Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 1 Biology and You

Biology is the study of life. All living organisms share certain general properties that separate them from nonliving things. Section 1: Themes of Biology

Characteristics of Living Organisms 1.Cellular organization - all living things composed of cells organelles, cell, tissue, organs, organ systems, organism 2. Reproduction 3. Metabolism 4. Homeostasis 5. Heredity 6. Responsiveness - respond to stimuli 7. Growth and development – grow (get bigger) & develop (change chemically Ex: adolescent to adult)

Biology & Natural Science

Unifying Themes of Biology 1. Cellular Structure and Function  Cells are highly organized, tiny structures with thin coverings called membranes.  All living things are made of one or more cells.  A cell is the smallest unit capable of all life functions.

2. Reproduction  Reproduction is the process by which organisms make more of their own kind.  This may be a sexual or asexual process

3. Metabolism  Metabolism is the sum of all the chemical reactions carried out in an organism.  Almost all energy used by living organisms comes from sunlight.

4. Homeostasis  Homeostasis is the maintenance of stable internal conditions  Illness occurs when internal conditions are compromised

5. Heredity  Heredity is the passing of traits from parent to offspring.  The basic unit of heredity is called a gene.  Genes are coded in a molecule called deoxyribonucleic acid (DNA).  Genes determine an organism’s traits.  A change in the DNA of a gene is called a mutation. Most mutations are harmful, but sometimes they may lead to a useful adaptation.

Heredity

6. Evolution  Evolution is change in the inherited characteristics of species over generations.  A species is a group of genetically similar organisms that can produce fertile offspring.  Natural selection is the process in which organisms with favorable traits are more likely to survive and reproduce.

Evolution

7. Interdependence  Ecology is the branch of biology that studies the interactions of organisms with one another and with the nonliving part of their environment.  Organisms are dependent on each other and on their environment.

Unifying Themes of Biology

Section 2 : Solving Real-World Problems Biologists are working to solve today’s problems, such as: Preserving our environment Conservation biologists must find ways to balance the growing need for land and the need to preserve the environment.

2. Improving the food supply  Genetic engineering of crop plants has made some plants resistant to herbicides, or poisonous to insect pests, or more nutritious.

3. Being Ready for Climate and Environmental Change

4. Understanding the human genome  A genome is the complete set of genetic information contained in an individual. Government-funded and private research teams from several countries completed sequencing of the human genome.

5. Fighting Disease A. AIDS is a fatal disease caused by HIV (human immunodeficiency virus), a virus that attacks and destroys the human immune system.  New vaccines are being tested that attack two or more parts of the HIV virus at the same time to compensate for the virus’s rapid mutation  Scientist are more hopeful for a vaccine to combat this world-wide epidemic

B. Cancer is a breakdown of the mechanism that controls cell division.  Several forms of cancer result from having too many copies of a certain protein.  Anticancer drugs that stick to these extra cell proteins appear to offer great promise.

C. Emerging diseases  Biologists are fighting new diseases not known in the past.  Some of these diseases include West Nile virus and mad cow disease.

D. Inherited disorders  Gene Therapy is the replacement of a defective gene with a normal one. Researchers believe it is possible to use a virus to transfer a normal copy of a gene into a cell.  Researchers hoped to cure cystic fibrosis, a hereditary disease in which a thick sticky mucus clogs the body’s breathing passages by using viruses

Cystic Fibrosis

Section 3: Scientific Processes Observation is the act of noting or perceiving objects or events using the senses & is the basis of sci research  Scientific investigations begin with observations.  Observations cause scientists to ask questions about their observations.

Stages of Scientific Investigations  The stages of sci investigations are called the Scientific Method (as follows) 1. Collecting observations 2. Asking questions (problem) 3. Forming hypotheses and making predictions 4. Confirming predictions (with experiments when needed) 5. Drawing conclusions

Hypothesis vs. Prediciton  Hypothesis— an explanation that might be true, a statement that can be tested by additional observations or experimentation. If… then…  Prediction—t he expected outcome of a test, assuming the hypothesis is correct. I predict that ___ will be the best.

Parts of an Experiment  Experiment— a planned procedure to test a hypothesis.  Control group— a group in an experiment that receives no experimental treatment. The control group is necessary for comparing the results of the experiment.  Experimental groups- All groups receiving the “treatment”

 Independent variable— the factor that is changed in an experiment. (the Cause)  Dependent variable— the variable that is measured in an experiment, the outcome of the dependent variable depends on what is done to the independent variable. (the effect)  Constants - anything that remains the same for both the experimental and control groups

Drawing Conclusions Once data are collected and analyzed, a conclusion is made as to whether the data support the hypothesis.

Viewing Conclusions in Context  There is often more than one possible reason for a result.  All of the factors that may affect an outcome must be considered.

Constructing a Theory Theory: set of related hypotheses that have been tested and confirmed many times by many scientists.  A theory unites and explains a broad range of observations.  The word theory is used by the general public to mean a guess, or lack of certainty.  In science, a theory is a well- supported scientific explanation that makes useful predictions.

Constructing a Theory Scientists report their results in journals.  Scientific reports are reviewed by other scientists & the info can be used or retested