Biology Chapter 6: Lipids
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Questions and Answers

What do fatty acids provide energy for in the body?

  • only the muscles
  • the liver only
  • the brain only
  • most types of cells (correct)

    • What is the part of the molecule called where the first carbon in the fatty acid has three hydrogen atoms attached to it?

  • the acid group
  • the hydrocarbon chain
  • the omega end (correct)
  • the alpha end

    • What is the characteristic of common fatty acids in nature?

  • having only 4 carbons
  • having even numbers of carbon atoms (correct)
  • having only 2 carbons
  • having odd numbers of carbon atoms

    • How are fatty acids identified by chemists?

    <p>by their number of carbon atoms and type of bond between carbon atoms</p> Signup and view all the answers

    What is the characteristic of short-chain fatty acids?

    <p>having 2 to 4 carbons</p> Signup and view all the answers

    What type of fatty acid is represented by the molecules shown in Figure 6.1?

    <p>long-chain fatty acid</p> Signup and view all the answers

    What are the two main categories of fatty acids?

    <p>saturated and unsaturated</p> Signup and view all the answers

    What influences how various fatty acids can affect a person's health?

    <p>both the number of carbon atoms and the type of bond between carbon atoms</p> Signup and view all the answers

    What is the primary source of essential fatty acids for babies after birth?

    <p>Breast milk from mothers who consume a diet rich in omega-3 and omega-6 fatty acids</p> Signup and view all the answers

    What is the Adequate Intake (AI) for alpha-linolenic acid for women?

    <p>1.1 g/day</p> Signup and view all the answers

    What is a sign of essential fatty acid deficiency?

    <p>Scaly skin</p> Signup and view all the answers

    What is the main source of omega-6 fatty acids in the American diet?

    <p>Vegetable oils</p> Signup and view all the answers

    What type of fatty acid has a 'kink' or bend in the carbon chain?

    <p>Cis fatty acid</p> Signup and view all the answers

    What is the effect of trans fatty acids on blood levels of cholesterol?

    <p>Raise unhealthy cholesterol levels</p> Signup and view all the answers

    What is the result of partial hydrogenation of liquid vegetable oil?

    <p>Conversion of cis fatty acids to trans fatty acids</p> Signup and view all the answers

    What is the name of the oils that contained artificial trans fatty acids?

    <p>Partially Hydrogenated Oils (PHOs)</p> Signup and view all the answers

    What is a benefit of consuming essential fatty acids?

    <p>Promotes nervous system development</p> Signup and view all the answers

    Why are trans fatty acids not essential for good health?

    <p>They raise blood levels of unhealthy cholesterol</p> Signup and view all the answers

    What type of fatty acid is shown in Figure 6.1a?

    <p>Saturated fatty acid</p> Signup and view all the answers

    What is the main difference between fats and oils?

    <p>Fats are solid at room temperature while oils are liquid</p> Signup and view all the answers

    What is the term for fatty acids that cannot be synthesized by the body?

    <p>Essential fatty acids</p> Signup and view all the answers

    What is the omega-3 fatty acid that is used to synthesize EPA and DHA?

    <p>Alpha-linolenic acid</p> Signup and view all the answers

    What is the main omega-6 fatty acid in the brain?

    <p>Arachidonic acid</p> Signup and view all the answers

    What percentage of the brain is composed of fat?

    <p>60%</p> Signup and view all the answers

    What is the percentage of total brain DHA content acquired by a fetus during the last 3 months of pregnancy?

    <p>80%</p> Signup and view all the answers

    What is the importance of consuming essential fatty acids during the first 2 years of life?

    <p>For good vision and normal brain and intellectual development</p> Signup and view all the answers

    What is the term for the fatty acid that has two or more double bonds between carbons?

    <p>Polyunsaturated fatty acid</p> Signup and view all the answers

    What is the name of the fatty acid that is shown in Figure 6.1b?

    <p>Monounsaturated fatty acid</p> Signup and view all the answers

    Why did food manufacturers use PHOs in their products?

    <p>To extend the shelf life of their products</p> Signup and view all the answers

    What is the main disadvantage of using unsaturated fatty acids in food products?

    <p>They are more susceptible to oxidation</p> Signup and view all the answers

    What is the function of antioxidants in food preservation?

