Introduction: Themes in the Study of Life Chapter 1 Introduction: Themes in the Study of Life Copyright © 2011 Pearson Education, Inc.

KEY CONCEPTS Connections Across Different Areas of Biology CORE THEME – Evolution important for unity and diversity of life Studying Nature by Observations – Scientists’ Life Co-operative Approach and Diverse Viewpoints Important for Sciences

Overview: Inquiring About Life An organism’s adaptations to its environment are the result of evolution For example, the ghost plant is adapted to conserving water; this helps it to survive in the crevices of rock walls Evolution is the process of change that has transformed life on Earth

Biology is the scientific study of life Biologists ask questions such as How does a single cell develop into an organism? How does the human mind work? How do living things interact in communities? Life defies a simple, one-sentence definition Life is recognized by what living things do Click to add notes

Which of the following properties or processes do we associate with living things? a) evolutionary adaptations b) energy processing c) responding to the environment d) growth and reproduction e) all of the above Answer: e

Properties of Life Figure 1.3 Some properties of life. Order Response to the environment Evolutionary adaptation Reproduction Figure 1.3 Some properties of life. Regulation Energy processing Growth and development

What is the lowest level of biological organization that can perform all the activities required for life? a) organelle—for example, a chloroplast b) cell—for example, a skin cell c) tissue—for example, nervous tissue d) organ system—for example, the reproductive system e) organism—for example, an amoeba, dog, human, or maple tree Answer: b

New Properties in Biological Hierarchy The biosphere Tissues Ecosystems Organs and organ systems Communities Cells Organelles Organisms Atoms Molecules Populations New Properties in Biological Hierarchy

Emergent Properties Emergent properties result from the arrangement and interaction of parts within a system Emergent properties characterize nonbiological entities as well For example, a functioning bicycle emerges only when all of the necessary parts connect in the correct way

Which of the following scientific studies would represent an example of a “systems biology” approach? measuring the effect of an invading insect that eats oak leaves on the numbers of oak trees and on any subsequent changes in the number and types of decomposer fungi in the soil discovering the structure of an enzyme that is important in digestion of protein comparing the microscopic structure of leaves of two different species of magnolias measuring the reproductive rate of emperor penguins during exceptionally warm and exceptionally cold years comparing the DNA sequence of two closely related plants and inferring their evolutionary histories Answer: a In the past, most research has been conducted on one or two levels of complexity (e.g., cells or population levels). Recently, however, scientists or teams of scientists have been studying how processes at one level affect processes at other scales. This question is designed to help students see connections among levels. Answers c-e address scientific questions at only one level: c is a study at the tissue level, d is a study at the population level, and e is a study at the molecular level). Answer b is likely a study simply at the molecular level, but a student might argue that it addresses two levels—molecular and cellular. It could certainly be expanded to a systems study if the scientists also studied molecular forces and folding of the protein chain. Answer a is likely the best answer because the two-species interaction between the invading insect and the oak (community level) affects the abundance of oak trees (population level) and the process of decomposition (ecosystem level). A possible extension of this question would be to ask students to broaden all the answers into systems biology studies.

Systems Biology A system is a combination of components that function together Systems biology constructs models for the dynamic behavior of whole biological systems The systems approach poses questions such as How does a drug for blood pressure affect other organs? How does increasing CO2 alter the biosphere?

Energy Transfer Like jackrabbits, elephants have many blood vessels in their ears that help them cool their bodies by radiating heat. Which of the following statements about this radiated energy would be accurate? The original source of the energy was the sun. The energy will be recycled through the ecosystem. The radiated energy will be trapped by predators of the elephants. More energy is radiated in cold conditions than in hot conditions. More energy is radiated at night than during the day. Answer: a Energy is a concept that is essential for all students to understand. This question will help students understand a number of ideas about energy. Answer a is the correct answer and students should understand that the energy from the sun powers all living systems (except deep ocean vent communities). Energy is lost to the system as heat, whereas atoms can be used over and over again; thus, answer b is incorrect. Answer c is related to answer b and is incorrect because the heat that is radiated from the ears is not available to other organisms—only the energy stored in the tissues of the jackrabbit is available to the predator. Answers d and e are incorrect for similar reasons—that more heat is radiated when the jackrabbit is warmer (either in hot conditions or during the day).

