) All of these are living things, or organisms. It might seem hard to think of similarities among such diverse organisms, but there are actually many similarities. The chemical processes inside all organisms are the same. For example, all living things encode their genetic information in the same way. And many organisms share the same needs, such as the need for energy and materials to build their bodies. Living things have so many similarities because all living things have evolved from the same common ancestor that lived billions of years ago.
All living organisms:
Need energy to carry out life processes
Are composed of one or more cells (the cell theory)
Evolve and share an evolutionary history
Respond to their environment
Grow, reproduce themselves, and pass on information to their offspring in the form of genes
Maintain a stable internal environment (homeostasis)
Figure 2.1
Life on Earth is very diverse, yet all these forms of life share some characteristics. Forms of life include: A) Bacteria, B) Algae, C) Fungi, D) Plants, and E) Animals.
Living Things Maintain Stable Internal Conditions
All living things have some ability to maintain a stable internal environment. The inside of an organism is separate and different from the outside world. Maintaining that separation and difference is known as homeostasis. For example, many animals work hard to keep their temperature within a certain range. If the animal gets too hot or too cold, it will die. As a result, many animals have evolved behaviors that regulate their internal temperature. A lizard may stretch out on a sunny rock to increase its internal temperature, and a bird may fluff its feathers to stay warm (Figure below).
Figure 2.2
A bird fluffs his feathers to stay warm (keep from losing energy) and to maintain homeostasis.
Mammals and birds are homeotherms--meaning they maintain the same temperature most of the time. A lizard or an earthworm is a heterotherm, meaning its temperature can change.
Humans and other mammals may deliberately do things to stay warm or to cool off, like lie down under a shady tree. But most mammals maintain a steady temperature primarily through unconscious processes. A portion of your unconscious brain regulates your body temperature. If you get too warm, you start to sweat and the blood vessels in your skin open up to let the blood flow to the surface of your body. If you are too cold, you start to shiver and the blood supply to your skin, hands and feet may be reduced.
There are many forms of homeostasis besides temperature regulation. Homeostasis can occur at both the level of the cell and the level of the organism. For example, when you have a big lunch, your body produces the hormone insulin, which helps maintain the right amount of sugar in your blood. Meanwhile, your kidneys are hard at work maintaining the right amount of water and salts in your blood. Both of these processes happen unconsciously and are part of homeostasis.
Living Things Grow and Reproduce
All living things reproduce. Organisms that do not reproduce go extinct, every time. As a result, there are no species that do not reproduce.
Figure 2.3
Like all living things, cats reproduce themselves and make a new generation of cats. When animals and plants reproduce they make tiny undeveloped versions of themselves called , which grow up and develop into adults. A kitten is a partly developed cat.
Reproduction, the process of creating a new organism, is different for different organisms. Many organisms reproduce sexually, where an egg and sperm go together to form a new individual. (Cats are one such species, Figure above.) Other organisms can reproduce without sex ("asexually"). For example, bacteria can simply split in two, producing two identical new cells. But it's not just bacteria that can reproduce without sex. Some lizards can produce clones of themselves. In such species, all individuals are female and simply lay their eggs when they are ready to reproduce. During all reproduction, the parents pass genetic information to their offspring, a process called heredity. Heredity is the passing of genes to the next generation. These genes influence all the traits of an organism, including overall body shape, size, whether it has fur or feathers, teeth or a beak, eye color, and so on. This genetic information is essential to an organism. In all organisms made of cells, this genetic information comes in the form of deoxyribonucleic acid, or DNA, which we will discuss in lesson 2.2. (In viruses, which are not made of cells, the genetic information is sometimes in the form of RNA, a d
ifferent nucleic acid.) DNA contains the "instructions" for building important molecules inside of cells.
Living Things are Composed of Cells
All living things are composed of cells (Figure below), the tiny units that are the building blocks of life. Cells are the smallest possible unit of life that is still considered living. Most cells are so small that they are usually visible only through a microscope. Some organisms, like the tiny plankton that live in the ocean, are composed of just one cell (Figure below). Other organisms have many millions of cells that make up different body tissues and organs. On the other hand, eggs are some of the biggest cells around, including chicken eggs and ostrich eggs. But most cells are tiny.
CK-12 Life Science Page 3