    <p>To extend the shelf life of products by preventing oxidation</p> Signup and view all the answers

    What is interesterified oil?

    <p>An artificial lipid used to replace PHOs in processed foods</p> Signup and view all the answers

    Where are triglycerides commonly found?

    <p>In both animal and plant-based foods</p> Signup and view all the answers

    What is the main difference between saturated and unsaturated fatty acids?

    <p>Saturated fatty acids have a single bond between carbon atoms, while unsaturated fatty acids have one or more double bonds</p> Signup and view all the answers

    Why did the FDA ban PHOs in foods?

    <p>Because they pose a health risk</p> Signup and view all the answers

    What is the function of glycerol in triglycerides?

    <p>It is the backbone of triglycerides</p> Signup and view all the answers

    What is the advantage of using lard in cooking?

    <p>It is often used in traditional recipes and has a unique flavor</p> Signup and view all the answers

    What is the recommendation of the Dietary Guidelines regarding trans fat intake?

    <p>To keep trans fat intake as low as possible</p> Signup and view all the answers

    What is a major difference between phospholipids and triglycerides?

    <p>One of the fatty acids in phospholipids is replaced by a chemical group that contains phosphorus.</p> Signup and view all the answers

    Why do phospholipids serve as emulsifiers?

    <p>Because they have a hydrophilic and a hydrophobic region.</p> Signup and view all the answers

    What is the primary source of cholesterol in the body?

    <p>Liver production</p> Signup and view all the answers

    What is the role of phospholipids in cell membranes?

    <p>They provide structure and flexibility to the membrane.</p> Signup and view all the answers

    What is the name of the phospholipid that is rich in egg yolks, liver, wheat germ, peanut butter, and soybeans?

    <p>Lecithin</p> Signup and view all the answers

    What is the function of cholesterol in the synthesis of vitamin D?

    <p>Serves as a precursor molecule</p> Signup and view all the answers

    What is the role of cholesterol in the human body?

    <p>It is a nutrient that is important for proper bodily function, but it is often avoided in diets.</p> Signup and view all the answers

    Which of the following foods is a rich source of cholesterol?

    <p>Egg yolk</p> Signup and view all the answers

    Why do manufacturers add emulsifiers to foods?

    <p>To keep oily and watery ingredients from separating during storage.</p> Signup and view all the answers

    What is the role of bile in the digestive system?

    <p>Facilitates lipid digestion</p> Signup and view all the answers

    What is the function of choline in the human body?

    <p>It is used to produce the neurotransmitter acetylcholine.</p> Signup and view all the answers

    Why are phytosterols and phytostanols added to certain foods?

    <p>To reduce the amount of cholesterol absorbed</p> Signup and view all the answers

    What is the primary function of cholesterol in the cell membrane?

    <p>To maintain cell membrane structure</p> Signup and view all the answers

    Why do diets rich in saturated fat and trans fat increase the risk of cardiovascular disease?

    <p>Because they can lead to high levels of unhealthy cholesterol in the blood.</p> Signup and view all the answers

    Which of the following is a function of cholesterol in the body?

    <p>Synthesizing steroid hormones</p> Signup and view all the answers

    What is the structure of sterols?

    <p>They have a ring structure of carbon atoms.</p> Signup and view all the answers

    What is the result of excessive cholesterol production in the body?

    <p>Increased risk of CVD</p> Signup and view all the answers

    What is the importance of understanding the differences between saturated, unsaturated, and trans fats?

    <p>Because they have different effects on cardiovascular health.</p> Signup and view all the answers

    What is the purpose of adding plant sterols and stanols to certain foods and dietary supplements?

    <p>To reduce the amount of cholesterol absorbed</p> Signup and view all the answers

    Which of the following is NOT a rich source of cholesterol?

    <p>Apple</p> Signup and view all the answers

    Study Notes

    Fatty Acids

    • A fatty acid is composed of a hydrocarbon chain, with a hydrophilic (omega) end and an acid group at the other end.
    • Fatty acids provide energy for muscles and most other types of cells.
    • Fatty acids can be saturated or unsaturated, depending on the presence of double bonds in the hydrocarbon chain.
    • Saturated fatty acids have single bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.
    • Monounsaturated fatty acids (MUFAs) have one double bond, while polyunsaturated fatty acids (PUFAs) have two or more.

