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BIOLOGY Life on Earth WITH PHYSIOLOGY Tenth Edition Audesirk Audesirk Byers 1 An Introduction to Life on Earth Lecture Presentations by Carol R. Anderson Westwood College, River Oaks Campus © 2014 Pearson Education, Inc. Chapter 1 At a Glance 1.1 What Is Life? 1.2 What Is Evolution? 1.3 How Do Scientists Study Life? 1.4 What Is Science? © 2014 Pearson Education, Inc. 1.1 What Is Life? Biology comes from the Greek words “bio” meaning “life” and “logy” meaning “the study of.” Organisms share common characteristics that, taken together, define life. Organisms: Acquire and use materials and energy Actively maintain organized complexity Perceive and respond to stimuli Grow Reproduce Have the capacity to evolve, collectively © 2014 Pearson Education, Inc. 1.1 What Is Life? The cell is the basic unit of life – It is separated from its surroundings by a membrane – It encloses a variety of structures and chemicals in a fluid environment © 2014 Pearson Education, Inc. Figure 1-1 The cell is the smallest unit of life nucleus cell wall plasma membrane organelles © 2014 Pearson Education, Inc. 1.1 What Is Life? Organisms acquire and use materials and energy – Materials and energy are required for organisms to maintain organization, to grow, and to reproduce – Important materials (minerals, water, & other simple chemical building blocks) are acquired from the air, water, soil, and bodies of other living things – Organisms use energy continuously to sustain themselves © 2014 Pearson Education, Inc. Figure 1-2 Properties of life Antennae and eyes: living things respond to stimuli Gut: living things acquire nutrients Eggs: living things reproduce © 2014 Pearson Education, Inc. 1.1 What Is Life? Organisms acquire and use materials and energy (continued) – Organisms obtain energy in two ways, coming directly or indirectly from the sun – Photosynthesis is the process by which plants and some single-celled organisms capture sunlight – Other organisms consume energy-rich molecules in the bodies of other organisms © 2014 Pearson Education, Inc. Figure 1-3 The flow of energy and the recycling of nutrients © 2014 Pearson Education, Inc. 1.1 What Is Life? Organisms actively maintain organized complexity – Living things use energy on a continuous basis to self-sustain – Cells pump chemicals in and out for appropriate chemical reactions to occur – Organisms maintain relatively constant internal conditions or homeostasis © 2014 Pearson Education, Inc. Figure 1-4 Organisms maintain relatively constant internal conditions © 2014 Pearson Education, Inc. 1.1 What Is Life? Organisms perceive and respond to stimuli – Organisms sense and respond to internal and external environmental stimuli – Sensory organs in animals can detect and respond to external stimuli such as light, sound, chemicals, etc. – Internal stimuli in animals are perceived by stretch, temperature, pain, and chemical receptors – Plants and bacteria respond to stimuli as well (e.g., plants grow toward the light, and bacteria move toward available nutrients in a medium) © 2014 Pearson Education, Inc. 1.1 What Is Life? Organisms grow – Every organism becomes larger over time – Plants, birds, and mammals grow by producing more cells to increase their mass – Bacteria grow by enlarging their cells; they divide in half to reproduce after genetic material is copied – Growth involves the conversion of acquired materials to molecules of the organism’s body © 2014 Pearson Education, Inc. 1.1 What Is Life? Organisms reproduce – Organisms reproduce by dividing in half, producing seeds, bearing live young, and laying eggs – Organisms give rise to offspring of the same type – The parent’s genetic material (DNA) is passed on to the offspring, creating continuity of life © 2014 Pearson Education, Inc. Figure 1-6 Organisms reproduce Dividing Streptococcus bacterium © 2014 Pearson Education, Inc. Dandelion producing seeds Panda with its baby Figure 1-7 DNA © 2014 Pearson Education, Inc. 1.1 What Is Life? Organisms, collectively, have the capacity to evolve – Evolution is the process by which modern organisms descended, with modifications, from preexisting forms of life – Changes in DNA within populations occur over the course of generations, which results in evolution – Populations are groups of the same type of organism living in the same area © 2014 Pearson Education, Inc. 1.2 What Is Evolution? Evolution explains the diversity of life on Earth Evolution provides an explanation for the similarities found among different types of organisms – Chimpanzees and people have