SAT Subject Test in Biology › Lipids
The phospholipid bilayer is critically important to the separation of the internal and external environment of the cell.
What drives the formation of the phospholipid bilayer?
The external environment pushes non-polar hydrophobic fatty acid tails to form the inner layer and the polar hydrophilic head groups to form the outer layer.
The external environment pushes non-polar hydrophilic fatty acid tails to form the inner layer and the polar hydrophobic head groups to form the outer layer.
The external environment pushes non-polar hydrophilic fatty acid tails to form the inner layer and the polar hydrophilic head groups to form the outer layer.
The external environment pushes non-polar hydrophobic fatty acid tails to form the inner layer and the polar hydrophobic head groups to form the outer layer.
None of these
The external hydrophilic environment attracts polar hydrophilic phosphate head groups to the exterior, while allowing non-polar hydrophobic fatty acids to remain shielded in the interior of what becomes the phospholipid bilayer.
Which organic compound serves as stored energy for living things?
Lipids
Nucleic acids
Carbohydrates
Proteins
Lipids make up the bulk of fat in animal tissues and thus stores energy.
Which of the following macromolecules are composed of long chains of amino acids?
Proteins
Carbohydrates
Lipids
Nucleic acids
Fats
By process of elimination, lipids and fats cannot be the correct answer-they are synonymous (lipids are also known as fats). Carbohydrates, eg sugars and starches are composed only of carbon, hydrogen, and oxygen. Nucleic acids contribute to DNA and RNA structure and function. The correct answer is proteins, made of long chains of amino acids-amino acids are sometimes called the "building blocks" of proteins.
Phospholipids are an essential component of the phospholipid bilayer necessary to the cell.
Which of the following correctly represents a phospholipid subunit with the corresponding polarity?
Fatty acid tail: nonpolar
Fatty acid head: nonpolar
Phosphate head: nonpolar
Fatty acid tail: polar
Phosphate tail: polar
A phospholipid generally consists of a phosphate head (polar) and a fatty acid tail (non-polar).
Lipids are made up of hydrocarbons linked to each other.
A hydrocarbon involves an atom of carbon with how many hydrogen atoms bonded to it?
Two
One
Three
Four
Five
A hydrocarbon is made up of a carbon and two hydrogen atoms attached to it.
Plants often have a waxy covering on the outside of their leaves to prevent water loss. This waxy covering probably contains mostly which organic compound?
A lipid
A carbohydrate
A nucleic acid
A protein
Major lipid groups include fats, steroids, and waxes. Because the question references a "waxy covering," we know that the plant covering must be composed of lipids.