Biology I Exam #2 | Questions with 100% Verified Answers
| Latest Update 2026/2027
Question: cell theory
Answer: the cell is the fundamental unit of life in all organisms & cells come only from
preexisting
cells
Question: key functions of lipids
Answer: makes up cell membrane, energy storage
Question: 2 primary functions of the cell membrane
Answer: 1. define cell boundary
2. regulation of molecules
Question: main components of the cell membrane
Answer: - lipids
- proteins
- carbohydrates
Question: what contributes to the fluidity of a membrane?
Answer: lipid types & characteristics of fatty acid chains
Question: amphipathic
Answer: having both hydrophilic & hydrophobic regions
Question: which part of a phospholipid is hydrophilic?
Answer: head
Question: which part of a phospholipid is hydrophobic?
Answer: fatty acid tails
Question: main function of a phospholipid
Answer: forms the cell membrane
Question: lipid bilayer
Answer: 2 layers of lipids
,Question: which part of the phospholipid is tucked inside the
membrane?
Answer: nonpolar, hydrophobic tail
Question: why is the polar part of the phospholipid facing outward?
Answer: can form bonds
Question: liposome
Answer: spherical bilayer structure
- forms in aqueous environment at neutral pH
Question: why is pH important?
Answer: ensures polar head is in ionized form--makes them hydrophilic
Question: 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
Question: saturated fats
Answer: - NO carbon=carbon double bonds
- straight structure
- tight packing --> reduces mobility (fluidity)
Question: unsaturated fats
Answer: - carbon=carbon double bonds
- kinked structure
- reduced tightness of packing --> enhances mobility (fluidity)
, Question: cholesterol
Answer: makes up 30% of cell membrane
Question: which part of cholesterol is hydrophilic?
Answer: hydroxyl group on steroid ring A
Question: what role does cholesterol play in a cell membrane?
Answer: helps with tight-packing
Question: 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
(interact w/ hydrophilic head of phospholipid)
Question: 2 types of membrane proteins
Answer: 1. integral
2. peripheral
Question: integral membrane proteins
Answer: permanently associated w/ membrane
- unable to be separated
- hydrophilic AND hydrophobic regions
| Latest Update 2026/2027
Question: cell theory
Answer: the cell is the fundamental unit of life in all organisms & cells come only from
preexisting
cells
Question: key functions of lipids
Answer: makes up cell membrane, energy storage
Question: 2 primary functions of the cell membrane
Answer: 1. define cell boundary
2. regulation of molecules
Question: main components of the cell membrane
Answer: - lipids
- proteins
- carbohydrates
Question: what contributes to the fluidity of a membrane?
Answer: lipid types & characteristics of fatty acid chains
Question: amphipathic
Answer: having both hydrophilic & hydrophobic regions
Question: which part of a phospholipid is hydrophilic?
Answer: head
Question: which part of a phospholipid is hydrophobic?
Answer: fatty acid tails
Question: main function of a phospholipid
Answer: forms the cell membrane
Question: lipid bilayer
Answer: 2 layers of lipids
,Question: which part of the phospholipid is tucked inside the
membrane?
Answer: nonpolar, hydrophobic tail
Question: why is the polar part of the phospholipid facing outward?
Answer: can form bonds
Question: liposome
Answer: spherical bilayer structure
- forms in aqueous environment at neutral pH
Question: why is pH important?
Answer: ensures polar head is in ionized form--makes them hydrophilic
Question: 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
Question: saturated fats
Answer: - NO carbon=carbon double bonds
- straight structure
- tight packing --> reduces mobility (fluidity)
Question: unsaturated fats
Answer: - carbon=carbon double bonds
- kinked structure
- reduced tightness of packing --> enhances mobility (fluidity)
, Question: cholesterol
Answer: makes up 30% of cell membrane
Question: which part of cholesterol is hydrophilic?
Answer: hydroxyl group on steroid ring A
Question: what role does cholesterol play in a cell membrane?
Answer: helps with tight-packing
Question: 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
(interact w/ hydrophilic head of phospholipid)
Question: 2 types of membrane proteins
Answer: 1. integral
2. peripheral
Question: integral membrane proteins
Answer: permanently associated w/ membrane
- unable to be separated
- hydrophilic AND hydrophobic regions
