Question

Please answer the following questions for numbers 7-9. If you are not sure please write it next to the problem number. I am a little confused with these. I will rate good!

. If the membrane shown in the beakers below is only permeable to Na", and the beaker on the left epresents the initial state, which of the following will occur over time? Na A, a. Na will diffuse to the left side of the membrane, causing a net positive charge on the right side of the membrane b. Na' will diffuse to the left side of the membrane, causing a net negative charge on the right side of the membrane c. Na will diffuse to the left side of the membrane, but there will be no separation of charges d. There will be no net movement of ions. 8. When two solutions exchange water by osmosis, water always moves... a. from the solution with the lower osmotic pressure to the one with the higher osmotic pressure. b. from the solution with the higher osmotic pressure to the one with the lower osmotic pressure. c. in the direction of gravity. d. via facilitated diffusion. Q 9-12. Hummingbirds are dietary specialists ingesting glucose rich nectar. Choose the correct answer from the following choices to describe the mechanisms by which glucose from the intestine is transported into the blood stream. Glu Glu/Na" Glu Glu Glu Na*/K 9. The Glucose transport mechanism from the gut lumen across the membrane into the intestinal epithelia cell cytoplasm is by. a. paracellular transport b. carrier-mediated facilitated diffusion c. Na*-glucose co-transporter (aka symporter) d. primary active transport

Answer 1

7. (b) Since, the membrane is only permeable to Na⁺ ions, these ions move from the right side of the membrane to the left. This leaves a number of unpaired anions (A^-) on the right side and additional positive charge on the left side (due to Na⁺ ions). This leads to a net negative charge on the right side of the membrane.

8. (a) Osmosis is the spontaneous net movement of solvent particles through a semi-permeable membrane from a region of low osmotic pressure (low solute concentration) to a region of high osmotic pressure (high solute concentration)

9. (c) Glucose is transported from the intestinal lumen into the epithelial cell via the Na⁺-glucose co-transporter. This Na⁺-glucose co-transporter protein is an integral membrane protein which is involved in the transport of two different types of molecules across the membrane called symporter proteins.