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Biology is the study of life!
Ch 2. Free Response Water Free Response
Lecture:
What makes something living?
-Living things are composed of cells
-Living things maintain homeostasis
-Living things respond to stimuli from their environment
-Living things acquire and use materials and energy from their environment
-Living things grow
-Living things reproduce themselves using DNA
-Living things, as a whole, have the capacity to evolve
Class Discussion:
Is fire alive?
-It responds to stimuli
-It uses material and energy
-It grows
-Reproduces???
Are Viruses alive?
Levels of Organization
Lecture:
Life is organized by levels
-Atom
-Molecule- Two or more atoms bonded together
-Cell- The smallest unit of life
-Tissue- A group of similar cells
-Organ- A group of similar cells working together
-Organ System- A group of organs working together
-Multicellular Organism- A complete living thing
-Species- Organisms that can reproduce and produce a fertile, viable, offspring
-Population- A group of the same species
-Community- All the species in an area
-Ecosystem- All the biotic (living) and abiotic (non-living) things in an area
-Biosphere- The earth
Each one of these levels has properties more complex than the last. These properties are known as emergent properties. The emergent properties work together in a system to perform a function. They cannot perform these functions on their own.
Organisms are divided through systemics and taxonomy
-Domain
-Kingdom
-Phylum
-Class
-Order
-Family
-Genus
-Species
The three domains are
-Bacteria
-Archaea
-Eukarya
-Prokaryotic cells are the most basic. They do not have organelles and they are lacking a nucleus.
-Without organelles prokaryotic cells cannot properly collaborate with other cells in forming a multicellular organism. For this reason all Prokaryotes are single celled.
Living organisms can be defined by their cell type and what they eat
Prokaryotes
-Bacteria and Archaea
Eukaryotes
-Fungi - Decomposers
-Plants - Producers
-Animals - Consumers
-Protists- ???
-Plant like protists are producers
-Animal like protists are consumers
-Fungi like protest are decomposers
-All protists are single celled organisms except seaweed
-Protists is a kingdom that will probably be reclassified
Evolution is the UNIFYING PRINCIPAL in biology
-Evolution explains and brings together all the principals of biology
-Without evolution life science makes no sense
EVOLUTION!
-The word evolution means change over time.
-We can apply this to anything. We can say that a band or musician's career has evolved. This does not mean that it got better it just means that it has changed over time.
-EVERYTHING CHANGES
-In biology, evolution means change of allele frequencies over time. Think of this as a change in genes over time
In order to pass on your genes you need to reproduce. Evolution is all about who reproduces
-The four mechanisms of evolution refer to who chooses who gets to reproduce
The four mechanisms of evolution
-Natural Selection
-Is when nature chooses who gets to reproduce
-Survival of the fittest
-Artificial Selection
-Humans choose who gets to reproduce
-How we turned wolves into Chihuahuas
-Sexual Selection
-The opposite sex chooses who gets to reproduce
-Usually goes against natural selection
-A peacock's feathers and a frog's croak are good examples
-Genetic Drift
-This is the only one that is not a selection
-It is usually an accident
-You reproduce with what you have because they are the only options
-The only ones in an area (Founder Effect) or a disaster kills off most of the group (Bottle Neck effect)
-Evolution is different than speciation.
-Speciation is when one species turns into another species.
-Speciation uses evolution to describe its process but it is separate from evolution
-History of life
-The first cell hypothesis is the hypothesis that one cell turned into all life on earth. This is a hypothesis that uses evolution to describe how it happened but is not evolution.
Evolutionary Structures
Homologous Structures
Analogous Structures
Vestigial Structures
Speciation
How does one species become two?
In order for speciation to happen there has to be some type of reproductive isolation
-The definition of a species is a group or populations whose members have the potential to interbreed in nature and produce viable, fertile offspring- but do not produce viable, fertile offspring with members of other such groups
-Because the definition has to do with mating a population needs to be kept reproductively isolated from another until they have changed so much that they can no longer breed
-There are two types of reproductive isolation
-Prezygotic barriers - Before sex
-Postzygotic barriers- after sex
Now lets label them
Allopatric and sympatric speciation
Allopatric speciation is when one species becomes two while being geographically isolated
Sympatric speciation is when one species becomes two while still living in the same geographical region
Sometimes Hybrid zones are created
A hybrid zone can go through 0ne of three phases
-Reinforcement
-Fusion
-Stability
Case Study on mouse population:
Does coat color affect predation?
(Pg 13)
Atoms
There are three subatomic particles
-Neutron
-Protron
-Electron
-Protons have a positive (+) charge
-Neutrons have no charge
-Electrons have a negative (-) charge
The number of protons is what makes an element
-Atomic Number = how many protons the element has
-Atomic Mass = how many protons + neutrons the element has
-If you subtract the atomic number from the atomic mass you will know how many neutrons the element has
The periodic table is organized by atomic number
There are 92 naturally occurring elements. All living organisms are made of the same elements. 96% of an organism is Oxygen, Carbon, Hydrogen, and Nitrogen
The other 4% is Calcium, Potasium, Sulfur, and a few other trace elements.
Humans need 25 elements and plants only need 17 to stay alive.
