BIOLOGY 1M03 Lecture Notes - Lecture 3: Cell Theory, Spontaneous Generation, List Of First Overall Nba Draft Picks
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Cell Theory (Cont'd); Pasteur Experiment
Spontaneous generation may not have occurred
• Maybe the broth wasn’t the right kind to support cells
• Maybe the flask was somehow discouraging or poisonous
Does this prove all cells come from cells?
• Maybe cells can generate spontaneously under other conditions
• Maybe that's not what's happening here
Hypothesis: We pursiue by evaluating hypothesis (sing. Hypothesis) these are
proposed explanations of facts
We use hypothesis to make predictions, use experiments to falisfy hypotheses to prove
they are false
• Most hypotheses cannot be proved to be true,instead if we fail to falsify them, we
say that they are supported
• If a hypothesis explains many facts, and survives attempts at falsification, we tend
to believe it
Observational Studies: Look for ways to collect data that will support or challenge
Scientists are cautious about making conclusions from observational studies
• Its hard to know if you’ve taken everything into account
• Experiments are more reliable
• But you cant always do experiments, which is why we do observational studies
Why are giraffes so tall?
• They eat from trees, so that probably has something to do with it
• They use their necks for dramatic fights so that probably has something to do with
• What can you do to investigate?
o How high do the giraffes feed?
o Do males with long necks win fights?
• Winners of the fights get the females; which is why they also have long necks?
• How do ants navigate landscapes? They find food and return to their nests; They
usually walk in the same line so they might be following a trail of smell to find their
• Saharan desert ants meander long distances to find food, in a squiggly line, but
then walk home ina straight line
• Maybe they have some quantitative sense by judging distance by counting steps
o After cutting ant legs or making them longer; they discovered that ants count
their steps to get home. With stumps, it didn't go far enough, with stilts, it went
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