Tag: functions and principal sources of lipids

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

The major site of lipid synthesis in most cells is?

  1. Cytoplasmic ribosome's

  2. Outer membrane of mitochondria

  3. Endoplasmic reticulum

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

The endoplasmic reticulum (specifically the smooth endoplasmic reticulum) is the primary site for the synthesis of most membrane lipids, phospholipids, and cholesterol in eukaryotic cells.

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.
Which of the following function does the lipid bilayer component of the cell membrane not provide for the cell?

  1. Controls the exchange of matter and chemical information between one cell and adjacent cells or the environment

  2. Provides an impermeable, self-sealing membrane capable of dividing or fusing the cell without breaking

  3. Provides the matrix into which proteins are inserted that facilitate the exchange of matter between the inside and outside of the cell

  4. Clearly defines a boundary preventing an equilibrium between the outside and inside of the cell
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The lipid bilayer of the cell membrane does not completely isolate the cell from its surrounding instead, it is a semipermeable membrane with pores and receptors that allows a selective exchange of material and information between the environment inside and the outside the cell.
So, the correct answer is 'Provides an impermeable, self-sealing membrane capable of dividing or fusing the cell without breaking'.
Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

The Lipid derivatives which occur in faecal material are

  1. Cholesterol

  2. Ergesterol

  3. Lanoline

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

Many animals, plants and yeast synthesize sterols and their derivatives. Sterols are widely distributed in living organisms as lipid constituents. Cholesterol is a major sterol found as component of plasma membrane lipid bilayer in higher animals such as humans and other mammals. Cholesterol is metabolised to bile acids and steroid hormones. Intestinal microorganisms reduce a certain amount of cholesterol to coprosterol which is then excreted out as faeces. A form of coprosterol termed as 5-coprosterol has a low water solubility and therefore remains stable for many hundreds of years in the environment. Coprosterol is therefore, also used as an indicator of faecal pollution in water from different sources. Ergosterol is a sterol found in fungi and protozoa necessary for their survival and has functions similar to that of cholesterol. Lanolin is a lipid derivative secreted by the sebaceous glands of wool bearing animals. Lanolin is a wax, but it is not a true fat since it lacks glycerides.
So, 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

This is wax.

  1. Palmitic acid

  2. Ethyl palmitate

  3. Hexacosyl palmitate

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

Wax is a long chain of sterol ester. These are hydrophobic. They are insoluble in water but soluble in organic and nonpolar solvents. It consists of long alkyl chains. Hexacosyl palmitate is an ester derived from the palmitic acid and cetyl alcohol. It is white in color and forms an important constituent of tissues of stony corals. It is the main constituent of bee wax.

So, the correct answer is option C.

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

Match the column I with column II and select the correct option from the codes given below.

 Sr. No  Column I  Sr.No  Column II
 A.  Fats made of three fatty acid chain attached to glycerol   (i)  Glycogen 
 B.  Glycolysis metabolic made from glycerol   (ii)  Glyceraldehyde 
 C.  Storage form of glucose  (iii)   Triglycerides
 D.  the common respiratory substrate of glycolysis  (iv)  Glucose

  1. A-(iv),B(ii),C(i),D(iii)

  2. A-(iii),B(ii),C(i),D(iv)

  3. A-(iv),B(iii),C(i),D(ii)

  4. A-(i),B(ii),C(iii),D(iv)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
 Column I  Column II
 A.Fats made of three fatty acid chain attached to glycerol iii)Triglycerides
B. Glycolysis metabolic made from glycerol  ii) Glyceraldehyde
 C. Storage form of glucose  i) Glycogen 
 D. common respiratory substrate for glycolysis iv) glucose 

So, the correct option is 'A-(iii),B(ii),C(i),D(iv)'.

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.
Which of the following factors would tend to increase membrane fluidity?

  1. A greater proportion of unsaturated phospholipids

  2. A high membrane potential

  3. A lower temperature

  4. A lower cholesterol concentration in the membrane
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The fluidity of the phospholipid bilayer depends on different factors like the length of the fatty acid chain, the temperature, the cholesterol content, and the level of saturation in the layer. As the amount or number of unsaturated fatty acids increases in the bilayer, so does the fluidity.

So, the correct answer is 'A greater proportion of unsaturated phospholipids'.