Biology: Exploring Life Chapter 1

Hierarchy of Life Atom Molecule Macromolecule Organelle Cell* Tissue Organ Organ System Organisms Population Community Ecosystem Biosphere Emergent properties-characteristics that arise from a more encompassing hierarchal level that was not present in the previous level

Cells are the structural and functional units of life Life emerges at the level of the cell Two main types of cells Prokaryotic cells lack membrane bound organelles simple and small, range in size from 1-10 µm ex. bacteria Eukaryotic cells Have membrane bound organelles; Can be a single cell, most are multicellular; 10-100 µm ex’s. plants, animals, fungi and protists

Prokaryotic cell Eukaryotic cell Membrane Organelles DNA (no membrane around nucleus) Membrane Nucleus = nuclear membrane around DNA) Organelles

True or False? 1. Life emerges at the level of the cell. 2. Prokaryotic cells are smaller and simpler than eukaryotic cells.

What is Life? ENERGY PROCESSING ORDER REGULATION GROWTH & DEVELOPMENT RESPONSE TO ENVIRONMENT REPRODUCTION EVOLUTIONARY ADAPTATION

Three Domains of Life

Domain Eukarya Includes Four Kingdoms: K. Protista K. Plantae Tree of Life Web Project: http://tolweb.org Video of an example from each kingdom K. Fungi K. Animalia

Living Organisms Interact with their Environments To be successful, an ecosystem must recycle chemicals necessary for life & move energy through the ecosystem Biotic and Abiotic components must interact to accomplish this https://www.youtube.com/watch?v=TybPNtGV6MY https://www.youtube.com/watch?v=5jBV9vJmXZI

Living Organisms Interact with their Environments Biotic components Abiotic components Producers: Photosynthetic organisms that provide food for a typical ecosystem Consumers: Eat plants (or eat animals that profit from/eat plants) Chemicals & nutrients required for life Examples: Oxygen, Carbon dioxide, water, visible light, etc.

Producers Consumers Ecosystem Sunlight Cycling of chemical nutrients Heat Chemical energy Consumers Figure 1.2 The cycling of nutrients and flow of energy in an ecosystem. Heat

The unity of life is Based on DNA and a common genetic code All cells have DNA DNA is the chemical substance of genes A gene is a discrete unit of inheritance that transmits information from parents to offspring DNA is composed of two strands, coiled in a helix

Evolution Explains the Unity and Diversity of Life In 1859, Charles Darwin published On the Origin of Species by Means of Natural Selection Darwin emphasized two points: 1. descent with modification 2. natural selection is the mechanism of evolution

Darwin started with two observations A population has genetic variation 2. Overproduction of offspring Population with varied inherited traits 1 Figure 1.6B An example of natural selection in action. Elimination of individuals with certain traits Reproduction of survivors

Evolution Explains the Unity and Diversity of Life Darwin inferred that unequal reproductive success would lead to the accumulation of favorable traits in a population Figure 1.6C Examples of adaptations to different environments. Pangolin: https://www.youtube.com/watch?v=gz4HXyxcess Killer whales: https://www.youtube.com/watch?v=dbbtaJs8AWw Killer whale Pangolin

Evolution Explains the Unity and Diversity of Life

THE PROCESS OF SCIENCE

Scientists Use Two Main Approaches to Learn About Nature Two approaches are used to understand natural causes for natural phenomena Discovery science which uses verifiable observations and measurements to describe science Hypothesis-based science—uses the data from discovery science to explain science. This requires proposing and testing of hypotheses

Hypotheses and Theories What is the difference between a theory and a hypothesis? A hypothesis is a proposed explanation for a set of observations The hypothesis must be testable and falsifiable A theory is supported by a large and usually growing body of evidence

Observations Question Figure 1.8A An example of hypothesis-based science.

Observations Question Hypothesis 1: Dead batteries Hypothesis 2: Burned-out bulb Figure 1.8A An example of hypothesis-based science.

Hypothesis 1: Dead batteries Hypothesis2: Burned-out bulb Observations Question Hypothesis 1: Dead batteries Hypothesis2: Burned-out bulb Prediction 1: If the batteries are replaced then it will fix problem Prediction 2: If the bulb is replaced then it will fix problem Figure 1.8A An example of hypothesis-based science.

Observations Test predictions Question Hypothesis 1: Dead batteries Hypothesis2: Burned-out bulb Prediction 1: If the batteries are replaced then it will fix problem Prediction 2: If the bulb is replaced then it will fix problem Figure 1.8A An example of hypothesis-based science. Test predictions

Observations Test predictions Test falsifies hypothesis Question Hypothesis 1: Dead batteries Hypothesis2: Burned-out bulb Prediction 1: If the batteries are replaced then it will fix problem Prediction 2: If the bulb is replaced then it will fix problem Figure 1.8A An example of hypothesis-based science. Test predictions Test falsifies hypothesis Test does not falsify hypothesis