Midterm Test Review-Intro to Biology
Distinguish between quantitative and qualitative data.
o Quantitative Data is a measurable observation, usually to do with numbers.
o Qualitative data is data that can be observed that can be described but not measured.
Example: primatologist Alison Jolly has spent over 40 years making
observations of lemur behavior during field research in Madagascar,
amassing data that is mostly qualitative.
Distinguish between a scientific theory and a hypothesis.
o Hypothesis is a proposed explanation for a set of observations. A good hypothesis leads
to predictions that scientists can test.
o Scientific theory is much broader in scope than a hypothesis.
Scientific theory has supported evidence
Scientific theory describes a great diversity of observations that are
supported by evidence.
Describe seven properties common to all life.
A highly ordered structure that typified life.
Living cells are the basis of this organization because they are the smallest units
Organisms reproduce their own kind
o Growth and Development
Inherited information in the form of DNA controls the pattern of growth and
development of all organisms.
o Energy Processing
When a predators eats its prey, the predator will use the chemical energy in its
prey to power its own activities and chemical reactions.
o Response to the environment
All organisms respond to environmental stimuli
Many types of mechanisms regulate an organisms internal environment, keeping
it within limits that sustain life.
o Evolutionary Adaptation
Adaptations evolve over many generations, as individual traits with traits best
suited for their environment have greater reproductive success and pass on their
traits to their offspring.
Describe the levels of biological organization from molecules to the biosphere, noting the
interrelationships between levels and discuss how hierarchical organization and evolution tie
together all major themes in biology.
o 1) Biosphere
All of the environments on earth that support life.
Includes: Regions of land, bodies of water and the lower atmosphere.
o 2) Ecosystem
All the organisms living in a particular area, as well as the physical component
with which the organisms interact with (such as air, soil, water and sunlight) o 3) Community
The entire array of organisms. So all the species inhabiting in a certain area.
o 4) Population
All the individuals of a particular species, living in an area.
o 5) Organism
An individual living thing
o 6) Organ System
Several organs that co-operate in a specific function. Such as circulatory system
or nervous system.
o 7) Organ
An organ is made up of several different tissues
Ex. Our brain
o 8) Tissue
Is made up of a group of similar cells that perform a specific function.
Ex. Nervous System
o 9) Cell
A fundamental unit of life.
Ex. Nerve cell
o 10) Organelle
A membrane-enclosed structure that performs a specific function in a cell
o 11) Molecule
Is a cluster of small chemical units called atoms held together by chemical bonds.
Discuss how Hierarchial organization and evolution tie together all major themes in biology.
o At each new property, there are novel properties that arise, properties that were not
present at the preceding level
o Emergent properties is an important theme in biology because everything is always
developing and coming together.
Explain why cells are a special level in biological organization.
o Cells are the fundamental unit of life
o Cells are the smallest unit of life
Chemistry and Macromolecules
Describe the importance of chemical elements to living organisms and relate major principles of
chemistry to the study of biology.
o All types of matter (anything that occupies space) are composed of elements. Elements
are substances that cannot be broken down to other substances by ordinary chemical
o About 25 elements are essential to life, the 4 most common are oxygen, carbon,
hydrogen, and nitrogen.
These 4 elements are the main ingredients for biological molecules such as
proteins, sugars, and fats. (these 4 elements make up 96% of human weight)
o Calcium and phosphorous are responsible for bone formation.
o Potassium, sodium, calcium, and chlorine are essential for nerve signalling (4% of human
o Trace elements are needed for all forms of life
Iron is vital for energy processing and for transporting oxygen in your
Iodine is essential for hormone produced by thyroid gland Iodine deficiency= goitre or retardation
o Fluoride reduces tooth decay
Describe the structure of an atom and be able to sketch a representative structure when given key
information about an element.
o An atom is the smallest unit of matter that retains properties of an element.
o The structure of an atom consists of 3 kinds of particles
Proton: a subatomic particle with a single positive electrical charge (+)
Electron: a subatomic particle with a single negative charge (-)
Neuron: a subatomic particle with a neutral charge (no charge)
Electrons move around the nucleus
The attraction between the electrons and the protons hold the electrons
near the nucleus
o Atomic Number: all atoms of a particular element have a unique number of protons (# of
protons = # of electrons, making the net electrical charge = 0)
o Mass Number: The sum of protons and neutrons in the nucleus in daltons.
