Calcium ions (Ca2+\text{Ca}^{2+}Ca2+) are actively accumulated inside plant vacuoles. This accumulation is mediated by a membrane-bound transport protein called CaA1, which co-transports one calcium ion (Ca2+\text{Ca}^{2+}Ca2+) and two protons (H+\text{H}^+H+) across the vacuolar membrane. This transport process is active and directly driven by the hydrolysis of ATP.
Use your knowledge of active transport across cell membranes to suggest how CaA1 carries out this transport.
Scientists investigated the potential of a natural compound called Naringenin to reduce fructose absorption in the small intestine. Naringenin is known to inhibit the facilitated diffusion transporter GLUT5, which is responsible for transporting fructose across the apical membrane of intestinal epithelial cells.
The scientists fed a diet containing a high concentration of fructose to two groups of mice, A and B.
One hour after feeding, the scientists humanely sacrificed the mice, extracted the contents of their small intestines, and immediately determined their mass.
Their results are shown in Table 1.
Table 1
| Concentration of Naringenin / mg kg−1\text{mg kg}^{-1}mg kg−1 | Mean mass of contents of the small intestine / g\text{g}g |
|---|---|
| 0 | 1.3 |
| 12 | 2.9 |
The scientists performed a statistical test to evaluate if the difference between the two means was statistically significant. The test yielded a PPP-value of less than 0.01.
They concluded that Naringenin successfully reduced fructose absorption in the small intestine.
Use all the information provided and your knowledge of water potential to explain how they reached this conclusion.
Severe liver disease, such as cirrhosis, can dramatically decrease the synthesis and secretion of plasma proteins (e.g. albumin) into the bloodstream. This often leads to a clinical condition known as ascites, which is characterized by a significant build-up of tissue fluid in the abdominal cavity. Explain how.
