Summary
Biol 151 Exam 1 Summary
- Course
- Biol 151
- Institution
- Virginia Commonwealth University
This is a comprehensive and detailed summary on exam 1 for Biol 151. *Essential for effective study!! *For you, at a price that's fair enough!!
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Bio 151 Study Guide #1Introduction to Life
Earth has been around for a hecking long time - 4.5 billion years
o First true cells = prokaryotes from 3.9 billion years ago
o Has water – important for life, required for life to exist
Early Earth was too hot for liquid water, it had to cool down first
Ice = potential for life
Came from icy comets
New life followed water
o Earliest cells = fossils found in Australia from 3.5 billion years ago
Similar to cyanobacteria – photosynthetic organism
Prokaryotic, small and simple – no complex parts
Able to live in hostile environment
Larger cells came 500 million years ago, plants and animals
o Humanoids came 2.5 million years ago
o Anatomically modern humans – 200,000 years ago
Life – things all living things have in common
o Cells
o Adaptation
o Reproduce
o Organized
o Growth
o Metabolism
o Homeostasis
o Response to Stimuli
Order + Cells
o All life organized on inside
Specific to carry out jobs
o All life consist of one or more cells
Atoms molecules cells organelles
Amoebas are single-celled
Bigger things consist of many cells
Specialized
Form stuff like tissue organs organ systems
o Failure of organization = bad
Response to stimuli
o Stimulus: Anything the organism can detect and respond to
o Organisms sense surroundings, responds accordingly
Ex: Venus fly trap
Reproduction
o Single cells just divide and make identical copies (same DNA)
Mitosis
Makes a copy of the DNA
One cell splits into two identical cells
Variation comes from mutations
o Multi-celled sexual reproduction
Involves the passing down of DNA from parent to offspring
Offspring are similar (but not identical) to parents
Combining parent’s DNA
Diverse offspring allows species to evolve more
Genetic diversity = required for evolution
Adaptation – organisms are well adapted to their environment due to natural selection
o Some traits more common because allows organism to thrive in environment
Growth and Development - Organisms grow & develop according to their genes
o Genes – recipe for proteins makes everything
Gene: Segment of DNA containing information for a protein
Provides instructions for each species’ unique traits
o Most individuals share traits within a species
Homeostasis: Steady state internally so everything functions properly
o Maintaining constant internal conditions
, o Organisms evolved to maintain homeostasis in certain environments
Ex: Temp, pH, concentration of chemicals
Not all organisms regulate body temperature
Ex: Camels with humps, polar bears, panda bears
Not always beneficial if environment is rapidly changing
Energy – needed for metabolic processes
o Attained from eating or photosynthesis (sun)
o Various chemical processes taking place in cells of organism
Adaptation + Energy - Making use of food available
o Ex: Koalas and eucalyptus leaves, anteater and ants, sloth and leaves
o Digestive system – determines what can be digested and how efficiently
o Behavior – ways to get food
o Anatomical Structures
Ex: Anteater and nose
o Metabolism - How much energy you could use
If the energy supply is limited, metabolic reactions proceed more slowly
Atoms, Bonds, and Water
Everything is made of atoms
o Atoms: Tiny particles that consists of protons, neutrons, and electrons
o 3 Main particles
Protons = +1, weighs 1
Neutrons = 0, weighs 1
Electrons = -1, weighs essentially nothing
o Most of an atom’s volume is empty space
Nucleus = size of a pea
Particles gives characteristics to an atom
o Protons determine atom identity
o Electrons determine bonding behavior – interaction with other atoms
Bond types – sharing or taking electrons
o Neutrons affect mass, no effect on identity
Element: Substance made of one atom type
o 94 = naturally occurring, 25 = made in lab
o Organized on periodic table based on atomic number (protons)
Electron number = same as proton number
No +/- = neutral
Can figure out number of neutrons from mass subtract mass from protons
Decimal point – due to variation in neutron number depending on element
o Has different properties - chemical and physical
Working with CHNOPS – makes up 96% of mass of all living organisms
Neutrons determine mass
o Atomic mass: Number of protons + neutrons
o Proton number will be smaller than atomic mass
Isotope: Atom with different neutron number
o Essentially the same but different mass
o Ex: Carbon
Used to track things
o Radioisotope: Unstable (radioactive) isotopes
Used for carbon dating – older fossils have different carbon makeups
Electrons are found in orbitals outside nucleus
o Orbitals: Regions around nucleus where we expect to find electrons
Each orbital holds 2 electrons
Can have various shapes
o Bigger atoms have more electrons, fills more orbitals
o Columns in periodic table based on orbitals
o Fill orbital in sequence, moving farther away from the nucleus
Located at different distances from nucleus
First shell fits 2
Second fits 8
3rd shell and beyond fits 8 – doesn’t really matter in bio
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