Lipids are

Options

A. Nucleic acids occurring in plants
B. Proteins occurring in animals
C. Carbohydrates occurring in plants
D. Fats of natural origin

Answer

**Step-by-Step Text Solution:**

1. **Definition of Lipids**: Lipids are a diverse group of organic compounds that are insoluble in water but soluble in organic solvents. They include fats, oils, waxes, and certain hormones.

2. **Types of Lipids**: The main types of lipids include:
- **Fats**: These are solid at room temperature and are primarily composed of triglycerides.
- **Oils**: These are liquid at room temperature and are also composed of triglycerides.
- **Waxes**: These are esters of long-chain fatty acids and long-chain alcohols.
- **Phospholipids**: These are major components of cell membranes.
- **Steroids**: These include hormones like cholesterol and testosterone.

3. **Functions of Lipids**: Lipids serve several important functions in biological systems:
- **Energy Storage**: Lipids store energy more efficiently than carbohydrates.
- **Structural Components**: They are key components of cell membranes (e.g., phospholipids).
- **Signaling Molecules**: Certain lipids act as hormones and signaling molecules (e.g., steroid hormones).
- **Vitamins**: Some vitamins (A, D, E, and K) are classified as lipids and are essential for various bodily functions.

4. **Conclusion**: Based on the information provided, lipids can be defined as "fats of natural origin," which aligns with the options presented in the question.

5. **Correct Option**: Therefore, the correct answer to the question "Lipids are" is "fats of natural origin."

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