various physical features in common – DNA of humans differs from that of chimpanzees by less than 5% © 2014 Pearson Education, Inc. Figure 1-8 Chimps and people are closely related © 2014 Pearson Education, Inc. 1.2 What Is Evolution? Three natural processes underlie evolution – Genetic variation among members of a population due to differences in their DNA – Inheritance of those variations by offspring of parents carrying the variation – Natural selection of individuals whose survival and enhanced reproduction are due to the favorable variations they carry © 2014 Pearson Education, Inc. 1.2 What Is Evolution? Mutations are the original source of differences in DNA – Variations are due to the differences in genes, which are components of DNA and the basic units of heredity – Mutations occur when changes in genes are mistakenly copied – Mutations can also result from DNA damaged by – UV rays from sunlight and toxic chemicals from cigarette smoke © 2014 Pearson Education, Inc. 1.2 What Is Evolution? Some mutations are inherited – Occur in sperm or egg cells – Effects of mutation – No effect (harmless) – A decrease in the organism’s ability to function – Death of the organism – An increase in an organism’s ability to survive and reproduce (rare) © 2014 Pearson Education, Inc. 1.2 What Is Evolution? Some inherited mutations help individuals survive and reproduce – Natural selection is the process by which organisms with certain inherited traits survive and reproduce better than others in a particular environment – Organisms that best meet environmental challenges leave the most offspring – Natural selection preserves genes that help organisms flourish © 2014 Pearson Education, Inc. 1.2 What Is Evolution? Some inherited mutations help individuals survive and reproduce (continued) – Adaptations are structures, physiological processes, or behaviors that aid in survival and reproduction – Adaptations that are good for one environment may be poor in another – Species that cannot adapt to environmental change become extinct, as for example, the dinosaurs – Extinction is the complete elimination of a particular species © 2014 Pearson Education, Inc. Figure 1-9 A fossil Tyrannosaurus rex © 2014 Pearson Education, Inc. 1.2 What Is Evolution? Some inherited mutations help individuals survive and reproduce (continued) – The many different habitats (environments) in an area coupled with evolutionary adaptive processes produce species variety, or biodiversity – Humans are responsible for accelerating the rate of environmental change (and therefore, the rate of extinction of species) © 2014 Pearson Education, Inc. 1.2 What Is Evolution? Some inherited mutations help individuals survive and reproduce (continued) – “Nothing in biology makes sense except in the light of evolution” Dobzhansky – Darwin and Wallace formulated the basis of our modern understanding of evolution when they devised the theory of evolution in the mid-1800s – Abundant evidence has been found to support evolutionary theory since the 1800s © 2014 Pearson Education, Inc. Levels of biological organization © 2014 Pearson Education, Inc. Fig. 1-10 1.3 How Do Scientists Study Life? Life can be studied at different levels – All matter is formed of elements – An atom is the smallest particle of an element retaining the properties of an element – Atoms combine to form molecules – Molecules provide the building blocks for cells, the smallest unit of life © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Life can be studied at different levels (continued) – Some forms of life consist of single cells – In multicellular forms, cells combine to form tissues – Tissues combine to form organs, which can be united as organ systems – Multicellular organisms are composed of multiple organ systems © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Life can be studied at different levels (continued) – Organisms of the same type that are capable of interacting and interbreeding are called a species – A group of organisms of the same species living in a given area is a population – Interacting populations make up a community – A community and its nonliving environment is an ecosystem – The entire surface of Earth, including living and nonliving components, is the biosphere © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Biologists classify organisms based on their evolutionary relationships – Scientists generally categorize organisms into three major groups, or domains – Bacteria – Archaea – Eukarya – The fundamental differences among cell types in organisms are reflected in classifications © 