In the biological sense, how is an organism's fitness determined?

• A. By its physical strength and ability to compete for resources
• B. By the number of viable offspring it produces that survive to reproduce
• C. By the amount of food it can consume in its lifetime
• D. By its lifespan and resistance to disease

Answer: (B)

Verified step by step guidance

1. Understand the concept of 'fitness' in biology: In evolutionary biology, fitness refers to an organism's ability to survive and reproduce in its environment. It is not solely about physical strength or lifespan but about passing on genes to the next generation.
2. Identify the key factor in determining fitness: The primary measure of fitness is the number of viable offspring an organism produces that survive to reproduce themselves. This ensures the continuation of the organism's genetic material in the population.
3. Eliminate misconceptions: Fitness is not determined by the amount of food consumed, physical strength, or resistance to disease alone. While these factors may contribute to survival, they are not direct measures of evolutionary fitness unless they lead to successful reproduction.
4. Relate fitness to natural selection: Organisms with higher fitness are more likely to pass on their genes, and traits that enhance fitness are more likely to become prevalent in the population over generations.
5. Conclude with the correct answer: The biological sense of fitness is determined by the number of viable offspring an organism produces that survive to reproduce, as this directly impacts the genetic contribution to future generations.