Some common safety equipment in a school lab:
Fire Extinguishers
Fire Blanket
Eye-Wash Fountain (Figure below)
First-Aid Kit
Figure 1.43
Symbol for the eyewash fountain.
Through the first three lessons, we have discussed what science is and how science is done. Now we need to turn our attention to Biology. Biology is the study of life. As the ‘study of life,’ a knowledge of biology is an extremely important aspect of your education. Biology includes the identification and analysis of characteristics common to all living organisms. What is known about biology is discovered or identified through the same processes as all other sciences, including the scientific method and peer review process.
Lesson Summary
The measurements that scientists use are based on the International System of Units (SI), which is form of the metric system. Based on multiples of ten, It is the world's most widely used system of units, both in science and business.
One important use for mathematics in science is the role it plays in expressing scientific models. Statistics allow scientists to assess the reliability and range of differences in experimental results.
Light microscopes use visible light and lenses to magnify objects. They are the simplest and most widely used type of microscopes. Electron microscopes use electrons instead of photons (light), because electrons have a much shorter wavelength than photons and therefore allow a researcher to see things at very high magnification, that greatly exceeds what an optical microscope can possibly magnify. Electron microscopes are larger and more expensive than light microscopes.
Equipment commonly found in a biology labs include microscopes, weighing scales or balances, water baths, glassware (such as test tubes, flasks, and beakers), Bunsen burners, tongs, pipettes, chemical reagents, lab coats, goggles, and biohazard waste containers.
Always wear personal protective equipment such as goggles and gloves, wear enclosed shoes, and do not eat or drink in the lab.
Review Questions
Which one of the following units of measurement would be the most appropriate in determining the mass of a banana? Kilograms, micrograms, or grams.
Identify the type of microscope that is most common in laboratories.
Contrast microscope magnification and resolution.
If an objective lens magnifies an object by 45×, and the optical lens magnifies by 10×. By how much will the object be magnified to the viewer?
Which object is larger? An object with a diameter of 1500 micrometers (µm) or an object with a diameter of 15 millimeters (mm)?
Why is it important that scientists use common units of measurement?
Name three pieces of safety equipment that you should wear while carrying out an investigation in the lab.
What should you first do if an accident happens in the lab?
If you saw this hazard sign on a chemical container, what do you think it might mean?
How are computer models similar to the real world, and how do they differ?
Further Reading / Supplemental Links
http://www.chem.unl.edu/safety/hslabcon.html
http://en.wikibooks.org/wiki/Nanotechnology/Electron_microscopy
Vocabulary
aseptic technique
Laboratory procedures that are carried out under sterile conditions.
compound microscope
An optical microscopes that has a series of lenses, and have uses in many fields of science, particularly biology and geology.
electron microscope
A microscope that uses electrons instead of light; allow a researcher to see things at very high magnification, far higher than an optical microscope can possibly magnify.
International System of Units (SI)
The measurements that scientists use; a form of the metric system.
lab coat
A knee-length overcoat that is usually worn while working in the lab; helps to protect the researcher’s clothes from splashes or contamination.
laboratory
A place that has controlled conditions in which scientific research, experiments, and measurement may be carried out.
lab techniques
The procedures used in science to carry out an experiment.
magnification
Enlarging an image of an object so that it appears much bigger than its actual size; also refers to the number of times an object is magnified.
microscopes
Instruments used to view objects that are too small to be seen by the naked eye.
model
A physical, mathematical, or logical representation of a system, phenomenon, or process; allow scientists to investigate a phenomenon in a controlled way.
optical microscope
A microscope that uses visible light and lenses to magnify objects.
resolution
A measure of the clarity of an image; it is the minimum distance two points can be separated and still be distinguished as two separate points.
scanning electron microscope (SEM)
Electron microscope that scans an electron beam over the surface of an object and measures how many electrons are scattered back.
scientific modeling
The process of making abstract models of natural phenomena.
simulation
A model that runs over time; brings a model to life and shows how a particular object or phenomenon will behave.
stereo microscope
A light microscope with two ocular lenses.
transmission electron microscope (TEM)
Electron microscope that shoots electrons through the sample and measures how the electron beam changes because it is scattered in the sample.
Points to Consider
Consider how much more difficult it would be to carry out investigations without the use of computers, and the types of models that have developed due to the development of computers.
Consider reasons why eating and drinking are not allowed in the lab.
What additional ethical considerations would there be if you were working with living organisms in the lab, such as mice, rats, or other mammals?
