BIOLOGY MIDTERM STUDY GUIDE 2015
*Look over textbook, notes, labs, tests and quizzes to enhance your studying*
I.
Scientific Method
a. Steps of scientific method
b. Hypothesis
c. Theory
d. Inference vs. Observation
e. Variables
f. Control
II. Tools of a Biologist
a. Microscope
i. Labeling
ii. Function of each part
b. Identifying Lab equipment
III. Characteristics of Life
a. All of the different characteristics and examples of each
b. Asexual vs. sexual reproduction
IV.
Ecology
a. Biodiversity
b. Abiotic vs Biotic Factors
c. Levels of ogranization
i. Organims, population, community, ecosystem, biome, biosphere
d. Autotroph (producers)
e. Heterotrophs (consumers)
i. Omnivores
ii. Carnivores
iii. Herbivores
f. Competition
i. Intraspecific vs Interspecific
g. Predation
h. Symbotic Relationships
i.
Mutualism
ii.
Commensalism
iii.
Parasitism
I. Food Chain vs. Food Web
V. Cells
a.
b.
c.
Microscopes
i. Compound light microscope
ii. Scanning electron microscope
iii. Transmission electron microscope
Endosymbiosis
Scientists
i. Redi
ii. Pasteur
iii. Hooke
iv. Leeuwenhoek
d.
e.
f.
g.
h.
i.
Cell Theory
Organization- celltissueorganorgan systemorganism
Prokaryotes vs. Eukaryotes
Plants vs. Animals
Domains
Organelles
i. Labeling
ii. Functions
VI.
Biochemistry
a. Elements
i. Definition
ii. Examples
b. Atoms
i. Definition
ii. Structure
1. Protons
2. Neutrons
3. Electrons
c. Macromolecules
i. Carbs
ii. Lipids
iii. Proteins
iv. Nucleic Acids
VII.
Cellular Transport
a. Membranes
i. Labeling
ii. Phospholipids, proteins, cholesterol
b. Passive transport
i. Diffusion
ii. Osmosis
1. hypertonic
2. hypotonic
3. isotonic
iii. Facilitated Diffusion
c. Active Transport
d. Vesicular Transport
i. Endocytosis
1. Pinocytosis
2. Phagocytosis
ii. Exocytosis
e. Diffusion Lab!
i. Indicators
1. Iodine- starch
2. Benedict’s solution- glucose
ii. What crossed the membrane?
VIII.
Cellular Energy
a. Types of energy
i. Chemical
ii. Solar
iii. Autotrophs
iv. Heterotrophs
b.
Photosynthesis
i. Reaction
ii. Starting materials
iii. Process
iv. Products
v. 2 Types of reactions
1. Label Diagram
2. Light reactions
a. Where do they occur?
b. What goes in, what comes out?
3. Dark Reactions/ Calvin Cycle
a. Where does it occur?
b. What goes in, what comes out?
4. Diagram of a chloroplast
a. Stroma
b. Thylakoid
c. Grana
I. What is the Scientific Method? The scientific method is a process that uses
questioning, analysis, and evidence to solve a problem or answer a question.

Step 1. Make an Observation. After making an observation of the natural world, define
the problem/question…Be specific and investigate one problem/question at a
time. ALL scientific experimentation starts with observation!
EXAMPLE: An OBSERVATION is any perceived characteristic of the natural world that is
OBJECTIVE (the same for everyone), this includes anything that can be QUANTIFIED (can
be measured) or QUALIFIED (has a describable quality like color or smell)

Step 2. Research the problem (question). Use all available resources to collect data on
the problem/question being investigated in order to form the most logical and informed
hypothesis you can. Libraries, Internet, books, magazines, personal interviews, etc.
EXAMPLE: Any time an observation is made, the observer makes one or many conscious or
subconscious INFERENCE(S). An INFERENCE is any SUBJECTIVE (may differ between
people) conclusion that is drawn from an observation. Inferences take into account logic,
prior experience, prior knowledge, and other factors.

Step 3. Develop a hypothesis (educated guess/proposed explanation). Make it a short
definitive statement that can be proven to be true or false. Hypotheses are often presented
as an “If…Then…” statement. The “if” part will establish a condition of the hypothesis
and the “then” part will make a prediction that will be proven or disproven at the end of
the controlled experiment. Hypotheses are often modified, or changed, over many rounds
of experimentation.
A PREDICTION is an outcome that is expected based on an OBSERVATION and a
given INFERENCE. Predictions may be correct or incorrect. A hypothesis is basically
a testable prediction with controlled conditions. Through experimentation we can test
the prediction to be correct or incorrect.
