Unit 2 Review AP Biology
Chapter 4 Cells
Chapter 5 Cell Membrane and
Signaling
1. Calculate surface area to volume
ratio
10 um
20 um
100 um
Surface Area
600 um2
2400 um2
60,000 um2
Volume
1000 um3
8000 um3
1000000 um3
Surface Area to
Volume Ratio
3:5
3:10
3:50
Reduced
0.6 : 1
0.3 : 1
0.06 : 1
Surface Area = 6 X length squared
Volume = length x length =x length
2. Which size cell would be the first to
get a toxin in the middle?
• The smallest cell would be first
• Why?
• The smallest cell has the greatest surface area
relative to its volume.
• The toxin would have greater opportunity to
enter the cell because of this ratio
3. Explain how prokaryotes carry out
enzymatically catalyzed biochemical
conversions without organelles?
• There are proteins in the cytoplasm moving
around.
• This motion ensures that reactions are taking
place at a rate sufficient for the cell to survive.
• There are also enzymes in the cytoplasm to
catalyze reactions.
4. Explain whether ribosomes are present
only in eukaryotes, only in prokaryotes, or
in both.
• Both
• Ribosomes make proteins and proteins are
essential in all living things
5. Describe the structure and function of as
many cellular organelles as you can in regard to
the synthesis and secretion of protein signals.
• RER – proteins are synthesized on the
ribosomes and then delivered to Golgi
• SER – stores Ca+ that trigger the secretion of
proteins that are secreted by cells
• Golgi Body – concentrates, packages, sorts
and modifies proteins to send them to their
destination
• Ribosomes – make proteins from amino acids
6. Label the membrane.
7.
Explain how the structure of the phospholipid is
amphipathic and can form a bilayer that is nonpolar
in middle and polar on the outsides
• Middle is hydrophobic due to the fatty acids
• Outside is hydrophilic due to the phosphate
groups.
8. What are the 2 primary factors that
influence membrane fluidity?
• Lipid composition and temperature
9. Explain how the ink diffused through the gel
even though there were no currents.
• By diffusion  its random and it will go until
equilibrium.
10. Describe 2 differences between passive and
active transport
Passive
• Moves materials from high
to low
• No energy needed
Active
• Moves materials from low
to high
• Requires energy
• All require proteins
11. Define and provide a description
• Isotonic
– Equal solute concentrations on each side of
membrane
– No net movement of water in/out of cell
• Hypotonic
– Low solute concentration outside the cell
– Causes enlargement of cells
• Hypertonic
– High solute concentrations outside the cell
– Causes shrinking of cells
12.
Is facilitated diffusion active or passive transport?
Explain why.
• Passive transport
• No energy is required even though there are
proteins involved.
13. Explain how cells are involved in the
transition from wilted to normal.
• Wilted  hypertonic resulting in a flaccid
appearance
• When a wilted plant is watered, water moves
in to the shrunken cells, expanding them.
Cells become plump again and has turgor
pressure.
19. Complete table.
Simple
Diffusion
Osmosis
Facilitated
Diffusion
Active
transport
Cellular Energy
required?
No
No
No
Yes
Driving force?
Concentration
Gradient
Concentration
Gradient
Concentration
Gradient
ATP hydrolysis
Membrane
protein
required?
No
Yes for some
cells, No for
others
Yes
Yes
Directional?
No
No
No
Yes
Specificity?
No
No
Yes
Yes
20. Explain the Na+K+ Pump
• 3 sodium ions get pumped OUT
• 2 potassium ions get pumped IN
• Requires 1 ATP – ATP gets broken down into
ADP + inorganic phosphate
16. Explain how phagocytosis and
pinocytosis are similar and different
Similar
• Both forms of endocytosis
• Both involve the folding of
the plasma membrane
• Both active transport
• Both bring materials into
the cell
Different
• Phagocytosis is bringing in
large particles/cells
• Pinocytosis is bringing in
fluids and dissolved
substances
17. Describe each step of cell signaling
• Signal
– Signal arrives at target. Signal molecule may be a
specific molecule or a physical stimulus.
• Receptor
– Signal molecule fits into the receptor protein and
binding occurs
• Response
– Receptor changes its 3D shape and this initiates a
cellular response
18. If a cell had no proteins, will it be able to
respond to any environmentally stimuli? Explain
• No
• Cells must have specific receptors to any
environmental stimuli and receptors are
always made of protein
19. Why doesn’t caffeine enter the
cell?
• Caffeine is large
• Caffeine is polar (see
nitrogens)
• It is unlikely to diffuse
through the plasma
membrane so it likely
will bind to a receptor
on the surfaces of nerve
cells in the brain
20. All cells have
• Cytoplasm
• Plasma membrane
• ribosomes
21. Animals HAVE (and plants
don’t)
•
•
•
•
•
•
Lysosomes
Centrioles
Flagella
Cilia
More rounder shape
Smaller and more vacuoles
22. Plants HAVE & animals don’t
•
•
•
•
Cell wall
Chloroplast
Square shape
Central vacuole
23. Prokaryote vs. Eukaryote
Pro
• Older
• No nucleus (nucleiod)
• No organelles
• Simpler ribosomes
• Bacteria is an example
Euk
• Younger
• Nucleus and nuclear
membrane
• Organelles
• Complex ribosomes
• Plants, animals, fungi and
protists are examples
Exam:
•
•
•
•
20 multiple choice – cells (chapter 4)
9 chapter 5
3 cell signalling ch 4
Short Answer
– Labeling Chapter 4
– Calculate % change in mass
– Calculate SA:V ratio
– Calculate solute potential
– Calculate standard deviation
• 10 point essay