Answer:

point mutation, change within a gene in which one base pair in the DNA sequence is altered. Point mutations are frequently the result of mistakes made during DNA replication, although modification of DNA, such as through exposure to X-rays or to ultraviolet radiation, also can induce point mutations
The answer is vascular plants.
Vascular plants have <span>specialized tissues that can transport fluids - vascular tissue. This tissue consists of</span><span> xylem and phloem. Xylem transports water and minerals from the root to the upper parts of the plant. Phloem transports food and nutrients from the leaves, where they are produced, to the growing or storage parts of the plants. </span>
Mechanical stress applied to bone increases osteoblast activity in bone tissue, and the removal of mechanical stress decreases osteoblast activity.
Explanation:
Osteoblasts are cells , that are produced in the bone marrow and are responsible for formation of bones and bone matrix.
Whenever a mechanical stress is applied on the bones , a series of reactions are triggered. As a result the activities of osteoblast increases to synthesize more and more bone matrix to provide strength.
Again on the other hand a decrease in mechanical causes a decrease in the activities of the osteoblasts.
Answer:
The nucleus (On the image, it's the sphere in the middle)