Problem 67 - Chemistry The Central Science In Si Units

Question

Indicate whether each statement is true or false: (a) Maltose is a monosaccharide. (b) Polysaccharides are a type of carbohydrate. (c) All carbohydrates have an oxygen to hydrogen ratio of 1: 2 .

Step-by-Step Solution

Answer

(a) False, (b) True, (c) True.

Step 1: Understanding the Types of Sugars

Let's examine part (a): Maltose is a disaccharide, which consists of two glucose molecules linked together. Monosaccharides are the simplest form of sugar, such as glucose or fructose. Since maltose contains two sugar units, it's not a monosaccharide.

Step 2: Evaluating Polysaccharides

For part (b): Polysaccharides are large molecules made by linking together multiple monosaccharides. They are indeed a type of complex carbohydrate, examples include starch, cellulose, and glycogen.

Step 3: Analyzing the Chemical Formula

Now, part (c): The general chemical formula of carbohydrates is represented by \\[ C_n(H_2O)_m \] \This implies that they generally have twice as many hydrogen as oxygen, which aligns with the statement given. An example is glucose, with a formula of \\[ C_6H_{12}O_6 \] \illustrating the 1:2 ratio of oxygen to hydrogen.

Key Concepts

Monosaccharides

Monosaccharides are the simplest form of carbohydrates. They are single sugar molecules, which means they cannot be broken down into simpler sugars. Monosaccharides serve as the building blocks for more complex carbohydrates. Common examples include glucose and fructose. Each monosaccharide consists of carbon, hydrogen, and oxygen atoms and can be categorized based on the number of carbon atoms they have, such as

• Trioses (3 carbons)
• Tetroses (4 carbons)
• Pentoses (5 carbons)
• Hexoses (6 carbons)

Glucose, for example, is a hexose because it contains six carbon atoms and is the primary energy source for most living organisms. Since monosaccharides are simple sugars, they are absorbed directly into the bloodstream during digestion. They play critical roles in bioenergetics and cellular respiration.

Polysaccharides

Polysaccharides are complex carbohydrates, made by linking many monosaccharide units together through glycosidic bonds. These long chains can be either linear or branched and can vary significantly in size. The most common polysaccharides include:

• Starch: the main storage form of glucose in plants
• Glycogen: the primary storage form of glucose in animals
• Cellulose: a major component of plant cell walls, providing structural support

These molecules serve various functions in organisms. For example, starch and glycogen act as energy reserves, which organisms can break down into glucose when needed. Cellulose, on the other hand, plays a structural role and is not digestible by humans.

Chemical Formulas of Carbohydrates

Carbohydrates are made up of carbon, hydrogen, and oxygen atoms, typically following the formula \( C_n(H_2O)_m \). This formula suggests that carbohydrates generally have twice as many hydrogen atoms as oxygen atoms. For instance, glucose, a common simple sugar, has the chemical formula \( C_6H_{12}O_6 \), displaying a perfect 1:2 ratio.This general formula does not strictly apply to all carbohydrates, but it is a useful approximation for most of them. The formula reflects the basic hydrate (water-like) pattern of these organic compounds, explaining their name: carbo (carbon) + hydrate (water). Understanding this formula helps predict the structure and function of various carbohydrates. It's crucial for studying their metabolism and role in the body.