2014 Pearson Education, Inc. Figure 1-11 The domains and kingdoms of life DOMAIN BACTERIA DOMAIN ARCHAEA FIRST CELLS Plants Fungi Animals © 2014 Pearson Education, Inc. DOMAIN EUKARYA Protists 1.3 How Do Scientists Study Life? Biologists classify organisms based on their evolutionary relationships (continued) – Bacteria and Archaea are single, simple cells – Eukaryotic organisms have one or more extremely complex cells – The domain Eukarya contains four subdivisions or kingdoms – Fungi – Plantae – Animalia – Protists © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Biologists classify organisms based on their evolutionary relationships (continued) – Three characteristics underlie the classification of an organism into a domain and kingdom – There are exceptions to any simple set of rules used to distinguish the domains and kingdoms, but three characteristics are particularly useful – Cell type—simple or complex – The number of cells in each organism—unicellular or multicellular – Energy acquisition © 2014 Pearson Education, Inc. Table 1-1 © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Cell type distinguishes the Bacteria and Archaea from the Eukarya – All cells share common features – Plasma membrane is a thin sheet of molecules surrounding the cell – Organelles are specialized structures that carry out specific functions – All cells contain DNA, the hereditary material © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Cell type distinguishes the Bacteria and Archaea from the Eukarya (continued) – The domains Bacteria and Archaea consist of prokaryotic cells – The domain Eukarya is composed of eukaryotic cells © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Cell type distinguishes the Bacteria and Archaea from the Eukarya (continued) – Two cell types are seen among all living things: prokaryotic and eukaryotic cells – Cell types are named after presence or absence of a nucleus – The nucleus is a membrane-enclosed sac containing the cell’s genetic material © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Cell type distinguishes the Bacteria and Archaea from the Eukarya (continued) – Eukaryotic (“true nucleus” in Greek) – They are larger than prokaryotic cells – They contain a variety of organelles, including a nucleus – This cell type is found only among members of the domain Eukarya – They are extremely complex © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Cell type distinguishes the Bacteria and Archaea from the Eukarya (continued) – Prokaryotic (“before nucleus” in Greek) – They are only 1–2 micrometers in diameter – They lack organelles enclosed by membranes – They lack a nucleus – This cell type is found in the domains Bacteria and Archaea – They are smaller and much simpler than the eukaryotic cell © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Multicellularity occurs only among the Eukarya – Unicellular (single-celled) organisms are found in – Bacteria – Archaea – Multicellular (many-celled) organisms are found in Eukarya, within the kingdoms – Fungi – Plantae – Animalia © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? The Eukarya acquire energy in different ways – Autotrophs (“self-feeding”) – Photosynthetic organisms that capture sunlight and store it in sugar and fats – Includes plants, some bacteria, and some protists – Heterotrophs (“other-feeding”) – Organisms that acquire energy through ingesting molecules in the bodies of other organisms – Includes many archaeans, bacteria, protists, fungi, and animals – The size of the food eaten varies from individual food molecules to ingestion and digestion of whole chunks © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Biologists use the binomial system to name organisms – Organisms are placed in a hierarchy of categories – Genus and species are the two smallest categories – Genus includes many different species with similar characteristics – Species includes organisms that can interbreed and are nearly identical © 2014 Pearson Education, Inc. 1.3 How Do Scientists Study Life? Biologists use the binomial system to name organisms (continued) – Binomial system based on Latin words two (bi) and names (nomial), and consisting of the genus and species – Genus name is capitalized – Both genus and species names are italicized – People are Homo sapiens © 2014 Pearson Education, Inc. 1.4 What Is Science? Science is the systematic inquiry – through observation and experiment – into the origins, structure, and behavior of living and nonliving environments © 2014 Pearson Education, Inc. 1.4 What Is Science? Science is based on the principle