Which of the following is the best definition of osmosis A T

Which of the following is the best definition of osmosis? A) The net movement of water across a selectively permeable membrane. B) The net movement of water from a region of low water potential to a region of high water potential. C) The net movement of water from a region of high water potential to a region of low water potential. D) The net movement of any substance down a solute concentration gradient. E) The net movement of glucose across a selectively permeable membrane. A fat differs from a phospholipid in that a fat contains: A) 3 fatty acids B) a wax C) a steroid D) 1 glycerol E) a phosphate group Which of the following are found in plant cells, but not animals cells? A) chloroplasts, ribosomes, vacuoles B) vacuoles, chloroplasts, cell walls C) ribosomes, cell walls, golgi D) mitochondria, ribosomes, peroxisomes E) cell walls, endoplasmic reticulum, DNA The three main processes of cellular respiration are (a)___(b)___(c)___and they occur in the (d)___ (e)___ and (f)___ respectively. What is the overall reaction for glucose oxidation (cellular respiration)? Is glucose being oxidized or reduced? Explain your answer.

Solution

23. Osmosis is the net movement of a substance from its high concentration to low concentration by the process of diffusion across a selectively permeable membrane. The random motion of molecules occurs both sides across the membrane but higher concentration on one side means there is more motion from that side to the other side resulting in the net motion from high concentration to low concentration. A selectively permeable membrane does not allow solutes to pass through but water can easily pass through the membrane due to the presence of special protein channels called aquaporins. So, the net motion will be from the side contaning higher water concentration (high water potential) to lower water concentration (low water potential).

So c) is the right answer that the osmosis is the net movement of water from a region of high water potential to a region of low water potential.

24. A fat contains a glycerol backbone alongwith 3 fatty acid chains reacted with the OH group of glycerol to form 3 ester bonds. A phospholipid also has a glycerol but only 2 fatty acid chains. The third position is occupied by a phosphate group.

So, a fat differs from phospholipid in having 3 fatty acid chains. So, the option A is the right option.

A common mistake here is that students think option E is also correct. But the question asked the component that fat contains. If in the last it would have stated phospholipid contains then option E would have been correct. Another mistake is marking 1 glycerol but as explained above, both of them contains 1 glycerol. So, option D is incorrect. The rest components are neither present in fat nor phospholipids.