Unit 1 AP Biology Insta-Review (Chemistry of Life)

What type of bond is found in water molecules?

• Covalent

• Hydrogen

• Ionic

• Van der Waals

Answer explanation

Bonds between hydrogen and oxygen in water are covalent bonds. The two atoms are sharing their valence electrons.

Recall: This is a POLAR covalent bond since it is unequal sharing of the electrons

What elements are found in all lipids?

• CHO

• CHON

• CHOS

• CHOP

Answer explanation

There are three types of lipids:

› Steroids: four fused rings with different functional groups

› Fats: glycerol and 3 fatty acids

› Phospholipids: glycerol, one phosphate, and three fatty acids

So, overall they are made up of carbon, hydrogen, and oxygen

Phospholipids are a type of lipid that include…

• Nitrogen

• Phosphorus

• Sulfur

Answer explanation

Phospholipids have:

› phosphate

› 2 fatty acids

› glycerol

Where are hydrogen bonds found in nucleic acids?

• Between carbons in the sugar ring

• Between nitrogenous bases

• Between nucleotides

• Between phosphates

Answer explanation

Hydrogen bonds are attractive bonds between an electronegative atom (e.g. O or N) and a hydrogen bonded to an electronegative atom. The nitrogenous bases have the nitrogen/hydrogen attracted to the oxygen of the carbonyl or nitrogen of another nitrogenous base.

How many valence electrons does Carbon have?

• 2

• 3

• 4

• 5

Answer explanation

Valence electrons are the electrons found in the outermost energy level. The first energy level can hold 2 electrons and the second energy level can hold 8 electrons. If you look at the periodic table, carbon has 6 electrons. There are 2 in the first level leaving 4 for the outermost energy level.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

What is the reaction used to synthesize polymers from monomers?

• Dehydration

• Hydrolysis

Answer explanation

Dehydration reactions will form bonds between monomers to make polymers. The water molecule is removed with forms a bond between the two molecules.

A macromolecule is found to contain C, H, O, N, and P. Identify it.

• Carbohydrate

• Lipid

• Nucleic Acid

• Protein

Answer explanation

All of the macromolecules have carbon (C), hydrogen (H), and oxygen (O). Nitrogen is found in proteins and nucleic acids. Phosphorous is found in nucleotides (and phospholipids) which is found in nucleic acids. Nucleic acids are the only macromolecule with C, H, O, N, and P.

Which of the following macromolecules include nitrogen?

• Carbohydrates & Lipids

• Lipids & Nucleic Acids

• Nucleic Acids & Proteins

• Proteins & Carbohydrates

Answer explanation

Nitrogen is

› found in the amine group of amino acids (which is protein’s monomer)

› found in the nitrogenous base of nucleotides (which is nucleic acid’s monomer)

Which lipid makes up the plasma membrane?

• Fats

• Phospholipids

• Steroids

Answer explanation

The plasma membrane or lipid bilayer is made up of two layers of phospholipids. They orient so the phosphate heads face the intracellular and extracellular regions while the fatty acids tails face the interior of the membrane.

What type of bond does Carbon make with other atoms?

• Covalent

• Hydrogen

• Ionic

• Van der Waals

Answer explanation

Carbon has four valence electrons (so it is equidistant from a complete valence shell). Due to this, carbon will share its valence electrons. Sharing valence electrons is due to covalent bonding.