Biology · Chemistry

Lipids, Fats, and Biochemistry

1,130 Questions

Lipids, fats, and biochemistry explore the structure and function of biological molecules. This includes fatty acids, cholesterol, trans-fats, and cellular membranes. Questions on this topic frequently appear in science sections of competitive government exams.

Types of fats and lipidsCholesterol and human bodyFatty acidsCellular membranes

Lipids, Fats, and Biochemistry Questions

Multiple choice chemistry petrochemicals and polymers food spoilage and food preservation methods of preserving food chemicals in food

________ act as protective agent on the surface of animals and plants.

  1. Carbohydrates

  2. Vitamins

  3. Nucleic Acids

  4. Wax
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Wax act as a protective agent on the surface of animals and plants. It protects animals and plants from excessive loss of moisture. It protects the plants and fruits from becoming infected with fungi and bacteria.


Wax contains esters of long chain fatty acids and long chain alcohols or sterol.

Hence, option D is correct.

Multiple choice chemistry petrochemicals and polymers food spoilage and food preservation methods of preserving food chemicals in food

High molecular weight alcohols are present in:

  1. waxes

  2. fats

  3. oils

  4. phospholipids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

waxes are monoglycerides, these are form by the condensation reaction between monohydroxy alcohol and fatty acid, this is the high molecular weight compound.

Example- Bee wax 
( Hexacosyl palimitate $\rightarrow$ Hexacosyl alcohol+ Palmitic acid)
$C _{26}H _{53}OH + C _{15}H _{31}COOH \overset{-H _2O}\rightarrow C _{26}H _{53}COOC _{15}H _{31}$ 

Multiple choice chemistry petrochemicals and polymers food spoilage and food preservation methods of preserving food chemicals in food

Four oils $A, B, C$ and $D$ have the following values of melting points.
(a) $258$ K (b) $273$ K (c) $295$ K (d) $303$ K
Among these, which oil is prohibited from consumption by cardiac patients?

  1. a

  2. b

  3. c

  4. d
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The oils having higher unsaturation in the fatty acid component have very low melting points. Hence, on the consumption of these oils there is less chance of blockage of blood vessels. The saturated oils have higher melting points and they get solidified easily. Therefore they block the blood vessels and so are prohibited from consumption by cardiac patients. Hence oil D is prohibited from consumption by cardiac patients.

Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

Cholesterol belongs to group

  1. Steroid

  2. Neutral fats

  3. Waxes

  4. Phospholipids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Steroids are the organic molecule which plays an important role in the growth and development of the body. The molecular structure consists of 17 carbon which are arranged in four fused structure. It is found in plants, animals and fungi. Steroids such as cholesterol forms an integral component of the cell membrane and alter the membrane fluidity. They also acts as hormone receptor for steroidal hormones. It acts as a precursor for the biosynthesis of steroid hormones, bile acid, and vitamin D. 
So, the correct answer is option A.
Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

Lipids are insoluble in water because lipids molecules are

  1. Hydrophilic

  2. Hydrophobic

  3. Neutral

  4. Zwitter ions
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lipids are hydrophobic (water repelling) and non-polar. Non-polar substances, for instance fats and oils cannot be dissolved in water because they have made up of only carbon-carbon and hydrogen-carbon bonds. Only polar solutes dissolve in polar solvents.

So, the correct option is 'Hydrophobic'.

Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

Which of these is not a lipid?

  1. Steroid

  2. Fat

  3. Polysaccharide

  4. Wax
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The polysaccharide is a carbohydrate that is formed by the bond formation between various monomers like glucose, fructose etc. Its examples are starch, cellulose, chitin, glycogen, etc.

Hence, the correct answer is 'Polysaccharide'.

Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

Jojoba (Simmondsia) possesses

  1. Triglyceride and wax

  2. Wax

  3. Triglyceride

  4. Sterol
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Wax is a long chain of sterol ester. It is also used in commercial production of lubricants, rust-preventive coatings, shoe polish. Jojoba is a liquid extracted from Simmondsia chinensis of mono-esters of long-chain fatty acids and alcohols, accompanied by only a tiny fraction of triglyceride esters. It has resistance to high temperatures. It is a fungicide. It  can be used for controlling mildew.
So, the correct answer is option B.
Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

Which one is a lipid?

