IB BIOLOGY EXAM SCRIPT VERIFIED
QUESTIONS WITH FULL SOLUTION
●● Discuss the evidence for the cell theory.
Answer: 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).
Answer: 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.
Answer: 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.
Answer: 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]
Answer: 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?
Answer: By expressing some of their genes but not others.
●● What two abilities do stem cells have?
Answer: Stem cells retain the capacity to divide and have the ability to
differentiate along different pathways.
●● Outline one therapeutic use of stem cells.
Answer: 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?
Answer: Binary fission
●● Compare prokaryotic and eukaryotic cells.
Answer: 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.
Answer: 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.
Answer: Hormone binding sites, immobilized enzymes, cell adhesion,
cell-to-cell communication, channels for passive transport, and pumps
for active transport.
QUESTIONS WITH FULL SOLUTION
●● Discuss the evidence for the cell theory.
Answer: 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).
Answer: 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.
Answer: 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.
Answer: 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]
Answer: 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?
Answer: By expressing some of their genes but not others.
●● What two abilities do stem cells have?
Answer: Stem cells retain the capacity to divide and have the ability to
differentiate along different pathways.
●● Outline one therapeutic use of stem cells.
Answer: 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?
Answer: Binary fission
●● Compare prokaryotic and eukaryotic cells.
Answer: 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.
Answer: 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.
Answer: Hormone binding sites, immobilized enzymes, cell adhesion,
cell-to-cell communication, channels for passive transport, and pumps
for active transport.
