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EOC Review Overview—Everything you need to know in one place for that last minute cram session!
Scientific Processes
Hypothesis:
*Is it a prediction of what you think will happen?
*does it directly answer the question for the experiment?
*does it include the variables? (If…(independent variable)…, then…(dependent variable)…
EX: Adding apple peelings to soil will increase the number of tomatoes that grow on my plants.
(If you prefer if/then: If I add apple peelings to the soil, then the number of tomatoes that grow will increase).
Independent Variable:
*the specific thing that you are changing/comparing in the experiment
EX: different additives to the soil (orange peels, potato peels, apple peels, zucchini peels)
Dependent Variable:
*the thing that will be affected by the changes of the independent variable (the ‘results’ of your experiment)
EX: the number of tomatoes on the plant
Control Group:
*not all experiments have one!
*this is something that is not affected by the independent variable—it is used for comparison
EX: tomato plants with no additives in the soil
Controlled Variables:
*the things that should stay the same in your experiment.
*you should only be changing your independent variable, so controlled variables include all of the
other details of the experiment
EX: amount of water, type of tomato plant, amount of sun, etc
Conclusion:
*similar to your hypothesis, but it is an answer instead of a prediction
*talk about your hypothesis—was is supported by this experiment? Was it not supported?
*should have at least two sentences!
EX: My hypothesis was not supported by the data. The data from this experiment shows that plants with potato plants in
the soil produced the most tomatoes.
***Remember that we need multiple trials for an experiment to be valid! More trials=more validity!!!
Biochemistry
Hydrogen bonds: weak bonds between molecules that contain hydrogen. EX: in a glass of water, the
bonds that hold the H2O molecules together
Ionic bonds: bond the atoms inside a molecule together when one atom gives electrons to another
atom, which results in a positive and negative charge. The charge attracts the atoms together
Covalent bonds: bond the atoms inside a molecule together when atoms share electrons. The sharing
‘binds’ the atoms together. EX: in H2O, the H’s are attached to the O because they are sharing electrons
Reactants: the ‘ingredients’ of a chemical reaction CH4 + 2O2  CO2 + 2H2O
Products: molecules created from a chemical reaction CH 4 + 2O2  CO2 + 2H2O
Catalyst: a substance that speeds up a chemical reaction and makes it require less energy
Enzyme: a protein that is a catalyst in a chemical reaction—it helps the reaction to happen, but it is not changed or ‘used
up’ in the reaction, so it can be re-used.
Organic Macromolecules: large molecules (polymers) made of smaller molecules (monomers), contain carbon, hydrogen, oxygen
Carbohydrates: made of smaller sugar molecules, used for cellular respiration (energy)
Proteins: made of amino acid molecules, used for enzymes and ‘building blocks’
Lipids: made of fatty acid molecules, used to store energy
Nucleic Acids: made of nucleotides, used in genetic information (DNA, RNA)
Cells
Two types of cells: prokaryotic and eukaryotic
Prokaryotic: no nucleus, simple cells, all unicellular, ex=all bacteria
Eukaryotic: have nucleus, membrane-bound organelles, mostly multicellular, ex=animals, plants, etc
Eukaryotic cell organelles: (*=plant cells only)
Nucleus: contains genetic information
Nuclear membrane: surrounds nucleus
Cell wall: thick, rigid, outside layer of cell, helps maintain shape
*Cell membrane: surrounds cell
Cytoplasm: substance inside of cell membrade (does not include nucleus)
*Chloroplast: turns sun energy into food molecules (glucose)—where photosynthesis happens
Mitochondria: turns food molecules into ATP (energy)—where cellular respiration happens
Ribosome: makes proteins
ER: pathway inside cell, makes lipids, contains ribosomes
Golgi body/apparatus: specializes and packages proteins
Vacuole: stores water and waste (plant cell vacuoles are large)
Lysosome: removes waste molecules in the cell
Hypertonic: more solute in the solution (if a salt solution is hypertonic, a cell in it will shrink because the water will move out of the
cell into the solution to try to make the salt less concentrated) Hyper=shrink
Hypotonic: less solute in the solution (if a salt solution is hypotonic, a cell in it will swell/explode because the water will move from
the solution into the cell to try to make the cell less concentrated) Hypo=swell like a hippo
Remember that the goal is BALANCE (equilibrium)--usually water is the only molecule that can move through the membrane to
create the balance, so just figure out which way the WATER would move to make things more equal. If your lemonade is too strong,
you add water to it to make it less concentrated.
