Cell & Molecular Biology Unit 1 Exam
UPDATED ACTUAL Questions and
CORRECT Answers
List the three assertions of the cell theory and describe their consequences. - CORRECT
ANSWER - 1. All organisms consist of one or more cells.
2. The cell is the basic unit of structure for all organism.
3. All cells arive from pre-existing cells.
Consequences??
Compare cellular components in terms of relative size. - CORRECT ANSWER -
Eukaryotic Cells are about 50 micrometers in total size and Prokaryotic Cells are about 2
micrometers in total size.
From largest to smallest components:
-Nucleus ~15 um
-Mitochondrion ~1x3um but some cells can have thousands
-Chloroplast ~3x10 um but only in plant cells which can have thosands as well
-Ribosome ~25nm
-Membrane ~8nm
-DNA ~2nm thick this can be miles long
Differentiate between a hypothesis and a theory. - CORRECT ANSWER - Hypothesis: a
purposed explanation
Theory: unifying principle that explains a body of facts, composed of many hypotheses and
cannot be proven wrong rather a piece of it or one of the hypothesis.
Define the term "model organism" and explain their value to research as well as their limitations.
- CORRECT ANSWER - A model organism is a well studied organism that is used in
biological studies to draw insight on other related organism.
-advantages: typically inexpensive, small, easy to care for, and extensively studied
, -disadvantages: pontential error in conclusions based on generalization
Describe the characteristics of carbon that make it the best atom for the construction of
biological molecules. - CORRECT ANSWER - Due to the atomic weight, valence, and
electronegativity of Carbon, it has high stability and diversity.
Carbon has high stability when all 4 valence shell openings are filled, commonly through 4
covalent bonds. In the purposes of biology covalent bonds are considered the strongest bonds,
differing from chemistry where ionic bonds are strongest but they are also highly dissolvable. In
biology carbon covalent bonds are used frequently in organic synthesis. Covalent Bond facts-
cannot be broken by vibrational energy unless heated (why homeostatis is important) and cannot
be broken by visible light but can be by UV light from the sun if not properly protected.
Carbon has high diversity due to carbon binding 4 molecules and the huge amount of variety this
can create. With the use of functional groups the different characteristics are created. Functional
groups facts- utility, polar/non-polar, energy conservbation selection (more complex = more
energy), less enzymes needed if use smaller amounts of functional groups with repeats.
Phosphate example- used for DNA backbone, ATP, and phospholipids, increases diversity while
conserving energy.
Electronegativity of carbon is high, meaning the nucleus of carbon attracks electrons stronger.
(Oxygen and Nitrogen are also used for organic molecules)
Describe the characteristics of water and its roles in the cell that make it so important to life. -
CORRECT ANSWER - Our bodies are 75-80% water.
The structure of water creates a asymmetric charge distribution creating polarity and hydrogen
bonds.
Cohesion - suface tension can keep molecules in and out, can move without an active pumping
system
Temerature Stabilization - water has a high heat for vaporization, when a constant release of
energy from chemical reactions only some loss of heat which dissipated throughout the water.
Describe the structure of a cell membrane and how it enables the membrane to function as a
selectively permeable barrier. - CORRECT ANSWER - The cell membrane is a define
boundary composed of a lipid bilayer serving as the physical barrier. This layer creates a
nonpolar fatty acid center and a polar phospholipid wall (amphiphilic structure) , this causes
polar molecules to be repealed by the membrane. Also the embedded proteins control exchange
through allowing specific pathways of entry for polar molecules or large molecules. The
structure is easily changed in fluidity and rigidity and is fairly self healing.
UPDATED ACTUAL Questions and
CORRECT Answers
List the three assertions of the cell theory and describe their consequences. - CORRECT
ANSWER - 1. All organisms consist of one or more cells.
2. The cell is the basic unit of structure for all organism.
3. All cells arive from pre-existing cells.
Consequences??
Compare cellular components in terms of relative size. - CORRECT ANSWER -
Eukaryotic Cells are about 50 micrometers in total size and Prokaryotic Cells are about 2
micrometers in total size.
From largest to smallest components:
-Nucleus ~15 um
-Mitochondrion ~1x3um but some cells can have thousands
-Chloroplast ~3x10 um but only in plant cells which can have thosands as well
-Ribosome ~25nm
-Membrane ~8nm
-DNA ~2nm thick this can be miles long
Differentiate between a hypothesis and a theory. - CORRECT ANSWER - Hypothesis: a
purposed explanation
Theory: unifying principle that explains a body of facts, composed of many hypotheses and
cannot be proven wrong rather a piece of it or one of the hypothesis.
Define the term "model organism" and explain their value to research as well as their limitations.
- CORRECT ANSWER - A model organism is a well studied organism that is used in
biological studies to draw insight on other related organism.
-advantages: typically inexpensive, small, easy to care for, and extensively studied
, -disadvantages: pontential error in conclusions based on generalization
Describe the characteristics of carbon that make it the best atom for the construction of
biological molecules. - CORRECT ANSWER - Due to the atomic weight, valence, and
electronegativity of Carbon, it has high stability and diversity.
Carbon has high stability when all 4 valence shell openings are filled, commonly through 4
covalent bonds. In the purposes of biology covalent bonds are considered the strongest bonds,
differing from chemistry where ionic bonds are strongest but they are also highly dissolvable. In
biology carbon covalent bonds are used frequently in organic synthesis. Covalent Bond facts-
cannot be broken by vibrational energy unless heated (why homeostatis is important) and cannot
be broken by visible light but can be by UV light from the sun if not properly protected.
Carbon has high diversity due to carbon binding 4 molecules and the huge amount of variety this
can create. With the use of functional groups the different characteristics are created. Functional
groups facts- utility, polar/non-polar, energy conservbation selection (more complex = more
energy), less enzymes needed if use smaller amounts of functional groups with repeats.
Phosphate example- used for DNA backbone, ATP, and phospholipids, increases diversity while
conserving energy.
Electronegativity of carbon is high, meaning the nucleus of carbon attracks electrons stronger.
(Oxygen and Nitrogen are also used for organic molecules)
Describe the characteristics of water and its roles in the cell that make it so important to life. -
CORRECT ANSWER - Our bodies are 75-80% water.
The structure of water creates a asymmetric charge distribution creating polarity and hydrogen
bonds.
Cohesion - suface tension can keep molecules in and out, can move without an active pumping
system
Temerature Stabilization - water has a high heat for vaporization, when a constant release of
energy from chemical reactions only some loss of heat which dissipated throughout the water.
Describe the structure of a cell membrane and how it enables the membrane to function as a
selectively permeable barrier. - CORRECT ANSWER - The cell membrane is a define
boundary composed of a lipid bilayer serving as the physical barrier. This layer creates a
nonpolar fatty acid center and a polar phospholipid wall (amphiphilic structure) , this causes
polar molecules to be repealed by the membrane. Also the embedded proteins control exchange
through allowing specific pathways of entry for polar molecules or large molecules. The
structure is easily changed in fluidity and rigidity and is fairly self healing.
