NATIONAL MEDICAL ADMISSIONS ASSESSMENT BOARD
MEDICAL COLLEGE ADMISSION TEST (MCAT) MCAT-BIO-
2026-01
COMPREHENSIVE BIOLOGY PRACTICE EXAMINATION
Pre-Medical / Undergraduate Advanced Biology
SPRING SEMESTER EXAMINATION 2025/2026
Why is water a liquid at high temperatures?
Hydrogen bonding bonds the water molecules closer together.
What is an ampipathic molecule? give an Example.
A molecule with both hydrophobic and hydrophilic regions.
Example: PhoshpoLipid (Phospho=philic,lipid= phobic)
What is a lipid?
A lipid is a biological molecule with low solubility in water.
Lipid means fat. Liposuction is fat removal.
Peptides are NOT lipids.
1
Page
, What are the 6 major groups of lipids?
1) fatty acids...
the next 3 have a 3 carbon back bone:
2) Tri-glyceride
3) Phospholipids
4) Glycolipids
5) Steroids
6) Terpenes - A large class of organic compounds. examples: smelly pine oils, beer hops aroma
and vitamin A.
What is the structure of a Tri-glyceride?
triglicerides are esters. Composed from 3 carbon glycerol backbone and 3 fatty acid chains
dangling. Each carbon chain is attached by an ester bond.
What happens if you add water to an ester group in a Tri-glyceride? How is this reaction rate
increased?
Water cleaves the ester bond into an alcohol and a carboxylic/ fatty acid. LIPASES speed are the
enzyme that speed this reaction.
in terms of water solubility, What is important to know about the longer the carbon chain in a
Tri-glyceride when broken down?
longer carbon chains are less water soluble.
2
In longer chains the polar carboxylic acid are less significant.
Page
, How soluble is a Shorter chain fatty acids?
Shorter chain fatty acids are slightly water soluble.
explain what is so special about Saturated Fatty Acids........Also, explain the melting point.
saturated fatty acids have only single, alkane bonds along the carbon chain. They have a
straighter chain and have more van der wall forces, and therefor a higher melting point.
explain what is so special about Unsaturated Fatty Acid.... Also, explain the melting point.
Unsaturated fatty acids have at least one double bond. They are not saturated with Hydrogen.
they have a LOWER melting point.
At room temperatures unsaturated fatty acids may be oily, like Healthy peanut butter.
explain the phospho-lipids structure. Where are phoshpo lipids common?
Phospholipids are also built on a 3 Carbon backbone.
One of the carbon has a Phosphate PO4 group. the other 2 carbons have carbon chains attached
by a ester bond.
This is the lollypop of the cell membrane. Esters have 2 oxygens.
What regions are poplar nonpolar in a membrane?
1)the phosphates are Polar, water lovin, hydro philic regions that face the outside.
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Page
2) Nonpolar, hydro phobic carbon chain regions face the inside.
, Explain glycolipids structure.
glycolipids have 3 carbon backbone with
2 Carbon chains attached by an ester group.
THe third carbon has a carbohydrate
What do steroids look like?
Slightly amphipathic 4 ring structures
lipids are insoluble. So how do they move through the blood?
They are usually carried by lipoproteins, like HDL or LDL.
What are the major classes of lipoproteins?
1) Chylomicrons which are the largest
2) VLDLs these are low denstiy, but large.
3) LDLs
4) HDLs. these high density lipids are the smallest, and called good proteins.
What are proteins made up of?
one or more chains of amino acids, perhaps in a crazy ass arrangement.
4
Page
MEDICAL COLLEGE ADMISSION TEST (MCAT) MCAT-BIO-
2026-01
COMPREHENSIVE BIOLOGY PRACTICE EXAMINATION
Pre-Medical / Undergraduate Advanced Biology
SPRING SEMESTER EXAMINATION 2025/2026
Why is water a liquid at high temperatures?
Hydrogen bonding bonds the water molecules closer together.
What is an ampipathic molecule? give an Example.
A molecule with both hydrophobic and hydrophilic regions.
Example: PhoshpoLipid (Phospho=philic,lipid= phobic)
What is a lipid?
A lipid is a biological molecule with low solubility in water.
Lipid means fat. Liposuction is fat removal.
Peptides are NOT lipids.
1
Page
, What are the 6 major groups of lipids?
1) fatty acids...
the next 3 have a 3 carbon back bone:
2) Tri-glyceride
3) Phospholipids
4) Glycolipids
5) Steroids
6) Terpenes - A large class of organic compounds. examples: smelly pine oils, beer hops aroma
and vitamin A.
What is the structure of a Tri-glyceride?
triglicerides are esters. Composed from 3 carbon glycerol backbone and 3 fatty acid chains
dangling. Each carbon chain is attached by an ester bond.
What happens if you add water to an ester group in a Tri-glyceride? How is this reaction rate
increased?
Water cleaves the ester bond into an alcohol and a carboxylic/ fatty acid. LIPASES speed are the
enzyme that speed this reaction.
in terms of water solubility, What is important to know about the longer the carbon chain in a
Tri-glyceride when broken down?
longer carbon chains are less water soluble.
2
In longer chains the polar carboxylic acid are less significant.
Page
, How soluble is a Shorter chain fatty acids?
Shorter chain fatty acids are slightly water soluble.
explain what is so special about Saturated Fatty Acids........Also, explain the melting point.
saturated fatty acids have only single, alkane bonds along the carbon chain. They have a
straighter chain and have more van der wall forces, and therefor a higher melting point.
explain what is so special about Unsaturated Fatty Acid.... Also, explain the melting point.
Unsaturated fatty acids have at least one double bond. They are not saturated with Hydrogen.
they have a LOWER melting point.
At room temperatures unsaturated fatty acids may be oily, like Healthy peanut butter.
explain the phospho-lipids structure. Where are phoshpo lipids common?
Phospholipids are also built on a 3 Carbon backbone.
One of the carbon has a Phosphate PO4 group. the other 2 carbons have carbon chains attached
by a ester bond.
This is the lollypop of the cell membrane. Esters have 2 oxygens.
What regions are poplar nonpolar in a membrane?
1)the phosphates are Polar, water lovin, hydro philic regions that face the outside.
3
Page
2) Nonpolar, hydro phobic carbon chain regions face the inside.
, Explain glycolipids structure.
glycolipids have 3 carbon backbone with
2 Carbon chains attached by an ester group.
THe third carbon has a carbohydrate
What do steroids look like?
Slightly amphipathic 4 ring structures
lipids are insoluble. So how do they move through the blood?
They are usually carried by lipoproteins, like HDL or LDL.
What are the major classes of lipoproteins?
1) Chylomicrons which are the largest
2) VLDLs these are low denstiy, but large.
3) LDLs
4) HDLs. these high density lipids are the smallest, and called good proteins.
What are proteins made up of?
one or more chains of amino acids, perhaps in a crazy ass arrangement.
4
Page
