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Functions of lipids - class-XI

Description: functions of lipids
Number of Questions: 23
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Tags: biochemistry lipids chemistry biomolecules: chemical constituents of living cells biology bio-chemistry
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Which tissue is responsible for providing insulation to the body?

  1. Epithelial tissue

  2. Adipose tissue

  3. Fibrous connective tissue

  4. Nervous tissue

  5. Muscle tissue


Correct Option: B
Explanation:

Adipose tissue, or fat, is an anatomical term for loose connective tissue composed of adipocytes. Its main role is to store energy in the form of fat, although it also cushions and insulates the body.

The greatest amount of energy per gram is produced by

  1. Sugar

  2. Starch

  3. Fat

  4. Proteins

  5. Vitamins


Correct Option: C
Explanation:
Our food contains three main constituents: carbohydrates, fats and proteins. The amount of energy released when one gram of any of these food elements is burned is known as calorific value. Thus calorific value of food indicates as to how much is the energy value of food which the human body can gain through metabolism. It is usually given in kcal/gm. Fats form the most concentrated source of energy in our diet. 1 gram of fat yields 9.5 kcal of energy which is the highest among the food components. 1 gram of carbohydrates and proteins yield almost similar amount of energy which is equal to 4 kcal.
Thus, the correct answer is option C.

Which is used for staining lipids?

  1. Rhodamine

  2. Iodine

  3. Ethidium bromide

  4. Sudan Red


Correct Option: D
Explanation:

 Lipids are the compound formed by alcohol and fatty acids ester linkage. They are characterized by solubility in the organic solvent. Sudan Red dye is used to stain lipids. It is water insoluble but dissolves with fats. Therefore, dye accumulates in the globules within the cells. Thus, the correct option is  D.

Study the given statement and select the correct answer  

  1. Lipids are micromolecules but obtained under-macromolecular fraction due to their insoluble nature in aquous medium of a cell.

  2. water is the most aboundant chemical in living organism

  3. First respiratory substrate = Lipid

  4. DIhydroxy acetone occur in d and I form.


Correct Option: A

Identify the statement which is incorrect about absorption of lipids.

  1. The lipids are absorbed in laymp capillaries present with the villi

  2. From the micelles ,fatty acids and glycerol are absorbed into the intestinal cells by active transport

  3. Micelles are formed with the help of bile salts and phospholipids in intestinal lumen

  4. The lacteals after absorption of lipids contains chyle


Correct Option: A

Biological function of lipids is/are

  1. Source of energy

  2. Insulating material

  3. Maintenance of cellular integrity with other macromolecules

  4. All of the above


Correct Option: D
Explanation:

Fats are an important class of biomolecules.They are compounds of carbon, hydrogen and oxygen where the ratio of hydrogen and oxygen is less than that of water. Lipids are a concentrated source of energy and serve for long term energy storage in body of animals and plants. Their respiratory quotient is less than one. Approximately 9 calories are provided by one gram of fat as compared to 4 by carbohydrates. Fats also act as insulating material because they are poor conductors of heat. Most of the animals have a layer of fat below the skin acting as insulating material. Lipids also serve as structural biomolecules for example conjugate lipid molecules like phospholipids, glycolipids, sphingolipids etc.

........... prevents the rupturing of lysosomal membrane.

  1. Cholesterol

  2. Vit. A

  3. Testosterone

  4. UV rays


Correct Option: A
Explanation:

Vitamin A, testosterone and UV rays induce lysis of lysosomal membrane under acidic pH which makes options B, C and D incorrect. Cholesterol exhibit scavenging effect on free radicals as well as prevent osmotic rupture of lysosomal membrane which makes option A correct answer. 

Which of the following molecular form is stored energy in animals?

I. Glucose

II. Glycogen

III. Lipid

IV. Protein

  1. I and II

  2. II and III

  3. I, II and III

  4. II, III and III

  5. I, II, III and IV


Correct Option: B
Explanation:

Glycogen is a polysaccharide that serves as a form of stored energy  in animals and fungi. Excess glucose is polymerised and stored as glycogen in the liver of animals and starch in plants. Excess of fatty acid is converted to lipids. Adipose tissue stores lipids in the form of “triglycerides”.
Thus, the correct answer is option "II and III". 

