Oceans streams and rivers.............................
Steroids
are complex structure four connected rings of carbon atoms. They are cholesterol which is in all body cells and used to synthesize other steroids:sex hormones, such as estrogen, and testosterone and several hormones from the adrenal glands.
Waxes
are comprised of an ester of a long-chain alcohol and a fatty acid. Many plants have leaves and fruits with wax coatings to help prevent water loss.
Phospholipids
consist of Glycerol portion and fatty acid chains. Only two fatty acids chains; in place of the third is portion that include a phosphate group. THe phosphate portion is soluble in water [hydrophobic] forms the ''head'' of the molecule, while the fatty acids portion is insoluble in water [hydrophobic] and forms a ''tail''.
Fats
to store energy for cellular activities. Carbohydrates fat molecules are composed of carbon, hydrogen and oxygen atoms.
Answer:
The correct answer will be option-B.
Explanation:
Sertoli cells are the large somatic cells present in the testis which helps in the formation of spermatozoa. The Sertoli cells create a suitable environment for the production and maturation of the sperms as they produce certain molecules which nourishes the sperms.
The Sertoli cells act as a barrier between the testis and blood and secrete enzymes like inhibin. They eliminate the apoptotic germ cells and also produce seminiferous fluid to nourish the sperm. They do not play any role in primary spermatocytes.
Thus, Option-B is the correct answer.
Answer:
Neutrophils help fight infections because they ingest microorganisms and secrete enzymes that destroy them. A neutrophil is a type of white blood cell, a type of granulocyte and a type of phagocyte.
Explanation:
Neutrophils display adhesion glycoproteins on their surface to bind endothelial and subendothelial structures. They move randomly until they find a damaged site. Unless neutrophils are activated, endothelial cells do not tend to adhere. When inflammation mediators (IL-1, FNT) activate endothelial cells, they express P-selectin and E-selectin on the surface. The expression of glycoproteins and L-selectin cause the initial adhesion of the non-stimulated neutrophil to the activated endothelium, slowing it down by rolling it over the endothelium. Activated endothelial cells, opsonized particles, immune complexes, FEC-G, FEC-GM and chemoattractants produce factors that stimulate neutrophil activation. Expressing β2 integrin (endothelium adhesion molecule) Neutrophils expand and form pseudopods. Neutrophil activation also promotes degranulation, superoxide generation, and arachidonate metabolite production.
