Question

1. what is the chemical formula for this oligosaccharide?

c6h12o6
c18h36o18
3c6h12o6
c18h32o16

1. which of the following refers to the process of hydrolysis?

in hydrolysis, a molecule of water is released when two molecules are joined together.
the end result of hydrolysis is a chain of molecules such as an oligosaccharide.
water is needed for hydrolysis to take place.
hydrolysis is the process in which plants and animals create complex molecules such as carbohydrates and proteins.

1. what will be the end product(s) of the following dehydration synthesis reaction?

c6h12o6 + c6h12o6 + c6h12o6 + c6h12o6 →?
c24h46o23 + h2o
c24h44o22 + 2h2o
c24h42o21 + 3h2o

Explanation:

Step1: Analyze the oligosaccharide structure

The oligosaccharide shown is made up of 3 monosaccharide units. Each monosaccharide has the formula $C_6H_{12}O_6$. When monosaccharides combine to form an oligosaccharide through dehydration - synthesis, a water molecule ($H_2O$) is removed for each bond formed. Here, since 3 monosaccharides combine, 2 water molecules are removed.
The total number of carbon atoms from 3 $C_6H_{12}O_6$ units is $3\times6 = 18$, hydrogen atoms is $3\times12=36$ and oxygen atoms is $3\times6 = 18$. Removing 2 water molecules (2 oxygen and 4 hydrogen atoms), we get $C_{18}H_{32}O_{16}$.

Step2: Recall the definition of hydrolysis

Hydrolysis is a chemical reaction in which water is used to break down a compound. Water is needed for hydrolysis to take place. In dehydration - synthesis, water is released when two molecules are joined together, which is the opposite of hydrolysis. The end - result of hydrolysis is the breakdown of a large molecule into smaller ones, not the formation of a chain like an oligosaccharide. Plants and animals create complex molecules through processes like dehydration - synthesis, not hydrolysis.

Step3: Analyze the dehydration - synthesis reaction

When 4 molecules of $C_6H_{12}O_6$ combine through dehydration - synthesis, for each bond formed between two monosaccharides, one water molecule ($H_2O$) is released. When 4 monosaccharides combine, 3 water molecules are released.
The total number of carbon atoms from 4 $C_6H_{12}O_6$ units is $4\times6=24$, hydrogen atoms is $4\times12 = 48$ and oxygen atoms is $4\times6=24$. Removing 3 water molecules (3 oxygen and 6 hydrogen atoms), we get $C_{24}H_{42}O_{21}+3H_2O$.

Answer:

1. D. $C_{18}H_{32}O_{16}$
2. C. Water is needed for hydrolysis to take place.
3. D. $C_{24}H_{42}O_{21}+3H_2O$