Question

\(=1\) 4\. Match Column - I with Column - II and select option from the codes given below. A. Humerus \(\quad\) Column.ll B. Hydrostatic skeleton (i) Thigh C. Femur (ii) Upper arm (iii) Flatworms (iv) Acetabulum' (v) Glenoid cavity (vi) Hydra (a) \(\mathrm{A}-(\mathrm{ii}),(\mathrm{v}) ; \mathrm{B}-(\mathrm{iii}),(\mathrm{vi}) ; \mathrm{C}-(\mathrm{i})\), (iv) (b) \(\mathrm{A}-(\mathrm{ii}),(\mathrm{iv}) ; \mathrm{B}-(\mathrm{iii}),(\mathrm{vi}) ; \mathrm{C}-(\mathrm{i}),(\mathrm{v})\) (c) \(\mathrm{A}-(\mathrm{i}),(\mathrm{v}) ; \mathrm{B}-(\mathrm{ii}),(\mathrm{iv}) ; \mathrm{C}-(\mathrm{iii}),(\mathrm{vi})\) (d) \(\mathrm{A}-(\mathrm{iii}),(\mathrm{vi}) ; \mathrm{B}-(\mathrm{i}),(\mathrm{v}) ; \mathrm{C}-(\mathrm{ii})\), (iv)

Short answer

Option (a) is correct. A-(ii), (v); B-(iii), (vi); C-(i), (iv)

Step-by-step solution

Identify the Correct Associations for Humerus

Humerus is the bone in the upper arm, so it should be associated with (ii). In addition, the glenoid cavity is the socket in the scapula that receives the head of the humerus bone, so it should be associated with (v).

Identify the Correct Associations for Hydrostatic Skeleton

A hydrostatic skeleton is a structure found in some soft-bodied animals such as flatworms and Hydra, so it should be associated with (iii) for flatworms and (vi) for Hydra.

Identify the Correct Associations for Femur

The femur is the bone in the thigh, so it should be matched with (i). The acetabulum is the socket in the hip bone that receives the head of the femur, so it should be matched with (iv).

Match Choices to the Information Gathered

Now match the correct associations to the choices given: A-Humerus is matched with (ii) and (v), B-Hydrostatic skeleton is matched with (iii) and (vi), and C-Femur is matched with (i) and (iv). The only option that matches this perfectly is option (a).

Key concepts

Human Skeletal System

The human skeletal system is a complex framework that provides structure, protection, and support to the body. It consists of 206 bones in adults and serves several critical functions, such as movement, protection of internal organs, and production of blood cells in the bone marrow.

Bones are connected by joints, which allow for varied types of movement. In the upper limb, the humerus is the long bone in the upper arm which articulates with the scapula at the glenoid cavity, forming the shoulder joint. Similarly, in the lower limb, the femur, which is the longest and strongest bone in the human body, articulates with the pelvis at the acetabulum, forming the hip joint.

The skeletal system is also essential for calcium storage and endocrine regulation, contributing to overall homeostasis. Understanding these roles can help students better grasp the purpose of the skeletal system beyond just naming bones.

Hydrostatic Skeleton

A hydrostatic skeleton, unlike the rigid skeletons found in humans and many other animals, is a flexible structure used by some invertebrates for movement and shape maintenance. It is composed of fluid-filled body cavities, called the coelom, encased by muscles.

When the muscles contract, the fluid in these cavities is displaced, causing the creature to change shape. This type of skeletal structure is typically found in soft-bodied animals such as flatworms, nematodes, and cnidarians like Hydra.

Advantages of a Hydrostatic Skeleton

The hydrostatic skeleton has the unique advantage of allowing these creatures to move without hard limbs or joints, squeeze through extremely small spaces, and even regenerate parts of their body with ease. It exemplifies an evolutionary solution to movement in the absence of bones.

Bone Structure

Bone structure in vertebrates is intricate and has been optimized over millions of years of evolution. It is made up of a complex matrix of collagen fibers, hardened by minerals like calcium and phosphorous. This composition gives bones both strength and a slight degree of flexibility.

The outer layer of bone is called the periosteum, which contains nerves and blood vessels that supply the bone. Internally, bones have a honeycomb-like structure made up of trabeculae, which offers resistance to stress while reducing weight.

Bone Marrow and Growth

Within the cavities of bones lies the bone marrow, a vital tissue where new blood cells are generated. During growth periods, the epiphyseal plate, or the growth plate, is an area of cartilage that allows for the longitudinal growth of long bones.

Maintenance of the skeletal system through proper nutrition and physical activity is essential for overall health, which underscores why understanding bone structure is not just academically relevant but also practically important for students.