Proton=1 Dalton, Neutron= 1 Dalton
Electron = 1/2000 dalton
Compare and contrast between ionic, hydrogen, and covalent bonds.
o Ionic Bonds:
Attraction between ions of opposite charges, when the attraction holds them
together it is called an ionic bond
The transfer of an electron between two atoms
An ion is an atom or molecule with an electrical charge resulting from a gain or
loss of one or more electrons.
Loose electron= electrical charge of +1
Gain of electron= electrical charge of -1
The environment affects the strength of an ionic bond
o Hydrogen Bonds:
The weakest kind of bond
Most large molecules are held in their 3-dimentional shape by weak hydrogen
A hydrogen atom that has formed a polar covalent bond with an electronegative
atom (ex: oxygen or nitrogen). The hydrogen atom then has a partially positive
charge which allows it to be attracted to partially negative atoms (usually
oxygen or nitrogen atom).
Hydrogen bonds help create a proteins shape (and thus its function) and hold two
strands of DNA molecules together..
o Covalent Bonds:
Is the strongest kind of chemical bond
Where two atoms share one or more pairs of outer shell electrons
Two or more atoms held together by covalent bonds form a molecule
An atoms attraction for shared electron is called its electronegativity.
The more electronegative an atom = the more strongly it pulls shared electrons
towards to nucleus.
o Non-polar covalent bonds:
o When electrons are shared between atoms.
o When two or more atoms exert an equal pull on the electrons. Ex. Molecules of only 1 atom
H2o or O2 (water or oxygen)
Oxygen O2 is the most electronegative atom
o Polar Covalent Bonds:
o Unequal sharing of electrons
o It is the pulling of shared, negatively charged electrons closer to the more
This makes the atom partially negative and the other atom partially
Ex. H2O=Oxygen is slightly negative and the hydrogens are
Ex. Polar molecules: an unequal distribution of charges.
Describe chemical reactions in terms of atomic structure and bonding and explain how they
change the composition of matter.
o Basic theme of chemistry:
The structure of atoms and molecules determine the way they behave.
o The chemical behaviour of an atom is determined by the number and arrangements of its
subatomic particles, particularly its electrons.
o Chemical reactions is the breaking and making of chemical bonds leading to changes in
composition of matter.
o Chemical reactions do not create nor destroy matter; they only rearrange it in various
o Properties emerge when atoms combine to form molecules and when molecules interact.
o In chemical reactions, they rearrange matter in various ways, which changes the shape
and therefore the function of the molecule.
List and define the life-supporting properties of water and relate them to the structure of water.
o We can trace waters life-supporting properties through their structure, interactions, of its
molecules, their polarity, and their hydrogen bonds between molecules.
o Hydrogen bonds make liquid more cohesive
Cohesion: the tendency of molecules of the same kind to stick together.
The cohesion for water is much stronger than it is for other liquids.
Adhesion: the clinging of one substance to another
Surface Tension: a measure of how difficult it is to stretch or break the surface of
Hydrogen bonds give water a high surface tension.
o Water has a stronger resistance to temperature change then most other substances
Heat is absorbed in order to break hydrogen bond
Heat is released in order to make hydrogen bonds
Waters resistance to temperature change stabilizes ocean temperatures
Water is 60% of body weight, the water helps moderate your temperature.
o When a water evaporates, the surface of liquid remains behind cools down, while the
molecules with the greatest energy (the hottest ones) leave.
Evaporative cooling prevents land-dwelling organisms form overheating.
o As water freezes, each molecule makes stable hydrogen bonds.
The ice has fewer molecules than an equal volume of liquid water. Hence ice is
less dense then liquid water so the ice floats on top. This ice ―blanket‖ prevents water below from freezing allowing aquatic
mammals to survive.
o In many cases water is a solvent (the dissolving agent) and other substances are the
solute (what gets dissolved, ex. like salt)
Water is a solvent because of the polarity of its molecules
o Water and ions are attracted to each other due to their opposite charges
The hydrogen end of a water molecule has a positive charge so it attracts
negatively charged ions.