EXAMPLE: I walk into a room and OBSERVE a pot of water bubbling and steaming;
I make an INFERENCE that the water is boiling; I PREDICT that if the water is
boiling, then I will get burned if I touch it. I can then create a hypothesis, “If I touch
the water, then I will get burned”

Step 4. Develop a controlled experiment. A controlled experiment is an experiment that
contains only one experimental variable. An experimental or independent variable is
the thing being tested (what the scientist changes). Everything else in the experiment
or all other variables must be the same. These variables are also called the controlled
variables. Keeping these variables the same allows the experimenter to show that it was
the experimental variable alone that caused the results. The dependent variable is what
changes when the independent variable changes - the dependent variable depends on the
outcome of the independent variable. Data should be organized into charts, tables, or
graphs.
EXAMPLE: If I am investigating the relationship between how much fertilizer I give a
plant and how much it grows, the amount of fertilizer would be my independent
variable and the amount of plant growth would be my dependent variable. Everything
else must be controlled variables (amount of sunlight, water, temperature, etc.) in order
to accurately measure the effect of the fertilizer on plant growth.

Step 5. Analyze the data and come up with a conclusion. Data may
be quantitative (numbers) or qualitative(appearance, properties, etc.). The conclusion
may or may not support the hypothesis. Additional experimentation must then take place
to build documentation concerning the problem/question. If the hypothesis is proven
wrong, change the hypothesis, not the data. Scientists must be unbiased (do not take
sides or make data fit their ideas).
WHAT FOLLOWS: Scientific research must be published, but first it must be reviewed by
peers (other scientists) and verified for accuracy/reproducibility. Research may result in a
scientific theory or law (accepted as “fact” or the “best explanation” by the scientific
community).
II. Tools of a Biologist
Microscopes
1. Compound Light microscope: Uses visible light to look at a thin sample; can observe cells but
not detailed organelles



Eyepiece/Ocular Lens is always 10X magnification
Can have objective lenses of 4X, 10X, and 40X OR 10X, 40X, and 100X
To find total magnification we multiply the 10X magnification of the eyepiece
and the magnification of whatever objective lens we are using
o EXAMPLE: 10X (eyepiece) and 40X (objective lens):10 * 40 = 400X
o The weakest magnification would be 4X objective: 10 * 4 = 40X
o The strongest magnification would be 100X objective: 10 * 100 = 1000X
2. Scanning Electron Microscope (SEM): Uses an electron beam to produce 3D, surface images
of a specimen at up to 100,000X Total Magnification (think SCANNING=SURFACE)
3. Transmission Electron Microscope (TEM): Uses and electron beam to penetrate a thin sample
and produce images of a specimen at up to 300,000X Total Magnification (think
TRANSMISSION=THROUGH)
Compound Light Microscope
Identifying Laboratory Equipment Names and Functions
1. Hand lens: magnifies small objects
2. Dissecting Tray: hold specimens for dissection
3. Dissecting Pins: hold specimen on the dissecting tray
4. Forceps: grasps small objects
5. Dissecting Scissors: cut specimens to be studied
6. Dissecting Probe: pointed object used to examine specimens
7. Scalpel: cuts specimens to be dissected
8. Safety Goggles: protects eyes from fire and chemicals
9. Hot Plate: heats objects
10. Graduated Cylinder: measures liquids
11. Test Tube: holds liquids
12. Beaker: holds and measures liquids
13. Test-Tube Rack: holds test tubes
14. Electronic Balance: measures mass
15. Dropper Pipette: measures out drops of liquid
16. Pipette: transfers measured amounts of liquid
17. Compound Microscope: magnifies very small objects
18. Microscope Slide: holds object for examination with the compound microscope
19. Coverslip: covers material on a glass slide
20. Petri Dish: shallow dish used for bacterial cultures
21. Thermometer: measures temperature
22. Funnel: transfers liquid from one container to another; filters materials with filter paper
23. Metric Ruler: measures length
24. Hot Hands: protective gear to hold extreme hot or cold objects
25. Weigh-Boat: used to hold materials when they are being weighed
26. Spatula: used for transferring small amounts of dry/solid material
27. Test-Tube Holder: grabs test tube for safe handling/holding
28. Mortar and Pestle: grinds/crushes material
29. Test-Tube Brush: used to clean glassware (test tubes, beakers, etc.)
III. Characteristics of Life
Living things are/display:
A. Composed of ONE or MORE Cells…
a. Unicellular: Organisms composed of only one cell
i. Directly exchange nutrients and waste with their environment
ii. Example: Bacteria, Algae, Amoebae, Paramecia
b. Multicellular: Organisms composed of multiple/many cells
i. Specialized cells that have specific forms and perform specific
functions working together to maintain the life functions of an
organism
ii. Living things can organism simple substances into complex ones (i.e.
