Nutrient cycling and energy flow in an ecosystem Sunlight Ecosystem Heat Cycling of chemical nutrients Producers (plants and other photosynthetic organisms) Chemical energy Consumers (such as animals)
Nuclei containing DNA Sperm cell Egg cell Fertilized egg with DNA from both parents Embryo’s cells with copies of inherited DNA Offspring with traits inherited from both parents Inherited DNA directs development of an organism
Regulation by Feedback Mechanisms Negative feedback Excess D blocks a step D D D A B C Enzyme 1 Enzyme 2 Enzyme 3 D (a) Negative feedback W Enzyme 4 X Positive feedback Enzyme 5 Y + Enzyme 6 Excess Z stimulates a step Z Z Z Z (b) Positive feedback
1.1 Section Check 1.Starting with the molecular level in figure 1.3, write a sentence that includes components from the previous (lower) level of biological organization, for example: “A molecule consists of atoms bonded together”. Continue with organelles, moving up the biological hierarchy. 2. Identify the theme or themes exemplified by (a) the sharp quill of a porcupine, (b) the development of a multicellular organism from a single fertilized egg, and (c) a hummingbird using sugar to power its flight.
An example of unity underlying the diversity of life: the architecture of cilia in eukaryotes Cilia of Paramecium Cross section of a cilium, as viewed with an electron microscope Cilia of windpipe cells 15 µm 5 µm 0.1 µm
Natural Selection Population with varied inherited traits. Elimination of individuals with certain traits. Reproduction of survivors. Increasing frequency of traits that enhance survival and reproductive success
Evolutionary adaptation Bats, the only mammals capable of active flight, have wings with webbing between extended “fingers”. Darwin proposed that such adaptations are refined over time by natural selection.
1.2 Section Check 1.How is a mailing address analogous to biology’s hierarchical taxonomic system? 2.Explain why “editing” is an appropriate metaphor for how natural selection acts on a populations heritable variation.
A campground example of hypothesis- based inquiry Observation s Question Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test falsifies hypothesis Test does not falsify hypothesis
The geographic ranges of a poisonous snake and its mimic South Carolina North Carolina Key Scarlet kingsnake (nonpoisonous) Eastern coral snake (poisonous) Range of scarlet kingsnake only Overlapping ranges of scarlet kingsnake and eastern coral snake
Does the presence of poisonous coral snakes affect predation rates on their mimics, kingsnakes? Artificial kingsnakes Brown artificial snakes 83% 84% 17% 16% Coral snakes absent Coral snakes present Percent of total attacks on artificial snakes RESULTS
Producers Consumers Energy Flow and Nutrient Cycling
Eukaryotic vs. Prokayotic Cells
Natural Selection Population of organisms Hereditary variations Overproduction and competition Differences in reproductive success of individuals Evolution of adaptations in the population Environmental factors