Cycling of chemical nutrients Sunlight Leaves absorb light energy from the sun. Leaves take in carbon dioxide from the air and release oxygen. CO2 O2 Cycling of chemical nutrients Animals eat leaves and fruit from the tree. Leaves fall to the ground and are decomposed by organisms that return minerals to the soil. Figure 1.5 Interactions of an African acacia tree with other organisms and the physical environment. Water and minerals in the soil are taken up by the tree through its roots.

Theme: Life Requires Energy Transfer and Transformation A fundamental characteristic of living organisms is their use of energy to carry out life’s activities Work, including moving, growing, and reproducing, requires a source of energy Living organisms transform energy from one form to another For example, light energy is converted to chemical energy, then kinetic energy Energy flows through an ecosystem, usually entering as light and exiting as heat

(a) Energy flow from sunlight to producers to consumers Heat When energy is used to do work, some energy is converted to thermal energy, which is lost as heat. Producers absorb light energy and transform it into chemical energy. An animal’s muscle cells convert chemical energy from food to kinetic energy, the energy of motion. Chemical energy A plant’s cells use chemical energy to do work such as growing new leaves. Chemical energy in food is transferred from plants to consumers. (a) Energy flow from sunlight to producers to consumers Figure 1.6 Energy flow in an ecosystem. (b) Using energy to do work

Theme: Structure and Function Are Correlated at All Levels of Biological Organization Structure and function of living organisms are closely related For example, a leaf is thin and flat, maximizing the capture of light by chloroplasts For example, the structure of a bird’s wing is adapted to flight

Theme: The Cell Is an Organism’s Basic Unit of Structure and Function The cell is the lowest level of organization that can perform all activities required for life All cells Are enclosed by a membrane Use DNA as their genetic information

The idea that form and function are related would not be exemplified by which of the following examples? Cells in the intestinal lining of vertebrates have many small projections that increase the surface area for absorption of nutrients. Plants that live in dry areas have large roots for absorbing water. Seeds that are dispersed by wind are very light. Fish that swim rapidly have bodies that are streamlined. None of the above. Answer: e The relationship between form and function is very important and results from the action of natural selection. In this question, all answers show a relationship between form and function and therefore none of them connect correctly to the stem.

A eukaryotic cell has membrane-enclosed organelles, the largest of which is usually the nucleus By comparison, a prokaryotic cell is simpler and usually smaller, and does not contain a nucleus or other membrane-enclosed organelles Prokaryotic cell DNA (no nucleus) Membrane 1 m

Nucleus (membrane- enclosed) Figure 1.8 Prokaryotic cell Eukaryotic cell DNA (no nucleus) Membrane Membrane Cytoplasm Figure 1.8 Contrasting eukaryotic and prokaryotic cells in size and complexity. Nucleus (membrane- enclosed) Membrane- enclosed organelles DNA (throughout nucleus) 1 m

Theme: The Continuity of Life Is Based on Heritable Information in the Form of DNA Chromosomes contain most of a cell’s genetic material in the form of DNA (deoxyribonucleic acid) DNA is the substance of genes Genes are the units of inheritance that transmit information from parents to offspring The ability of cells to divide is the basis of all reproduction, growth, and repair of multicellular organisms

DNA bears the blueprint of life Copyright © 2011 Pearson Education, Inc.

Genomics: Large-Scale Analysis of DNA Sequences An organism’s genome is its entire set of genetic instructions The human genome and those of many other organisms have been sequenced using DNA- sequencing machines Genomics is the study of sets of genes within and between species

Theme: Feedback Mechanisms Regulate Biological Systems Feedback mechanisms allow biological processes to self-regulate Negative feedback means that as more of a product accumulates, the process that creates it slows and less of the product is produced Positive feedback means that as more of a product accumulates, the process that creates it speeds up and more of the product is produced

A Negative feedback B D Excess D blocks a step. D D C D Enzyme 1 B D Enzyme 2 Excess D blocks a step. D D C Enzyme 3 Figure 1.13 Regulation by feedback mechanisms. D (a) Negative feedback