Diffusion: molecules easily move from an area of high concentration to an area of low concentration (broken perfume)
Osmosis: diffusion of water molecules
Facilitated diffusion: diffusion that requires a ‘passageway’; does not require energy
Active transport: moving molecules against the concentration gradient (from low to high)—requires energy
Photosynthesis/Cellular Respiration
Photosynthesis
What is it? Chemical reaction that converts the sun’s energy into food molecules (energy is stored in food molecules)
In which organisms does it happen? Autotrophs-plants, algae, and some bacteria make their food molecules in their cells
Where does it happen? In the chloroplasts of autotrophs’ cells
What happens? Carbon Dioxide + Water + Sun’s energy  Food/Glucose
+ Oxygen (waste)
CO2
+ H2O + sunlight 
C6H12O6
+ O2
Explained: The cells use carbon dioxide and water to convert the sun’s energy into food molecules (also referred to as
glucose/sugar/carbohydrate). Oxygen is a waste product of photosynthesis
Cellular Respiration
What is it? Chemical reaction that converts food molecules into energy molecules called ATP (cells use ATP as ‘fuel’)
In which organisms does cellular respiration happen? ALL organisms perform cellular respiration in their cells! Plants,
animals (yes, YOU!), fungi, protists, bacteria
Where does it happen? In the mitochondria of organisms’ cells
What happens? Glucose (food) + Oxygen  Energy! + Carbon Dioxide (waste) + Water (waste)
C6H12O6
+ O2
 ATP
+
CO2
+
H2O
Explained: Food molecules contain stored energy, but cells can only use energy from ATP molecules, so cells use food
molecules and oxygen to make the ATP they need. Carbon dioxide and water are waste products, which is why you breathe
out CO2. From one glucose molecule, a cell can gain as many as 36 ATP molecules!
What if there is not enough oxygen available for cellular respiration? Fermentation is a process that can make ATP from glucose
without oxygen. It is kind of like mini-cellular respiration, without oxygen. The cell only gains 2 ATP from fermentation (better than
none!). Lactic acid or alcohol are waste products of fermentation.
This ATP molecule you speak of—how does it work? ATP (adenosine TRIphosphate) is a molecule with three phosphates. When a
cell needs energy, it breaks off one phosphate, which releases the energy that the cell needs! This leaves ADP (adenosine
DIphosphate), which can be recycled back to ATP again in cellular respiration.
It looks like Photosynthesis is just the opposite of Cellular Respiration--what is up with that? It IS the opposite! Since autotrophs
(plant cells) do BOTH photosynthesis and cellular respiration, the molecules that come out of photosynthesis are used for cellular
respiration and the molecules that come out of cellular respiration are used for photosynthesis. The overall reason it all happens is
to convert the sun into food and then convert the food into ATP. It is a big process to transform the sun’s energy into energy the cell
can use (ATP).
Heterotrophs (animals, fungi, etc) don’t do photosynthesis, so where do they get the ‘ingredients’ for cellular respiration?
From eating other organisms and breathing!
DNA/Protein Synthesis
DNA is a molecule made of smaller molecules called nucleotides. A nucleotide is made of a sugar, a phosphate, and a nitrogen base.
Three nitrogen bases in a row are called codons and they are codes for amino acids. When you combine amjno acids, you get a
protein. DNA is codes for your proteins.
