Question

Spongy bone a. contains osteons. b. contains red bone marrow, where blood cells are formed. c. lends no strength to bones. d. takes up most of a leg bone. e. All of these are correct.

Short answer

The correct answer is b. "contains red bone marrow, where blood cells are formed."

Step-by-step solution

Analyze statement a - "contains osteons"

We need to verify whether spongy bone contains osteons or not. Osteons, also known as Haversian systems, are the structural units found in the compact bone. However, spongy bone does not have the osteon system. Hence, statement a is incorrect.

Analyze statement b - "contains red bone marrow, where blood cells are formed"

Spongy bone is also called cancellous bone or trabecular bone. It is porous and houses red bone marrow, which is responsible for the production of blood cells (hematopoiesis). Therefore, statement b is correct.

Analyze statement c - "lends no strength to bones"

Spongy bone provides structural support by filling the spaces in between the compact bone, and it also helps to distribute the weight and stress placed on the bones during movement. Therefore, it's incorrect to say that spongy bone lends no strength to bones. Statement c is incorrect.

Analyze statement d - "takes up most of a leg bone"

Spongy bone is located primarily at the ends of long bones like the leg bones, also called metaphysis, where it forms the core of these bones. However, the shaft (diaphysis) of long bones is mainly made of compact bone, providing strength and stability. Thus, statement d is incorrect.

Analyze statement e - "All of these are correct"

As we have discussed in previous steps, not all the given statements are correct. Hence, statement e is incorrect.

Identify the correct statement(s)

Based on the analysis above, only statement b is correct. Therefore, the correct answer is: b. "contains red bone marrow, where blood cells are formed."