The oxygen end of a water molecule has a negative charge so it attracts to
positively charged ions.
Water surrounds and separates all ions.
o Water dissolves other ionic compounds as well.
o Water dissolves non-ionic compounds as well
o Water dissolves large molecules, with ionic or polar regions as well.
Solvent inside all blood cells.
Water dissolves an enormous variety of solutes necessary for life.
What is the difference between heat and temperature?
o Heat is the amount of energy associated with the movement of atoms and molecules in a
body of matter. So the total amount of heat energy
o Temperature is the intensity of heat, so the average speed of molecules.
Explain the pH scale and the formation of acid and base solutions.
o pH stands for potential of hydrogen
o Use pH scale to describe how acidic or basic a solution is
o The pH of 1 is very acidic
o The pH of 14 is very basic
o The pH of 7 is neutral, neither an acidic or basic (H+) = (OH-)
The pH of most living things is close to 7. A slight change can be very harmful
because the proteins and other complex molecules in the cell are very sensitive to
the concentration of (H+) and (OH-)
o Each level down the pH scale has 10 times more hydrogen ions (H+), hence ten times
o Each pH unit represents a 10-fold change in the concentration of H+
Ex. For example, lemon juice at pH 2 has 10 times more H than an equal of a
cola at amount pH 3 and 100 times more H than tomato juice at pH 4.
o A compound that donates hydrogen ions (H+) to solutes is called an acid
An acidic solution has a higher concentration of hydrogen ions (H+) then
hydroxide ions (OH-)
o A base is a compound that accepts hydrogen ions and removes them from a solution.
Base donate OH- , this OH- combines with H+ to form H2O, therefore reducing
the H+ concentration
Basic solutions are called alkaline solutions
o What is a buffer?
Biological fluids contain buffers
Buffers are substances that minimize changes in pH, they do this by accepting
H+ when it is an excess and donating H+ when it is depleted.
Add small amount of acid to water, pH goes from 7 to 2
Add same amount to acid of blood (with buffers) pH goes from 7.4 to 7.3 Describe the importance of caron to life’s molecular diversity (NOT ON LEARNING
OBJECTIVES BUT DID IT ANYWAYS)
o Almost all molecules a cell makes are composed of carbon atoms bounded to one another
and atoms of other elements.
o Carbon has the ability to form large and complex molecules, which built the structures
and carry out the functions required for life.
o Carbon-based molecules are called organic compounds
o Carbon is considered the lead player in chemistry because it only has 4 electrons in its
valence shell, and it is able to hold another 4 bonds.
The number of electrons in the outermost shell of its atoms determines an
element’s chemical properties. A carbon atom has 4 electrons in a valence shell
that holds 8. Carbon completes its outer shell by sharing electrons with other
atoms in four covalent bonds ( see Module 2.6). Thus, each carbon atom is a
connecting point from which a molecule can branch in up to four directions.
Each carbon can branch off in 4 different directions
Compounds composed of only carbon and hydrogen are called hydrocarbons.
Methane and propane are examples of hydrocarbon fuels. As components of fats,
longer hydrocarbons provide fuel to your body cells.
The chain of carbon atoms in an organic molecule is called a carbon skeleton (
shaded in gray in the figure).
o Compounds with the same formula but different structural formulas are called isomers
Isomers can result from different spatial arrangements of the 4 partners bonded to
a carbon atom.
The different shapes of isomers result in unique properties and add to the
diversity of organic molecules.
o Six Chemical Groups important to life
The first 5 are functional groups. These groups are polar because oxygen and
nitrogen atoms exert a strong pull on shared electrons. This polarity tends to
make these groups hydrophilic (water loving) and therefore soluble in water.
The sixth group is a methyl group, this group is non-polar and not reactive, but it
affects molecular shape and therefore its function.
o HYDROXYL GROUP- A hydroxyl group consists of a hydrogen atom bonded to an
oxygen atom, which in turn is bonded to the carbon skeleton. Ethanol, shown in the table,
and other organic compounds containing hydroxyl groups are called alcohols.
o CARBONYL GROUP- In a carbonyl group, a carbon atom is linked by a double bond
to an oxygen atom. If the carbonyl group is at t