Lactose is composed of ________ and glucose.
Galactose
Understanding Lactose Composition
The question asks about the composition of lactose. Lactose is a type of sugar commonly found in milk. Sugars are carbohydrates, and they can be classified based on their structure and the number of sugar units they contain.
Lactose is classified as a disaccharide. Disaccharides are composed of two monosaccharide units linked together. Common monosaccharides include glucose, fructose, and galactose.
Let's look at the components of lactose:
- Lactose is formed by the linkage of two simpler sugars: glucose and galactose.
- The bond between glucose and galactose in lactose is a glycosidic bond.
Therefore, lactose is composed of glucose and galactose.
Analyzing the Options
Let's consider why the other options are not correct components of lactose:
- Fructose: Fructose is a monosaccharide, but it is a component of sucrose (table sugar), not lactose. Sucrose is made of glucose and fructose.
- Sucrose: Sucrose is a disaccharide itself, composed of glucose and fructose. It is not a component of lactose.
- Galactose: Galactose is a monosaccharide and is indeed one of the two components of lactose, along with glucose.
- Maltose: Maltose is also a disaccharide. It is composed of two glucose units linked together. It is not a component of lactose.
Based on the composition of lactose, which is glucose and galactose, the correct sugar that completes the statement is galactose.
Revision Table: Common Disaccharides
| Disaccharide | Composition (Monosaccharides) | Common Source |
|---|---|---|
| Lactose | Glucose + Galactose | Milk |
| Sucrose | Glucose + Fructose | Table sugar, cane sugar, beet sugar |
| Maltose | Glucose + Glucose | Breakdown product of starch (e.g., in malted grains) |
Additional Information on Carbohydrates
Carbohydrates are one of the main types of nutrients. They are the most important source of energy for your body. They are organic compounds made of carbon, hydrogen, and oxygen atoms, usually in the ratio 1:2:1, although this isn't always the case.
Carbohydrates are broadly classified into three main types:
- Monosaccharides: These are the simplest form of carbohydrates. They are single sugar units and cannot be hydrolyzed further. Examples include glucose, fructose, and galactose. They have the general formula $ \text{(C}_6\text{H}_{12}\text{O}_6) $ for hexoses.
- Disaccharides: These are composed of two monosaccharide units linked together by a glycosidic bond. Examples include lactose, sucrose, and maltose. They have the general formula $ \text{(C}_{12}\text{H}_{22}\text{O}_{11}) $ after the removal of a water molecule during formation.
- Polysaccharides: These are complex carbohydrates formed by the linkage of many monosaccharide units (hundreds or thousands). Examples include starch, glycogen, cellulose, and chitin. They serve storage or structural functions. Their formula is generally $ \text{(C}_6\text{H}_{10}\text{O}_5)_n $.
Understanding the basic building blocks of carbohydrates like lactose is crucial for studying biochemistry and nutrition.
Important Questions from Biomolecules
- Which one of the following statements about fertilizers is not correct?
Which one of the following organelles of mammalian cells is rich in hydrolytic enzymes?
A typical adult human body contains about ________ of magnesium.
Match Column - A with Column - B.
Column-A (Vitamin)
Alternative name
i.
Vitamin A
a.
Ascorbic acid
ii.
Vitamin B12
b.
Retinol
iii.
Vitamin C
c.
Cobalamin
iv.
Vitamin D
d.
Ergocalciferol
Capsaicinoids, carotenoids, phenolics, and vitamins are dominant chemicals in which of the following foods?
