This set of Cell Biology Multiple Choice Questions & Answers (MCQs) focuses on “Chemical Basis of Life – Lipids”.
1. Lipids cannot dissolve in _____________
a) organic solvents
Explanation: Lipids are vital biomolecules that have a characteristic property of being able to dissolve in organic solvents such as benzene and chloroform and their inability to dissolve in water.
2. Which types of bonds are found in fats?
Explanation: Fatty acids consist of one glycerol moiety linked to three fatty acids via ester bonds; the composite molecule is called triacylglycerol or neutral fat.
3. How many carboxyl groups are present in fatty acids?
Explanation: Fatty acids are long chain hydrocarbons containing only one carboxyl group at the end of the molecule. Three fatty acid chains link up via ester bonds to a glycerol molecule to form triacylglycerol. The hydrocarbon chain of fatty acids is hydrophobic and the carboxyl group is hydrophilic.
4. Fatty acids that lack double bonds are call saturated.
Explanation: Fatty acids differ from each other by the length of hydrocarbon chain present and the nature of bonds between the atoms. Those with presence of double bonds are called unsaturated fatty acids and the other group is called saturate fatty acids.
5. Which type of bonds present in vegetable fats account for their liquid state?
a) Single bonds
b) Double bonds
c) Amide bonds
d) Glycosidic bonds
Explanation: Double bonds are profusely present in the vegetable fats which account for their liquid state at room temperature. Due to this reason they are also known as polyunsaturated. Fats that are liquid at room temperature are called oils.
6. Margarine is formed using unsaturated vegetable fats by _________________
Explanation: Solid shortenings such as margarine are formed by chemically reducing the double bonds present in polyunsaturated vegetables with hydrogen atoms. This hydrogenation process also converts some of the cis-double bonds to trans-double bonds which are straight rather than kinked; called partially hydrogenated or trans-fats.
7. Fats contain more chemical energy than carbohydrates.
Explanation: Fats contain more energy content than carbohydrates. A gram of fat contains twice the energy than a gram of carbohydrates. Carbohydrates serve as short-term, readily available energy whereas fat reserves store energy on long-term basis.
8. In most animals, fats are stored in special cells called _____________
c) lymphoid cells
Explanation: In many animals, fats are stored in adipocytes cytoplasm of which contains one or a few large droplets of lipids. Adipocytes have the ability to change their shape to accommodate varying quantities of fats.
9. Which of the following steroids is a precursor of hormones such as testosterone, progesterone and estrogen?
Explanation: Steroids are built on a four-ringed hydrocarbon skeleton. Cholesterol is a steroid and is found majorly in animal cell membranes, it is also a precursor in the synthesis of various steroid hormones such as testosterone, progesterone and estrogen.
10. What is the major difference between a fat (triacylglycerol) and a phospholipid (diacylglycerol)?
a) Glycerol conformation
b) Hydrogen bonding
c) Fatty acid chain
Explanation: A phospholipid molecule resembles a fat molecule but differs in the sense that it contains only one less fatty acid chain (diacylglycerol) whereas fats contain three fatty acid chains (triacylglycerol).
Sanfoundry Global Education & Learning Series – Cell Biology.
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