BIOL 1010

A researcher was interested in the impact on tumor growth in mice. She took 50 mice with tumors and measured the size of their tumors. She then had them walk each day on the treadmill for 6 weeks. All of the mice were fed the same diet, held under the same environmental conditions and required to walk the same amount on the treadmill. At the ned of the experiment, she measured the size of their tumors and calculated the change in size. What is the control in the experiment? What is the dependent variable? What is the independent variable? What is the biggest flaw in her experimental design?

- control: the size of the tumors before the experiment - DV: the change in size of the tumors - IV: The exercise - flaw: she lacks a control group

What are the 6 functions of water?

1. Participates in chemical reactions like hydrolysis or dehydration (condensation) 2. Provides support for all living systems 3. Detoxify 4. Evaporative cooling 5. Cohesion and adhesion 6. Surface tension

What are the 6 properties of water?

1. Polar 2. Solvent 3. High heat capacity 4. High heat evaporation 5. Cohesion/adhesion 6. Less dense as a solid

What are the 3 subatomic particles of an atom?

1. Protons 2. Neutrons 3. Electrons

What are 4 common features of chemical reactions?

1. chemical reactions that occur in cells require catalysts 2. Proceed toward equilibrium 3. take place in a watery environment 4. require a source of energy

In pure water, the concentrations of H+ and OH- ions are:

10-7 M each

Nitrogen's atomic number is 7. How many electrons are in carbon's outer shell?

5 (2 in the inner shell. outer valence shell can have 8, need 5 to to get to 7)

The chemical formula of glucose is C6H12O6. How many oxygen atoms are in one molecule of glucose?

6

Oxygen has eight electrons. How many valence electrons does it have?

6 (reason: oxygen has a total of 8 electrons. 2 are in the first shell, and the remaining 6 are in the valence shell)

In humans, water comprises approximately ____ of body weight.

60-70%

Oxygen contains eight protons, eight electrons, and eight neutrons. What is its atomic number?

8

14C is an isotope of 12C which has an atomic number of 6. How many neutrons does 14C have?

8 (b/c 14 neutrons - 6 protons (atomic #) = 8 neutrons)

Magnesium chloride (MgCl2) is a salt formed form ionic bonds between 1 Mg ion and 2 Cl ions, Mg atoms have 2 electrons in their outer (3rd) shell and Cl atoms have 7 electron sin their outer shell. How many electrons would be in the outer shell of Mg once it becomes an ion?

8 - Mg transfers 2 electrons to each Cl to make them stable (see image in notes)

Theory

A concept that has been tested with a significant amount of data and makes many correct predictions.

Compared with liquid water, ice has:

A more orderly arrangement of water molecules & greater hydrogen bonds between individual water molecules

Hypothesis

A proposed explanation for an observation that has yet to be widely tested. Must be testable or falsifiable.

Element

A pure substance made of only one kind of atom

A substance that releases hydrogen ions into solution is called a(n)

Acid

Matter

Anything that has mass and takes up space

Isotopes

Atoms of the same element that have different numbers of neutrons

covalent bond occurs between?

Atoms whose outer electron shells are not full.

A substance that absorbs hydrogen ions in solution is called a(n)

Base

Why does sodium chloride (NaCl) dissolve in water?

Because covalent bonds in water stronger than the ionic bonds in salt molecules. - Positively charged water molecules attracted to negatively charged chloride ions AND Negatively charged water molecules attracted to positively charged sodium ions. - H20 molecules pull the sodium and chloride ions apart, breaking the ionic bond that help them together. - Water molecules surround Na and Cl molecules; salt dissolves in solution.

Living organisms minimize changes in their internal pH using compounds called:

Buffers

The amount of solute (in grams) dissolved in a given volume of solution is the solution's:

Concentration

In the process of digestion, large molecules need to be broken down into smaller molecules. Therefore when you eat you should be sure to

Drink enough water

A polar covalent bond is between atoms that differ in ____?

Electronegativity

The ______ of an atom is a measure of its ability to attract electrons when in a bond with another atom.

Electronegativity

nonpolar covalent bond

Electrons shared equally by bonded atoms. Balanced distribution of electrical charge

chemical bond

Force that holds two atoms together

ionic bonds

Formed when one or more valence electrons are transferred from one atom to another

In the formation of salt (NaCl) the chlorine atom?

Gains an electron from sodium. (Na+Cl-)

What are the physical states of water in order based on the intermolecular distances between water molecules.

Gaseous, liquid, solid

control group

Group not exposed to the treatment (variable being tested) in an experiment. Contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.

When two water molecules are near each other, a hydrogen bond will form between the more positive _____ and the more negative _____ atoms of neighboring water.

Hydrogen Oxygen

Hydrochloric acid is considered an acid because it releases _____ ions into solution

Hydrogen (H+)

What 4 elements are the most common in living organisms?

Hydrogen, Carbon, Oxygen and Nitrogen

The cells of living things are made mainly of what 4 elements?

Hydrogen, oxygen carbon and nitrogen

____ reactions break apart molecules via water

Hydrolysis

A base will release _____ ions when dissolved in water.

Hydroxide (OH-)

Within an atom's structure, electrons can be found?

In cloud-like orbitals

____ compounds and polar substances ____ in water

Ionic Dissolve

Molecules are likely to dissolve easily in water if they contain what type of bonds?

Ionic and polar covalent bonds

A hypothesis is falsifiable if?

It can be shown to be incorrect via experimentation.

A hypothesis is testable if?

