Biology Ch. 2 Review Questions

Once dietary fats are digested and absorbed, why can they not be released directly into the bloodstream?

All lipids are hydrophobic and unable to dissolve in the watery environment of blood. They are packaged into lipoproteins, whose outer protein envelope enables them to transport fats in the bloodstream.

which of the following statements about chemical bonds is true?

Covalent bonds are stronger than ionic bonds.

Oxygen, whose atomic number is eight, has three stable isotopes: 16O, 17O, and 18O. Explain what this means in terms of the number of protons and neutrons.

Oxygen has eight protons. In its most abundant stable form, it has eight neutrons, too, for a mass number of 16. In contrast 17O has nine neutrons, and 18O has 10 neutrons.

AB-- A + B is a general notation for a(n)_____ reaction

decomposition

C6 H12 O6 is the chemical formula for...

hexose monosaccharide

The characteristic that gives an element its distinctive properties is its number of

protons

During a party, Eli loses a bet and is forced to drink a bottle of lemon juice. Not long thereafter, he begins complaining of having difficulty breathing, and his friends take him to the local emergency room. There, he is given an intravenous solution of bicarbonate. Why?

Lemon juice, like any acid releases hydrogen ions in solution. As excessive H+ enters the digestive tract and is absorbed into blood, Eli's blood pH falls below 7.35. Recall that bicarbonate is a buffer, a weak base that accepts hydrogen ions. By administering bicarbonate intravenously, the emergency department physician helps raise Eli's blood pH back toward neutral.

When you do a load of laundry, why do you not just drop a bar of soap into the washing machine? In other words, why is laundry detergent sold as a liquid or powder?

Recall that the greater the surface area of the reactants, the more quickly and easily they will interact. It takes energy to separate particles of a substance Powder and liquid laundry detergent , with relatively more surface area per unit, can quickly dissolve into their reactive components when added to the water.

the most abundant elements in the foods and beverages you consume are oxygen, carbon, hydrogen, and nitrogen. Why might having these elements in consumables be useful?

These four elements--oxygen, carbon, hydrogen, and nitrogen--together make up more than 95 percent of the mass of the human body, and the body cannot make elements, so it is helpful to have them in consumables.

In a hurry one day, you merely rinse your lunch dishes with water. As you are drying your salad bowl, you notice that it still has an oily film. Why was the water alone not effective in cleaning your bowl?

Water is a polar molecule. It has a region of weakly positive charge and a region of weakly negative charge. These regions are attracted to ions as well as to other polar molecules. Oils are nonpolar, and are repelled by water.

The smallest unit of an element that still retains the distinctive behavior of that element is an

atom

Egg white once fried is not liquid anymore. This shape change is an example of protein

denaturation

What organic compound do brain cells primarily rely on for fuel?

glucose

When an atom donates an electron to another atom, it becomes an

ion

A pentose sugar is a part of the monomer used to build which type of macromolecule?

nucleic acids

Together, just four elements make up more than 95 percent of the body's mass. These include ________.

oxygen, carbon, hydrogen, and nitrogen

Jenny mixes up a batch of pancake batter, then stirs in some chocolate chips. As she is waiting for the first few pancakes to cook, she notices the chocolate chips sinking to the bottom of the clear glass mixing bowl. The chocolate chip batter is an example of a ________. a. solvent b. solute c. solution d. suspension

suspension