MCQ on Fatty Acids with Answer Key (Biochemistry MCQ-9)


Difference between cis and trans fatty acid

‘cis’ and ‘trans’ fatty acids (source wikipedia)

MCQ on Fatty Acids
Biochemistry MCQ 009
(Multiple Choice Questions in Biology / Life Science)
(Sample/Model/Practice Questions for JRF/NET Life Science Examination, ICMR JRF, DBT BET JRF, GATE, ICAR NET, PG Entrance)


(1). Most commonly occurring fatty acids in nature are:

a.       Even number of carbon atoms in an un-branched chain of 12 – 24 carbons
b.      Odd number of carbon atoms in an un-branched chain of 12 – 24 carbons
c.       Even number of carbon atoms in a branched chain of 12 – 24 carbons
d.      Odd number of carbon atoms in a branched chain of 12 – 24 carbons

(2). In most of the naturally occurring mono-unsaturated fatty acids, the double bonds will be placed between ____________.

a.      C6 – C7
b.      C7 – C8
c.       C8 – C9
d.      C9 – C10

(3). Which of the following molecule acts as a sugar carrier in animals?

a.       Warfarin
b.      Ubiquinone
c.       Plastoquinone
d.      Dolichol

(4). The best source of trans fatty acid in diet is ____________.

a.       Vegetables
b.      Ground nut
c.       Dairy products
d.      Fruits

(5). LDL and HDL are commonly known as __________ and ________ respectively.

a.       Good cholesterol and bad cholesterol
b.      Bad cholesterol and good cholesterol
c.       Assimilatory cholesterol and oxidative cholesterol
d.      Oxidative cholesterol and assimilative cholesterol

(6). The solubility of fatty acids in water ________________

a.       Increase with increase in chain length and fewer the double bonds
b.      Increase with increase in chain length and increase in double bonds
c.       Decrease with chain length and decrease with number of double bonds
d.      Decrease with chain length and increase with double bonds

(7). At room temperature (25oC), a fat with saturated fatty acid of  12 – 20 carbon have:

a.       Liquid consistency
b.      Solid consistency
c.       Cannot be predicted

(8). Carbon atoms in fatty acid are __________ than those of sugars.

a.       Less reduced
b.      More reduced
c.       Less oxidized
d.      More oxidized

(9). In naturally occurring unsaturated fatty acids, the double bonds are in _______ conformation.

a.       Cis conformation
b.      Trans conformation
c.       A mixture of cis and trans conformation
d.      Cis and trans conformation alternatively

(10).  Increased dietary uptake of trans fatty acid causes blood level __________

a.       Increase of HDL
b.      Increase of LDL
c.       Increase of LDL and decrease of HDL
d.      Increase of HDL and decrease of LDL

(11).  Which of the following is a cyclic fatty acid?

a.      Cerebronic acid
b.      Ricinoleic acid
c.       Chaulmoorgic acid
d.      Oleic acid

(12).  Which of the following is NOT an essential fatty acid?

a.      Linoleic acid
b.      LInolenic acid
c.      Arachidonic acid

(13).  Which of the following statement is true?

a.       Cholesterols are present in both plants and animals
b.      Sterol is the only type of cholesterol in plants
c.       Cholesterol is not found in plants
d.      Cholesterol is completely absent in liver cells of cold blood animals

(14).  Heart attach possibility in women is fewer than men. The probable reason for this may be ______.

a.      Blood HDL level in female is more than male
b.      Blood HDL in female is less than male
c.       Blood of female individuals do not contain HDL
d.      Blood of female individuals do not contain LDL

(15).  At room temperature (25oC) an unsaturated fatty acid will have ___

a.      Liquid consistency
b.      Solid consistency
c.       Waxy consistency
d.      Cannot be predicted

(16).  Which of the following statement is true?

A. Sodium salt of higher fatty acid is called soft soaps
B. Potassium salt of higher fatty acid is called soft soaps
C. Sodium salt of higher fatty acid is called hard soaps
D. Potassium salt of higher fatty acid are called hard soaps

a.      A
b.      A, B, C
c.       B, C
d.      B, D

(17).  The number of OH groups in fatty acids can be expressed as:

a.      Polenske number
b.      Reichert-Meissl number
c.       Acetyl number
d.      Iodine number

(18).  The triterpenoid which acts as the precursor of all animals sterols:

a.      Lanosterol
b.      Cholesterol
c.       Cycloartenol
d.      Isoprenoids

(19).  The precursor of all fungal sterols is _______.

