IB Bio HL I Semester 1 Exam Review
questions with correct answers
Outline the Cell Theory - .......🔷ANSWERS🔶......✔✔ -All organisms are composed of one or more
cells
-Cells are the smallest unit of life
-All cells come from pre-existing cells
Discuss the evidence for Cell Theory - .......🔷ANSWERS🔶......✔✔ -Robert Hooke uses microscope
to observe living cells
-Louis Pasteur performs chicken broth experiment to prove that cells come from pre-existing cells
Outline the therapeutic uses of stem cells - .......🔷ANSWERS🔶......✔✔ -Implanted stem cells to
rebuild brain tissue for Parkinson's and Alzheimer's
-Replace any lost cell due to injury or disease
Compare Prokaryotic and Eukaryotic cells - .......🔷ANSWERS🔶......✔✔ prokaryotes- much smaller
and simpler than eukaryotes; 1st cell to appear on earth; makes up bacteria
eukaryotes- bigger/more complex than prokaryotes; have more organelles; make up algae, protozoa,
fungi, plants and animals
State three differences between plant and animal cells - .......🔷ANSWERS🔶......✔✔ - smaller
vacuoles in animal cells
- plants have cell wall
- plants have chloroplasts
Outline two roles of extracellular components - .......🔷ANSWERS🔶......✔✔ cell wall-
protects/maintains plant cell; provides filtering mechanism to keep cell from overflowing with water
glycoproteins- secreted by animal cells; composed of a protein and a carb; found in ECM; allow for
movement of cell
, How do hydrophobic and hydrophilic properties of phospholipids help maintain the structure of cell
membranes? - .......🔷ANSWERS🔶......✔✔ The membrane is made up of phospholipid molecules
that have hydrophobic tails and hydrophilic heads. Because the cell is surrounded in water, the tails
face inward to each other and the heads face outward. This phospholipid bilayer allows for a stable
but flexible cell membrane. Since the phospholipids are in a fluid shape, it allows the cell to easily
change shape.
List the functions of membrane proteins - .......🔷ANSWERS🔶......✔✔ Membrane proteins can act
as:
-hormone binding sites
-electron carriers
-pumps for active transport
-channels for passive transport/enzymes
-cell to cell communication
-cell adhesion
Define diffusion and osmosis - .......🔷ANSWERS🔶......✔✔ Diffusion-passive movement of particles
from a region of high concentration to a region of low concentration.
Osmosis-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
- .......🔷ANSWERS🔶......✔✔ Simple diffusion- diffusion of molecules through phospholipid bilayer
Facilitated diffusion- uses channel proteins embedded in the membrane
Explain the role of protein pumps and ATP in active transport across membranes
- .......🔷ANSWERS🔶......✔✔ Active transport uses ATP to transport substances through the
membrane, which allows for substances to move against the gradient. This is possible b/c the cell
membrane has embedded protein pumps, which only allows for a certain substance to control what
goes in and out of the cell.
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