The energy storing molecules in animals are
I. Glucose
II. Glycogen
III. Lipid
IV. Protein

  1. I and II

  2. II and III

  3. I, II and III

  4. II, III and IV

  5. I, II, III and Iv


Correct Option: B
Explanation:

Glycogen is also homopolysaccharide of D-glucose and serves as an energy storing molecule in animals as glucose as storage material can increase the osmotic pressure of storage cell enormously. Proteins do not serve as energy storage molecule. Fat and oil are storage lipids and are derivatives of hydrocarbon that produce enormous energy upon oxidation. Thus, the correct answer is B.

Which of the following is the function of lipids?

  1. Regulation of membrane permeability

  2. Regulation of fluidity of membranes

  3. Electrical insulation to nerve fibre

  4. All of the above


Correct Option: D
Explanation:

Lipids are broken down in the digestive tract to form fatty acids and cholesterol. Fatty acids and cholesterol are key components of cell membranes that regulate its fluidity and permeability. Lipids of the nervous system are localized in myelin sheaths thereby providing electrical insulation. Thus the correct answer is option D.

Which of the following derived lipids helps in emulsifications and encapsulation?

  1. Lecithins

  2. Cephalins

  3. Carotenoids

  4. All of the above


Correct Option: A
Explanation:

Lecithin is a group of yellow-brownish fatty substances present in animal and plant tissues.In the pharmaceutical industry, it is used in emulsifications and encapsulation of drugs and is a good dispersing agent. Thus the correct answer is option A.

The phospholipid which is mainly found in the white matter of brain and spinal chord is 

  1. Lecithins

  2. Cephalins

  3. Waxes

  4. None of the above


Correct Option: D
Explanation:

Phosphatidylethanolamines are phospholipids found in all living cells, They are found mainly in the nervous tissue such as the white matter of the brain, nerves, neural tissue and in the spinal cord. 

So, the correct answer is option D.

Which of the following lipid is mainly used for membrane biogenesis?

  1. Carotenoids

  2. Terpenes

  3. Phospholipids

  4. Glycolipids


Correct Option: C
Explanation:

Membrane biogenesis is structuring/rebuilding/repairing of the cell membrane. As the cell membrane is made of a bilayer of phospholipids embedded with proteins.It is a process carried out by the cell with the help of smooth endoplasmic reticulum (SER) and Golgi apparatus (GA). Where the SER synthesizes lipids which are added with phosphate group and modified to phospholipids by the process of phosphorylation in the GA and transported through vesicles to the cell membrane.

So, the correct answer is 'Phospholipids'

Which of the following lipid act as a precursor of bile acids, Vitamin D and steroids?

  1. Phosphoglycerides

  2. Cholesterol

  3. Phospholipids

  4. None of the above


Correct Option: B
Explanation:

De novo synthesis of cholesterol from acetyl-CoA takes place in the liver. Cholesterol is an essential metabolite for the normal functioning of the endocrine system, regulation of cell membrane processes, and absorption of dietary lipids. They are important structural components of membranes. Cholesterol also serves as precursor for the synthesis of steroid hormones, vitamin D, and bile salts which are important in fat absorption from the small intestine into the blood circulatory system and secretion of liver waste products through feces. Thus the correct answer is option B.

Commonly candles are prepared from

  1. Bee's wax

  2. Paraffin wax

  3. Stearic acid

  4. Both B and C


Correct Option: D
Explanation:

Commonly candles are prepared from stearic acid and paraffin wax. Candles that made from paraffin wax only burn quicker than those made from paraffin wax and stearic acid together.

Thus, the correct answer is option D.

Source of turpentine oil is

  1. Bark of Cinchona

  2. Lichen

  3. Gymnospermous wood

  4. Algae


Correct Option: C
Explanation:

Turpentine oil is an oil which is a volatile oil which is mainly obtained from pines a gymnospermic plant. It is obtained by distillation of resin. Terpenes are the derivative of terpene oil. It is used for thinning oil based paints. It is a very good source of organic synthesis. It is highly viscous in nature. The solid material left behind after distillation is known as rosin.

