Chapter 1 Exploring Life on Its Many Levels 1. Briefly Briefly describe describe the unifying unifying themes themes that that characteriz characterize e the biologica biologicall sciences. sciences. • •
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the cell – an organism’s basic unit of structure and function. heritable information – inheritance of biological information in the form of DNA which is encoded in the nucleotide sequence of DNA emergent properties – emerge as result of interactions among components at the lower levels regulation – maintains a relatively steady state for internal factors, such as body temperature interaction with the environment – organisms are open systems that exchange materials and energy with their surroundings energy and life – all organisms must perform work, which requires energy unity and diversity – diversity is grouped into three domains: Bacteria, Archaea, and Eukarya. Unity is found through universal genetic code evolution – explains both unity and diversity of life. The adaptation of population to their environments through the differential reproductive success of varying individuals structure and function – form and function are correlated at all levels of biological organization scientific inquiry – includes observation-based discovery and the testing of explanations through hypothesis-based inquiry sciences, technology, and society – applications of science lead o technology which are create for the society
1. Diagram Diagram the hierar hierarchy chy of structura structurall levels levels in biologica biologicall organiza organization. tion.
The hierarchy of structural levels of biological organization, from the bottom upward, is: molecules, organelles, cells, tissues, organs and organ systems, organisms, population, community, ecosystems, and the biosphere. 2. Explain Explain how the the properties properties of of life emerge emerge from from complex complex organiz organizatio ation. n.
At the lowest level are atoms that are ordered into complex biological molecules. Biological molecules are organized into structures called organelles, the components of cells. Cells are the fundamental unit of structure and function of living things. A group of a certain kind of cells completing a certain function makes up tissues, which make up the organs of organ systems. This is needed for all individual living things, things, also known as organisms. Organisms belong to populations, localized groups of organisms belonging to the same species. Populations of several species in the same area comprise a biological community. Populations interact with their physical environment to form an ecosystem. The biosphere consists of all the environments on Earth that are inhabited by life. 3. Describe Describe the the two major dynamic dynamic processe processess of any any ecosys ecosystem. tem.
The two major dynamics of any ecosystem include two processes: the cycling of nutrients and the flow of energy from sunlight to the producers to the consumers. 4. Distingui Distinguish sh between between prokaryoti prokaryoticc and and eukaryot eukaryotic ic cells. cells.
Eukaryotic cells are subdivided by internal membranes into various organelles. In most eukaryotic cells, the largest organellis the nucleus, which contains the cell’s DNA as chromosomes. The other organelles are located in the cytoplasm, the entire region between the nucleus and outer membrane of the cell. Prokaryotic cells are much simpler and smaller than eukaryotic cells. In a prokaryotic cell, DNA is not separated from the cytoplasm in a nucleus. There are no membrane-enclosed organelles in the cytoplasm. 5. Describe Describe the the basic basic structure structure and function function of of DNA. DNA.
DNA, deoxyribonucleic acid, is the substance of genes, the units of inheritance that transmit information from parents to offspring. DNA in human cells is organized into chromosomes. Each chromosome has one very long DNA molecule, with hundreds or thousands of genes arranged along its length. The DNA of chromosomes replicates as a ce ll prepares to divide. In each cell, the genes along the length of DNA molecules encode the information for building the cell’s other molecules. DNA thus directs the development and maintenance of the entire organism.
6. Descri Describe be the the dilemm dilemma a of redu reducti ctioni onism sm..
The dilemma of Reductionism, reducing complex systems to simpler components, is that we cannot fully explain a higher level of organization by breaking it down into its component parts. At the same time, it is futile to try to analyze something as complex as an organism or cell without taking it apart. 7. Discuss Discuss the goals goals and activities activities of systems systems biology. biology. List List three research research developments developments that that have advanced advanced systems systems biology.
The ultimate goal of systems biology is to model the dynamic behavior of whole biological systems. Three key research developments have led to the increased importance of systems biology: 1.
2. 3.
High-thro High-throughp ughput ut technolog technology y – systems systems biology biology depend dependss on methods methods that that can analyze analyze biolog biological ical material materialss very quickly and produce enormous amounts of data. An example is the automatic DNA-sequencing machines used by the Human Genome Project. Bioinformatics – the huge databases from high-throughput methods require computing power, software, and mathematical models to process and integrate information. Interdisciplinary research teams – systems biology teams may include engineers, medical scientists, physicists, chemists, mathematicians, and computer scientists as well as biologists. biologists.
1. Explain Explain the importance importance of regulatory regulatory mechanisms mechanisms in living living things. Distingu Distinguish ish between between positive and negative negative feedback.