macromolecules)
iii. Example: Animals, Plants, most Fungi
B. Organized
a. Living things display organization and forms that fit the functions necessary
to maintain life functions
b. Living things exhibit body plans that allow them to survive in their
environment
C. Growth and Development
a. Cells can growth in size
b. Cells can divide/reproduce
D. Respond to Stimuli
a. Living things display responses to environmental stimuli
b. A stimulus (plural: stimuli) is a thing or event that elicits a response from an
organism
c. Example: Shivering (response) because it is cold (stimulus: drop in internal
temperature); Pulling away hand (response) from a fire (stimulus: tissuedamaging heat)
E. Require Energy
a. While some life processes occur spontaneously (require no input of energy),
the vast majority require an input of energy
b. Cells utilize energy in the form of ATP (Adenosine Triphosphate) in order to
drive the biochemical processes necessary to maintain life functions
c. The SUN is the ultimate source of all energy used by organisms on Earth
d. Cells obtain energy from their environment and produce waste
F. Reproduction
a. Organisms produce offspring (new members of the parent(s)’ species)
i. Asexual Reproduction: offspring are produced by a single parent,
offspring are genetically identical to the parent
1. Example: Bacteria
ii. Sexual Reproduction: offspring are produced by two parents,
offspring are a mix of each parent’s genetic material
G. Heredity
a. The passing of traits/characteristics from one generation to the next (all
qualities: physical, mental, behavioral, etc.) genetically
b. Genetic information is carried by molecules of DNA (Deoxyribonucleic Acid)
and acts as the “blueprint” or “body plan” for an organism
c. Offspring receive DNA from one (asexual reproduction) or two (sexual
reproduction) parents that dictates all aspects of their biology
H. Evolve and Adapt
a. Adaptation: the ability of an organism to change with its environment in
order to increase its chances of survival and reproduction
b. Evolution: the modification of a species (on the genetic level) over many
generations in order to maximize survival and reproduction in a dynamic
(changing) environment
i. Example: camouflage, thick fur, large brains, sharp teeth, etc.
c. A series of adaptations over many generations produces evolution and the
diversification of life we see on Earth. It is the ability of life to adapt that
allows it to endure catastrophes (like the meteor that wiped out the
dinosaurs) and drastic climate changes (think ice age)
I. Homeostasis
a. The state of stability that organisms maintain in order to continue life
functions (pH, solute concentration, temperature, etc.)
b. Although the ideal stable state varies from organism to organism, all
organisms must maintain a stable internal environment despite the state of
the external environment to survive
i. Example: Humans maintain an internal temperature of about 98.6 F
despite living in a wide range of external temperatures
IV. Ecology
Ecology: The study of interactions between organisms and their environments. Ecology includes the
study of individuals, populations, communities, ecosystems, biomes, and the biosphere.
Biodiversity: The degree of diversity present amongst living things on Earth. Diversity is indicated by
the genetic variation (number of different species) present in the various ecosystems on Earth (biosphere).
Biotic: Anything that is, or has ever been, ALIVE. Biotic factors also include organic products of life
such as waste. Examples of biotic factors in an environment include organisms, organic molecules, and
cells. Biotic is the opposite of abiotic.
Abiotic: Anything that is not, nor has ever been, alive. Some examples of abiotic factors in an
environment include precipitation, sunlight, and minerals. Abiotic is the opposite of biotic.
Niche: An organism's role/place in an environment, including how it uses its resources, relates to other
organisms, and times its reproduction. Each individual organism has a niche in its population,
community, and ecosystem, but niches are flexible and change depending on circumstances.
Habitat: The physical environment where a population of a single species lives, or inhabits. A habitat
consists of all the abiotic, or nonliving, resources influencing the population. A habitat is only understood
in terms of the population it describes. For instance, we say "the black bear habitat" or "the whale
habitat." It doesn’t describe the entire ecosystem, or a community of organisms, or even the home of a
single individual. Habitats of different species do overlap (Ex. The habitat of a lion overlaps with the
habitat of a gazelle).
Autotroph: Any living organism that makes its own food by converting simple inorganic molecules into
complex organic compounds like carbohydrates, fats, and proteins. Autotrophs are the "producers" in a
food chain or web. Autotrophs are able to capture sunlight and convert/store it as chemical energy that is
accessible to the cell (“creating” its own food in the form of glucose).
Heterotroph: An organism that cannot convert sunlight into "food" (carbohydrates). Heterotrophs must
obtain their nutrients by consuming other organisms. All animals, all fungi, and some kinds of bacteria
are heterotrophs. This means that all carnivores, herbivores, and omnivores are also heterotrophs.
Food Chain: A simple, direct, and trophic (eating) relationship among a group of organisms, where one
organism, like a plant, is the food source for the next organism, like a cow, which in turn is the food
source for the next organism, like a human, and so on and so forth. A food chain traces the flow of energy
from one type of producer to one type of primary consumer (and perhaps one type of secondary
consumer, etc.)