  1. Stachyose

  2. Lycopene

  3. Leucine

  4. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Stachyose is a tetrasaccharide consisting of 2 galactose, one glucose and one fructose units. It occurs naturally in green beans, soya beans and other beans. It is less sweet than sucrose. Its molecular formula is $C _{24}H _{42}O _{21}$

Lycopene is a naturally occurring carotenoid pigment which gives fruits and vegetables its red colour. It is found in watermelon, tomato and red carrots. It protects lipids, proteins and DNA against oxidative damage. It is a powerful antioxidant which protects the body from damage against various diseases.
Leucine is an amino acid which stimulates muscle protein synthesis and also prevents the deterioration of muscles with proteins. It is found in cheese, soyabean, beef, pork, nuts, seeds, fish etc.
Thus, the correct answer is option D. 

Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

Lipids are classified into $3$ main types, which includes

  1. Simple lipids

  2. Compound lipids

  3. Derived lipids

  4. All of them
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Lipids are classified into simple, compound and derived lipids. 

  1. Simple lipids are esters of fatty acids with various types of alcohols.
  2. Compound lipids are esters of fatty acids with various types of alcohols in addition to a prosthetic group.
  3. Derived lipids are those produced by the hydrolysis of the first two groups.
So the correct option is 'All of them'

Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

Choose the odd one out w.r.t. polymer _____________.

  1. Proteins

  2. Lipids

  3. Polysaccharides

  4. Nucleic acids
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Proteins are made of amino acids (monomers) and polysaccharides or sugars are made of monosaccharides (monomers).  Nucleic acids or DNA and RNA are made of nucleotides again monomers. However, lipids are not polymers made of smaller monomeric units. 

So, the correct answer is, 'Lipids'.

Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

Choose the correct answer from the alternatives given.
In a phospholipid bilayer, the

  1. Phosphate groups are hydrophobic

  2. Fatty acid tails are hydrophilic

  3. Proteins are located only between the two layers

  4. Phosphate heads are oriented towards the exterior of the cell or toward the cytoplasm
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
In the fluid mosaic model, the phospholipid bilayer has integrated as well as peripheral proteins embedded in it. This bilayer is composed of hydrophilic phosphate heads and hydrophobic tails. The phosphate heads are oriented towards the exterior or towards the cytoplasm.

So, the correct answer is 'Phosphate heads are oriented towards the exterior of the cell or toward the cytoplasm'.
Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

A phospholipid molecule has a head and two tails, The tails are found

  1. At the surfaces of the membrane

  2. In the interior of the membrane

  3. Spanning the membrane

  4. Both (a) and (b)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
In a cell membrane, the hydrophobic ends of phospholipid molecules in the outer monolayer of the membrane are sandwiched between the hydrophilic heads of the phospholipid bilayer and are not exposed to the environment.

So, the correct answer is 'In the interior of the membrane'.
Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

The properties of lipids are

  1. Insoluble in water and soluble in fat solvents.

  2. High energy content.

  3. Structural component of cell membrane.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Lipids are compounds of carbon, hydrogen and oxygen where ratio of hydrogen and oxygen is less than that of water. Lipids are esters of fatty acids and alcohol which form emulsion with water but are soluble in organic solvents. Some of the common examples of lipids are butter, ghee, cholesterol, carotene etc. Lipids are used as energy source. Lipids provide 9.3 kcal per gram as compared to 4.5 kcal per gram by carbohydrates. Lipids have other important uses also like they lubricate hairs and feathers in animals, reduce transpiration in plants and form components of cell membranes in organisms.

Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

A triglyceride molecule has?

  1. Three fatty acids with one glycerol molecule

  2. Three fatty acids with two glycerol molecules

  3. Two fatty acids with two glycerol molecules

  4. One fatty acids with one glycerol molecule
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A triglyceride is an ester derived from glycerol and three fatty acids. The structure consists of one glycerol molecule backbone with three fatty acid chains attached.

Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

The maximum number of double bonds present in essential fatty acids is 

  1. 1

  2. 2

  3. 3

  4. 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Unsaturated fatty acids have one or more double bonds like oleic acid (one), linoleic acid (two), linolenic acid (three), and arachidonic acid (four). An unsaturated fatty acid with one double bond is called mono unsaturated fatty acid (MUFA). Fatty acid with more than one double bond is called as polyunsaturated fatty acid (PUFA). Animals cannot synthesize fatty acids with double bonds (Linoleic, Linolenic and Arachidonic acids). Hence, these fatty acids must be obtained in diet and are thus called essential fatty acids.