In biology, SG refers to specific gravity, which is more formally known as relative density. It's a measurement of a substance's density compared to the density of water.
Understanding Specific Gravity
Specific gravity helps us understand how dense a substance is relative to water, which is typically used as the reference. Since the density of water is roughly 1 g/cm³ at standard conditions, the specific gravity of a substance effectively indicates its density in g/cm³.
Here's a breakdown:
- Definition: Specific gravity is the ratio of the density of a substance to the density of a reference substance, most often water.
- Calculation: It's calculated by dividing the density of the substance by the density of water.
- Unit: It is a dimensionless quantity, meaning it doesn't have any units (like grams or milliliters).
Practical Implications
Specific gravity has many important applications in biology:
- Buoyancy: It helps predict whether an object will float or sink in water. If an object’s specific gravity is less than 1, it will float. If it’s greater than 1, it will sink.
- Cell Density: In cell biology, specific gravity can help measure cell density during experiments.
- Fluid Analysis: It is used in fluid analysis, such as urine and blood analysis, to detect abnormalities.
- Organismal Studies: For example, in aquatic organisms, their specific gravity plays a crucial role in their ability to stay afloat in water.
Example:
If a substance has a density of 1.2 g/cm³, its specific gravity would be 1.2. This indicates that it's 1.2 times denser than water and it would sink.
Summary Table
| Concept | Definition | Unit |
|---|---|---|
| Specific Gravity | Ratio of a substance's density to the density of water | Dimensionless |
| Density of Water | Approximately 1 g/cm³ | g/cm³ |
Therefore, "SG" in biology is a term referring to specific gravity, a key parameter in understanding and comparing the density of substances relative to water, offering insights into buoyancy, cell densities, and more.
