Tag: lipids

Questions Related to lipids

An essential fatty acid is

bio-chemistry biological molecule lipids and their function some biomolecules lipids

  1. Palmitic acid

  2. Arachidonic acid

  3. Stearic acid

  4. Arachidic acid

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Correct Option: B
Explanation:

Arachidonic acid is not one of the essential fatty acids. Rather it is conditionally essential fatty acid which, becomes essential if its precursor, linoleic acid is deficient thereby resulting in the inability to convert linoleic acid to arachidonic acid. However, some mammals lack the ability or have a very limited capacity to convert linoleic acid to arachidonic acid, making it an essential part of their diets. So, the correct answer is 'Arachidonic acid'.

Higher animals cannot synthesise a few essential fatty acids; these are typically

bio-chemistry biological molecule lipids and their function some biomolecules lipids

  1. Saturated

  2. Branched

  3. Unsaturated

  4. Cyclic

Show answer
Correct Option: C
Explanation:
Unsaturated fats are liquid at room temperature as they have double bonds. Those unsaturated fatty acid which are not synthesized by the body are essential amino acid. Higher animals cannot synthesize a few essential fatty acids which are typically unsaturated because they lack desaturases that introduce double bonds beyond the ninth carbon atom. 
So, the correct answer is option C.

Higher animals cannot synthesize few fatty acids which are very essential for their growth and development. These fatty acids are typically

bio-chemistry biological molecule lipids and their function some biomolecules lipids

  1. Saturated

  2. Cyclic

  3. Unsaturated

  4. Branched

Show answer
Correct Option: C
Explanation:
Essential fatty acids are those which our body cannot synthesize but we need them for good health. Alpha-linolenic acid and linoleic acid are the two fatty acids which are essential for humans. These are long chain polyunsaturated fatty acids. Desaturase enzyme removes two hydrogen atoms from a fatty acid, creating a carbon-carbon double bond (unsaturation). Due to the absence of this enzyme in humans, they cannot synthesize the unsaturated essential fatty acids.

An essential fatty acid is 

bio-chemistry biological molecule lipids and their function some biomolecules lipids

  1. Arachidonic acid

  2. Arachidic acid

  3. Palmitic acid

  4. Stearic acid.

Show answer
Correct Option: A
Explanation:

Essential fatty acids are those compounds which cannot be synthesized by human and must be ingested externally. Examples of essential fatty acid include linoleic (omega-6 fatty acid) and alpha-linolenic acid (omega-3 fatty acid). Linoleic acid is converted to arachidonic acid. Arachidonic acid is an omega-6 unsaturated fatty acid required by proper functioning of body. 

Stearic acid, oleic acid, palmitic acid are nonessential fatty acids. They are synthesized by a human.
Thus, the correct answer is option A.

Number of fatty acid residues found in one molecule of fat is 

bio-chemistry biological molecule lipids and their function some biomolecules lipids

  1. 1

  2. 2

  3. 3

  4. 4

Show answer
Correct Option: C
Explanation:

Fatty acids are long, straight chain carboxylic acids. A fat (or oil) is formed when three fatty acid molecules react with a glycerol molecule to yield a triglyceride. Fats in the body are transported and stored as triglycerides.

So, the correct answer is option C.

Consider the following statements.
a. Cutin is a fatty acid polymer
b. Starch is composed only of glucose residues
Which of the statements given is/are correct?

bio-chemistry biological molecule lipids and their function some biomolecules lipids

  1. $1$ only

  2. $2$ only

  3. Both $1$ and $2$

  4. Neither $1$ nor $2$

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Correct Option: A

Consider the following fatty acids.
a. Linolenic acid
b. Oleic acid
c. Palmitic acid
d. Stearic acid
Which of these is/are unsaturated fatty acids?

bio-chemistry biological molecule lipids and their function some biomolecules lipids

  1. $1$ only

  2. $1$ and $2$

  3. $3$ and $4$

  4. $2, 3$ and $4$

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Correct Option: A

Which of the following statements concerning unsaturated fats is correct?

bio-chemistry biological molecule lipids and their function some biomolecules lipids

  1. They have fewer fatty acid molecules per fat molecule

  2. They have double bonds in the carbon chains of their fatty acids

  3. They generally solidify at room temperature

  4. They contain more hydrogen than do saturated fats having the same number of carbon atoms

Show answer
Correct Option: B
Explanation:

When one or more double bonds are present between the carbon chains of the fatty acids it is known as unsaturated fats. They have a large number of fatty acid molecules per fat molecule. Due to the presence of double bonds they contain a lesser number of hydrogen bonds as compared to the saturated fatty acid molecules.

Hence, the correct answer is 'They have double bonds in the carbon chains of their fatty acids'

Select the correct option:

Which of the following is a saturated fatty acid?

bio-chemistry biological molecule lipids and their function some biomolecules lipids

  1. Oleic acid

  2. Linoleic acid

  3. Arachidonic acid

  4. Palmitic acid

Show answer
Correct Option: D
Explanation:

Fatty acids are two main types- saturated and unsaturated fatty acids are without double bonds in their carbon chains. They have higher melting points and are solids at room temperature. They have a general formula of $C _nH _{2n}O _2$,e.g., $C _{16}H _{32}O _2$ (palmitic acid), $C _{18}H _{36}O _2$ (stearic acid).

Animal fats are mostly saturated fats.
Unsaturated fatty acids contain one or more double bonds in their carbon chains. They have lower meting points and are liquids at room temperature. Their general formula is $C _nH _{2n-2x} O _2$,e.g., oleic acid (with one double bond, monoene, $C _{18}H _{34}O _2)$, linoleic acid (with two double bonds, diene,$C _{18}H _{32}O _2$),linolenic acid (with three double bonds,triene, $C _{18}H _{30}O _2$).arachidonic acid (with four double bonds,tetraene,$C _{20}H _{32}O _2$).Plant fats are generally unsaturated fats.
So, the  correct answer is 'Palmitic acid'.

Which among the following is not a common saturated fatty acids encountered in nature?

bio-chemistry biological molecule lipids and their function some biomolecules lipids

  1. Butyric acid

  2. Palmitoleic

  3. Acetic and palmitic

  4. None of the above

Show answer
Correct Option: B
Explanation:

Fatty acids are carboxylic acids with hydrocarbon chains of 4 to 36 carbons. In some fatty acids, this chain is fully saturated (meaning it cannot accept any more hydrogens) and unbranched; other fatty acids contain one or more double bonds (thus, they can be hydrogenated when the double bonds will get converted into single bonds).

Common examples of saturated fatty acids are butyric acid having four carbon atoms, lauric acid having twelve carbon atoms, myristic acid having fourteen carbon atoms, palmitic acid having sixteen carbon atoms, etc. Common unsaturated fatty acids are palmitoleic acid having sixteen carbon atoms and one double bond, oleic acid having eighteen carbon atoms and one double bond, linolenic acid having eighteen carbon atoms and two double bonds, etc.