Principles of Biology
Lesson Objectives
List some of the different areas of study in biology.
Identify the seven characteristics of living things.
Identify the four unifying principles of modern biology.
List two different types of interactions that organisms can have with each other.
Outline the formation of modern evolutionary theory.
Introduction: Characteristics of Life
Biology examines the structure, function, growth, origin, evolution, and distribution of living things. It classifies and describes organisms, their functions, how species come into existence, and the interactions they have with each other and with the natural environment. Four unifying principles form the foundation of modern biology: cell theory, evolution, genetics and homeostasis.
Most biological sciences are specialized areas of study. Biology includes biochemistry, cell biology, microbiology, immunology, genetics, physiology, zoology, ecology, evolutionary biology, and botany. Biochemistry is the study of the chemicals that make up life. Cell biology is the study of life at the level of the cell. Microbiology is the study of microscopic organisms. Immunology is the study of an organism's resistance to disease. Genetics is the study of how organisms pass traits to their offspring. The study of how the human body works is called physiology. Zoology is the study of animals. The study of how organisms interact with their environment and each other is called ecology. Evolutionary biology is the study of how populations and species change over time. Botany is the study of plants. The four unifying principles are important foundations for each and every field of biology. Applied fields of biology such as medicine and genetic research involve many specialized areas of study.
What is Life?
Not a
ll scientists agree exactly about what makes up life. Many characteristics describe most living things. However, with most of the characteristics listed below we can think of one or more examples that would seem to break the rule, with something non-living being classified as living or something living classified as non-living.
There is not just one distinguishing feature that separates a living thing from a non-living thing. A cat moves but so does a car. A tree grows bigger, but so does a cloud. A cell has structure, but so does a crystal. Biologists define life by listing characteristics that living things share. Something that has all of the characteristics of life is considered to be alive. The duck decoy in Figure below may look like a duck, act like a duck in that it floats about, but it is not alive. The decoy cannot reproduce offspring, respond to its environment, or breathe.
Figure 1.44
Is it a duck? Both of these objects move across the waters surface. But, how can you tell which one is alive and which is not? You can tell by seeing which of them have all of the characteristics of life.
An individual living creature is called an organism. There are many characteristics that living organisms share. They all:
respond to their environment
grow and change
reproduce and have offspring
have a complex chemistry
maintain homeostasis
are built of structures called cells
pass their traits onto their offspring
Responding to the Environment
If you step on a rock, it will just lie there, but if you step on a turtle, it may move or even snap at you. Living things know what is going on around them, and respond to changes in the environment. An adaptation refers to the process of becoming adjusted to an environment. Adaptations may include structural, physiological, or behavioral traits that improve an organism's likelihood of survival, and thus, reproduction.
Growth and Change
A seed may look like a pebble, but under the right conditions it will sprout and form a seedling that will grow into a larger plant. The pebble of course will not grow.
Reproduction
Living things make more organisms like themselves. Whether the organism is a rabbit, or a tree, or a bacterium, life will create more life.
Have Complex Chemistry
A flower has a complicated and beautiful structure. So does a crystal. But if you look closely at the crystal, you see no change. The flower, on the other hand, is transporting water through its petals, producing pigment molecules, breaking down sugar for energy, and undergoing a large number of other chemical reactions that are needed for living organisms to stay alive. We call the sum of the chemical reactions in a cell its metabolism.
Maintain Homeostasis
A human body has a temperature of 37° Celsius, (about 98.6° Fahrenheit). If you step outside on a cold morning, the temperature might be below freezing. Nevertheless, you do not become an ice cube. Your shiver and move your arms and legs about to stay warm. Eating food also gives your body the energy to keep warm. Living organisms keep their internal environments within a certain range (they maintain a stable internal condition), despite changes in their external environment. This process is called homeostasis.
Built of Cells
If you look closely at any organism you can see that it is made of structures called cells. Organisms that are very different such as ferns, and fish, and elephants all look very similar at the cellular level. All living organisms are made of one or more cells. Organisms are organized in the microscopic level from atoms up to cells. The matter is structured in an ordered way. Atoms are arranged into molecules, then into macromolecules, which make up organelles, which work together to form cells. Beyond this, cells are organized in higher levels to form entire multicellular organisms, as shown in Figure below. Cells together form tissues, which make up organs, which are part of organ systems, which work together to form an entire organism. Of course, beyond this, organisms form populations which make up parts of an ecosystem. All of Earth's ecosystems together form the diverse environment that is Earth.
