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