HESI Entrance Exam: Biology
1. What is the main function of the lipid bi layer
It is a barrier between the inside and outside of a cell. It is impermeable
2. Why is it called lipid bilayer?
2 layers of lipid (fat) molecules
3. phospholipid has what 2 distinct regions
Hydrophilic: attracted to water
Hydrophobic: repelled from water
4. Phospholipid is considered a?
Amphipathic because it is both polar and non-polar
5. Why aren’t the 2 layers of lipid bilayer identical?
Because of the fluidity. lipids and proteins freely move around
6. Will you find the same set of membrane proteins in each cell membrane? -
No. Different proteins are needed in different regions of cells
7. What are the names of the two membrane proteins? explain each?
Integral: embedded in lipid bilayer, aren’t easily removed, transmembrane protein peripheral:
attached to the exterior of lipid bilayer, easily separated, less mobile
8. Alpha helix: adopts DNA naturally
9. which class of proteins, integral or peripheral, are freer to move around in lipid bilayer:
integral
10.The cell is covered in an additional set of molecules. what is their name and function:
glycocalyx, protects cell from damage
11. Why is it necessary for cell membranes to have proteins help transport molecules?
The lipid bi layer is impermeable, so outside structures have to help transport large polar
molecules across membrane
12.what is the name of the natural process where molecules flow from an area of higher
concentration to an area of lower concentration? diffusion
13.difference between behavior of channel and carrier proteins?
Channel: no binding required, allow molecules to diffuse across membrane
1/6
, carrier: allow molecules to pass through by undergoing a change when molecule binds. the
change opens a hole where the molecule can enter or exit 14. function of ionophore:
increase membranes permeability to an ion
15. 3 functions of membrane transport:
• 1.maintain distribution of ions across cell membrane
• maintain proper cellular pH
• mediate communication between cells
16. Cell Wall: Thick rigid layer covering plasma membrane in cells. composed of fat and sugar
molecules
17. chloroplast: containing chlorophyll and responsible for photosynthesis
18. chlorophyll: absorbs sunlight
19. photosynthesis: changing light in to sources for life in plant
20 vacuoles: found only in plants, fluid filled, composes of 90 percent of cells volume and performs
many functions like digestion
21. plant and animal cells are both: eukaryotic
22. animal cell is? micrometers: 10-30
23. plant cell is? micrometers: 10-100
24. plant cells use? as energy source: sunlight
25. inner membrane of chloroplast encloses: stoma
26. stoma: houses dan, RNA, ribosomes, and different enzyme
27. cell wall surrounds: cell membrane
28. cell wall is? micrometers: .1-10
29. cell wall is composed of: fats and sugars
30. what is purpose of cell wall: stability and protection
31. vacuoles are: large liquid filled organelles
32. vacuoles take of? % of cell volume: 90 %
33. vacuoles are what kind of membrane: single membrane
34. 4 roles of vauoles: space filler, digestive, stores nutrients a place to degrade unwanted
substances
35. name 3 things different in a plant cell then in an animal cell: vacuoles, cell wall,
chloroplasts
36. why are chloroplasts found in plant cells but not animal cells: because they are
responsible for photosynthesis
2/6
1. What is the main function of the lipid bi layer
It is a barrier between the inside and outside of a cell. It is impermeable
2. Why is it called lipid bilayer?
2 layers of lipid (fat) molecules
3. phospholipid has what 2 distinct regions
Hydrophilic: attracted to water
Hydrophobic: repelled from water
4. Phospholipid is considered a?
Amphipathic because it is both polar and non-polar
5. Why aren’t the 2 layers of lipid bilayer identical?
Because of the fluidity. lipids and proteins freely move around
6. Will you find the same set of membrane proteins in each cell membrane? -
No. Different proteins are needed in different regions of cells
7. What are the names of the two membrane proteins? explain each?
Integral: embedded in lipid bilayer, aren’t easily removed, transmembrane protein peripheral:
attached to the exterior of lipid bilayer, easily separated, less mobile
8. Alpha helix: adopts DNA naturally
9. which class of proteins, integral or peripheral, are freer to move around in lipid bilayer:
integral
10.The cell is covered in an additional set of molecules. what is their name and function:
glycocalyx, protects cell from damage
11. Why is it necessary for cell membranes to have proteins help transport molecules?
The lipid bi layer is impermeable, so outside structures have to help transport large polar
molecules across membrane
12.what is the name of the natural process where molecules flow from an area of higher
concentration to an area of lower concentration? diffusion
13.difference between behavior of channel and carrier proteins?
Channel: no binding required, allow molecules to diffuse across membrane
1/6
, carrier: allow molecules to pass through by undergoing a change when molecule binds. the
change opens a hole where the molecule can enter or exit 14. function of ionophore:
increase membranes permeability to an ion
15. 3 functions of membrane transport:
• 1.maintain distribution of ions across cell membrane
• maintain proper cellular pH
• mediate communication between cells
16. Cell Wall: Thick rigid layer covering plasma membrane in cells. composed of fat and sugar
molecules
17. chloroplast: containing chlorophyll and responsible for photosynthesis
18. chlorophyll: absorbs sunlight
19. photosynthesis: changing light in to sources for life in plant
20 vacuoles: found only in plants, fluid filled, composes of 90 percent of cells volume and performs
many functions like digestion
21. plant and animal cells are both: eukaryotic
22. animal cell is? micrometers: 10-30
23. plant cell is? micrometers: 10-100
24. plant cells use? as energy source: sunlight
25. inner membrane of chloroplast encloses: stoma
26. stoma: houses dan, RNA, ribosomes, and different enzyme
27. cell wall surrounds: cell membrane
28. cell wall is? micrometers: .1-10
29. cell wall is composed of: fats and sugars
30. what is purpose of cell wall: stability and protection
31. vacuoles are: large liquid filled organelles
32. vacuoles take of? % of cell volume: 90 %
33. vacuoles are what kind of membrane: single membrane
34. 4 roles of vauoles: space filler, digestive, stores nutrients a place to degrade unwanted
substances
35. name 3 things different in a plant cell then in an animal cell: vacuoles, cell wall,
chloroplasts
36. why are chloroplasts found in plant cells but not animal cells: because they are
responsible for photosynthesis
2/6