Food Web: A complex trophic relationship among a group of organisms, consisting of interactions
among multiple food chains (see definition above). A food web describes how
multiple producers and consumers directly or indirectly interact in a community.
Herbivore: An organism that only eats autotrophic organisms, like plants and algae. Some examples of
herbivores include members of the bovine family, like cows, bison, antelope, and sheep; members of the
deer family, like moose, reindeer, and elk; and many insects, like leaf beetles, lady bugs, and aphids.
Carnivore: An organism that only eats animals. Most predators and scavengers are exclusively
carnivorous. Some examples of carnivores include members of the feline family—like lions, tigers, and
house cats, and birds of prey—like eagles, hawks, and owls.
Omnivore: An organism that eats both plants and animals. Some examples of omnivores include
members of the hominid family—like humans, chimpanzees, and orangutans, and many bird species—
like chickens, ducks, and woodpeckers.
Decomposer: An organism that feeds on and breaks down dead or decaying matter in the process
of ecological decomposition. Examples of decomposers include fungi—like mushrooms and molds;
worms—like earthworms and some nematodes; and some bacteria. Decomposers are essential for
recycling nutrients in an ecosystem.
Detritivore: An organism that consumes detritus, aka decomposing organic matter, to obtain nutrients.
All decomposers are detritivores, including fungi, worms, and some bacteria. Decomposers are usually
associated with eating things like dead animals (think vulture eating a carcass) while detritivores are
usually associated with breaking down biotic materials (think fungus breaking down a rotting log).
Competition: An interaction where individuals of different species (interspecific competition) or the
same species (intraspecific competition) fight for limited resources.
Examples of interspecific competition include trees of different species fighting for limited
sunlight in a rainforest, birds of different species fighting for limited prey in a prairie, and even
bacteria of different species vying for limited oxygen in your large intestine.
Examples of intraspecific competition include lions fighting for mates on the Savannah, piglets
vying for limited milk from their mother, and even humans vying for limited space to build a
home.
Predation: A type of species interaction where one organism, aka the predator, consumes, in part or in
whole, another organism, aka the prey. Examples of predators include snakes and members of the big cat
family, such as lynx. The difference between parasitism and predation is that predators kill their prey
almost immediately while parasites live in or on their hosts for an extended period of time and do not
necessarily kill them.
Symbiosis: An ecological interaction between individuals of different species. Symbiotic relationships
include mutualism, parasitism, and commensalism. They DO NOT include predator-prey interactions
or competition.
Mutualism: Two organisms interact in a way that is BENEFICIAL to both
Ex. Bees and Flowers
Commensalism: Two organisms interact in a way that is BENEFICIAL to one organism and has
no impact (either beneficial or harmful) on the other.
Ex. Clownfish and Sea Anemone
Parasitism: Two organisms interact in a way that is BENEFICIAL to one organism and
HARMFUL to the other
Ex. Ticks and Mosquitoes
Levels of Biological Organization:
Organism: A single living member of a species. Ex. Humans, wolf, cucumber plant, etc.
Population: A group of organisms of the same species living in the same geographic area at the same
time. For example, all of the coyotes in a desert ecosystem, or all of the oak trees in a forest ecosystem.
Community: A group of two or more populations of organisms from different species inhabiting the
same location at the same time. Communities are composed only of biotic factors. Abiotic factors like
sunlight, temperature, and terrain are not considered part of a community; these factors are part of the
ecosystem, which can contain one or more communities of organisms.
Ecosystem: A term describing all the living and nonliving things in a certain location. Ecosystem studies
in ecology explore the interactions between organisms, like individuals, populations, or communities, and
the abiotic components in the environment, like chemical composition, landscapes, and weather patterns.
Biome: A large grouping of area that contains a number of different ecosystems. The defining
characteristics of a biome are the dominant plant life and the climate. Examples include Deserts,
Rainforests, Deciduous Forests, Savannahs, etc.
Biosphere: The entire area of the earth that supports life. The biosphere is made up of all of the
individuals, populations, communities, ecosystems, and biomes found on Earth.
V. Cells
Endosymbiotic Theory: MITOCHONDRIA and CHLOROPLASTS were once distinct
organisms that were absorbed into larger, pre-eukaryotic cells. Over billions of years, the
symbiosis between MITOCHONDRIA/CHLOROPLASTS and the EUKARYOTIC HOST
CELLS has evolved to the point that they are inseparable. MITOCHONDRIA are found in ALL
eukaryotic cells, while CHLOROPLASTS are found only in eukaryotes that perform
PHOTOSYNTHESIS. This implies that MITOCHONDRIA were acquired before the split of
animals and plants and CHLOROPLASTS were acquired after.
