Chapter 1 The science of Life Section 1 – the world of biology Section 2 – themes in biology Section 3 – the study of biology

Section 1 – the world of biology objectives Relate the relevance of biology to a person’s daily life. Describe the importance of biology in human society. List the characteristics of living things. Summarize the hierarchy of organization within complex multicellular organisms. Distinguish between homeostasis and metabolism and between growth, development, and reproduction.

Biology and you Biology is the study of life How living things work How they Interact with the environment How they change over time Biologists study many different types of living things.

Biology and You Microorganisms – Microbiology Insects – Entomology Bacteria – bacteriology Fungi – mycology Viruses – virology Insects – Entomology Plants - Botany Birds – Ornithology Fish – Ichthyology Amphibians and reptiles – Herpetology Cancer – Oncology Cells and Tissues – Histology Diseases and Human Health – Epidemiology

Biology and You Biologists of various types spend their lives trying to better understand the living world. Biologists work hard to solve problems that society feels are important Cure for Cancer Sustainable farming Cleaning up pollution Better treatments for diseases Vaccines and pharmaceuticals The better you understand the world around you the better you can direct scientists’ research. You will help determine what important topics get funding. (by electing government officials)

Characteristics of Life When is something considered alive? What are the characteristics necessary for life?

Characteristics of Life Organization and the presence of one or more cells Response to stimulus Homeostasis Metabolism Growth and development Reproduction Change through time

Organization and cells Organization is the high degree of order within an organism’s internal and external parts. Also its interactions with the living world Compare an Owl and a Rock

Organization and cells All living things are made up of one or more cells A cell is the smallest unit that can perform all life’s processes Unicellular – made up of one cell Multicellular – made up of multiple cells Who remembers the hierarchy of Cellular Organization?

Hierarchy of organization

Response to Stimuli Stimulus is a physical or chemical change in the internal or external environment. Examples: What happens when you get cold? What happens when you walk into a dark area after being in the sun? Organisms must be able to respond and react to changes in their environment in order to stay alive.

Homeostasis Homeostasis is the maintenance of a stable level of internal conditions even though environmental conditions are constantly changing. Maintaining a state of balance Organisms have systems that help to regulate temperature, water content, and uptake of nutrients by the cells. Multicellular organisms usually have more than one way to maintain these conditions. Burning cellular energy for heat or fluffing of feathers or fur to remain warm when the external conditions are cold.

Metabolisms Metabolism is the sum of all the chemical reactions that take in and transform energy and material from the environment. Photosynthesis Eating food

Growth and Development All living things grow and increase in size. Crystals or icicles grow by accumulating more of the same material Growth of living things results from the division and enlargement of cells Cell division is the formation of two new cells from an existing cell Unicellular organisms typically grow after division Multicellular organisms mature through cell division, cell enlargement, and development

Growth and Development Development is the process by which an organism becomes a mature adult. Involves cell division and cell differentiation, or specialization Adults organisms are composed of many cells specialized for different functions

Reproduction Reproduction is the process by which organisms produce new organisms like themselves. Reproduction is not essential for the survival of an individual organism. However, it is necessary for the survival of a species as a whole During reproduction, organisms transmit hereditary information to their offspring. This information is encoded on DNA. DNA carries genes

Reproduction Sexual Reproduction – hereditary information recombines from two organisms of the same species. Resulting in offspring that are similar but not identical to their parents. Plants and animals Asexual Reproduction – hereditary information from different organisms is not combined Resulting in the offspring being genetically identical to the parent Bacteria – binary fission Hydras and sponges – Budding Planarians- Fragmentation

Asexual Reproduction

Change Through Time The ability of a population of organisms to change over time is important to for the survival in a changing world The ability to Evolve – Change physically and Genetically over time

Section 2 – Themes in biology objectives Identify three important themes that help explain the living world. Explain how life can be diverse, yet unified. Describe how living organisms are interdependent. Summarize why evolution is an important these in biology.

