Ch.5 - Biological MoleculesSee all chapters
All Chapters
Ch.1 - Introduction to Biology
Ch.2 - Chemistry
Ch.3 - Water
Ch.4 - Carbon
Ch.5 - Biological Molecules
Ch.6 - Cells
Ch.7 - The Membrane
Ch.8 - Energy and Metabolism
Ch.9 - Respiration
Ch.10 - Photosynthesis
Ch.11 - Cell Signaling
Ch.12 - Cell Division
Ch.13 - Meiosis
Ch.14 - Mendelian Genetics
Ch.15 - Chromosomal Theory of Inheritance
Ch.16 - DNA Synthesis
Ch.17 - Gene Expression
Ch.18 - Regulation of Expression
Ch.19 - Viruses
Ch.20 - Biotechnology
Ch.21 - Genomics
Ch.22 - Development
Ch.23 - Evolution by Natural Selection
Ch.24 - Evolution of Populations
Ch.25 - Speciation
Ch.26 - History of Life on Earth
Ch.27 - Phylogeny
Ch.28 - Prokaryotes
Ch.29 - Protists
Ch.30 - Plants
Ch.31 - Fungi
Ch.32 - Overview of Animals
Ch.33 - Invertebrates
Ch.34 - Vertebrates
Ch.35 - Plant Anatomy
Ch.36 - Vascular Plant Transport
Ch.37 - Soil
Ch.38 - Plant Reproduction
Ch.39 - Plant Sensation and Response
Ch.40 - Animal Form and Function
Ch.41 - Digestive System
Ch.42 - Circulatory System
Ch.43 - Immune System
Ch.44 - Osmoregulation and Excretion
Ch.45 - Endocrine System
Ch.46 - Animal Reproduction
Ch.47 - Nervous System
Ch.48 - Sensory Systems
Ch.49 - Muscle Systems
Ch.50 - Ecology
Ch.51 - Animal Behavior
Ch.52 - Population Ecology
Ch.53 - Community Ecology
Ch.54 - Ecosystems
Ch.55 - Conservation Biology
Nucleic Acids
Additional Practice
Cumulative Macromolecules

Concept #1: Lipid Structure

Practice: Fats are polymers of fatty acids.

Practice: Which of the following lipids can interact with water?

Practice: It requires energy for phospholipids to form a lipid bilayer in water

Practice: The addition of cholesterol molecules _________________________ membrane fluidity.

Additional Problems
A common lipid for energy storage is a. phospholipid b. steroid c. triglycerides d. cholesterol
Biological membranes contain bilayers of which of the following lipids? a. phospholipids b. oils c. triglycerides d. sex hormones
Part of a phospholipid is nonpolar.a. Draw a square around the portion of the molecule that is nonpolar.b. Would this portion of the phospholipid interact well with water? Explain your reasoning.
Explain why the flexibility (fluidity) of a membrane increases when more of the hydrocarbon tails in the phospholipids layers contain double bonds.
Which of the following describes an example of self-assembly in cells? a. formation of a phospholipid bilayer through hydrophobic interactions. b. formation of sugar polymers from sugar monomers from enzyme reactions. c. folding of proteins through local structure formation. d. All of the above describe self-assembly.
The molecule cholesterol plays an important role in a. keeping membranes liquid at low temperature. b. keeping membranes solid at high temperature. c. both a and b. d. neither a nor b.
Saturated fats have long straight tails of fatty acids, while unsaturated fats from vegetables have kinks in their tails due to double bonds. These kinks prevent the fats from packing together as tightly. Hydrogenated vegetable oils have hydrogens added back to the double bonds and thus behave like ____. a. Unsaturated fatsb. Carbohydratesc. Proteind. Saturated fats
What essential function would lipids play in the origin of life?  a. The formation of membranes b. Storage of information c. Catalysis of reactions d. Formation of a cytoskeleton e. Anaerobic fermentation
A fatty acid is unsaturated if there is at least one double bond between the carbon atoms in that fatty acid.  a. True b. False
Consumption of fats with unsaturated fatty acids is supposed to be better for humans than fats with saturated fatty acids. How do unsaturated fatty acids differ from saturated fats? How does that change affect their properties?
How does a triglyceride differ from a carbohydrate?
A phospholipid is a _____.A. nonpolar lipid molecule that is made amphipathic by the addition of a phosphateB. polar lipid molecule that fully interacts with waterC. nonpolar lipid molecule that is made polar by the addition of a phosphateD. polar lipid molecule that fully repels water
When phospholipids are added to water, they spontaneously form cell memranes. Explain this observation.
Which of the following lipids would not be found in cell membranes?A. cholesterolB. free fatty acidsC. phospholipidsD. All of the above are components of cell membranes
Do fats and waxes have similar structures? Explain.
Which of the following statements regarding the fatty acid tails of phospholipids is FALSE?a) Phospholipids with unsaturated tails make the bilayer more fluid because the tails contain fewer hydrogen atoms and thus form fewer hydrogen bonds with each other.b) Saturated phospholipid tails pack more tightly against each other than do unsaturated tails.c) Most membrane phospholipids have one fully saturated tail.d) Phospholipid tails in a membrane can interact with each other via van der Waals interactions.e) Fatty acid tails vary in length.
Which of the following is NOT a function in which lipids play an important role?A. Storing genetic informationB. Chemical signalingC. VisionD. Storing energyE. Membrane structure
Lipids and their derivatives can be _____.A. insoluble in waterB. All of these statements regarding lipids are correct.C. important constituents of biological membranesD. important for energy storageE. hydrophobic or amphipathic
Which of the following statements about a micelle and a ipid bilayer is NOT true?A. Both assemble spontaneuosly in water.B. Both are made up of amphipathic molecules.C. Both are very large, sheetlike structures.D. Both are stabilized by hyrdophobic interaction, van der Waals forces, hydrogen bonds, and electrostatic interactions.
A phospholipid contains each of the following components except:A. triacylglycerolB. fatty acid tails (2)C. polar head groupD. phosphoryl groupE. glycerol backbone
Distinguish between saturated and unsaturated fats and stinguish between saturated and unsaturated ats and n dis and trans fat molecules.
The steroid structure contains _____ six-carbon and _____ five-carbon rings.
What is the difference between a saturated and an unsaturated fat?
Describe the structure characteristics of water and phospholipids. Include how these characteristics result in bilipid membrance formation. Mention the bonds and forces involved.