Scientists (make sure you know what they discovered and what their experiment was)
1. Robert Hooke:


Observed dead cork cells under a microscope
Called what he saw “cells” after the cells that monks occupied in
monasteries
2. Anton von Leeuwenhoek


First person to observe living cells
Observed living cells in a sample of pond water
3. Francesco Redi


Spontaneous Generation: In Redi’s time—the 1600s—it was commonly
believed that living organisms would randomly come in to being from
non-living materials.
Fly/Meat Experiment: A commonly-held assumption by Redi’s
contemporaries was that maggots (fly larvae) were generated in decaying
meat and dead flesh. In order to test this hypothesis, Redi placed rotten
meat in both an OPEN CONTAINER and in a CLOSED CONTAINER.
Although adult flies tried to get into BOTH containers, they could only
gain access to the meat in the OPEN CONTAINER. After some time,
maggots appeared ONLY on the meat in the open container, suggesting
that THE ADULT FLIES WERE THE SOURCE OF THE MAGGOTS
and SPONTANEOUS GENERATION DID NOT OCCUR!!
4. Louis Pasteur


Pasteurization: Process developed by Louis Pasteur after discovering that
bacteria in the air could contaminate food. By superheating and then
rapidly cooling food items, bacterial concentrations can be greatly
reduced—prolonging shelf-life and reducing spoilage/infection.
Bacteria/Broth Experiment: Preparing two flasks containing a broth
(proteins, carbohydrates, etc. to support bacterial growth), Pasteur then
sterilized them using high heat to kill any bacteria potentially present in
the broth. Now, with both flasks bacteria free, Pasteur left one flask OPEN
and left one flask CLOSED AIR-TIGHT. After some time, the OPEN
FLASK HAD BACTERIAL GROWTH, while the CLOSED FLASK
HAD NO BACTERIAL GROWTH. After opening the closed flask and
exposing it to air, it went on to DEVELOP BACTERIAL GROWTH.
This was strong evidence that bacteria is present in the air around us and
led Pasteur to develop the technique for sanitizing foods called
Pasteurization (see above). The results of this experiment also
demonstrated that CELLS MUST COME FROM OTHER CELLS!!!!
CELL THEORY: 3 Parts
1. ALL LIVING THINGS ARE COMPOSED OF ONE OR MORE CELLS
2. THE CELL IS THE MOST BASIC STRUCTURAL AND FUNCTIONAL UNIT
OF LIFE
3. ALL CELLS ARISE FROM EXISTING, LIVING CELLS
Levels of Organization within an Organism:
SimplestMost Complex
CellTissueOrganOrgan SystemOrganism
Prokaryotes vs. Eukaryotes
Prokaryote: Means “before nucleus” and includes the domains Bacteria and
Archaea
Eukaryote: Means “true nucleus” and includes the domain Eukarya
Biological Domain: The highest and most inclusive classification for life on
Earth.



Bacteria: this domain includes all bacteria, which are PROKARYOTIC
Archaea: similar to bacteria but unique in a number of ways, also PROKARYOTIC
Eukarya: this domain includes all plants, animals, and fungi, which are EUKARYOTIC
ORGANELLE STRUCTURE, FUNCTION, and LOCATION:
Cilia and Flagella
Used for movement/moving substances around
outside of the cell
Central Vacuole
Maintains shape of cell, stores water, nutrients
and waste
Chloroplast
Captures light energy and converts to sugar
Cell Wall
Maintains cell shape, works with central vacuole
to maintain turgor pressure
Centriole
organelles made of microtubules involved in cell
division
Golgi Apparatus
process materials manufactured by the cell
Smooth Endoplasmic Reticulum
Site of lipid synthesis
Rough Endoplasmic Reticulum
Site of protein synthesis
Ribosome
produces proteins
Cell Membrane
support, protection, controls movement of
materials in/out of cell
Nucleus
controls cell activities
Mitochondrion
breaks down sugar molecules into energy
Cytoplasm
fluid substance that fills the interior of the cell
Lysosome
breaks down cellular waste products and debris
(contains enzymes)
VI. Biochemistry
HINT: ATOMIC MASS will always be larger than
ATOMIC NUMBER, this will help with deciding
which one is which!!!!
ELEMENT: A substance that cannot be broken down into simpler substances by chemical
means. An element is composed of atoms that have the same atomic number, that is, each atom
has the same number of protons in its nucleus as all other atoms of that element.
MATTER: Anything that has mass and takes up space.
COMPOUND: A compound is a substance formed when two or more chemical elements are
chemically bonded together.
Acids and Bases:
Acid: Solution containing a higher concentration of H+ ions than OH- ions
Base: Solution containing a higher concentration of OH- ions than H+ ions
Neutral: Solution containing an equal concentration of H+ and OH- ions
pH SCALE:
*****Alkali is another word for BASIC*****
NEUTRALIZATION REACTION: The reaction of an acid and base to form a neutral
solution…Hydrogen Ions (H+) and Hydroxide Ions (OH-) are balanced to produce a pH 7
solution.
