Which statement best explains how the structure of a starch molecule relates to its function?
A- A branching structure makes the molecule stronger.
B- A branching structure has more chemical bonds than an unbranched structure.
C- A branching structure provides many points where enzyme digestion can take place and release glucose molecules.
D- A branching structure contains bonds that are harder to break.
My choice is C.
Which characteristic do glycogen and starch share?
A- Both are storage forms of glucose.
B- They are the most energy-rich organic molecules.
C- They are proteins.
D- Both are difficult to digest.
My choice is A.
Most lipids contain long chains of which two atoms?
A- water and phosphorus
B- water and carbon
C- carbon and hydrogen
D- carbon and oxygen
My choice is C.
Which statement best relates to how the structure of a lipid influences the lipid’s function?
A- The ends of the lipid are attached to each other.
B- Lipids contain fatty acids and glycerol.
C- A phospholipid has a charged head and an uncharged tail.
D- A lipid is made up of a long chain of phosphorus molecules.
My choice is C.
To determine the correct answer for the first question, you would need to understand the structure and function of starch molecules. Starch is a polysaccharide composed of glucose monomers. The answer choice C states that a branching structure provides many points where enzyme digestion can take place and release glucose molecules, which is the correct explanation for its function. To understand this, you can break down starch molecules using enzymes, such as amylase, that break the glycosidic bonds between glucose units at the branching points, releasing glucose for energy.
For the second question, you need to identify the shared characteristic between glycogen and starch. Both glycogen and starch are storage forms of glucose, serving as a reserve of energy for cells. Therefore, the correct answer is A.
To answer the third question, you need to determine the atoms present in most lipids. Lipids are composed of carbon, hydrogen, and occasionally oxygen atoms. The correct answer is C because carbon and hydrogen atoms are two fundamental components of lipid molecules.
For the fourth question, you need to relate the structure of a lipid to its function. The structure of a phospholipid consists of a charged head (hydrophilic) and an uncharged tail (hydrophobic). This arrangement allows phospholipids to form the lipid bilayer of cell membranes, with the hydrophilic heads facing the watery environment inside and outside the cell, while the hydrophobic tails point towards each other, creating a barrier. Therefore, the correct answer is C.
For the first question, you chose option C: A branching structure provides many points where enzyme digestion can take place and release glucose molecules. This is the correct answer. Starch is made up of long chains of glucose molecules that can be branched or unbranched. The branching structure of starch allows for more points where enzyme digestion can occur, leading to the release of glucose molecules.
For the second question, you chose option A: Both are storage forms of glucose. This is the correct answer. Both glycogen and starch are storage forms of glucose in living organisms. They are used to store energy and can be broken down when needed to provide glucose for cellular processes.
For the third question, you chose option C: carbon and hydrogen. This is the correct answer. Most lipids are composed of long chains of carbon and hydrogen atoms. This is what gives lipids their hydrophobic properties and allows them to serve as a source of energy storage, insulation, and protection for cells.
For the fourth question, you chose option C: A phospholipid has a charged head and an uncharged tail. This is the correct answer. The structure of a phospholipid consists of a hydrophilic (charged) head and a hydrophobic (uncharged) tail. This unique structure allows phospholipids to form the lipid bilayer in cell membranes, which controls the movement of substances in and out of the cell.