AP BIOLOGY QUARTERLY 1
Exam 1
Levels of biological hierarchy starting with atoms
atoms, molecules, cells, tissue, organ, organ system, organism, population, community, ecosystem.
Define science
making observations and building models using those observations.
How is the visual field actually you doing science?
Light enters our eyes (visual data/observations), and our brains generate an image (model of the environment).
Why can we never be 100% certain of any model?
Models can always be changed since new evidence is always being found.
The major difference between scientific theory and law is that a theory provides ___, and an example of a scientific theory is:
an explanation; evolutionary theory
Mitochondria and chloroplast were once free-living bacteria. What is this theory known as? What evidence is there to back this up?
endosymbiotic theory; They have an outer membrane due to phagocytosis but the inner membrane is the original one; they have circular chromosomes similar to eubacteria; they have prokaryotic 70s ribosomes coded for by their chromosomes.
What’s the other name for phylogenetic tree?
cladogram
Chronological order, scientist who made observations, etc. to create the current DNA structure model.
Levene; behavior of polarized light passing through molecular structures. found 4 nucleotides of DNA covalently bind to each other and form rings
Chargaff; paper chromatography; A:T and C:G both have ratios of 1:1 but A/T:C/G ratios differ; this refuted the tetranucleotide model
Franklin; x-ray crystallography; observed DNA’s helical structure; found that DNA is a double helix, there are A form and B form DNA
Goal of paper chromatography and how is it able to do this
separate substances in a mixture, based on charge or solubility
First organisms on earth were likely heterotrophs. What is this idea known as? Why do we think this?
heterotroph hypothesis; Aerobic respiration would have been too complex for the first organisms on earth (they were likely bacteria-like and simple)
First major biological macromolecule to evolve is _? Why?
RNA because it makes proteins, which make DNA.
Universe is composed of almost entirely 2 elements:
Hydrogen and helium. Some larger elements like carbon and iron form within stars, but most elements form during a supernova, forming a nebula, that will eventually coalesce to form planets.
Conclusion of the Miller-Urey Experiment?
Early Earth was likely able to create organic molecules abiotically.
Exam 2
Identify the 2 general cell types on Earth.
Eukaryotic; Eukaryotes
Prokaryotic; Eubacteria and Archaebacteria
Differences:
eukaryotes have a nucleus and membranous organelles
prokaryotes have 1 circular chromosome, while eukaryotes have many linear chromosomes
Two common organelles:
cell membrane
ribosomes
Define temperature. What is happening on the molecular level when the temperature of a substance increases?
Temperature is the average kinetic energy of all particles in a substance. When temperature increases, the velocity increases and particles in the substance speed up and move faster.
Explain why valence electrons in atoms with more than one shell don’t experience the full nuclear charge.
Shielding; kernel electrons repel valence electrons.
How to calculate Zeff?
number of protons - number of kernel electrons = Zeff
The atomic number is the number of __
protons. Isotopes have a different number of neutrons. The mass number is the number of protons plus neutrons while the atomic mass is the average mass of all isotopes of an element/
Explain why a C-H covalent bond is relatively non-polar while an O-H bond is polar.
C-H is relatively nonpolar since distance of H is closer to the nucleus, but C has a higher Zeff of 4+ (H has a Zeff of 1+). O-H is polar since O pulls e- closer to its nucleus than H does, and its Zeff of 6+ is higher than H’s (1+).
Why does oxygen have a higher attraction for its valence electrons than nitrogen?
larger Zeff (6+ while N has 5+), pulls e- closer to nucleus since it is a smaller atom than nitrogen.
Why can’t nitrogen take an electron beyond octet?
Electrons would be repelled, and nitrogen only needs 3 bonds to fill its valence shell.
Why are non-polar substances hydrophobic?
no charge
structure waters create around nonpolar substance?
hydration cage
Why Nitrogen makes the number of bonds that it does in a neutral molecule
A nitrogen-16 atom has 9 neutrons and 7 protons in its nucleus, and therefore 7 electrons. In the ground state, there are 2 electrons in the first shell and 5 in the second shell. Therefore it will make 3 covalent bonds. This is because it needs 3 electrons to fill the valence shell and become stable. Valence shell needs 8 electrons to be full.
Within nucleus there are 2 relevant universal forces…
Strong force; holds protons and neutrons together
Electronegativity; protons repel each other because they have the same charge.
gravity
weak force
A force is that which causes an object to…
accelerate, which means to speed up, slow down, or change direction.
Exam 3
Why does water have a bent geometry but CO2 is linear?
Lone pairs on water’s O repel bonds with H, creating its bent shape (that’s the farthest they can be repelled). C of CO2 has no lone pairs, and the farthest that the bonds with O repel each other to create CO2’s linear shape.
What about ATP’s structure gives it energy? What universal force?
3 negative phosphates repelling each other on ATP; electronegativity
What’s the other main function of ATP?
RNA nucleotide
What makes a molecule “Organic”?
It must have carbon and hydrogen
Why does water have an unusually high specific heat and heat of vaporization?
Water has a really high concentration of hydrogen bonds.
Water is a really good substance to use for evaporative cooling because it has a relatively high __
heat of vaporization
Potential energy is stored in an object due to the object’s ___
free energy.
Define energy
ability to accelerate
What parts of organic molecule specifically contain available energy?
valence electrons not bound to oxygen
What force allows these particles to have this energy?
electromagnetic force.
Define oxidation
losing electrons
Define reduction
gaining electrons
A bunch of glucose is on fire in a beaker. In the chemical reaction, which substance is losing electrons, and which is gaining?
Oxygen gains electrons, glucose loses electrons.
Why is the substance above spontaneously taking electrons from the other substance?
Oxygen is more electrophilic than most atoms in glucose.
Why do organic molecules not just ignite at room temperature?
high activation energy
what are the products of a combustion reaction?
CO2 + H2O
Where does energy go during cellular respiration?
ATP, other atoms, air/environment
Function of a buffer
make pH of a solution harder to change.
Exam 4 + 5
Different proteins have different structures and functions because they have different __
amino acid sequences. Many proteins require additional tools to function. These tools are known as cofactors. Two examples are zinc and ATP
Two general groups of amino acids are ___
nonpolar and polar, with the latter group further dividing into those that are ionic and hydrophilic. We would expect to find amino acids from the polar group on the SURFACE of a soluble protein. The group to which an amino acid belongs is determined by its side chain, also known as the R-group. When amino acids are part of a polypeptide we no longer refer to them as amino acids, but instead call them peptides. Additionally, if a protein consists of multiple polypeptides, each is typically called a subunit, and hemoglobin would have 4.
Rationale for why humans turn off the gene that codes for lactase + what is the advantage?
Energy conservation/it takes too much energy to digest lactose. By turning it off, you can give that energy to other enzymes/other crucial processes. Another advantage is adapting to the surrounding resources/not as reliant on milk.
Looking at the tripeptide above, the next amino acid will be added to the
C terminus by the ribozyme, which catalyzes the reaction known as dehydration synthesis. This catalyst is made mostly of ribosome, which is where it gets its name, and is known as a
When 2 cysteine side chains come close together in a protein, a
disulfide bond could form between them, which is a covalent bond and will stabilize the protein structure allowing it to tolerate a wider range of temperatures.