a.      Lanosterol
b.      Cholesterol
c.       Cycloartenol
d.      Isoprenoids

(20).  The triterpenoid which acts as the precursor of almost all plant sterols:

a.      Lanosterol
b.      Cholesterol
c.       Cycloartenol
d.      Isoprenoids

(21).  A sterol present in the plasma membrane of fungi and protozoans instead of cholesterol is ________________

a.      Lanosterol
b.      Cholesterol
c.       Ergosterol
d.      Cycloartenol

(22).  The sterol which acts as the precursor of Vitamin D2 (provitamin D2) is:

a.      Colcalciferol
b.      Lanosterol
c.       Cholesterol
d.      Ergosterol

(23).  Which of the following is an example for phytosterol?

a.      β-sitosterol
b.      Campesterol
c.       Brassicasterol
d.      All of these
e.       None of these

(24).  A naturally occurring fatty acid with C-C triple bond in the hydrocarbon chain:

a.      Digitoxin
b.      Oubain
c.       Nemotinic acid
d.      None of these

(25).  Which of the following is NOT an omega-6 fatty acid?

a.      Alpha-linolenic acid
b.      Linoleic acid
c.       Eicosadienoic acid
d.      Arachidonic acid


Answer key and explanations:

1. Ans. (a). Even number of carbon atoms in an un-branched chain of 12 – 24 carbons

Fatty acids with odd number of carbon, branched chain and more than 24 carbon atoms do occurs in nature but very rarely.

2. Ans. (d). C9 – C10

In majority of naturally occurring mono-unsaturated fatty acids, the double bond is between C9 and C10 of the hydrocarbon chain.

3. Ans. (d). Dolichol

Dolichol is an alcohol functional group containing long chain organic compound made up of many isoprene units. Dolichol has important function in N-glycosylation of proteins in the form of dolichol phosphate. Dolichol also functions as membrane anchor point for the formation of oligosaccharides.

4. Ans. (c). Dairy products

5. Ans. (b). bad cholesterol and good cholesterol

6. Ans. (c). Decrease with chain length and decrease with number of double bonds

Fatty acids are partially soluble in water. The partial solubility is due to presence of hydrophilic COOH group at the tip the hydrocarbon chain. The hydrocarbon chains are completely insoluble in water. When the fatty acids are of shorter length, it will be more soluble in the water since the chain length reduction reduces the hydrophobic interactions of hydrocarbons.

7. Ans. (b). Solid consistency

Saturated fatty acids do not have double bounds and hence molecules can be packed compactly. When unsaturation is present in the fatty acids, due to double bonds there will be kinks in the fatty acid chains and this hinders the compact packing of fatty acid residues. Since the molecules are not compactly packed in the unsaturated fats, they acquire a liquid consistency.

8. Ans. (b). More reduced

Carbon atoms in fatty acids are more reduced than those in sugars. This is why fatty acids are more energy rich than sugars.

9. Ans. (a). Cis conformation

10.  Ans. (c). Increase of LDL and decrease of HDL

11.  Ans. (c). Chaulmoorgic acid

Chaulmoorgic acid is a cyclic fatty acid obtained from Chaulmoorgra seeds. Chaulmoorgic acid is used in the treatment of leprosy.

12.  Ans. (d). Arachidonic acid

Arachidonic acid is a poly unsaturated ω fatty acid. It is not an essential fatty acid. Arachidonic acid is synthesized from linoleic acid in the body. If there is any inability to convert linoleic acid to arachidonic acid, it becomes a conditionally essential fatty acid.

Essential fatty acids: (EFAs) are fatty acids in humans which are very essential for the normal functioning of the body and it is not synthesized in the cells. They should be obtained from the diet. Only two fatty acids are essential to human, they are alpha linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid).

13.  Ans. (c). Cholesterol is not found in plants

Cholesterol is not found in plants but other sterols do occurs in plants.

14.  Ans. (a). Blood HDL level in Female is more than male

15.  Ans. (a). Liquid consistency

16.  Ans. (c). B, C

17.  Ans. (c). Acetyl number

18.  Ans. (a). Lanosterol

19.  Ans. (a). Lanosterol

20.  Ans. (c). Cycloartenol

21.  Abs. (c). Ergosterol

22.  Ans. (d). Ergosterol

23.  Ans. (d). All of these

24.  Ans. (c). Nemotinic acid

Nemotinic acid is a rare fatty acid with C-C triple bond. Santalbic acid which is present in the sandal wood oil also contains one triple bond.

25.  Ans. (a). Alpha-linolenic acid

Alpha linolenic acid is an omega 3 fatty acid.


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