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Exploring Life Chapter 1. Advanced Placement Biology. Figure 1.1. Life. Defies a simple, one-line definition. Lends itself to mysticism. What is biology?. Biology. Bios = Greek for “life” Logos = Greek for “study” or “thought” Biology - the study of living things.
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Exploring LifeChapter 1 Advanced Placement Biology
Figure 1.1 Life • Defies a simple, one-line definition. • Lends itself to mysticism.
Biology • Bios = Greek for “life” • Logos = Greek for “study” or “thought” • Biology - the study of living things
Concept 1.1: Biologists explore life from the microscopic to the global scale. • The study of life: • Extends from the microscope scale of molecules and cells to the global scale of the entire living planet.
What does it mean to be alive? What characteristics define life? What are the criteria for something to be alive?
(b) Evolutionary adaptation (a) Order (c) Response to the environment (e) Energy processing (d) Regulation (g) Reproduction (f) Growth and development Figure 1.2
What does it mean to be “living?” Some Characteristics: 1. Order- have a hierarchical organization (Fig 1.3).
A Hierarchy of Biological Organization • The hierarchy of life • Extends through many levels of biological organization
1 The biosphere Figure 1.3 1.a.biome • From the biosphere to organisms… 2. Ecosystems 3. Communities 4. Populations 5. Organisms
9Organelles 1 µm Cell 8Cells Atoms 10Molecules 10 µm 7Tissues 50 µm 6Organs and organ systems Figure 1.3 • From cells to atoms.
Order Beyond the Organism • Population- a group of individuals of same species occupying a given area at the same time. • Community- a number of interacting populations in a common environment.
Order in Biology • Ecosystem- organisms (biotic) interacting with their nonliving (abiotic) environment. • Biomes- major groupings of plants, animals, and microorganisms that occur over a wide geography and have distinct characteristics (ex. deserts, tropical rainforests)
The Emergent Properties of Systems • Biological systems are much more than the sum of their parts. • Due to increasing complexity • New properties emerge with each step upward in the hierarchy of biological order
The Power and Limitations of Reductionism • Reductionism- Involves reducing complex systems to simpler components that are more manageable to study.
The study of DNA structure, an example of reductionism • Has led to further study of heredity, such as the Human Genome Project Figure 1.9
A Closer Look at Ecosystems • Each organism… • Interacts with its environment. • Both organism and environment… • Are affected by the interactions between them.
Ecosystem Dynamics • The dynamics of any ecosystem include two major processes • Cycling of nutrients, in which materials acquired by plants eventually return to the soil • The flow of energy from sunlight to producers to consumers
Energy Conversion • Activities of life… • Require organisms to perform work, which depends on an energy source. • The exchange of energy between an organism and its surroundings involves the transformation from one form of energy to another.
Sunlight Ecosystem Producers (plants and other photosynthetic organisms) Heat Chemical energy Consumers (including animals) Heat Figure 1.4 • Energy flows through an ecosystem • Usually entering as sunlight and exiting as heat
What does it mean to be “living?” 2. Responsiveness or Sensitivity- have a response to stimuli. • Chemotactic • Phototactic • Thigmotropic • Gravitropic
25 µm Figure 1.5 A Closer Look at Cells • The cell • Is the lowest level of organization that can perform all activities required for life
Sperm cell Nuclei containing DNA Fertilized egg with DNA from both parents Embyro’s cells with copies of inherited DNA Offspring with traits inherited from both parents Egg cell Figure 1.6 The Cell’s Heritable Information • Cells contain chromosomes made partly of DNA, the substance of genes • Which program the cells’ production of proteins and transmit information from parents to offspring
Nucleus DNA Cell A C Nucleotide T A T A C C G T A G T A (a) DNA double helix. (b) Single strand of DNA. . Figure 1.7 • The molecular structure of DNA • Accounts for it information-rich nature.
What does it mean to be “living?” 3. Growth, Development, and Reproduction- all use hereditary molecules to pass genetic information to offspring.
Two Main Forms of Cells • All cells share certain characteristics • They are all enclosed by a membrane • They all use DNA as genetic information • There are two main forms of cells: • Eukaryotic • Prokaryotic
EUKARYOTIC CELL PROKARYOTIC CELL DNA (no nucleus) Membrane Membrane Cytoplasm Organelles 1 µm Nucleus (contains DNA) Figure 1.8 • Prokaryotic cells • Lack the kinds of membrane-enclosed organelles found in eukaryotic cells.