Diversity and Unity of Life Diversity, or variety, of life is amazing. Scientists have identified 1.5 million species on earth.

Unity in the Diversity of Life Even with the vast diversity living things are characterized by unity Genetic code Presence of organelles that carry out all cellular functions Share certain genes, but not all. The “tree of life” shows how organisms are similar and different

Three Domains of Life Three Main Branches, or domains, on the “Tree” Bacteria Archaea Eukarya Under these three domains are 6 kingdoms Bacteria or Eubacteria Animalia Fungi Plantae Protista

Interdependence of Organisms Organisms interact with each other and their environment. Ecology studies organisms and how they interact with each other and their environment. It can be very complicated and understanding every detail of these interactions is difficult

Evolution and Life Individual organisms change during their lifetime, but their basic genetic characteristics do not change. However, population of living organisms do change through time, or evolve. Evolution, or descent with modification, is the process by which the inherited characteristics within populations change over generations, sometimes giving rise to new species. Evolution helps us to understand how the various branches of the “tree of Life” came into existence and have changed over time.

Natural Selection Natural selection is one of the mechanisms of evolution. Survival of the fittest. Those organisms with the best traits will survive, breed, and pass those traits on to the next generation. We will spend more time on evolution and natural selection in later chapters.

Section 3 – The study of biology objectives Outline the main steps in the scientific method. Summarize how observations are used to form hypotheses. List the elements of a controlled experiment. Describe how scientist use data to draw conclusions. Compare a scientific hypothesis and a scientific theory. State how communication in science helps prevent dishonesty and bias.

Science as a process The scientific method is an organized approach to solve or answer scientific questions. Helps us to learn how the natural world works. Who remembers the steps of the scientific Method?

Steps in the Scientific Method Observation – observe something that causes you to question. Hypothesis – educated guess Prediction – what may happen Experiment – step wise instructions Analysis – analyze your data Conclusion – summarize and restate

Observation In order to use the scientific method you must observe something that is testable. Owls can catch prey in total darkness. How?

Forming a Hypothesis Before you can form your hypothesis you must do some research. What has been done on this topic. This helps you to develop your hypothesis Should be in an “If...Then” statement and can contain a prediction about what may occur. If Owls use hearing to catch prey at night, then in a lighted room, the owl will pounce closer to the mouse’s head. But, in a dark room, the owl will pounce closer to a rustling leaf attached to the mouse.

Designing an Experiment The experiment must be well organized and contain all necessary information for the experiment to be repeated. It must also contain an experimental and a control group The experimental group is the group you are testing your hypothesis on. The control group is the normal standard against which the biologist can compare results. The experimental group has the independent variable, the variable that is manipulated by the experimenter. Presence or absence of light. The dependent variable is the outcome or response. Where the owl strikes

Blind Study Is a study that is done where the identity of the control and the experimental group is kept hidden. This helps to eliminate bias. Double Blind Drug trials

Collecting and Analyzing Data Data should be kept neat and organized. Charts and graphs should be used to convey the information

Drawing Conclusions Hypotheses are supported or not supported, they are not Proven. The conclusion should summarize the experiment and its main points. It will state areas of possible error, or future studies.

Hypothesis vs Theory A hypothesis may be supported, but it does not mean that it is true. A hypothesis should be repeatable. Scientists should get the same or similar results to further support the hypothesis. When a hypothesis has been supported by many experiments it can become a theory. Theories are not written in stone. As new research and tools become available theories can be modified.

Communication of Ideas It is important that scientists share their results. It helps to verify their work and leads to new areas of research. We would not have the scientific advances we have today if scientists did not share their results. Scientists will publish their results in Peer reviewed journals. (primary Journals) These are journals that other scientists in their field will read their research to ensure it is done in a scientifically sound manner.

Honesty and bias Honesty is essential in science. Falsifying results could mean death for an individual. Repeating another’s experiment helps to prevent this. Conflicts of interest are important to avoid. A scientist who owns a biotech company may not be the best to perform the experiments to Ensure its safety.