Regulatory mechanisms in living things is important for the output, or product, of a process through enzymes, specialized protein molecules that make sure that chemical processes within cells are accelerated, or catalyzed. In negative feedback, or feedback inhibition, accumulation of an end product of a process slows or stops that process. This type of feedback is most common. In positive feedback, though less common, an end product speeds up its production Evolution, Unity, and Diversity 2. Distingui Distinguish sh among the three three domains domains of life. List and distingui distinguish sh among the three three kingdoms kingdoms of multicellul multicellular, ar, eukaryotic life.
The three domains of life are Bacteria, Archaea, and Eukarya. The first two domains consist of prokaryotes. Eukaryotes are grouped into the kingdom Eukarya of which there are three more kingdoms: Plantae, Fungi, and Animalia. Plants produce their own sugars and food by photosynthesis. photosynthesis. Fungi are decomposers that absorb nutrients by breaking down dead organisms and organic wastes. Animals obtain food by ingesting other organisms. 3. Explain Explain the the phrase phrase “life’s “life’s dual nature nature of unity unity and and diversity diversity.” .”
The process of evolution explains both the similarities and differences among living things. There is unity in the kinship among species that descended from common ancestors and diversity in the modifications that evolved as species branched from their common ancestors. 4. Describe Describe the observation observationss and inferences inferences that led Charles Charles Darwin Darwin to his theory of evolution evolution by natural natural selection. selection.
Darwin inferred natural selection due to two observations. One observation was individual variation. Individuals in a population of any species vary in many heritable traits. The second observation was overpopulation and competition which brought him to the conclusion that any population can potentially produce far more offspring than the environment can support. This creates a struggle for existence among variant members of a population. One of the inference he made is unequal reproductive success. Darwin inferred that those individuals with traits best suited to the local environment would leave more healthy, fertile offspring. The Second had to do with evolutionary adaptation. Unequal reproductive success can lead to adaptation of a population to its environment. Over generations, heritable traits that enhance survival and reproductive success will tend to increase in frequency among a population’s individuals. The population evolves.
5. Explain Explain why why diagrams diagrams of evolutio evolutionary nary relatio relationships nships have have a treelik treelikee form.
Diagrams of evolutionary relationships have a treelike form because just as individuals have a family tree, each species is one twig of a branching tree of life. The Process of Science 6. Distingui Distinguish sh between discovery discovery science science and hypothesis-b hypothesis-based ased science. science. Explain Explain why both types of exploration exploration contribute to our understanding of nature.
Discovery science is mostly about discovering nature while hypothesis-based science is about explaining nature. Discovery science describes natural structures and processes as accurately as possible through careful observation and analysis of data and it can lead to important conclusions based on inductive reasoning. In hypothesis-based science, deduction usually takes the form of predictions about what we should expect if a particular hypothesis is correct. It must be both testable and falsifiable to create an ideal so that it can be used to frame two or more alternative hypotheses and design design experiments to falsify them. 7. Distingui Distinguish sh between between quantitati quantitative ve and and qualitat qualitative ive data. data.
Quantitative data are numerical measurements and qualitative data are usually in the form of descriptions of certain observations. 8. Distingui Distinguish sh betwee between n inductiv inductivee and and deducti deductive ve reason reasoning. ing.
In inductive reasoning, generalizations are based on a large number of specific observations. However, in deductive reasoning, reasoning flows from the general to the specific 9. Explain Explain why why hypotheses hypotheses must must be testable testable and and falsifiab falsifiable le but are not not provable. provable.
The ideal in hypothesis-based science is to frame two or more alternative hypotheses and design experiments to falsify them. No amount of experimental testing can prove a hypothesis. A hypothesis gains support by surviving various tests that could falsify it, while testing falsifies alternative hypotheses. 10. Describe Describe what is meant meant by a controlled experim experiment. ent.
In controlled experiments, scientists design experiments to test the effect of one variable by canceling out the effects of unwanted variables. 11. Distinguish
between the everyday meaning of the term theory and its meaning to scientists.
Everyday use of the term theory implies an untested speculation. Theory in terms of science explain many observations and are supported by a great deal of evidence. 12. Explain how science is influenced influenced by social social and cultural factors.
Cultural factors cause new ideas to come up in science, new hypothesis to be tested and falsified, and new theories from same observations by growth of knowledge and leaving of ignorance. The social factor is the type of scientists now in the field and the new ideas they bring, such a s women in science. 13. Distinguish between science science and technology. Explain Explain how science and technology are interdependent.
The goal of science is to understand natural phenomena. Technology applies scientific knowledge for some specific purpose. Technology results from scientific discoveries applied to the development of goods and services. Scientists put new technology to work in their research.