    Essential Fatty Acids

    • Essential fatty acids are fatty acids that cannot be synthesized by the body and must be obtained through the diet.
    • The two essential fatty acids are alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid).
    • These fatty acids are important for nervous system development, wound healing, and immune function.
    • The body can convert alpha-linolenic acid to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and linoleic acid to arachidonic acid (AA).

    Trans Fats

    • Trans fats are unsaturated fatty acids with a trans configuration, where the hydrogen atoms are on opposite sides of the double bond.
    • Trans fats can be naturally occurring or artificially created through partial hydrogenation.
    • Artificial trans fats, also known as partially hydrogenated oils (PHOs), are used to extend the shelf life of foods and have been banned in the US.
    • Trans fats can increase the risk of heart disease by raising blood levels of an unhealthy form of cholesterol.

    Triglycerides

    • Triglycerides are the main form of lipids in the body and in food.
    • A triglyceride is composed of three fatty acids attached to a glycerol backbone.
    • Triglycerides are often referred to as fats and oils.
    • The body stores energy as triglycerides (fat).

    Phospholipids

    • Phospholipids are similar to triglycerides, but with one of the fatty acids replaced by a phosphate group.
    • Phospholipids are naturally found in plant and animal foods.
    • Lecithin is a major phospholipid in food and is found in egg yolks, liver, wheat germ, peanut butter, and soybeans.
    • Phospholipids are partially water-soluble and can serve as emulsifiers, keeping water-soluble and water-insoluble compounds mixed together.

    Sterols

    • Sterols are lipids with a ring structure, making them more complex than triglycerides or phospholipids.
    • Cholesterol is the most well-known sterol and is a component of every cell membrane in the body.
    • Cholesterol is used to synthesize vitamin D, steroid hormones, and bile.
    • Cholesterol is found only in animal foods, but the body also produces it in the liver.

    Plant Sterols and Stanols

    • Plant sterols and stanols are substances that have chemical structures similar to cholesterol.
    • These substances are not well absorbed by the human intestinal tract, but they can compete with cholesterol for absorption, reducing the amount of cholesterol that is absorbed.### Phytosterols and Phytostanols
    • Phytosterols and phytostanols are added to certain foods, beverages, and dietary supplements to lower elevated blood cholesterol levels, a risk factor for heart disease.
    • Examples of functional foods that contain plant sterols and stanols include cholesterol-lowering margarine-like spreads such as Benecol® and Promise Activ®.

    Fatty Acids

    • The major lipids in food and the body include fatty acids.
    • The difference between a saturated and an unsaturated fatty acid is the presence of double bonds in the unsaturated fatty acid.
    • The difference between a monounsaturated and a polyunsaturated fatty acid is the number of double bonds, with monounsaturated having one and polyunsaturated having multiple.

    Food Sources of Fatty Acids

    • At least one food that is a rich source of saturated fat, monounsaturated fat, and polyunsaturated fat is not specified, but examples could include nuts, seeds, avocados, and oils.

    Essential Fatty Acids

    • The two essential fatty acids are not specified, but they are omega-3 and omega-6 fatty acids.
    • Signs of an essential fatty acid deficiency include not specified, but may include dry skin, brittle hair, and poor wound healing.

    Phospholipids and Triglycerides

    • A phospholipid differs from a triglyceride in its structure and function, with phospholipids having a phosphate group and being involved in cell membranes, and triglycerides being composed of three fatty acid chains and being an energy source.

    Omega-3 Fatty Acids

    • An omega-3 fatty acid is a type of polyunsaturated fatty acid with a double bond at the third carbon atom from the end of the chain.

    Emulsification

    • To keep oil and milk emulsified in a recipe, a common food that could be added is an emulsifier such as lecithin or egg yolk.

    Cholesterol

    • Foods that contain cholesterol include animal products such as meat, dairy, and eggs.
    • At least three functions of cholesterol in the body include being a component of cell membranes, being involved in hormone production, and being involved in bile production.

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    Description

    This quiz covers the chemical structures and food sources of various lipids, including fatty acids, triglycerides, phospholipids, and cholesterol.

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