The backbone vertebrae, skull, and rib cage make up the skeleton. Among other types of cells, bone marrow produces blood cells, which carry oxygen in the blood. can eventually become osteocytes. If bones rapidly deconstruct faster than new bone tissue grows, this can lead to less dense and more fragile bones. When severe, this condition is called . such as the MCL and ACL connect bone to other bone at joints. ANSWERS :

1.axial
2. red
3. Osteoblasts
4. osteoporosis
5. Ligaments
6. Osteoblasts are cells that build bone tissue, and are called osteocytes when they become surrounded by the bone that they have built. Osteoclasts are cells that break down bone tissue. The building and breaking down of bone tissue continues throughout a person’s lifetime and makes bones strong. If osteoclasts break down more bone than osteoblasts build, this can lead to osteopenia and osteoporosis, causing bones to be fragile and break more easily.

1. axial

2. red

3. Osteoblasts

4. osteoporosis

5. Ligaments

Explanation:

The axial skeleton consists of the bones of the head and trunk of a vertebrate including skull, and rib cage.

Bone marrow produces red blood cells, which carry oxygen in the blood.

Osteoblasts can become osteocytes, which are the third type of bone cells.

Osteoporosis  is a bone resorption disease in which bones rapidly deconstruct faster than new bone tissue grows, and decreases the mechanical strength of bones.

Ligaments connects one bone to other at joint such as medial collateral ligament (MCL) and anterior cruciate ligament (ACL) that joins knee.

Hence, the correct answer for the question is as follows:

1.axial

2. red

3. Osteoblasts

4. osteoporosis

5. Ligaments

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).