Bio4A Chapter 4

hydroxyl

-OH (Alcohol) ethanol Polar, forms hydrogen bond with water

phosphate

-OPO3 2- (organic phosphate) glycerol phosphate Contributes negative charge

carbonyl

>C=O (ketone aldehyde) acetone, propanol Ketoses or aldoses

Which of the following molecules is polar? C3H7OH C2H5COOH

A) C3H7OH and C2H5COOH are both polar molecules. B) Neither C2H5COOH or C3H7OH is polar. C) C2H5COOH is polar, but C3H7OH is not polar. D) C3H7OH is not polar, but C3H7OH is polar. Answer: A

7) Which of the following is true of carbon?

A) It forms only polar molecules. B) It can form a maximum of three covalent bonds with other elements. C) It is highly electronegative. D) It can form both polar and nonpolar bonds. Answer: D

8) Why is carbon so important in biology?

A) It is a common element on Earth. B) It has very little electronegativity, making it a good electron donor. C) It bonds to only a few other elements. D) It can form a variety of carbon skeletons and host functional groups. Answer: D

11) Why are hydrocarbons insoluble in water?

A) The majority of their bonds are polar covalent carbon-to-hydrogen linkages. B) The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages. C) They exhibit considerable molecular complexity and diversity. D) They are less dense than water. Answer: B

12) Which of the following statements correctly describes cis-trans isomers?

A) They have variations in arrangement around a double bond. B) They have an asymmetric carbon that makes them mirror images. C) They have the same chemical properties. D) They have different molecular formulas. Answer: A

26) Which of the functional groups below acts most like an acid in water?

A) amino B) carbonyl C) carboxyl D) hydroxyl Answer: C

29) Amino acids are acids because they always possess which functional group?

A) amino B) carbonyl C) carboxyl D) phosphate Answer: C

54) Which of the following is a FALSE statement concerning amino groups? Amino groups _____.

A) are basic with respect to pH B) are found in amino acids C) contain nitrogen D) are nonpolar Answer: D

32) Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates. In what way(s) do these molecules differ from each other? Testosterone and estradiol _____.

A) are structural isomers but have the same molecular formula B) are cis-trans isomers but have the same molecular formula C) have different functional groups attached to the same carbon skeleton D) are enantiomers of the same organic molecule Answer: C

27) A compound contains hydroxyl groups as its predominant functional group. Therefore, this compound _____.

A) lacks an asymmetric carbon and is probably a fat or lipid B) should dissolve in water C) should dissolve in a nonpolar solvent D) will not form hydrogen bonds with water Answer: B

5) Stanley Miller's 1953 experiments supported the hypothesis that _____.

A) life on Earth arose from simple inorganic molecules B) organic molecules can be synthesized abiotically under conditions that may have existed on early Earth C) life on Earth arose from simple organic molecules, with energy from lightning and volcanoes D) the conditions on early Earth were conducive to the origin of life Answer: B

30) A hydrocarbon skeleton is covalently bonded to an amino group at one end and a carboxyl group at the other end. When placed in water this molecule would function _____.

A) only as an acid because of the carboxyl group B) only as a base because of the amino group C) as an acid and a base D) as neither an acid nor a base Answer: C

6) When Stanley Miller applied heat and electrical sparks to a mixture of simple inorganic compounds such as methane, hydrogen gas, ammonia, and water vapor, what compounds were produced?

A) only simple organic compounds such as formaldehyde and cyanide B) mostly hydrocarbons C) only simple inorganic compounds D) simple organic compounds, amino acids, and hydrocarbons Answer: D

3) The experimental approach taken in current biological investigations presumes that _____.

A) simple organic compounds can be synthesized in the laboratory from inorganic precursors, but complex organic compounds like carbohydrates and proteins can be synthesized only by living organisms B) a life force ultimately controls the activities of living organisms and this life force cannot be studied by physical or chemical methods C) living organisms are composed of the same elements present in nonliving things, plus a few special trace elements found only in living organisms or their products D) living organisms can be understood in terms of the same physical and chemical laws that can be used to explain all natural phenomena Answer: D

2) The complexity and variety of organic molecules is due to _____.

A) the chemical versatility of carbon atoms B) the variety of rare elements in organic molecules C) the diverse bonding patterns of nitrogen D) their interaction with water Answer: A

14) What determines whether a carbon atom's covalent bonds to other atoms are in a tetrahedral configuration or a planar configuration?