So, the correct answer is option C.

Prostaglandins are made from

  1. Steroid

  2. Carbohydrate

  3. Amino acid

  4. Fatty acid


Correct Option: D
Explanation:
Arachidonic acid is a polyunsaturated omega-6 fatty acid. It is present in the phospholipids and helps in the formation of membranes. It is the most abundant fatty acid in the brain. It is a precursor for the synthesis of prostaglandins. The prostaglandins synthesized is PG$ _2$. They are autocrine and paracrine lipid mediators that act upon platelets, endothelium, uterine and mast cells. 
So, the correct answer is option D.

Prostaglandins synthesized from

  1. Amino acids

  2. Fatty acids

  3. Carbohydrates

  4. Steroids


Correct Option: B
Explanation:
Prostaglandins are synthesized by arachidonic acid. Arachidonic acid is a polyunsaturated omega-6 fatty acid. It is present in the phospholipids and helps in the formation of membranes. 
The prostaglandins synthesized is PG$ _2$. They are autocrine and paracrine lipid mediators that act upon platelets, endothelium, uterine and mast cells. It belongs to a class of fatty acid derivative.
So, the correct answer is option B.

What is true of membrane lipids and proteins?

  1. None can flip-flop

  2. Both can flip-flop

  3. Proteins can flip-flop but lipids cannot.

  4. Lipids flip-flop but proteins rarely flip-flop


Correct Option: D
Explanation:

Lipid bilayer of the cell membrane contains hydrophilic head groups facing outward and hydrophobic tails facing each other. The transport of phospholipids and lipid-linked oligosaccharides is difficult to achieve due to this bipolar nature. The transmembrane lipid transporter proteins called flippases transport lipids across cell membrane through transverse diffusion by flipping their orientation. Floppases transport in reverse direction. In mammals, this affects various processes such as blood coagulation, immune recognition, and programmed cell death.Most protein molecules do not flipflop due to their extensive polar regions, which are unfavorable in the hydrophobic core of the membrane.

Option D is correct.

The exine of mature pollen grain is composed chiefly ____________.

  1. Lipids

  2. Cellulose

  3. Pectocellulose

  4. Sporopollenin


Correct Option: A

Why tails of lipids in the membrane are towards inner part?

  1. The tails is non-polar hydrocarbon and so, protected with an aqueous environment

  2. The tail is polar hydrocarbon and so, is protected from aqueous environment

  3. The non-polar or hydrophobic hydrocarbon trails of lipid, being on inner side ensure their protection from aqueous environment.

  4. The tail is hydrophilic so, it tends to be located in the aqueous inner side of membrane


Correct Option: C
Explanation:

The tails of the lipids are made up of fatty acids. These are non-polar hydrophobic so they tend to arrange away from the cytoplasmic face as well as the extracellular face. So, they avoid aqueous medium by arranging themselves towards the inner part of the cell membrane.

Hence, the correct answer is 'The non-polar or hydrophobic hydrocarbons tails of lipid, being on inner side ensure their protection from the aqueous environment.

Which of the following can be traced in phospholipids of brain tissue and soybeans?

  1. Phosphoglycerides

  2. Phosphoinositides

  3. Cholesterol

  4. None of the above


Correct Option: B
Explanation:

Phosphoinositides make up a small fraction of cellular phospholipids, They play a fundamental role in controlling membrane-cytosol interfaces, regulation of membrane traffic and the permeability and transport functions of membranes. They are found in brain tissue in animals and soybean seeds. Thus the correct answer is option B.

Deficiency of EFA causes

  1. Follicular keratosis

  2. Kidney failure

  3. Sterility

  4. All the above


Correct Option: D
Explanation:

Essential fatty acids (EFA) are those fatty acids that body cannot produce on its own and therefore must be supplied from the diet. Deficiency of EFA causes many disease conditions like dry and scaly skin, follicular keratosis (hard and dry skin around hair follicles), bumps on back of upper arms, color variation of skin, dry eyes, mouth and throat, menstrual cramps, dry vagina, excessive thirst, eczema, asthma, hay fever, painful joint. In severe cases, it may result in kidney failure and sterility.

Thus, the correct answer is option D. 

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