that all events have natural causes – The belief that some events happen through supernatural forces (e.g., the actions of Greek gods) – The belief that all events can be traced to natural causes that we can comprehend (natural causality) – Corollary: Evidence gathered from nature has not been deliberately distorted to fool us © 2014 Pearson Education, Inc. 1.4 What Is Science? The scientific method is an important tool of scientific inquiry – The scientific method consists of six interrelated elements – Observation – Question – Hypothesis – Prediction – Experiment – Conclusion © 2014 Pearson Education, Inc. 1.4 What Is Science? The scientific method is an important tool of scientific inquiry (continued) – Scientific inquiry is a rigorous method for making observations – The scientific method for inquiry follows six steps © 2014 Pearson Education, Inc. 1.4 What Is Science? The six steps of scientific inquiry 1. Observation of a specific phenomenon 2. The observation, in turn, leads to a question 3. The question leads to formulation of a hypothesis, based on previous observations, which is offered as an answer to the question © 2014 Pearson Education, Inc. 1.4 What Is Science? The six steps of scientific inquiry (continued) 4. The hypothesis leads to a prediction, which is the expected outcome of testing if the hypothesis is correct 5. The prediction is tested by carefully designed additional observations or carefully controlled manipulations called experiments 6. The experiments produce results that either support or refute the hypothesis, allowing the development of a conclusion © 2014 Pearson Education, Inc. 1.4 What Is Science? Biologists test hypotheses using controlled experiments – Two types of situations are established – A baseline or control situation in which all possible variables are held at a constant – An experimental situation in which one factor, variable, is manipulated to test the hypothesis to determine that this variable is the cause of an observation – Science is useless unless communicated – The scientific method is illustrated by experiments by Francesco Redi and Malte Andersson © 2014 Pearson Education, Inc. Figure E1-1 The experiment of Francesco Redi illustrates the scientific method Observation: Flies swarm around meat left in the open; maggots appear on the meat. Question: Where do maggots on the meat come from? Hypothesis: Flies produce the maggots. Prediction: IF the hypothesis is correct, THEN keeping the flies away from the meat will prevent the appearance of maggots. Experiment: Obtain identical pieces of meat and two identical jars Place meat in each jar Leave the jar uncovered gauze prevents the entry of flies Leave exposed for several days Controlled variables: Flies swarm around and maggots appear Results Control situation Conclusion: © 2014 Pearson Education, Inc. Experimental variable: time, temperature, place Cover the jar with gauze Leave covered for several days Flies are kept from the meat; no maggots appear Experimental situation The experiment supports the hypothesis that flies are the source of maggots and that spontaneous generation of maggots does not occur. Figure E1-2 The experiment of Malte Andersson Observation: Male widowbirds have extremely long tails. Question: Why do males, but not females, have such long tails? Hypothesis: Males have long tails because females prefer to mate with long-tailed males. Prediction: IF females prefer long-tailed males, THEN males with artificially lengthened tails will attract more mates. Experiment: Divide male birds into four groups Manipulate the tails of the males Do not change the tail Cut the tail and re-glue in place Experimental variable: Cut the tail to half of the original length Add feathers to double the tail length Release the males, wait a week, count the nests Release the males, wait a week, count the nests Average of less than half a nest per male Average of About two nests per male length of tail Release the males, wait a week, count the nests Release the males, wait a week, count the nests Average of about one nest per male Average of about one nest per male Control groups Conclusion: © 2014 Pearson Education, Inc. Controlled variables: location, season, time, weather Results Experimental groups The hypothesis that female widowbirds prefer to mate with long-tailed males (and are less likely to mate with short-tailed males) is supported. 