You can change an elements number of electrons and number of neutrons but you cant change its number of protons. If you change the number of protons you change the element.
-Isotope = different number of neutrons than protrons
-Ion = different number of electrons than protrons
-Ions have a charge. If they have more electrons than protrons then they are negatively (-) charged. If they have less electrons than protrons then they are positively (+) charged.
Electron Shell
-The first shell holds 2 electrons
-The second shell holds 8 electrons
-All atoms want to have a full outer electron shell. The last shell of an atom is called the valence electron shell and all electrons in that shell are called valence electrons
-The amount of valence electrons an atom has determines its properties and how it reacts
-The nobel gases all have full valence electron shells so they do not react with anything
-Some elements will try to take electrons or get rid of electrons to fill its shell
-If an atom has less than 4 valence electrons it is easier to just get rid of them and drop down to its other shell making it a positive (+) ion
-If an atom has more than 4 valence electrons it will try to take electrons to get to 8 to become a negative (-) ion
Molecules and Bonding
The valence electrons of atoms interact to form bonds.
-Molecule = two or more atoms bonded together
-There are multiple types of bonds
-Ionic bond = The electrical attraction between positively and negatively charged ions
-When ions are formed they either give up an electron becoming positive or they take an electron becoming negative. This charge causes them to be attracted to oppositely charged ions. If an ion is negatively charged by one it will be attracted to an ion that is positively charged by one.
-Ionic bonds are not very strong. The atoms are not sharing electrons, they are only attracted to each other and stick in a crystal like pattern.
-Covalent Bond = When two or more atoms share valence electrons.
-Sometimes atoms will share their outermost electrons in order to complete their last shell. When they do this they are forming a covalent bond. This type of bond is very strong because the electrons are orbiting both atoms.
-Electronegativity- The level of energy an atom exerts to pull the shared electrons closer to itself. This can cause an unequal level of sharing
-Polar Covalent Bond = sometimes when a covalent bond is formed by atoms the electrons are not shared evenly. When the electrons spend more time around one atom than the other that atom becomes slightly negative and the other becomes slightly positive.
-Nonpolar Covalent Bond = When the electrons are shared evenly between the atoms.
-Water is a Polar Covalent Bond!
Water!
Water has many amazing properties that allow life on this earth possible. If water did not have the structure it does we would not exist!
Polar molecule- A molecule having a positive end and a negative end
-When water molecules stick to other water molecules it is called a hydrogen bond.
-Hydrogen Bond = When the positive ends of hydrogen stick to the negative end of oxygen. Hydrogen bonds are very weak.
-Cohesion = Water sticking to water because of the hydrogen bonds
-Cohesion causes surface tension which is the waters surface resisting being broken
Video:
-Adhesion = water sticking to other molecules other than water
-Water is a polar molecule giving it many important features
-Because water is polar, molecules that have a charge tend to dissolve in water. This happens because the positive hydrogen atoms pull at the negative part of a molecule and the negative oxygen pulls at the positive part of a molecule. Water is known as a solvent because it dissolves things. Water does not have an affect on molecules without a charge such as oils.
-If a molecule dissolves in water it is known as hydrophilic (water loving)
-If a molecule does not dissolve in water it is known as hydrophobic (water fearing)
-The human body is mostly water. In order to send a chemical message in the body would the chemical have to be hydrophobic or hydrophilic?
-The most important feature of water is that it is less dense in its solid form than its liquid form
-Three states of matter
-Solid
-Liquid
-Gas
-Ice floats because water is more dense than ice
-Ice is 10% less dense than water so only 10% of ice breaches the water
Class Demonstration:
Each group take a beaker that is half full of water and a beaker half full of ice. Start placing ice into your beaker of water and observe how much of the ice floats above the surface.
Lecture:
-Since ice floats it is the surface of the ocean that freezes. The sheet of frozen ocean that forms insulates the water underneath which allows organisms to continue thriving under the ice without freezing.
Clouds have mass. They have a weight. That is why they can only float so high. The denser the cloud the lower it will float
High specific heat
-Because the water molecules are attracted to each other in a hydrogen bond it takes a lot of energy to break them apart. The hydrogen bonds need to be broken in order for water to change state...ice-water-steam
-This is referred to as high specific heat
-Water's high specific heat is important for many reasons. Many marine organisms need to maintain a consistent body temperature. Since it takes a large amount of energy to change the temperature of water the ocean's temperature changes subtly.
Class Demonstration:
The teacher will hold a balloon up to a candle and the students will observe what happens. The teacher will then hold a balloon to a candle that has a little bit of water added to it and the students will observe what happens. Students will then write about what they observed.
Water as a solvent
Because of water's polarity it makes a perfect solvent. It pulls ions apart separating them from their ionic bonds. This is why things dissolve in water.
pH Scale
-An Acid is something that releases H+ ions when it is added to water
-A Base is something that releases OH- ions when added to water
-A buffer is something that releases the opposite ion causing the base or acid to become neutralized.
-Hydrophobic-is something that does not mix with water (Afraid of water)
-Usually because the molecule has no charge
-Hydrophilic- is something that mixes with water (Attracted to water)
-Usually because the molecule is polar
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