RNA is a
DNA Replication-making copies of DNA
Each cell needs a full set of DNA, so before a cell divides, it does DNA replication. The DNA opens and a new strand is build
on each side. This results in two identical DNA molecules, each half old and half new.
Protein Synthesis-using DNA codes to make protein molecules; happens in two steps:
Step 1: Transcription-the DNA can’t leave the nucleus, but the codes of DNA need to get to the ribosome, so mRNA copies
DNA’s codes in the cell’s nucleus, then the mRNA travels to the ribosome
Step 2: Translation-the ribosome ‘reads’ the DNA codes off of the mRNA and it makes the proteins according to the codes.
Remember, the codes are for amino acids, which are put together to create proteins.
How are DNA and RNA different?
DNA is double stranded, it has deoxyribose sugar, and it contains the nitrogen bases A, T, C, and G
RNA is a single strand, it has ribose sugar, and it contains the nitrogen bases A, U, C, and G
Genetics
You get two of each type of chromosome; one set from your mom’s egg and one set from you dad’s sperm. Your genetics are
determined by the genes on those chromosomes.
Alleles are different genes for a trait. Ex: the alleles for hair line are straight and widow’s peak
Some alleles are dominant and some are recessive. Dominant alleles turn off recessive alleles, which ‘hides’ your recessive
alleles. Ex: if you have an allele for dimples and an allele for no dimples, the ‘dimples’ allele turns off the ‘no dimples’ allele
and you will have dimples. We use letters to make an easy key: A=dimples, a=no dimples (recessive is always lower case)
Your genotype is the alleles you get for a trait. Possible genotypes:
Homozygous dominant-two of the same dominant allele (AA)
Heterozygous-two different alleles (Aa)
Homozygous recessive-two of the same recessive allele (aa)
Your phenotype how your body expresses your genes (aka-what you look like)
If someone’s genotype is AA or Aa, their phenotype would be ‘has dimples’
If someone’s genotype is aa, their phenotype would be ‘no dimples’
You use a Punnett square to determine the probability of the offspring of parents. Put the possible alleles from the mom on one
side and the possible alleles from the dad on the other side and see what combinations the kids can get.
Ex, Mom is Aa and dad is aa:
dad
A
a
a
Aa
a
Aa
aa
a
aa
Mom’s genotype: Aa, heterozygous
mom Mom’s phenotype: has dimples
Dad’s genotype: aa, homozygous recessive
Dad’s phenotype: does not have dimples
Possible kid genotypes: 50% Aa, 50% aa
Possible kid phenotypes: 50% with dimples
50% no dimples
Sometimes, alleles are codominant, which means that they are BOTH equally dominant and they BOTH show up in the phenotype.
Ex: red and white hair in cattle is codominant, so R=red and W=white (both are capital because both are cominant) RR=red cow,
WW=white cow, and RW=roan cow (has both red and white hairs)
Sometimes, alleles are incompletely dominant, which means that neither allele is dominant, and they blend together. Ex:
snapdragon flower color is incompletely dominant, so R=red, r=white RR=red flowers, rr=white flowers, and Rr=pink flowers
(neither allele shows, but the phenotype is a blending of the two)
Some alleles are sex-linked (on your sex chromosomes). A girl gets two of the same sex chromosomes (X’s), so she gets two alleles
for those traits. A boy gets one X chromosome from his mom and a Y chromosome from his dad, so he only gets ONE allele for sexlinked traits because X and Y chromosomes have different genes. Color blindness is recessive trait on the sex chromosomes
A=normal, a=color blind If a girl is XAXa, she is not colorblind. If a boy is XaY, he will be colorblind. For sex-linked crosses, you need
to include their X and Y chromosomes in the Punnett squares.
Natural Selection: if your genetic traits help you to survive your environment (=fitness), then you will be able to reproduce more
and contribute your ‘good’ genes into the population for future generations. If your genes are not good for the environment, you
will not be able to reproduce as much and your ‘bad’ genes will not be added to the population.
Gene Pool-the genes that are present in a population of organisms