Unit 2 - Chemistry of Life Study Guide

Question 1

What is the difference between an organic molecule and an inorganic molecule?

Answer 1

Organic molecules contain Hydrogen and carbon while inorganic molecules don’t

Question 2

How is an ionic bond created?

Answer 2

Transfer of electrons between ions

Question 3

How is a covalent bond created?

Answer 3

two atoms share electrons (ex. the H and the O share electrons in H2O)

Question 4

When is a hydrogen bond useful?

Answer 4

Causes high specific heat in liquids like water, which organisms can easily adapt to because of little temperature changes

Question 5

Which bond type is strongest and most prevalent in nature?

Answer 5

Covalent bonds

Question 6

What does it mean for a molecule to be polar?

Answer 6

Has a positive and negative atom; uneven distribution of charge

Question 7

What are the characteristics of an enzyme?

Answer 7

Protein that speed up chemical reactions (catalyst) in our bodies by lowering the activation energy to build or break down substances. If exposed to extreme temperatures and pH, enzymes change shape making them unable to function (denatured enzyme).

Question 8

Explain the lock and key model for an enzymatic reaction.

Answer 8

Models the enzyme-substrate interaction and shape

Question 9

What is a high surface tension?

Answer 9

“Thin skin” that resists an external force. ex. when you hit the water it splashes rather than hitting it hard

Question 10

What is pH?

Answer 10

Measure of how acidic or basic a substance is

Question 11

What pH range denotes a base? An acid? A neutral?

Answer 11

Acid: 7-
Neutral: 7
Base: 7+

Question 12

Why are buffers important to organisms?

Answer 12

Buffers neutralize the pH of substances to maintain homeostasis

Question 13

What are the characteristics, element composition, and building blocks of a Carbohydrate?

Answer 13

Carbohydrates (sugars) are an organism’s main source of energy that is metabolized in cells to release energy either starches, sugars, or fiber (all commonly end in -ose). Monosaccharides are the monomer of carbs. Carbs are monosaccharides (simple sugars) if there is one glucose molecule, disaccharides if there are two glucose moleculers, and Polysaccharides (complex carbs) if there is many glucose molecules.

Question 14

What are the characteristics, element composition, and building blocks of a Protein?

Answer 14

Proteins are long chains of amino acids, linked by peptide bonds (small proteins are called peptides). Proteins do many things like build tissues and make enzymes, regulated by cell DNA. Commonly end in ‘-ase’.

Question 15

What are the characteristics, element composition, and building blocks of a Nucleic Acid?

Answer 15

Nucleic acids store genetic information for bodily functions. Nucleic acids are made up of nucleotides made of sugar molecules, a phosphate, and a nitrogen base. Living things have two types of nucleic acids: DNA and RNA. They differ in many ways like how DNA contains sugar deoxyribose while RNA contains sugar ribose.

Question 16

What are the characteristics, element composition, and building blocks of a Lipid?

Answer 16

Lipids are an energy supply for cells including steroids, waxes, oils, and fats. Fatty acids are the monomers of lipids which have two types: unsaturated and saturated. Unsaturated fats have double bonds in their molecules, while saturated fats have no double bonds and should be avoided as they can cause health issues. In cells, fats form oil droplets called globules which store energy for the body.

Question 17

What is the test used to indicate the presence of a starch? What does a positive test look like?

Answer 17

Lugol Iodine Solution tests the presence of starch; blue/black precipitate forms if positive

Question 18

What is the test used to indicate the presence of a sugar? What does a positive test look like?

Answer 18

Benedict’s solution tests the presence of sugar; yellow/red if positive

Question 19

What is the test used to indicate the presence of a protein? What does a positive test look like?

Answer 19

Biuret test tests the presence of protein; purple if positive

Question 20

What is the test used to indicate the presence of a lipid? What does a positive test look like?

Answer 20

Brown bag test tests the presence of lipids; translucent if positive

Question 21

What are the four categories of organic compounds?

Answer 21

• Nucleic Acids
• Proteins
• Carbohydrates
• Lipids

Question 22

Why aren’t tests done to show the presence of nucleic acids?

Answer 22

All living organisms contain genetic material

Question 23

Why do plants have waterproof leaves?

Answer 23

Plant cells contain lipids

Question 24

Why don’t lipids dissolve in water?

Answer 24

Lipids aren’t polar molecules

Question 25

What is water made up of?

Answer 25

1 oxygen atom (-negatively charged) + 2 hydrogen atoms (+positively charged) + combined by covalent bonds

Question 26

Plants store glucose as _____

Answer 26

starch

Question 27

What determines a protein’s job?

Answer 27

shape

Question 28

What do buffers do in the human body?

Answer 28

Ensure the blood pH remains close to neutral

Question 29

Why does water expand when frozen (ice floats on water)?

Answer 29

When water is frozen, the hydrogen bonds form ice crystals that are spread out and less dense

Question 30

What types of molecules can water dissolve?

Answer 30

polar molecules; molecules with uneven distribution of charge

Question 31

How does water aid in digestion and movement?

Answer 31

water is a lubricant (substance that reduces friction in the body)

Question 32

Difference between a solute and solvent

Answer 32

Solute - dissolved in a solvent
solvent - dissolves a solute
(ex. in salt water, water is solvent, salt is solute

Question 33

Hydrogen bond

Answer 33

weak bond between + charged Hydrogen atom and a - charged atom (ex. bond between two water molecules in H2O)