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Derived lipids - class-XII

Description: derived lipids
Number of Questions: 28
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Tags: bio-chemistry lipids biology biomolecules: chemical constituents of living cells cell membrane
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Sterols are not fats but solid alcohols. These are put as lipids because they form

  1. Fats and fatty acids

  2. Triglycerides

  3. Cholesterol

  4. Ester and fatty acids


Correct Option: C

Cholesterol is a precursor for each  of the following except

  1. bile salts

  2. Vitamins D

  3. insulin

  4. steroids


Correct Option: A

At physiological temperature, sterols in biological membranes

  1. Increase their fluidity

  2. Decrease their fluidity

  3. Increase their permeability to water

  4. Decrease their permeability to water


Correct Option: A
Explanation:

Biological membranes are made up of lipid bilayer. These sterols affects the fluidity and rigidity of the membrane. At physiological temperature, sterols in biological membranes increase their fluidity but makes them more stronger and rigid. Environmental conditions like higher temperatures or unsaturated fatty disrupts close packing of lipids. This results in increase in the fluidity of the membrane. The membranes become more permeable to water. However, at lower temperatures, membranes become rigid. 

So the correct option is 'Increase their fluidity'.

Which of the following is a precursor of vitamins and steroid hormones

  1. Lipids

  2. Cholesterol

  3. Lipoic acid

  4. None of the above


Correct Option: B
Explanation:

Cholesterol acts as precursor of Vitamin D and steroid hormones like estrogen, testesterone

So, the correct answer is 'Cholesterol'

Beta-oxidation mainly takes place in _________.

  1. Cytoplasm

  2. Mitochondria

  3. Golgi bodies

  4. None of the above


Correct Option: B
Explanation:

In biochemistry and metabolism, beta-oxidation is the catabolic process by which fatty acid molecules are broken down in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA, which enters the citric acid cycle, and NADH and FADH2, which are co-enzymes used in the electron transport.

Which among the following is the anabolic process?

  1. Glucose converts to lactic acid.

  2. Acetic acid is converted to cholesterol

  3. Glucose converted to pyruvic acid

  4. Glycogen converted to glucose


Correct Option: B
Explanation:
Anabolic process involves the synthesis of complex molecules from simple molecules. Cholesterol is a large and complicated molecule. The starting point of cholesterol synthesis is acetic acid.
So, the correct option is 'Acetic acid is converted to cholesterol'

Steroid is derived from

  1. Cholesterol

  2. Thyroxine

  3. Vitamin A

  4. Fatty acid ester


Correct Option: A
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 carbons which are arranged in four fused structure. It is found in plants, animals and fungi. Cholesterol which is the derivative of steroid forms an integral component of the cell membrane and alter the membrane fluidity. The also acts as hormone precursor for steroidal hormones.
So, the correct answer is option A.

Misuse of anabolic steroids cause various side-effects in males and females. Which  of the following  side-effects of anabolic steroids is not observed in females?

  1. Masculinisation

  2. Breast enlargement

  3. Excessive hair growth on face and body

  4. Deepening of voice


Correct Option: A
Explanation:

Masculinisation is a side-effect which is not commonly observed in females due to the intake of anabolic steroids. so, 'the correct option is - masculinisation'. "So, the correct answer is 'A' ".

Which of the following is a major substrate for synthesis of fats?

  1. Acetyl- CoA

  2. Pyruvate

  3. Glycogen

  4. None of the above


Correct Option: A
Explanation:

Fatty acids are components of the phospholipids that make up the bulk of the lipid bilayers of all cellular membranes. It is synthesized by cytosolic acetyl-CoA  through carboxylation by acetyl-CoA carboxylase into malonyl CoA. This conversion occurs primarily in the liver, adipose tissue and lactating mammary glands, where the fatty acids are combined with glycerol to form triglycerides

So, the correct answer is option A.

Stability of the plasma membrane is enhanced by _________ .

