IB Biology HL Exam Review Questions and
Answers
Outline the cell theory. - -Living organisms are composed of cells.
Cells are the smallest unit of life.
Cells come from pre-existing cells.
-Discuss the evidence for the cell theory. - -The nature of scientific theories could be
introduced here: the accumulation of evidence that allows a hypothesis to become a theory;
whether a theory should be abandoned when there is evidence that it does not offer a full
explanation; and what evidence is needed for a theory to be adopted or rejected.
-State that unicellular organisms carry out all the functions of life (Name the six functions).
- -Metabolism, response, homeostasis, growth, reproduction, and nutrition.
-Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria,
organelles, and cells using the appropriate SI unit. - -Molecules: 1 nm
Thickness of membranes: 10 nm
Viruses: 100 nm
Bacteria: 1 um
Organelles: (up to) 10 um
Most cells: (up to) 100 um
-Explain the importance of the surface area to volume ratio as a factor limiting cell size. - -
The rate of heat production/waste production/resource consumption of a cell is a function
of its volume, whereas the rate of exchange of materials and energy (heat) is a function of
its surface area.
-State that multicellular organisms show emergent properties. [pen analogy] - -Emergent
properties arise from the interaction of component parts: the whole is greater than the sum
of its parts.
-How do multicellular organisms differentiate to carry out specialized functions? - -By
expressing some of their genes but not others.
-What two abilities do stem cells have? - -Stem cells retain the capacity to divide and have
the ability to differentiate along different pathways.
-Outline one therapeutic use of stem cells. - -In 2005, stem cells were used to restore the
insulation tissue of neurons in laboratory rats, resulting in subsequent improvements in
their mobility.
-How do prokaryotic cells divide? - -Binary fission
, -Compare prokaryotic and eukaryotic cells. - -Naked DNA vs. DNA associated with
proteins
DNA in cytoplasm vs. DNA enclosed in a nuclear envelope
No mitochondria vs. mitochondria
70s vs. 80s ribosomes.
Eukaryotic cells have internal membranes that compartmentalize their functions.
-Outline two roles of extracellular components. - -The plant cell wall maintains cell shape,
prevents excessive water uptake, and holds the whole plant up against the force of gravity.
Animal cells secrete glycoproteins that form the extracellular matrix. This functions in
support, adhesion, and movement.
-List the functions of membrane proteins. - -Hormone binding sites, immobilized enzymes,
cell adhesion, cell-to-cell communication, channels for passive transport, and pumps for
active transport.
-Define diffusion. - -Diffusion is the passive movement of particles from a region of high
concentration to a region of low concentration.
-Define osmosis. - -Osmosis is the passive movement of water molecules, across a partially
permeable membrane, from a region of lower solute concentration to a region of higher
solute concentration.
-Explain passive transport across membranes by simple diffusion and facilitated diffusion.
- -Simple: just passing through
Facilitated: passive
-Briefly explain a sodium-potassium pump. - -3 Na out, 2 K in
-What are tumors a result of? - -Uncontrolled cell division
-Outline interphase. - -Interphase is an active period in the life of a cell when many
metabolic reactions occur, including protein synthesis, DNA replication, and an increase in
the number of mitochondria and/or chloroplasts.
-Insulin - -Beta cells of the pancreas; converts glucose to glucogen; released when blood
sugar is high.
-Glucagon - -Alpha cells of the pancreas; converts glycogen to glucose; released when
blood sugar is low.
-Adrenaline - -"Fight or flight" increases heart rate
-Testosterone - -Sperm production, male body development
-FSH - -Stimulates oocyte development
Answers
Outline the cell theory. - -Living organisms are composed of cells.
Cells are the smallest unit of life.
Cells come from pre-existing cells.
-Discuss the evidence for the cell theory. - -The nature of scientific theories could be
introduced here: the accumulation of evidence that allows a hypothesis to become a theory;
whether a theory should be abandoned when there is evidence that it does not offer a full
explanation; and what evidence is needed for a theory to be adopted or rejected.
-State that unicellular organisms carry out all the functions of life (Name the six functions).
- -Metabolism, response, homeostasis, growth, reproduction, and nutrition.
-Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria,
organelles, and cells using the appropriate SI unit. - -Molecules: 1 nm
Thickness of membranes: 10 nm
Viruses: 100 nm
Bacteria: 1 um
Organelles: (up to) 10 um
Most cells: (up to) 100 um
-Explain the importance of the surface area to volume ratio as a factor limiting cell size. - -
The rate of heat production/waste production/resource consumption of a cell is a function
of its volume, whereas the rate of exchange of materials and energy (heat) is a function of
its surface area.
-State that multicellular organisms show emergent properties. [pen analogy] - -Emergent
properties arise from the interaction of component parts: the whole is greater than the sum
of its parts.
-How do multicellular organisms differentiate to carry out specialized functions? - -By
expressing some of their genes but not others.
-What two abilities do stem cells have? - -Stem cells retain the capacity to divide and have
the ability to differentiate along different pathways.
-Outline one therapeutic use of stem cells. - -In 2005, stem cells were used to restore the
insulation tissue of neurons in laboratory rats, resulting in subsequent improvements in
their mobility.
-How do prokaryotic cells divide? - -Binary fission
, -Compare prokaryotic and eukaryotic cells. - -Naked DNA vs. DNA associated with
proteins
DNA in cytoplasm vs. DNA enclosed in a nuclear envelope
No mitochondria vs. mitochondria
70s vs. 80s ribosomes.
Eukaryotic cells have internal membranes that compartmentalize their functions.
-Outline two roles of extracellular components. - -The plant cell wall maintains cell shape,
prevents excessive water uptake, and holds the whole plant up against the force of gravity.
Animal cells secrete glycoproteins that form the extracellular matrix. This functions in
support, adhesion, and movement.
-List the functions of membrane proteins. - -Hormone binding sites, immobilized enzymes,
cell adhesion, cell-to-cell communication, channels for passive transport, and pumps for
active transport.
-Define diffusion. - -Diffusion is the passive movement of particles from a region of high
concentration to a region of low concentration.
-Define osmosis. - -Osmosis is the passive movement of water molecules, across a partially
permeable membrane, from a region of lower solute concentration to a region of higher
solute concentration.
-Explain passive transport across membranes by simple diffusion and facilitated diffusion.
- -Simple: just passing through
Facilitated: passive
-Briefly explain a sodium-potassium pump. - -3 Na out, 2 K in
-What are tumors a result of? - -Uncontrolled cell division
-Outline interphase. - -Interphase is an active period in the life of a cell when many
metabolic reactions occur, including protein synthesis, DNA replication, and an increase in
the number of mitochondria and/or chloroplasts.
-Insulin - -Beta cells of the pancreas; converts glucose to glucogen; released when blood
sugar is high.
-Glucagon - -Alpha cells of the pancreas; converts glycogen to glucose; released when
blood sugar is low.
-Adrenaline - -"Fight or flight" increases heart rate
-Testosterone - -Sperm production, male body development
-FSH - -Stimulates oocyte development
