Chapter 32, Problem 19A

Summary Introduction

Introduction:

Bone and cartilages are types of connective tissue. The skeleton system of the human body is made up of bones of different shapes and sizes. Long bones are present in arms and legs. Wrist bones are short bones. Skull is made up of flat bones. Vertebrae and facial bones are irregular bones.

Answer to Problem 19A

Correct answer:

The correct answer is option (b) it contains bone marrow.

Explanation of Solution

Explanation/justification for the correct answer:

Option (b) it contains bone marrow. In a diagram part marked is spongy bone. Spongy bone is present in the centre of short and flat bone. In long bones, they are found on the ends. Spongy bone is less dense and contains many cavities that have bone marrow. Thus, it contains bone marrow is a correct answer.

Explanation for incorrect answer:

Option (a) it contains no living cells. In the diagram, the part marked is a spongy bone. Spongy bone contains bone marrow in cavities present in them. Bone marrow is of two types red bone marrow and yellow bone marrow. Blood cells are produced inside red bone marrow. Thus, it contains no living cell and cannot be a characteristic of spongy bone.

Option (c) it is the only type of bone tissue in long bones. Spongy bones are present on the ends of the long bones. The outer layer of all bones is made up of compact bones. Thus, this cannot be a correct answer as both compact and spongy types of bones are present.

Option (d) it is made up of overlapping osteon systems. The Osteon system is also known as the Haversian system. It is a tube-like structure that contains blood vessels and nerves. Osteon is present in compact bone. Thus, it cannot be a characteristic of spongy bone.

Conclusion

Spongy bone is present in a centre of short and flat bones and in long bones they are present at ends. Spongy bone contains many cavities that have bone marrow in it. Thus, option (b) it contains bone marrow is the correct answer.