Problem 28 - Objective Biology for NEET

Question

Lipids may be (a) Fatty acid (b) Glycerol (c) Compound respectively of both (d) All of these

Step-by-Step Solution

Answer

The answer is (d) All of these.

Step 1: Understand Lipids

Lipids are a diverse group of hydrophobic organic compounds. They are made up of carbon, hydrogen, and oxygen atoms. The structure of lipids usually consists of a glycerol backbone attached to fatty acid chains.

Step 2: Evaluate Options

Option (a) is 'Fatty acid', which is one component of lipids, therefore correct. Option (b) is 'Glycerol', which also makes up part of a lipid's structure, thus correct as well. Option (c) refers to 'Compound respectively of both' implying a lipid can be a compound of both glycerol and fatty acids, which is true, making this option correct as well. Option (d) is 'All of these', indicating all the previous options are part of the lipid's composition, which we have established as true in previous steps.

Key Concepts

Fatty acids

Fatty acids are fundamental components of lipids. They are long chains of hydrocarbons with a carboxyl group (-COOH) at one end. This structure is crucial because it is what gives fatty acids their acidic properties.
They can be either saturated or unsaturated, which defines their structural and functional properties in biological systems.

• Saturated fatty acids: These have no double bonds between carbon atoms, making them typically solid at room temperature. They are commonly found in animal fats.
• Unsaturated fatty acids: These contain one or more double bonds and are usually liquid at room temperature. They are often found in plant oils.

Fatty acids store energy efficiently, making them an essential energy reserve for organisms. They are vital for building cell membranes because they form phospholipids, essential components of the cell's protective outer layer.

Glycerol

Glycerol is a simple compound and a key building block for lipids, especially triglycerides. It’s a three-carbon polyol with each carbon atom bearing a hydroxyl (-OH) group. These hydroxyl groups can react with fatty acids to form ester bonds, leading to the formation of triglycerides.
This bonding is what makes glycerol fundamental in forming lipids.

• Triglycerides: These are the most common form of fat found in the body and the main constituents of body fat in humans and animals. They store energy for later use.
• Solubility: Due to its hydroxyl groups, glycerol is highly soluble in water, which assists in lipid transport in living organisms.

Besides its role in forming lipids, glycerol is also used in various industrial and medical applications. It is found in food products as a sweetener and is used in pharmaceuticals for its lubricating properties.

Organic compounds

Organic compounds are essential for life and are primarily made of carbon atoms bonded with other elements such as hydrogen, oxygen, nitrogen, sulfur, and phosphorus. Lipids are a subtype of organic compounds, characterized by their hydrophobic nature, meaning they do not mix well with water. This property is crucial for the formation of biological membranes.

• Carbon Backbone: The carbon atoms form the backbone of organic compounds, providing a strong and stable framework that supports complex structures.
• Functional Groups: Different functional groups, like hydroxyl, carboxyl, and phosphate, attach to the carbon backbone and define the compound’s properties and functions.

Lipids, as organic compounds, play a vast range of roles, from energy storage to acting as signaling molecules. This diversity highlights the versatility of carbon-based life.