  1. cholesterol molecules

  2. phospholipids

  3. glycoproteins

  4. glycolipids


Correct Option: A
Explanation:

Cholesterol helps to keep the membrane stable. This stability is maintained  as: At high temperatures, cholesterol reduces membrane fluidity by restraining the movement of phospholipids. At low temperatures, cholesterol gives solidification of the membrane because it prevents the close packing of phospholipids.

So, the correct answer is 'cholesterol molecules'

Heterotrophs can metabolize lipids by a process called ___________ into monomers of _____________ and fatty acids.

  1. Hydrolysis; Glycerol

  2. Dehydration synthesis; Glycerol

  3. Hydrolysis; Glycolipids

  4. Dehydration synthesis; Glycolipids


Correct Option: A
Explanation:

Heterotrophs can metabolize lipids by a process of hydrolysis, where water molecule is added to break down a chemical compound (lipids). 

Lipids on hydrolysis yield fatty acids and glycerol
So, the correct answer is 'Hydrolysis; Glycerol'

Cholesterol content is minimum in

  1. Fish

  2. Cow's skimmed milk

  3. Liver

  4. Vegetable oils


Correct Option: D
Explanation:

Cholesterol content is minimum in vegetable oils as plant have ergosterol as the major sterol present in them. Cholesterol is present in animals and 20 % of total cholesterol is sythesised in liver.

Animal membranes contain

  1. Steroids

  2. Chlorophyll

  3. Prostaglandins

  4. Vitamin A


Correct Option: A
Explanation:
Steroids are the organic molecule which plays an important role in the growth and development of the body. It is a four-ring structure. Steroids such as cholesterol form an integral component of the cell membrane and alter the membrane fluidity. It provides the stability to the cell membrane by limiting the membrane fluidity. 
So, the correct answer is option A.

Saturated fatty acid that reduces oil quality is

  1. Palmitic acid

  2. Stearic acid

  3. Erucic acid

  4. All the above.


Correct Option: C
Explanation:

Fatty Acid Composition of Canola Oil The decrease in the level of erucic acid in rapeseed oil resulted in a marked increase in C18 acids, which make up approximately 95% of all fatty acids present in canola oil. 

Hence C is the correct answer. 

 .......... is the regulatory enzyme in the fatty acid biosynthesis.

  1. Aminoacyl synthetase

  2. Acetyl CoA carboxylase

  3. Peptidyl transferase

  4. None of the above


Correct Option: B
Explanation:
Fatty acids are components of the phospholipids that make up the bulk of the lipid bilayers of all cellular membranes. It is synthesized by cytosolic acetyl-CoA  through carboxylation by acetyl-CoA carboxylase into malonyl CoA. This conversion occurs primarily in the liver, adipose tissue and lactating mammary glands, where the fatty acids are combined with glycerol to form triglycerides
So, the correct answer is option B.

The molting hormone ecdysone belongs to the category of

  1. Amines

  2. Long chain peptides

  3. Steroids

  4. Fatty acids


Correct Option: C
Explanation:
Ecdysone is a steroidal prohormone of the major insect molting hormone 20-hydroxyecdysone, which is secreted from the prothoracic glands.

So, the correct answer is 'C'.

Consider the following fatty acids.
a. Stearic acid
b. Oleic acid
c. Linoleic acid
d. Linolenic acid
Which of these are found in plants?

  1. $1$ and $2$

  2. $1, 3$ and $4$

  3. $2, 3$ and $4$

  4. $1, 2, 3$ and $4$


Correct Option: A

The plastids which are filled with a large amount of lipids are called.

  1. Etiolates

  2. Elastoplasts

  3. Leucoplasts

  4. Amyloplasts


Correct Option: A

The oil of which one of the following plants is edible and rich in poly unsaturated fatty acids?

  1. Aleurites fordii

  2. Cocos nucifera

  3. Carthamus tinctorius

  4. Ricinus communis


Correct Option: A

Cholesterol belongs to which of the following groups

  1. Steroids

  2. Neutral fats

  3. Waxes

  4. Phospholipids


Correct Option: A
Explanation:

The steroids are composed of seventeen carbon atoms, bonded in four fused rings: three six-membered cyclohexane rings and one five-membered cyclopentane ring. The steroids differ in the functional group attached to this four-ring core and by the oxidation state of the ring.