Figure 1.45
Levels of organization in a tree. (a)The tree is the organism; (b) a leaf is an organ, (c) a leaf tissue is made up of different types of cells; (d) a plant cell; (e) chloroplast is an organelle inside a plant cell; (f) chlorophyll is the photosynthetic molecule that is found in chloroplasts.
Unifying Principles of Biology
There are four unifying principles of biology that are important for types of biology studies. These are:
The Cell Theory
The cell is the basic unit of life. The Cell Theory states that all living things are made of one or more cells, or the secretions of those cells, such as the organisms shown in Figure below. For example, shell and bone are built by cells from substances that they secrete into their surroundings. Cells come from cells that already exist, that is, they do not suddenly appear from nowhere. In organisms that are made of many cells (called multicellular organisms), every cell in the organism's body derives from the single cell that results from a fertilized egg. You will learn more about cells and the Cell Theory in the Cell Structure and Function chapter.
Figure 1.46
Tiny diatoms and whale sharks are all made of cells. Diatoms are about 20 m in diameter and are made up of one cell, whereas whale sharks can measure up to 12 meters in length, and are made up of billions of cells.
Gene Theory
A living organism's traits are encoded in their DNA, the large molecule, or macromolecule, that holds the instructions needed to build cells and organisms. DNA makes up the genes of an organism. Traits are passed on from one generation to the next by way of these genes. Information for how the organism appears and how its cells work come from the organism’s genes. Although the appearance and cell function of the organism may change due to the organism’s environment, the environment does not change its genes. The only way that genes can change in response to a particular environment is through the process of evolution in populations of organisms. You will learn more about DNA and genes in the Molecular Genetics chapter.
Homeostasis
Homeostasis is the ability of an organism to control its body functions in order to uphold a stable internal environment even when its external environment changes. All living organisms perform homeostasis. For example, cells maintain a stable internal acidity (pH); and warm-blooded animals maintain a constant body temperature. You will learn more about homeostasis in The Human Body chapter.
Homeostasis is a term that is also used when talking about the environment. For example, the atmospheric concentration of carbon dioxide on Earth has been regulated by the concentration of plant life on Earth because plants remove more carbon dioxide from the atmosphere during the daylight hours than they emit to the atmosphere at night.
Evolution
Evolution by natural selection, is the theory that maintains that a population's inherited traits change over time, and that all known organisms have a common origin. Evolutionary theory can explain how specialized features, such as the geckos sticky foot pads shown in Figure below, develop in different species. You will learn more about evolution in the Evolutionary Theory and Evolution in Populations chapters.
Figure 1.47
A Tokay Gecko. The pads at the tip of the Tokay gecko's foot are covered in microscopic hairs, each split into hundreds of tips that measure about 200 nanometers in diameter. By using these tiny hairs that can cling to smooth surfaces, the geckos are able to support their entire body weight while climbing walls, definately a product of evolution.
Interdependence of Living Things
Biological interactions are the interactions between different organisms in an environment. In the natural world no organism is cut off from its surroundings. Organisms are a part of their environment which is rich in living and non-living elements that interact with each other in some way. The interactions of an organism with its environment are vital to its survival, and the
functioning of the ecosystem as a whole.
These relationships can be categorized into many different classes. The interactions between two species do not necessarily need to be through direct contact. Due to the connected nature of ecosystems, species may affect each other through such relationships involving shared resources or common enemies.
The term symbiosis comes from a Greek word that means “living together.” Symbiosis can be used to describe various types of close relationships between organisms of different species, such as mutualism and commensalism, which are relationships in which neither organism is harmed. Sometimes the term symbiosis is used only for cases where both organisms benefit, sometimes it is used more generally to describe all kinds of close relationships, even when one organism is killed by another, as shown in Figure below. Symbiosis can also be used to describe relationships where one organism lives on or in another, called parasitism, or when one organism kills and eats another organism, called predation.
Figure 1.48
There are many different types of symbiotic interactions between organisms. Clockwise from top left: bacteria live inside your intestines in a mutualistic relationship; the bacteria produce Vitamin K for you, and they get their food from what you eat. Lions are predators that feed on other organisms such as this Cape buffalo. Similar to the E. , this bee has a mutualistic relationship with the flower, the bee feeds from the flower, and the flower gets pollinated by the bee. Clownfish that live among the tentacles of sea anemones protect the anemone from anemone-eating fish, and in turn the stinging tentacles of the anemone protect the clownfish from its predators (a special mucus on the clownfish protects it from the stinging tentacles).
CK-12 Biology I - Honors Page 8