Tag: bio-chemistry

Questions Related to bio-chemistry

Ptyalin enzyme is secreted by

bio-chemistry digestive system of human digestive system- glands mouth and buccal cavity digestive glands

  1. Salivary glands

  2. Mouth

  3. Oesophagus

  4. Stomach

Show answer
Correct Option: A
Explanation:

Ptyalin is a form of amylase found in saliva of humans. Another name of ptyalin is salivary amylase. It is the most important amylolytic enzyme secreted in mouth (buccal cavity) by the salivary glands. The main function of ptyalin is to catalyze the hydrolysis of starch into maltose and dextrin. 

Sterols are not fats but solid alcohols. These are put as lipids because they form

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Fats and fatty acids

  2. Triglycerides

  3. Cholesterol

  4. Ester and fatty acids

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Correct Option: C

Cholesterol is a precursor for each  of the following except

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. bile salts

  2. Vitamins D

  3. insulin

  4. steroids

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Correct Option: A

At physiological temperature, sterols in biological membranes

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Increase their fluidity

  2. Decrease their fluidity

  3. Increase their permeability to water

  4. Decrease their permeability to water

Show answer
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

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Lipids

  2. Cholesterol

  3. Lipoic acid

  4. None of the above

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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 _________.

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Cytoplasm

  2. Mitochondria

  3. Golgi bodies

  4. None of the above

Show answer
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?

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Glucose converts to lactic acid.

  2. Acetic acid is converted to cholesterol

  3. Glucose converted to pyruvic acid

  4. Glycogen converted to glucose

Show answer
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

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Cholesterol

  2. Thyroxine

  3. Vitamin A

  4. Fatty acid ester

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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?

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Masculinisation

  2. Breast enlargement

  3. Excessive hair growth on face and body

  4. Deepening of voice

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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?

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Acetyl- CoA

  2. Pyruvate

  3. Glycogen

  4. None of the above

Show answer
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.