Bio Lecture 2

Question 1

What forms the atomic nucleus?

Answer 1

Neutrons and protons with electrons forming a cloud around the nucleus

Question 2

What are covalent bonds?

Answer 2

Sharing of a pair of valence electrons by 2 atoms. In a covalent bond, shared electrons count as part of each atom’s valence shell

Question 3

What is electronegativity?

Answer 3

An atom’s attraction for the electrons in a covalent bond. The more electronegative an atom, the more strongly it pulls shared electrons toward itself

Question 4

Differentiate between polar and non polar covalent bonds?

Answer 4

Non polar covalent bonds are where atoms share electrons equally and polar covalent bonds are when one atom is more electronegative and the atoms do not share electrons equally

Question 5

Ch4 would have which type of bond?

Answer 5

Non polar covalent bond

Question 6

Is a water molecule polar or non polar

Answer 6

A water molecule is polar
- unequal sharing of electrons causes a partial positive or negative charge for each atom of a molecule

Question 7

What are ionic bonds?

Answer 7

When atoms strip electrons from their bonding partners, both atoms have charges. A charged atom or molecule is called an ion

Question 8

What are hydrogen bonds?

Answer 8

A hydrogen bond forms when a hydrogen atom covalently bound to an electronegative atom is also attracted to another electronegative atom. In living cells, electronegative partners are usually oxygen or nitrogen

Question 9

Explain Van der waal’s interactions

Answer 9

Attractions between molecules that are close together as a result of asymmetrically distributed electrons in molecules or atoms which can result in “hot spots” of positive or negative charges

Question 10

Why is molecular shape important?

Answer 10

Molecules recognize, interact and respond to each other based on molecular shape. Molecules with similar shapes can have similar biological effects (naturally produced endorphins and morphine)

Question 11

Define chemical reactions

Answer 11

Making and breaking of chemical bonds. The starting molecules of a chemical reaction are called reactants and the final molecules are called products

Question 12

Define photosynthesis and the equation

Answer 12

Important chemical reaction where sunlight provides energy that is used to convert carbon dioxide and water to glucose and oxygen
6CO2 + 6H2O = C6H12O6 + 6O2

Question 13

Water is the…..

Answer 13

Biological medium of earth. Due to climate change, the ratio of liquid water to ice is changing affecting organisms in the arctic

Question 14

How many hydrogen bonds can one water molecule participate in and why?

Answer 14

4
Regions of neighbouring water molecules with opposite partial charges are attracted to each other forming hydrogen bonds. Each water molecule can hydrogen bond to several others

Question 15

Why is the oxygen atom important in a water molecule?

Answer 15

Water is a polar molecule due to the highly electronegative oxygen atom with the overall charge being unevenly distributed. Polarity allows water molecules to form hydrogen bonds with each other

Question 16

What are the 4 emergent properties of water that contribute to earth’s suitability for life?

Answer 16

Cohesive behaviour
Ability to moderate temperature
Expansion upon freezing
Versatility as a solvent

Question 17

Explain the cohesion of water molecules

Answer 17

Hydrogen bonds hold water molecules together through cohesion which helps transport water against gravity in a plant

Question 18

Define surface tension

Answer 18

Measure of how hard it is to break the surface of a liquid. Water has an unusually high surface tension due to hydrogen bonding between the molecules at the air- water Interface and to the water molecules below

Question 19

Explain moderation of temperature by water

Answer 19

Water absorbs heat from warmer air and releases stored heat to cooler air. Water absorbs or releases a large amount of heat with little change in its own temperature

Question 20

What is specific heat?

Answer 20

Amount of heat that must be absorbed or lost for 1g of a substance to change temp

Question 21

Why does water have high specific heat?

Answer 21

Due to hydrogen bonding. Heat absorbed when hydrogen bonds break and heat is released when hydrogen bonds form. The high specific heat of 1 cal/g Celsius minimizes temperature fluctuations to within limits that permit life

Question 22

Why does ice float on liquid water?

Answer 22

Hydrogen bonds in ice are more “ordered” making ice less dense

Question 23

Explain hydrophilic and hydrophobic substances

Answer 23

Hydrophilic substance has an affinity for water while hydrophobic substance does not have an affinity for water

Question 24

Explain the process of ocean acidification

Answer 24

CO2 dissolved in sea water forms carbonic acid. As seawater acidifies, H+ ions combine with carbonate ions to produce bicarbonate. Carbonate is required for calcification (production of calcium carbonate) by many marine organisms such as corals

Question 25

Why is carbon important

Answer 25

Living organisms consist of mostly carbon based compounds since carbon is able to form large, complex and diverse molecules such as proteins, DNA and carbohydrates

Question 26

What is electron configuration?

Answer 26

Key to an atom’s characteristics since it determines kinds and number of bonds an atom will form with other bonds
(Carbon can form 4 covalent bonds)

Question 27

What shape does a carbon single bonded to 4 other atoms have?

Answer 27

Tetrahedral shape

Question 28

What are the “building codes” of living molecules?

Answer 28

Hydrogen, oxygen, nitrogen and carbon

Question 29

Define hydrocarbons

Answer 29

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

Question 30

Define isomers and the 3 types of isomers

Answer 30

Compounds with same molecular formula but different structures and properties
Structural isomers: have different covalent arrangements
Cis-trans isomers: have the same covalent bond by differ in spatial arrangements
Enantiomers: mirror images of each other

Question 31

Why is it dangerous to not understand the function of an isomer of a molecule?

Answer 31

One isomer might be safe for use while the other isomer could cause serious damage to the body

Question 32

Define ATP and its importance

Answer 32

Adenosine triphosphate is the primary energy transferring molecule in the cell
ATP consists of an organic molecule called adenosine attached to a string of 3 phosphate groups. ATP stores potential energy that can be released in a reaction with water and used by the cell