MACROMOLECULES: Large, organic molecules essential for life
Proteins: Responsible for Growth, repair, enzymes, and transport.
Carbohydrates: Gives us energy. Examples include glucose and fructose.
Lipids: Can be saturated or unsaturated. Used for storing energy, signaling, and acting as
structural components of cell membranes.
Nucleic Acids: Encode, transmit, and express genetic information. Found in the form of DNA
and RNA.
VII. Cellular Transport
Fluid Mosaic Model: This is a model that describes the plasma (cell) membrane of animal cells
(including humans). The membrane is composed of two layers of phospholipids
(PHOSPHOLIPID BILAYER) which are fluid (flexible and capable of movement) at animal
body temperature. The membrane functions to give the cell a definite volume (separate the
components of the cell from the surrounding environment) and to moderate what goes in and out
of the cell (keep/let beneficial things in and keep/send harmful things out). Because the
membrane is selective in what it permits in and out of the cell, it is described as
SELECTIVELY-PERMEABLE. Within the bilayer are proteins, cholesterol, and
carbohydrate chains that give it the look of a mosaic (a type of art that uses many colored
pieces). Because the components of the membrane can move freely through the membrane (like
things floating on water), the plasma membrane is described/modeled as FLUID-MOSAIC.
REMEMBER THAT PHOSPHOLIPIDS ARE A TYPE OF LIPID!!
Phospholipids: Each layer in the bilayer is composed of many units called PHOSPHOLIPIDS,
and each phospholipid is composed of a hydrophilic (“water-loving”) HEAD and a
hydrophobic (“water-fearing”) TAIL. The head of each phospholipid always faces towards
either the watery fluid outside of the cell (extracellular fluid; extra: beyond, cellular: having to do
with cellbeyond-cell fluid) or the watery fluid within the cell (intracellular fluid; intra:
withinwithin-cell fluid). The tail of each phospholipid always faces away from the extra and
intracellular fluids, so a bilayer forms with the heads on the outside and the tails facing each
other on the inside. Think of a sandwich, with the heads representing the bread on the top and the
bottom…and the middle representing the tails!
Proteins: Provide structure, enables
transport of materials through the
membrane, and anchor carbohydrate chains
Carbohydrate Chains: Acts a
receptorsending and receiving chemical
messages for the cell
Cellular Transport: The movement of materials across the plasma membrane. Transport can be
either PASSIVE or ACTIVE.
Passive Transport: The movement of particles (atoms or molecules) from a higher
concentration to a lower concentration (down the concentration gradient). Passive transport
DOES NOT REQUIRE ENERGY and will happen spontaneously until dynamic equilibrium is
reached.
DYNAMIC EQUILIBRIUM: A condition where constantly moving particles are balanced.
Equilibrium: a state in which opposing forces (motion, charges, etc.) are balanced
Dynamic: constantly changing
**In the natural world, at the molecular level, things never stop moving; because of this constant
motion they tend to spread out and become balanced through random motion. Although
atoms/molecules never stop moving, if the same amount are coming as are going, there is no
change in concentration.**
SIMPLE DIFFUSION: The movement of particles from a higher concentration to a lower
concentration. For the cell membrane, diffusion takes place across the membrane between the
outside and inside of the cell. There are a number of factors which affect the rate of diffusion
(how long it takes to reach dynamic equilibrium).
1. Temperature: higher temperatures= faster particles= faster diffusion
2. State of matter: gasses diffuse faster than liquids, liquids diffuse faster than solids
3. Concentration: The greater the difference in concentration, the faster diffusion occurs
(steeper concentration gradient). For example, diffusion would occur faster if the
concentration of glucose outside of the cell is 10x that of the inside of the cell vs. 3x.
4. Size of particles: Smaller particles diffuse faster than larger particles. This makes sense
because for the same amount of energy, something smaller can move faster than
something bigger (What can you move faster if you give it all you got: a shopping cart or
a truck?) **With a membrane, size can determine whether a substance will even be
capable of diffusion. For example, O2 (oxygen gas) can readily diffuse through the cell
membrane while large sugars cannot. Think of the permeability of a membrane as a net,
with bigger holes letting more through than smaller holes**
OSMOSIS: The diffusion of liquid water across a semi-permeable membrane. Osmosis can only
take place with liquid water and is used mostly when talking about the cell
FACILITATED DIFFUSION: To facilitate something is to help it occur. Remember how some
particles where too large to cross the cell membrane by SIMPLE DIFFUSION, or move too
slowly? This is where membrane protein channels help out by FACILITATING the diffusion of
these particles.
