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(i) Which of the following could not be ciassed as a lipid? (a) fats and oils (b) waxes (c) anthocyanin pigments (d) photosynthetic pigments. (ii) The 20 -carbon fatty acid represented by cis- \( 5,8,11,14 \) is called: (a) eicosaenoate (b) octadecanoate (c) eicosatetraenoate (d) hexadecaenozle. (iii) Propionyl CoA is formed on oxidation of (a) monounsaturated fatty acids (b) polyunsaturated fatty acids (c) fatty acids with odd number of carbon atoms (d) none of the above. K(iv) Fatty acids synthesized de novo in human beings generally: (a) have one double bond (b) are branched (c) have an even number of carbon atoms (d) have ! 5 carbon atoms. (v) All the following contain nitrogen except: (a) lecithin (b) cephalin (c) phosphatidyl inositol (d) phosphatidyl serine. (vi) Two enzymes essential for ketogenesis are: (a) \( \beta \)-Hydroxy- \( \beta \)-methylglutaryl (HMG) CoA synthetase and HMG CoA lyase (b) HMG CoA synthetase and HMG CoA reductase (c) HMG CoA reductase and HMG CoA lyase (d) HMO COA recuciase andi \( { }^{3} \)-hydroxybutyrate dehydrogenase. (vii) The number of carbon atoms in cholesterol is: \( \quad \) (a) 27 (b) 30 (c) 19 (d) 17 . (viii) The nitrogenous base in lecithin is: (a) choline (b) ethanolamine (c) serine (d) betaine. (ix) Sphingosine is present in: (a) ceramide (b) cardiolipin (c) cephalin (d) lecithin. (x) Which is odd amongst others? (a) glycerol-3-phosphate (b) phosphatidyl choline (c) phosphatidyl glycerol (d) phosphatidy! inosito!. (xi) \( \beta \)-oxidation of fatty acids requires all of the following coenzymes, except (a) CoA (b) NADP (c) NAD (d) FAD. (xii) Lysolecithin is formed from lecithin by removal of: (a) fatty acid from position 1 (b) fatty acid from position 2 (c) phosphorylcholine (d) ct:oline. (xiii) Cerebrosides contain a!l of the fo:lowing, except: (a) galactose (b) sulphate (c) sphingosine (d) fatty acid.

Ask by George Vaughn. in Nigeria
Mar 13,2025

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(i) **(c) anthocyanin pigments** (ii) **(c) eicosatetraenoate** (iii) **(c) fatty acids with odd number of carbon atoms** (iv) **(c) have an even number of carbon atoms** (v) **(c) phosphatidyl inositol** (vi) **(a) \( \beta \)-Hydroxy-\( \beta \)-methylglutaryl (HMG) CoA synthetase and HMG CoA lyase** (vii) **(a) 27** (viii) **(a) choline** (ix) **(a) ceramide** (x) **(a) glycerol-3-phosphate** (xi) **(b) NADP** (xii) **(b) fatty acid from position 2** (xiii) **(b) sulphate**

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(i) The compounds classified as lipids include fats, oils, waxes, and many pigments such as chlorophyll. However, anthocyanin pigments are water‐soluble and are not lipids. Answer: **(c) anthocyanin pigments** (ii) A 20‑carbon fatty acid with double bonds at positions 5, 8, 11, and 14 (all in cis configuration) has four double bonds. A 20‑carbon fatty acid with four double bonds is termed eicosatetraenoate. Answer: **(c) eicosatetraenoate** (iii) Propionyl CoA is generated from the oxidation of fatty acids that have an odd number of carbon atoms (since the final cycle releases a 3‑carbon unit instead of the usual 2‑carbon acetyl CoA). Answer: **(c) fatty acids with odd number of carbon atoms** (iv) Fatty acids synthesized de novo in human beings are typically synthesized by successive additions of \(2\)-carbon units, thus they almost always have an even number of carbon atoms. Answer: **(c) have an even number of carbon atoms** (v) Among the given phospholipids, lecithin, cephalin, and phosphatidyl serine all contain a nitrogen–containing head group. Phosphatidyl inositol, however, contains inositol (a carbohydrate alcohol) which does not contain nitrogen. Answer: **(c) phosphatidyl inositol** (vi) Ketogenesis involves the formation and cleavage of HMG CoA. The two essential enzymes in this process are HMG CoA synthetase (which condenses acetyl CoA units) and HMG CoA lyase (which cleaves HMG CoA to form acetoacetate). Answer: **(a) \( \beta \)-Hydroxy-\( \beta \)-methylglutaryl (HMG) CoA synthetase and HMG CoA lyase** (vii) Cholesterol is a sterol with a total of \(27\) carbon atoms. Answer: **(a) 27** (viii) Lecithin is a common name for phosphatidylcholine, which contains the nitrogenous base choline. Answer: **(a) choline** (ix) Sphingosine is an amino alcohol that forms the backbone of sphingolipids. It is a component of ceramide, which is sphingosine linked to a fatty acid. Answer: **(a) ceramide** (x) Out of the list, glycerol-3-phosphate is not a phospholipid but rather a precursor molecule in phospholipid synthesis. The others are phospholipids. Answer: **(a) glycerol-3-phosphate** (xi) The \(\beta\)-oxidation of fatty acids requires the coenzymes CoA, \(\text{NAD}^+\), and FAD. \(\text{NADP}^+\) is not used in this process. Answer: **(b) NADP** (xii) Lysolecithin is derived from lecithin by the removal of a fatty acid. This removal predominantly occurs from the sn-2 position of the glycerol backbone. Answer: **(b) fatty acid from position 2** (xiii) Cerebrosides are glycosphingolipids containing a ceramide (which is a combination of sphingosine and a fatty acid) linked to a single sugar (such as galactose). They do not contain sulfate; sulfated derivatives are known as sulfatides. Answer: **(b) sulphate**

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Did you know that lipids play crucial roles in energy storage, cell membrane structure, and signaling? They have been a topic of fascination for scientists since the late 19th century when they began to understand that fats stored significant energy. The discovery that certain lipids can influence our health has sparked ongoing research into diet and nutrition, showcasing their importance not just in biochemistry but also in everyday life! Now, if you’re diving into the depths of fatty acids and ketogenesis, consider this: while some fatty acids are synthesized de novo in humans with even carbon chains, it's important not to underestimate those with odd numbers. They play unique metabolic roles, particularly in energy metabolism. An interesting tidbit: humans can’t synthesize certain essential fatty acids, which must be obtained through diet. So, let’s celebrate those healthy fats!

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