According to the fluid mosaic model of cell membranes which

According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids? They frequently flip-flop from one side of the membrane to the other. They can move laterally along the plane of the membrane. They are free to department from the membrane and dissolve in the surrounding solution. They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane. How do unsaturated fatty acids help keep any membrane more fluid at lower temperatures? The double bonds form kinks in the fatty acid tails that prevent adjacent lipids from packing tightly together. The double bonds result in shorter fatty acid tails and therefore thinner membranes. Unsaturated fatty acids are more polar than saturated fatty acids. Unsaturated fatty acids have a higher cholesterol content that prevents adjacent lipids from packing tightly together. A primary function of polysaccharides attached to glycoproteins and glycolipids of animal cell membranes is to facilitate diffusion of active transport of molecules into the cell. maintain the integrity of a fluid mosaic membrane. maintain membrane fluidity at low temperatures. mediate cell-to-cell recognition. Which of the following provides the most likely explanation for why cell membranes are asymmetrical? Proteins only function on the cytoplasmic side of the cell membrane, which results in asymmetry across the membrane. The molecular composition of the inner and outer layers of the cell membrane is determined by genes. Cell-to-cell communication requires different proteins on the surfaces of interacting cells. The two sides of a cell membrane face different environments and carry out different functions. Which of the following statements about diffusion is correct? It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration. It requires an expenditure of energy by the cell. It is a passive process in which molecules move from a region of lower concentration to a region of higher concentration. It is an active process in which molecules move from a region of lower concentration to one of higher concentration. The cellular process of breaking down large molecules into smaller ones is defined as anabolism. catabolism. dehydration metabolism. Which of the following is a statement of the first law of thermodynamics? The entropy of the universe is decreasing. The entropy of the universe is constant. Energy cannot be created or destroyed. Energy cannot be transferred or transformed. Which of the following is true of metabolism in its entirety in all organism. Metabolism consists of all the energy transformation reactions in an organism. Metabolism manages the increase of entropy in an organism. Metabolism specifically refers to the biochemical pathways involved in synthesis of macromolecules. Metabolism depends on a constant supply of energy from food.

Solution

23) According to the Fluid Mosaic model, phospholipids form a bilayer in which the nonpolar regions of the lipid molecules in each layer face the core of the bilayer, while their polar head groups face the aqueos phase. Proteins are embedded in this bilayer sheet by hydrophobic interactions with the membrane ipids and the hydrophobic domains of the protein. The individual lipid and protein units in a membrane form a mosaic pattern, which is free to move laterally in the plane of the membrane. The transfer of a phospholipid molecule or flip-flop is rare because the polar head would have to penetrate the hydrophobic core of the bilayer. Therefore, option (B) is the correct choice.

24). The unsaturated fatty acids in the membrane help keep the liquid more fluid at low temperatures as they reduce the packing efficiency. The double bonds form \"kinks\" in the fatty acid tails which push the neighbouring phospholipid molecules, thereby maintaining fluidity and preventing the membrane from freezing at low temperatures. Thus, the correct answer choice for this question is option (A).

25). The primary function of polysaccharides in glycoproteins and glycolipids of animal cell is to provide critical information about the targeting of newly synthesized proteins ans to allow for specific recognition by other proteins. Therefore, playing a key role in cell to cell recognition, making the correct answer choice option (D).

26).The cell membrane is an asymmetric structure as the two sides of membrane are structurally and functionally different. The reason why such an asymmetry is essential is because the two monolayers of the lipid bilayer faces two different environments and carry out different functions. Therefore, the correct answer choice for this question is option (D).

27). Diffusion is a passive process by which molecules move from a region higher concentration to a region of lower concentration. The movement continues until the concentration of substances is uniform throughout. Thus, the correct answer choice for this question is option (A).

28). Metabolism can be defined as the complete set of enzyme catalyzed transformations of organic molecules in living cells. It is the sum of anabolism and catabolism. While, anabolism can be defined as that phase of metabolism which is concerned with the enrgy requiring biosynthesis of cell components from small precursors. Catabolism on the other had,is that phase of intermediary metabolism that is concerned with the energy yielding degradation of nutrient molecules. Therefore, the correct answer choice for this question is option (D).

29). The first law of thermodynamics applies the conservation of energy principle and states that energy can neither be created nor destroyed, it can only be trasferred from one location to another and converted to and from other forms of energy. Thus, the correct answer choice is option (D).

30). As mentioned in Q.28, metabolism is the sum of all anabolic and catabolic reactions. It comprises of all the enzyme catalyzed transformations of organic molecules in living cells. Option C is incorrect as it says only synthesis, but metabolism also consists of catabolism or the degradation of larger molecules to smaller ones. Therefore, the crrect answer choice is option (A).