Active Transport: The movement of particles AGAINST the concentration gradient. This
REQUIRES CELLULAR ENERGY to perform. This is commonly seen in nerve cells, where
ions must be pumped against their concentration gradient (by…you guessed it…membrane
proteins!) in order to create an electric potential (like a battery) for signal transmission.
ENDOCYTOSIS: **”into cell” ENDO think IN** A cell envelopes an object of interest until it
forms a “bubble” around the object. The cell membrane then changes shape so that the cell
membrane is reestablished and a vesicle (containing the object) is on the inside of the cell. When
the object is solid (Ex. White blood cell “eating” a bacterial cell) it is called PHAGOCYTOSIS
(cell “eating”). When the object is some amount of liquid it is called PINOCYTOSIS (cell
“drinking”).
EXOCYTOSIS: **“out of cell” EXO think EXIT** A cell moves a vesicle (typically
containing wastes) towards the border of the cell membrane. The vesicle and the cell membrane
merge expelling the vesicle’s contents outside of the cell and reestablishing the cell membrane. It
looks a lot like endocytosis in reverse.
***When comparing the fluid within a cell and a fluid outside of a cell, we can characterize the
solution a cell is in by describing it as HYPOTONIC, ISOTONIC, or HYPERTONIC**
Hypotonic solution- the concentration of solute particles is greater within the cell than outside of
the cell; this will cause to water to enter the cell through osmosis, and the cell will swell
(possibly bursting in the process depending on a number of factors).
Isotonic solution- the concentration of solute particles in both the inside fluid and outside fluid of
the cell is in equilibrium (balanced); water content of the cell is stable and thus ideal. Although
there is no observable change, water is moving in and out of the cell at the same rate. The cell
and solution are in DYNAMIC EQUILIBRIUM.
Hypertonic solution- the concentration of solute particles is greater outside the cell than within
the cell; this will cause water to leave the cell through osmosis, and the cell will shrivel.
DIFFUSION LAB
This lab made use of two indicators—Iodine Solution and Benedict’s Solution
What is an indicator? An indicator is a chemical/substance that produces a visible color change
in the presence of another chemical/substance at certain concentrations. For instance,
Phenolphthalein will turn bright pink in solution with a high OH- concentration (base indicator).
Remember, indicators enable QUALITATIVE observation, not quantitative as there is nothing
that can be accurately and practically measured.
Iodine Solution: Tests for the presence of STARCH. Iodine solution is an amber/yellow by
itself, but in the presence of starch it turns a dark black/purple/blue. The color change can very
quickly be observed at room temperature.
Benedict’s Solution: Tests for the presence of simple sugars, in the case of the lab we tested for
GLUCOSE. Benedict’s Solution is a light, bright blue by itself, but in the presence of glucose
sugars turns orange. BENEDICT’S SOLUTION MUST BE HEATED IN ORDER TO SEE
A COLOR CHANGE!!!
EXPERIMENTAL SETUP:
Recall that we placed a solution of GLUCOSE and STARCH into dialysis tubing and tied it off
to create an environment that was isolated from the outside. Dialysis tubing forms a
SEMIPERMEABLE (allows some substances to diffuse, while preventing others from
diffusing) membrane meant to simulate a cell. We then placed the water-tight dialysis tubing
“cell” in a solution of water and iodine. After some time, it was observed that the contents of the
dialysis bag turned a dark blue/black/purple. Additionally, the water in the beaker was found to
test positive for glucose, and the mass of the dialysis bag increased in mass (after drying and
weighing). So what happened? What was able to diffuse into and out of the bag?
ABLE TO diffuse:
A. Water: the mass of the bag increased, suggesting that water was small enough to diffuse
into the bag
B. Iodine: the contents of the bag turned dark black/blue/purple, suggesting that iodine was
small enough to diffuse into the bag and contact the starch
C. Glucose: the sample from the solution surrounding the bag tested positive for glucose,
suggesting that glucose was small enough to diffuse out of the bag
UNABLE TO Diffuse
A. Starch: the solution surrounding the bag did not change color to dark black/blue/purple,
suggesting that the starch molecules were too large to diffuse out of the bag. This was
later supported when the bag was cut open, and the entire beaker solution immediately
turned dark black/blue/purple.
VIII. CELLULAR ENERGY
Types of Energy: Although energy may be classified in a number of different ways and as a
number of different types, two forms of energy are of particular interest to biologists: SOLAR
and CHEMICAL
I.
Solar Energy: Energy emitted from the Sun (essentially a nuclear fusion reactor) in
the form of LIGHT and HEAT. Light can be described by its WAVELENGTH.
Wavelength is the distance between
two identical points on a repeating
wave, in this case peak (crest) to peak,
however any repeating points could be
used (for example, trough [bottom] to
trough)
Wavelength directly relates to the energy
carried by light, with shorter wavelengths carrying more energy than longer wavelengths.