1.4 What Is Science? Scientific theories have been thoroughly tested – A scientific theory is a general and reliable explanation of important natural phenomena that has been developed through extensive and reproducible observations and experiments – A scientific theory is best described as a natural law, a basic principle derived from the study of nature, which has never been disproven by scientific inquiry © 2014 Pearson Education, Inc. 1.4 What Is Science? Scientific theories have been thoroughly tested (continued) – The cell theory (that all living organisms are composed of cells) and the theory of evolution are fundamental to the study of biology – Natural causality is the principle that all events can be traced to natural causes – Natural laws apply to every time and place – Scientific inquiry is based on the assumption that people perceive natural events in similar ways © 2014 Pearson Education, Inc. 1.4 What Is Science? Scientific theories have been thoroughly tested (continued) – New scientific evidence may prompt radical revision of existing theory – For example, the discovery of prions © 2014 Pearson Education, Inc. 1.4 What Is Science? Scientific theories have been thoroughly tested (continued) – Before 1980, all known infectious diseases contained DNA or RNA – In 1982, Stanley Prusiner showed that the infectious sheep disease scrapie is caused by a protein (a “protein infectious particle,” or prion) – Prions have since been shown to cause “mad cow disease” and diseases in humans – The willingness of scientists to revise accepted belief in light of new data was critical to understanding and expanding the study of prions © 2014 Pearson Education, Inc. 1.4 What Is Science? Scientific theories involve both inductive and deductive reasoning – Inductive reasoning is used in the development of scientific theories – A generalization is created from many observations that support it and none that contradict it – For example, the theory that Earth exerts gravitational forces on objects began from repeated observations of objects falling downward toward Earth and from no observations of objects falling upward away from Earth © 2014 Pearson Education, Inc. 1.4 What Is Science? Scientific theories involve both inductive and deductive reasoning (continued) – Deductive reasoning is the process of generating hypotheses based on a well-supported generalization (such as a theory) – For example, based on the cell theory, any newly discovered organism would be expected to be composed of cells © 2014 Pearson Education, Inc. 1.4 What Is Science? Scientific theories are formulated in ways that can potentially be disproved – Basic principles of science are referred to as theories because theories can be disproved or falsified – Falsifying theories is distinctly different between scientific theories and faith-based beliefs – “Each creature on Earth was separately created” cannot be subjected to scientific inquiry because it is a belief rooted in faith © 2014 Pearson Education, Inc. 1.4 What Is Science? Science is a human endeavor – Human personality traits are part of “real science” – Scientists, like other people, may be driven by pride, ambition, or fear – Scientists sometimes make mistakes – Accidents, lucky guesses, intellectual powers, and controversies with others contribute strongly to scientific advances © 2014 Pearson Education, Inc. 1.4 What Is Science? Science is a human endeavor (continued) – In the 1920s, bacteriologist Alexander Fleming grew bacteria in cultures – One of the bacterial cultures became contaminated with a mold – Fleming was about to destroy the culture when he noticed the mold (Penicillium) inhibited bacterial growth in the culture © 2014 Pearson Education, Inc. 1.4 What Is Science? Science is a human endeavor (continued) – Fleming hypothesized that the mold produced an antibacterial substance – Further tests using broth from pure Penicillium cultures lead to the discovery of the first antibiotic, penicillin © 2014 Pearson Education, Inc. Figure 1-12 Penicillin kills bacteria A Petri dish contains solid growth medium Bacteria grow in dense red colonies on the growth medium A substance diffuses from the mold and kills the bacterial colonies, which lose their color as they die A colony of the mold Penicillium © 2014 Pearson Education, Inc. 1.4 What Is Science? Science is a human endeavor (continued) – Fleming continued beyond a lucky “accident” with further scientific investigation to a great discovery – “Chance favors the prepared mind” Louis Pasteur © 2014 Pearson Education, Inc. 1.4 What Is Science? Knowledge of biology illuminates life – Science is NOT a dehumanizing activity © 2014 Pearson Education, Inc. Figure 1-13 Adaptations in lupine flowers Pollen is forced onto the bee’s abdomen © 2014 Pearson Education, Inc.