Which of the following examples would represent negative feedback? As carbon dioxide levels rise in the blood of a mammal, the rate of breathing increases, leading to a decrease in blood levels of carbon dioxide. As global temperatures rise, more ice melts, leading to greater planetary absorption of sunlight and additional temperature increase. The speed of a racehorse decreases after running a mile. The metabolic rate and energy consumption of grizzly bears decrease during hibernation. Frog eggs hatch after 5 days of development at 28C but after 10 days of development at 23 C. Answer: a All of the answers relate to a measurement of a rate. Answers c and d simply show a change in rate as the physiology changes in a individual but are incorrect because there is no feedback. Answer e is incorrect because it simply mentions a difference in development rates at different temperatures. Answer b is incorrect because it shows positive feedback. Answer a is correct because it shows that when one factor (carbon dioxide concentration) rises, a second factor (breathing rate) increases and leads to a reduction in the first factor.

Excess Z stimulates a step. Z Y Z W Enzyme 4 X Positive feedback  Enzyme 5 Excess Z stimulates a step. Z Y Z Z Enzyme 6 Figure 1.13 Regulation by feedback mechanisms. Z (b) Positive feedback

Unity and Diversity of Life Imagine that you have just discovered a new multicellular but microscopic organism that swims in ponds. You see that it is propelled by cilia on the outside of the organism. What can you say about the evolutionary relationships of this organism? The presence of cilia shows that it is more closely related to Paramecium than to humans. The presence of cilia shows that it shares a common ancestor with Paramecium and humans. It is probably closely related to pond algae. It is probably most closely related to prokaryotes. The presence of cilia demonstrates the diversity, but not the unity, of life. Answer: b It can seem contradictory to students that “evolution can account for both the unity and diversity of life,” but this is an important concept for them to understand. Organisms share traits that they have inherited from a common ancestor (the unity of life) but differ in traits if natural selection, or perhaps genetic drift, leads to change (the diversity of life). Cilia occur in both Paramecium and humans and, most notably, have the same internal structure. This pattern shows that they have a common ancestor (i.e., answer b is correct) but the differences between Paramecium and humans show they have diverged over evolutionary time. The mere presence of cilia cannot help us decide what the new organism is closely related to (either Paramecium as in answer a, pond algae as in answer c, or prokaryotes as in answer d). Answer e is incorrect because the presence of cilia shows the unity not the diversity of life.

Evolution, the Overarching Theme of Biology Evolution makes sense of everything we know about biology Organisms are modified descendants of common ancestors Evolution explains patterns of unity and diversity in living organisms Similar traits among organisms are explained by descent from common ancestors Differences among organisms are explained by the accumulation of heritable changes

Theories in Science People who characterize evolution as “just a theory” show that they know the difference between a hypothesis and a theory. do not understand that “theory” in science is a broad, overarching concept that explains a variety of observations and instead think scientists use the term “theory” as a synonym for “hypothesis.” understand how science accumulates information about the nature of the natural world. understand how to develop scientific experiments. Answer: b The term “theory” is important for students to understand, especially in the context of criticism of evolutionary theory by creationists. In everyday language, “theory” and “hypothesis” are used interchangeably. In science, however, “theory” refers to a conceptual construct with a great deal of supporting evidence. Other theories in science are cell theory, theory of gravitation, and Einstein’s theory of general relativity.

Classifying the Diversity of Life Approximately 1.8 million species have been identified and named to date, and thousands more are identified each year Estimates of the total number of species that actually exist range from 10 million to over 100 million Taxonomy is the branch of biology that names and classifies species into groups of increasing breadth Domains, followed by kingdoms, are the broadest units of classification

Ursus americanus (American black bear) Figure 1.14 Species Genus Family Order Class Phylum Kingdom Domain Ursus americanus (American black bear) Ursus Ursidae Carnivora Mammalia Chordata Figure 1.14 Classifying life. Animalia Eukarya

(a) Domain Bacteria (b) Domain Archaea (c) Domain Eukarya 2 m 2 m Figure 1.15 (a) Domain Bacteria (b) Domain Archaea 2 m 2 m (c) Domain Eukarya Kingdom Animalia 100 m Kingdom Plantae Figure 1.15 The three domains of life. Protists Kingdom Fungi