Below is the Electromagnetic Spectrum of light—a useful tool in visualizing the different
forms light can take. REMEMBER SHORTER WAVELENGTH=MORE
ENERGY!!
Reds---------Oranges----Yellows—Greens-----Blues--------Violets
***Note: the units of length are in nanometers which are one billionth of a meter!!
II.
Chemical Energy: Type of potential energy where the energy is stored in the
chemical bonds that form molecules. When certain chemical reactions takes place,
bonds are broken and energy is released. Chemical reactions can be represented using
a chemical equation in the form: ReactantsProducts. The Law of Conservation of
Mass dictates that all matter that enters a chemical reaction must leave (although in
different forms), so this helps in that we can see and track everything going in and
everything going out. SOMETIMES YOU WILL SEE SOMETHING WRITTEN
ABOVE THE ARROW (an enzyme, light, ATP, etc.) THIS MEANS THAT IT
PLAYED A ROLE IN THE REACTION BUT DID NOT DIRECTLY
PARTICIPATE. (EX. An enzyme helps a reaction take place but is not
chemically altered in the process; light is essential for photosynthesis but is not
matter and cannot, therefore, be accounted for in the reaction; the energy to
produce ATP is provided by a chemical reaction, but the reaction itself does not
involve ATP)
What we think of as food is chemical energy! Where does it come from?
Photosynthesis: photo means “light” and synthesis means “putting together”,
so photosynthesis means “putting together with light”. What is being put together?
MoleculesFOOD. Photosynthesis is a process used by plants and other
organisms to convert light energy, normally from the Sun, into chemical energy (in
the form of molecular bonds) that can be later released to fuel the organisms'
activities.
Photosynthesis takes place in a very specialized organelle found
in plant cells called the CHLOROPLAST which contains
specialized pigments that absorb visible light.

Pigment: A chemical/substance that absorbs certain wavelengths of light and reflects
others.
o Absorbance: A wavelength, or series of wavelengths, of light is/are trapped
by a pigment along with energy it/they contain(s) the visible light
wavelengths absorbed never reach your eye and, thus, are not seen.
o Reflection: A wavelength, or series of wavelengths, of light is/are scattered by
a substance the visible light wavelengths reflected are the ones that enter
your eye and are seen.
o Example: A leaf that appears green absorbs all wavelengths except for green,
and reflects it in all directions (some of this light enters your eye and causes
you to perceive the leaf as green); something that appears black absorbs all
wavelengths of visible light and appears to have no color (because no visible
light is reflected into your eye); something that appears white reflects ALL
wavelengths and appears to have every color (light of all visible wavelengths
is reflected into the eye and the brain perceives this as “white”)
**Now you know why light colors keep you cooler in the summer and dark
colors get hot faster…dark colors ABSORB more light and ENERGY (which
dissipates as heat)!!**
Important Pigments used in Photosynthesis:
I.
II.
Chlorophyll- pigment with strong absorbance in the blue and violet wavelengths, and
moderate absorbance in the orange-red wavelengths. There are two types
Chlorophyll-α (A) and Chlorophyll-β (B) CAUSES THE GREEN APPEARANCE
OF PHOTOSYNTHESIZING PLANTSREFLECTS GREEN LIGHT!!
Carotenoids- pigment with moderate absorbance in the blue and green wavelengths.
Causes the orange-yellow-red appearance of photosynthesizing plants. Typically seen
in the Fall when plants stop replenishing their chlorophyll (absorbs orange-red
wavelengths) concentrations in preparation for winter (decreased sunlight).
The Chloroplast—the Site of Photosynthesis:
Thylakoid: Site of the LIGHTDEPENDENT REACTIONS
Granum (plural Grana): Stack
of thylakoids surrounded by
the stroma
Stroma: Watery fluid (like the
cytoplasm, but thicker), site of
the LIGHT-INDEPENDENT
REACTIONS
Photosynthesis takes place through two stages:
I.
II.
The Light-Dependent Reaction (aka Light Reaction)
The Light-Independent Reaction (aka Dark Reaction aka Calvin Cycle)
The Light-Dependent Reaction:
LOCATION: THYLAKOID
 Inputs (what goes in):
o Light energy(from the Sun) In photosynthesis equation as reactant
o Water (H2O) In photosynthesis equation as reactant
o NADP+
o ADP + P
 Outputs (what comes out):
o Oxygen gas (O2) In photosynthesis equation as product
o ATP
o NADPH
The Light-Independent Reaction (Calvin Cycle):
LOCATION: STROMA
 Inputs (what goes in):
o Carbon Dioxide gas
(CO2) In
photosynthesis
equation as reactant
o NADPH
o ATP
 Outputs (what comes out):
o Glucose (C6H12O6) In
photosynthesis
equation as product