A) the presence or absence of bonds with oxygen atoms B) the presence or absence of double bonds between the carbon atom and other atoms C) the polarity of the covalent bonds between carbon and other atoms D) the solvent in which the organic molecule is dissolved Answer: B

methyl

-CH3 (Methylated compound) 5-methyl cytosine Affects shape and function of sex hormones

carboxyl

-COOH (carboxyl acid or organic acid) acetic acid Acts as an acid

amino

-NH2 (amine) glycine Acts as base

sulfhydryl

-SH (thiol) cysteine

9) How many electron pairs does carbon share to complete its valence shell?

A) 2 B) 3 C) 4 D) 8 Answer: C

31) Which chemical group can act as an acid?

A) amino B) carbonyl C) carboxyl D) methyl Answer: C

15) Compared to a hydrocarbon chain where all the carbon atoms are linked by single bonds, a hydrocarbon chain with the same number of carbon atoms, but with one or more double bonds, will _____.

A) be more flexible in structure B) be more constrained in structure C) be more polar D) have more hydrogen atoms Answer: B

28) Which two functional groups are always found in amino acids?

A) carbonyl and amino groups B) carboxyl and amino groups C) amino and sulfhydryl groups D) hydroxyl and carboxyl groups Answer: B

4) Differences among organisms are caused by differences in the _____.

A) elemental composition from organism to organism B) types and relative amounts of organic molecules synthesized by each organism C) sizes of the organic molecules in each organism D) types of inorganic compounds present in each organism Answer: B

16) Organic molecules with only hydrogens and five carbon atoms cannot _____.

A) have a branching carbon skeleton B) have different combinations of double bonds between carbon atoms C) have different positions of double bonds between carbon atoms D) form enantiomers Answer: D

13) Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; that is, molecules that _____.

A) have identical chemical formulas but differ in the branching of their carbon skeletons B) are mirror images of each other C) differ in the location of their double bonds D) differ in the arrangement of atoms around their double bonds Answer: B

1) The element present in all organic molecules is _____.

A) hydrogen B) oxygen C) carbon D) nitrogen Answer: C

10) A carbon atom is most likely to form what kind of bond(s) with other atoms?

A) ionic B) hydrogen C) covalent D) ionic bonds, covalent bonds, and hydrogen bonds Answer: C

ATP

An important organic phosphate is adenosine triphosphate (ATP) ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups ATP stores the potential to react with water,a reaction that releases energy to be used bythe cell

molecular function

Distinctive properties of organic molecules depend on the carbon skeleton and on the chemical groups attached to it. A number of characteristic groups can replacethe hydrogens attached to skeletons of organic molecules.

electron configuration

Electron configuration is the key to an atom's characteristics. Electron configuration determines the kinds and number of bonds an atom will form with other atoms.

valence electrons

H- 1 O- 2 N- 3 C- 4

hydrocarbons

Hydrocarbons are organic molecules consisting of only carbon and hydrogen. Many organic molecules, such as fats, have hydrocarbon components. Hydrocarbons can undergo reactions that release a large amount of energy.

seven functional groups

Hydroxyl group Carbonyl group Carboxyl group Amino group Sulfhydryl group Phosphate group Methyl group

Carbon the living backbone

Living organisms consist mostly of carbon-based compounds. Carbon is unparalleled in its ability to form large, complex, and varied molecules. Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds.

carbon electron configuration

With four valence electrons, carbon can form four covalent bonds with a variety of atoms. This ability makes large, complex molecules possible In molecules with multiple carbons, each carbon bonded to four other atoms has a tetrahedral shape However, when two carbon atoms are joined by a double bond, the atoms joined to the carbons arein the same plane as the carbons.

carbon skeletons

carbon chains form skeletons of most organic molecules. vary in length and shape

isomers

compounds with the same molecular formula but different structures and properties.

structural isomers

have different covalent arrangements of their atoms

cis-trans isomer

have same covalent bonds but differ in spatial arrangement

most frequent partners of carbon

hydrogen, oxygen, and nitrogen (building code for the architecture of living molecules)

enantiomer

isomers that are mirror images of each other (important to pharmaceutical industry)

vitalism

belief in a life force outside the jurisdiction of physical and chemical laws. organic compounds could only be produced by living organisms. (disproved when chemists synthesized organic compound)

organic chemistry

study of compounds containing carbon. range from simple molecules to colossal ones. most organic compounds contain hydrogen also