What does it mean to be “living?” 4. Regulation- have regulatory mechanisms to coordinate functions (transportation of nutrients, wastes, etc.); maintainhomeostasis.
Feedback Regulation in Biological Systems • A kind of supply-and-demand economy: • Applies to some of the dynamics of biological systems. • The output, or product, of a process regulates that very process -feedback regulation.
A A Negative feedback Enzyme 1 Enzyme 1 B B Enzyme 2 C C Enzyme 3 D D D D D D D D D D D Figure 1.11 • In negative feedback: • An accumulation of an end product slows the process that produces that product.
W W Enzyme 4 Enzyme 4 X Positivefeedback X Enzyme 5 Enzyme 5 Y Y Enzyme 6 Enzyme 6 Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Figure 1.12 • In positive feedback: • The end product speeds up production.
Grouping Species: The Basic Idea • Diversity is a hallmark of life. • Taxonomy: • is the branch of biology that names and classifies species according to a system of broader and broader groups
Species Genus Family Order Class Phylum Kingdom Domain Ursusameri- canus (American black bear) Ursus Ursidae Carnivora Mammalia Chordata Animalia Eukarya Figure 1.14 • Classifying life
The Three Domains of Life • At the highest level, life is classified into three domains: • Bacteria • Archaea • Eukarya • Domain Bacteria and domain Archaea • Consist of prokaryotes • Domain Eukarya, the eukaryotes • Includes the various protist kingdoms and the kingdoms Plantae, Fungi, and Animalia
Kingdom Plantae consists of multicellula eukaryotes that carry out photosynthesis, the conversion of light energy to food. 4 µm Bacteria are the most diverse and widespread prokaryotes and are now divided among multiple kingdoms. Each of the rod-shapedstructures in this photo is a bacterial cell. 100 µm Protists (multiple kingdoms) are unicellular eukaryotes and their relatively simple multicellular relatives.Pictured here is an assortment of protists inhabiting pond water. Scientists are currently debating how to split the protistsinto several kingdoms that better represent evolution and diversity. DOMAIN ARCHAEA Kindom Animalia consists of multicellular eukaryotes thatingest other organisms. Kindom Fungi is defined in part by thenutritional mode of its members, suchas this mushroom, which absorb nutrientsafter decomposing organic material. Many of the prokaryotes known as archaea live in Earth‘s extreme environments, such as salty lakes and boiling hot springs. Domain Archaea includes multiple kingdoms. The photoshows a colony composed of many cells. 0.5 µm Figure 1.15 • Life’s three domains
15 µm 1.0 µm Cilia of Paramecium.The cilia of Parameciumpropel the cell throughpond water. 5 µm Cross section of cilium, as viewed with an electron microscope Cilia of windpipe cells. The cells that line the human windpipe are equipped with cilia that help keep the lungs clean by moving a film of debris-trapping mucus upward. Figure 1.16 Unity in the Diversity of Life • As diverse as life is • There is also evidence of remarkable unity
Figure 1.17 • Concept 1.4: Evolution accounts for life’s unity and diversity • The history of life • Is a saga of a changing Earth billions of years old
Figure 1.18 • The evolutionary view of life… • Came into sharp focus in 1859 when Charles Darwin published On the Origin of Species by Natural Selection
Figure 1.19 • The Origin of Species articulated two main points… • Descent with modification • Natural selection
Population of organisms Overproduction and struggle for existence Hereditary variations Differences in reproductive success Evolution of adaptations in the population Figure 1.20 Natural Selection • Darwin proposed natural selection • As the mechanism for evolutionary adaptation of populations to their environments
1 Populations 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 1.21 • Natural selection is the evolutionary process that occurs… • When a population’s heritable variations are exposed to environmental factors that favor the reproductive success of some individuals over others.
Darwin’s Evidence of Evolution • Fossil Record (Glyptodont -->armadillo) • Geographical Distribution (similar climates have unrelated plants and animals; climate not causing diversity) • Oceanic Islands (Galapagos finches and Cape Verde Island birds are not similar)
