The defecation reflex involves two postive feedback loops. these loops are the stretch receptors in the rectal walls and the sacral parasympathetic system. Defecation reflex empties the rectum by peristaltic movements push fecal matter from the sigmoid colon into the rectum. Then this distension of the rectal walls stimulates stretch receptors which results in defecation.
The <em>TYR </em>gene is responsible for the production of the enzyme tyrosinase which is crucial in the production of melanin which is primarily responsible for skin pigmentation and for pigmentation of other organs. In albinism, there is mutation of the <em>TYR </em>gene therefore there will be no transcription of DNA to mRNA and no translation of mRNA to the enzyme tyrosinase leading to its deficiency. The deficiency of tyrosinase will eventually lead to the absence of melanin and ultimately, the absence of pigmentation in an organism.
Answer:
volume
surface area
Explanation:
The growth of the cell includes the increase in the mass of the cell by the absorption of nutrients and elimination of the wastes. This process helps the cell to grow in size. In this process, the volume of the cell increases faster than the surface area. This gradually leads to the decrease in the surface area of the cell. The increase in the volume expands the cell membrane also.
