Answer;
Mesoderm
The mesoderm is a layer of the embryo, which will become the circulatory system, bones, muscles, excretory system, and reproductive system.
Explanation;
-The germ layers develop early in embryonic life, through the process of gastrulation. An inner layer, called endoderm, and an outer layer, called ectoderm and a middle layer called mesoderm.
-The embryonic endoderm develops into the interior linings of two tubes in the body, the digestive and respiratory tube. the lining of the follicles of the thyroid gland and the epithelial component of the thymus.
-Ectoderm develops into parts of the skin, the brain and the nervous system. Mesoderm gives rise to bones, muscles, the heart and circulatory system, and internal sex organs.
Answer:
a. destroyed
b. osteoclasts
c. proteolytic enzymes
d. hydrochloric acid
e. blood
f. low
Explanation:
Resorption is the loss of substance from any mineralized tissue, mediated by cellular and humoral systems of their own. The four mineralized tissues of our economy, bone, cement, dentin (mineralized fraction of the dentino-pulp functional complex) and enamel, offer different degrees of resistance to resorption. The bone has the greatest lability and the enamel the least. The fact that the bone tissue is the least resistant to resorption is used to move and reposition teeth by controlled forces (orthodontics); and the fact that the enamel is the most resistant has led to think that it does not suffer from resorption.
Osteoclasts They are the spring cells par excellence; they belong to the lineage of the monocitomacrophages. They are large, multinucleated mobile cells, with a clear area and a rough brush border that live for about two weeks and disappear by apoptosis (cell death programmed by fragmentation in membrane particles that allows their phagocytosis without inflammation). They are responsible for the destruction of the organic and inorganic parts of the mineralized bone fraction. They are active both in the processes of the physiological renewal of the bone and in those of its pathological loss.
Answer:
B) ecological succession
Explanation:
The analogy given in this question describes ECOLOGICAL SUCCESSION, which is the series of changes that an ecosystem undergoes over a period of time. Ecological succession is of two types viz: Primary succession and Secondary succession.
Primary succession involves the series of changes that occurs on a new habitat that has never been previously colonized. This is the case of the colonization of bare rocks with no plant life by LICHENS. The action of the lichen, which involves secretion of acids that disintegrates the rocks into soil, paves way for the colonization of that area by new species.
Lichens, via the role they play in primary succession by helping alter a barren area into a fertile one that accommodates other organisms, makes them be regarded as PIONEERS of primary succession.
In humans, the medulla region of the brain is mainly responsible for the regulation process of respiration. It is also called the respiratory rhythm centre. The chemosensitive area located near the respiratory centre sends signals across nerve impulses to alter the rate of expiration to eliminate compounds.