Unity in the Diversity of Life DNA is the universal genetic language common to all organisms Unity in the Diversity of Life 15 m 5 m Cilia of Paramecium Cilia of windpipe cells 0.1 m Cross section of a cilium, as viewed with an electron microscope

Charles Darwin and the Theory of Natural Selection Charles Darwin published On the Origin of Species by Means of Natural Selection in 1859 Darwin made two main points Species showed evidence of “descent with modification” from common ancestors Natural selection is the mechanism behind “descent with modification” Darwin’s theory explained the duality of unity and diversity

Darwin observed that Individuals in a population vary in their traits, many of which are heritable More offspring are produced than survive, and competition is inevitable Species generally suit their environment Individuals that are best suited to their environment are more likely to survive and reproduce Over time, more individuals in a population will have the advantageous traits Evolution occurs as the unequal reproductive success of individuals

Explain what could “evolve” from here?????? 1 Population with varied inherited traits 2 Elimination of individuals with certain traits 3 Reproduction of survivors 4 Increasing frequency of traits that enhance survival and reproductive success Figure 1.20 Natural selection.

Cactus-flower- eaters Green warbler finch Certhidea olivacea Warbler finches Insect-eaters COMMON ANCESTOR Gray warbler finch Certhidea fusca Sharp-beaked ground finch Geospiza difficilis Seed-eater Vegetarian finch Platyspiza crassirostris Bud-eater Mangrove finch Cactospiza heliobates Woodpecker finch Cactospiza pallida Tree finches Insect-eaters Medium tree finch Camarhynchus pauper Large tree finch Camarhynchus psittacula Small tree finch Camarhynchus parvulus Large cactus ground finch Geospiza conirostris Cactus-flower- eaters Cactus ground finch Geospiza scandens Figure 1.22 Descent with modification: adaptive radiation of finches on the Galápagos Islands. Ground finches Seed-eaters Small ground finch Geospiza fuliginosa Medium ground finch Geospiza fortis Large ground finch Geospiza magnirostris

Concept 1.3: In studying nature, scientists make observations and then form and test hypotheses The word science is derived from Latin and means “to know” Inquiry is the search for information and explanation The scientific process includes making observations, forming logical hypotheses, and testing them

Types of Data Data are recorded observations or items of information; these fall into two categories Qualitative data, or descriptions rather than measurements For example, Jane Goodall’s observations of chimpanzee behavior Quantitative data, or recorded measurements, which are sometimes organized into tables and graphs

Forming and Testing Hypotheses Observations Observations and inductive reasoning can lead us to ask questions and propose hypothetical explanations called hypotheses Question Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb A hypothesis is a tentative answer to a well-framed question A scientific hypothesis leads to predictions that can be tested by observation or experimentation Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test of prediction Test of prediction Test falsifies hypothesis Test does not falsify hypothesis

Experimental Controls and Repeatability A controlled experiment compares an experimental group (the artificial kingsnakes) with a control group (the artificial brown snakes) Ideally, only the variable of interest (the effect of coloration on the behavior of predators) differs between the control and experimental groups A controlled experiment means that control groups are used to cancel the effects of unwanted variables A controlled experiment does not mean that all unwanted variables are kept constant In science, observations and experimental results must be repeatable

Science, Technology, and Society Which of the following is an activity that would not be classified as science or technology? development of methods to insert human genes into pig embryos measurement of the flavor and ripening speed of tomatoes that have had different flavor-enhancing genes inserted into their genetic material investigation of the allergic effect of peanut genes inserted into tomatoes when the tomatoes are eaten by people allergic to peanuts discussion of whether government-granting agencies should support research into treatment of Parkinson's disease with products from human fetal cells comparison of the growth rates of different strains of wheat grown at different temperatures Answer: d An important idea for students to grasp is the difference between the acquisition of scientific knowledge and social decisions about scientific investigations. Answers a, b, c, and e are strictly scientific or technological investigations. Answer d involves societal decision making as to whether certain scientific investigations should be pursued. A follow-up activity to this question could be to ask students to write other answers that would correctly match the stem.