Biology Chapter 3

Question 1

Describe the causes and consequences of lactose intolerance

Answer 1

Instead of being broken down in the small intestine, lactose is broken down in the large intestine (causing gas and discomfort)

Question 2

Describe the special bonding properties of carbon that allow it to form an endless variety of organic molecules.

Answer 2

Carbon atoms have four electrons in a shell that can hold up to eight, so carbon atoms can form up to four covalent bonds

Question 3

Compare a dehydration reaction to hydrolysis.

Answer 3

Dehydration: links two monomers together, removes a particle of water

Hydrolysis: breaks bond between two monomers, adds a particle of water (the opposite of dehydration)

Question 4

Compare the structures and roles of monosaccharides, disaccharides, and polysaccharides in living organisms. Give examples of each.

Answer 4

Monosaccharides: simple sugars that cannot be broken down by hydrolysis into smaller sugars (monomers of carbohydrates. Main fuels for cellular work. Example: fructose in fruit, glucose in sports drinks

Disaccharides: double sugar–two monosaccharides joined by dehydration reaction. Example: lactose in milk, maltose in beer

Polysaccharides: long chain polymers of sugars. Complex carbohydrates. Example: Glycogen (used by animals to store energy)

Question 5

Describe the unique properties of lipids.

Answer 5

Lipids are neither macromolecules nor polymers, and they are hydrophobic (unable to mix with water)

Question 6

Compare the structure and properties of saturated and unsaturated fatty acids.

Answer 6

Saturated fatty acids: has the maximum number of hydrogens

Unsaturated fatty acids: fewer than the maximum number of hydrogens

Question 7

Distinguish between steroids and anabolic steroids, and explain how the use of anabolic steroids can be dangerous to a person’s health.

Answer 7

Steroids: naturally occuring in the body, such as estrogen and testosterone

Anabolic steroids: synthetic testosterone, mimics some of the testosterone’s effect

Question 8

Describe the structure of proteins. Distinguish between the primary structure and the final three-dimensional shape.

Answer 8

Polymers made of amino acid monomers (long chains of amino acids in a specific order).

The final three-dimensional shape of a protein is determined when the protein binds to another molecule, which allows the protein to fulfill its function in a cell.

Question 9

Describe and compare the structures of DNA and RNA.

Answer 9

DNA: is a double helix, nitrogenous bases hang off of a sugar-phosphate backbone, bases from one strand bond to bases from the other

RNA: single helix made of sugar and ribose

Question 10

Explain why we think that lactose intolerance has a genetic basis.

Answer 10

An experiment was conducted that found 100% of people with lactose intolerance had a common nucleotide near the lactase gene

Question 11

Explain why lactose intolerance has evolved differently in humans spread throughout the world.

Answer 11

Cultures that were heavily reliant on dairy products, such as Northern European and East African cultures, developed mutations that made them tolerant to lactose (though the mutation is different for both separate cultures) . Meanwhile, other cultures never developed these mutations, so 80% of African Americans and Native Americans and 90% of Asian Americans are lactose intolerant, but only 10% of European Americans are.