BIOLOGY B ACTUAL EXAM FINAL SCRIPT 2026
SOLVED QUESTIONS WITH FULL SOLUTIONS
◉ key functions of lipids. Answer: makes up cell membrane, energy
storage
◉ 2 primary functions of the cell membrane. Answer: 1. define cell
boundary
2. regulation of molecules
◉ main components of the cell membrane. Answer: - lipids
- proteins
- carbohydrates
◉ what contributes to the fluidity of a membrane?. Answer: lipid
types & characteristics of fatty acid chains
◉ amphipathic. Answer: having both hydrophilic & hydrophobic
regions
◉ which part of a phospholipid is hydrophilic?. Answer: head
,◉ which part of a phospholipid is hydrophobic?. Answer: fatty acid
tails
◉ main function of a phospholipid. Answer: forms the cell
membrane
◉ lipid bilayer. Answer: 2 layers of lipids
◉ which part of the phospholipid is tucked inside the membrane?.
Answer: nonpolar, hydrophobic tail
◉ why is the polar part of the phospholipid facing outward?.
Answer: can form bonds
◉ liposome. Answer: spherical bilayer structure
- forms in aqueous environment at neutral pH
◉ why is pH important?. Answer: ensures polar head is in ionized
form--makes them hydrophilic
◉ van der Waals forces. Answer: weak binding of temporarily
polarized molecules due to attraction of opposite charges
- helps w/ sticking of cholesterol/phospholipids in a cell membrane
, ◉ saturated fats. Answer: - NO carbon=carbon double bonds
- straight structure
- tight packing --> reduces mobility (fluidity)
◉ unsaturated fats. Answer: - carbon=carbon double bonds
- kinked structure
- reduced tightness of packing --> enhances mobility (fluidity)
◉ cholesterol. Answer: makes up 30% of cell membrane
◉ which part of cholesterol is hydrophilic?. Answer: hydroxyl group
on steroid ring A
◉ what role does cholesterol play in a cell membrane?. Answer:
helps with tight-packing
◉ what is the orientation of cholesterol?. Answer: amphipathic
- hydrophobic, rigid planar group of rings & hydrophobic
hydrocarbon tail
(interacts w/ hydrophobic fatty acid tails of phospholipid)
- hydrophilic head group
SOLVED QUESTIONS WITH FULL SOLUTIONS
◉ key functions of lipids. Answer: makes up cell membrane, energy
storage
◉ 2 primary functions of the cell membrane. Answer: 1. define cell
boundary
2. regulation of molecules
◉ main components of the cell membrane. Answer: - lipids
- proteins
- carbohydrates
◉ what contributes to the fluidity of a membrane?. Answer: lipid
types & characteristics of fatty acid chains
◉ amphipathic. Answer: having both hydrophilic & hydrophobic
regions
◉ which part of a phospholipid is hydrophilic?. Answer: head
,◉ which part of a phospholipid is hydrophobic?. Answer: fatty acid
tails
◉ main function of a phospholipid. Answer: forms the cell
membrane
◉ lipid bilayer. Answer: 2 layers of lipids
◉ which part of the phospholipid is tucked inside the membrane?.
Answer: nonpolar, hydrophobic tail
◉ why is the polar part of the phospholipid facing outward?.
Answer: can form bonds
◉ liposome. Answer: spherical bilayer structure
- forms in aqueous environment at neutral pH
◉ why is pH important?. Answer: ensures polar head is in ionized
form--makes them hydrophilic
◉ van der Waals forces. Answer: weak binding of temporarily
polarized molecules due to attraction of opposite charges
- helps w/ sticking of cholesterol/phospholipids in a cell membrane
, ◉ saturated fats. Answer: - NO carbon=carbon double bonds
- straight structure
- tight packing --> reduces mobility (fluidity)
◉ unsaturated fats. Answer: - carbon=carbon double bonds
- kinked structure
- reduced tightness of packing --> enhances mobility (fluidity)
◉ cholesterol. Answer: makes up 30% of cell membrane
◉ which part of cholesterol is hydrophilic?. Answer: hydroxyl group
on steroid ring A
◉ what role does cholesterol play in a cell membrane?. Answer:
helps with tight-packing
◉ what is the orientation of cholesterol?. Answer: amphipathic
- hydrophobic, rigid planar group of rings & hydrophobic
hydrocarbon tail
(interacts w/ hydrophobic fatty acid tails of phospholipid)
- hydrophilic head group
