{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Notes mid 1 - BIS 1A Class Notes Characteristics of Life...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
BIS 1A Class Notes Characteristics of Life - Evolutionary milestones o Planet: 4.5 billion years old o 3.8 bya – 1 st life – prokaryotic “protocell,” probably anaerobic heterotroph o 3.5 bya – 1 st fossils (cyanobacteria_ - photoautotroph o 2.5 bya – oxygen more abundant o 1.5 bya – unicellular Eukaryotes appear (via endosymbiosis) - Cell Theory o What is a cell? Water-based compartment, filled with concentrated chemicals and surrounded by a membrane o 72% of lean tissue in humans is water o 55% of dry weight is protein - Hallmarks of Cell Theory o 1) All life consists of one or more cells o 2) All cells come from preexisting cells o 3) The cell is the smallest unit of life o Theory: using a pattern-based inductive reasoning to predict future results o Spontaneous generation: life arises (full-blown) from non-living materials Mice from rags and grain, flies from meat and air, etc o Pasteur disproved spontaneous generation of microbes Experiment: leave out some growth media, v. boil and seal other media cells can only come from preexisting cells - Levels of Biological Organization o Molecules o Cell/organelles o Tissues o Organs o Organ systems o Organism o Populations o Community o Biosphere - viruses contain hereditary material enclosed in a protein coat (and sometimes a membrane) o not considered alive because they can’t reproduce or metabolize on their own - Biologists study: o Structures – patterns, descriptions of parts of a cell, leaf, animal, etc o Functions – like how plants make sugars
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
o Structure is correlated with function - The Scientific Method o 1. Observation o 2. Hypothesis o 3. Experiment o 4. Draw conclusions o 5. Accept or reject hypothesis - How (functional mechanisms) and Why (adaptation and evolution) questions - Hypothesis testing – based on results of experiment - Theory o Hypothesis that has been repeatedly tested and never disproved o Has to have broad predictive power o Has a rigorously tested statement of general principles o Examples: Germ Theory of Medicine, Cell Theory, Atomic Theory, Theory of Relativity, Theory of Evolution Evolution is the Framework of Biology - 1859 – Darwin develops the Theory of Evolution in Origin of the Species - Theorized that natural selection is the mechanism that causes change in populations, leading to adaptation - A.R. Wallace also independently developed the theory of evolution by natural selection, but a little too late - Evolution – in a scientific sense, it doesn’t require progress; is only any process of change - Populations or species can evolve (not individuals) – involves changing gene frequencies - Increased complexity is not an evitable consequence of evolution - Used to think that Man was the ultimate goal of life - Darwin’s Logic o Observation 1: More offspring are produced that are strictly necessary to replace their parents o Observation 2: Nonetheless, population sizes are relatively stable o Observation 3: Resources are limited o Inference 1: There is a struggle for existence, and only a fraction survive o
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}