Steroids such as cholestrol decrease membrane fluidity. Like lipids, these are highly concentrated energy stores. They are normally metabolized and excreted.
So, the correct option is 'Steroids'.

Which one of the following is not correctly matched?

  1. Cutin- Consists of long chain fatty acids and polyhydroxy derivatives of these fatty acids

  2. Pectin-Methylated polymer of flacturonic acid

  3. Lignin- Formed by condensation on coniferyl alcohol

  4. Callose- Glycosylated aliphatic acid


Correct Option: A

Which one of the following is not a correct statement regarding the design of biological membranes?

  1. Carbohydrate molecules associated with membranes tend to be associated with protein molecules embedded in the membrane

  2. Hydrophobic ends of phospholipid molecules in the outer monolayer of the membrane are exposed directly to the extracellular environment

  3. Cholesterol is a type of lipid frequently found in membranes of animal cells

  4. Protein molecules can be located on the inner and outer surfaces of the membrane as well as traverse the entire thickness of the bilayer


Correct Option: B
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 extracellular environment.

So, the correct answer is 'Hydrophobic ends of phospholipid molecules in the outer monolayer of the membrane are exposed directly to the extracellular environment'.

In the fluid mosaic membrane model, the phospholipid bilayer

  1. Is sandwiched between two protein layers

  2. Is covered by a single protein layer

  3. Has proteins embedded in it

  4. Lies on top of a single protein layer


Correct Option: C
Explanation:

In the fluid mosaic model, the phospholipid bilayer has integrated as well as peripheral proteins embedded in it. The integrated proteins are found on the inside and span across the bilayer, while the peripheral proteins are found at the periphery of the lipid layers.

So the correct answer is 'has proteins embedded in it'.

Function of smooth endoplasmic reticulum is?

  1. Synthesis of lipid

  2. Synthesis of minerals

  3. Synthesis of protein

  4. None


Correct Option: A
Explanation:

Its main functions are the synthesis of lipids, steroid hormones, the detoxification of harmful metabolic byproducts and the storage and metabolism of calcium ions within the cell. The smooth ER is distinguished from the other parts of the endoplasmic reticulum by the absence of membrane-bound ribosomes.

Thus A is the correct option. 

CPPP which is the important component of sterol is mainly stood for?

  1. Cyclopentanoperhydrophenanthrene

  2. Pentanoperhydrophenanthrene

  3. Cycloperhydrophenanthrene

  4. None of the above


Correct Option: A
Explanation:

CPPP is the abbreviated form of Cyclopentanoperhydrophenanthrene. It is an important component of sterol. Thus the correct answer is option A.

Select the correct option:

Lecithin is a 

  1. Sterol

  2. Glycolipid

  3. Phospholipid

  4. Sphingolipid


Correct Option: C
Explanation:

Phospholipids are triglyceride lipids, in which one fatty acid is replaced by phosphoric acid residue often linked to additional nitrogenous group,eg., choline in lecithin.

So, the correxct answer is 'Phospholipid'.

Steroids are

  1. Tetraterpenes

  2. Polyterpenes

  3. Triterpenes and their derivative

  4. Phenolic compounds


Correct Option: C
Explanation:

Steroids are hormonal substances in animals, but they are components of membranes in most organisms. Triterpenes are precursors to steroids in both plants and animals. Steroids are derivatives of triterpenes with 26 or more carbon atoms that have undergone a characteristic type of rearrangement. So, the correct answer is option C.

Two important processes in a cell, which take place outside the membrane bound organelles, are

  1. Enzyme synthesis and DNA replication

  2. Nucleotide synthesis and mutation

  3. Fatty acid synthesis and spindle assembly

  4. Glycolysis and photophosphorylation


Correct Option: C
Explanation:
The process of fatty acid synthesis takes place in the cytoplasm and not in a membrane-bound organelle. Also, spindle assembly takes place in the centrioles which also lack a membrane.

So, the correct answer is 'fatty acid synthesis and spindle assembly'.
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