It can be supported or rejected via experimentation or observational studies

As an electron moves from a higher shell to a lower one, what happens?

It loses energy

The bonds within water molecules are covalent and the bonds between water molecules are hydrogen bonds. What does this mean?

It's easier to pull apart the bonds between the water molecules

Which component of humans has the greatest percent of water

Lungs (nearly 90%)

Electronegativity

Measure of the ability of an atom in a chemical compound to attract electrons

Compound

Molecule composed of two or more separate elements.

Anion

Negatively charged ion that gained an electron

Isotopes of an element differ from one another in the number of _____ they contain.

Neutrons

Isotopes of the same element differ in their number of:

Neutrons

Which two particles are the primary determinants of an element's atomic mass?

Neutrons & Protons (Reasons: Electrons have negligible mass. An element's atomic mass is the sum of the number of protons and neutrons it contains).

The atomic mass (atomic weight) of an element is the total number of which particles?

Neutrons + protons

What part of an amphipathic molecule would be oriented toward the center of a micelle?

Nonpolar region

Most of the mass of an atom is found in its?

Nucleus (because protons + neutrons have the most mass)

When water ionizes, it produces what ions?

OH- and H+

Water is a polar molecule because?

Of its shape; different parts of the molecule have slightly different charges.

There are ____ type(s) of atoms that can be found in a single element

One

The region within an atom that surrounds the nucleus and in which there is a high probability of finding an electron is called a(n)?

Orbital

Unlike other lipids ____ are soluble in water.

Phospholipids

In a ____ covalent bond the shared electrons are closer to one nucleus than to another.

Polar

Two molecules have very different electronegativities. If they form a bond it's likely to be which type?

Polar covalent

If you could measure the charge coming from various parts of an atom, what charge would the nucleus have?

Positive

Cation

Positively charged ion that released (lost) an electron

The atomic number of an element is the total number of which particles in the nucleus?

Protons

Why are the shared electrons in a polar covalent bond loser to one nucleus than to another?

Reason: - The two atoms have different electronegativity values - Electrons are shared unequally between the two atoms in the bond - When one or more electrons in transferred from one atom to another, an ionic bond, may form

Scientific Method (7 Steps)

Series of steps followed to validate hypothesis. (1) Make an observation (2) ask a question and conduct background research. (3) formulate a hypothesis. (4) Test the hypothesis through experimentation (5) analyze data and draw conclusions (6) verify conclusions through peer review verification (7) Communicate the results

A researcher is examining swimming speed in goldfish. She uses a small net to catch 20 goldfish from a large tank of 100 and has them swim along a narrow raceway one at a time. She measures the swimming speed of each fish to determine the average swimming speed of a goldfish. All fish are held at the same temp, were fed the same food, swim the same distance and were the same age and gender. What is wrong with her experiment?

She did not use a random sample

A liquid that can dissolve substances is known as a _____.

Soluble

covalent bond

Strong bonds; chemical bond formed when two atoms share electrons. 2 types

Ionic bonds are

Stronger than hydrogen bonds, but weaker than covalent bonds

A water strider is an insect that can walk on water. How is this possible?

Surface tension. (b/c the hydrogen bonds hold the water molecules together, creating surface tension)

Hydrogen bonding between water molecules makes them tend to stick together, how does this affect the heat capacity (HC) and heat of vaporization (HOV) of water?

The HC and HOV of water are high (b/c hydrogen bonds are pulling those water molecules together and preventing them from coming apart)

It takes a great deal more energy to walk through water than air. This is due to

The cohesion of water molecules which increases viscosity

valence electrons

The electrons in the outermost shell (energy level) of an atom.

dependent variable

The measurable effect/outcome or response. Dependent on the independent variable.

sample size

The number of subjects used in an experiment or study. Generally, the larger the better.

In a micelle, which portion of the amphipathic molecules are oriented toward the surface of the sphere?

The polar region

Phospholipids are able to form a stable cell membrane because

Their polar (hydrophilic) head is attracted to water molecules, while their non-polar (hydrophobic) tails are repelled by them

polar covalent bond

Unequal sharing of electrons. Partial charges on atoms.

independent variable

Variable that is manipulated

hydrogen bonds

Very weak bonds; occurs when a partially positive hydrogen atom in one molecule is attracted to the partially negative atom in another molecule.

Water's adhesive properties are responsible for?

allowing water to stick to substances other than itself

Phospholipids are a type of

amphipathic molecule that makes up cell membranes

The hydrogen bonds between water molecules form between:

an oxygen atom on one water molecule and a hydrogen atom on a second water molecule

# of protons =

atomic number # of electrons in a neutral atom

All matter is composed of?

atoms

Electronegativity is the ability of an atom to:

attract electrons

What occurs during all chemical reactions?

chemical bonds are broken or formed

In a polar covalent bond, shared electrons are pulled ____ to the more electronegative atom, making is slightly ____ and the other atom slightly ____.

closer negative postive

Bonds created when electrons are shared are called ____

covalent bonds

What are the 3 types of chemical bonds?

covalent, hydrogen, ionic

A hypothesis may be ____ but never proven ____

disproved true

Ions that carry full electric charges & carbohydrates that contain -OH groups are predicted to easily ____ in water

dissolve

polar molecules ____ in water

dissolve

The more ____ Oxygen of 1 water molecule attracts the ____ of a nearby molecule.

electronegative hydrogen

Hydrogen bonds do not share ____

electrons

electron shells (energy levels)

electrons occupy orbits or fixed regions of space around the nucleus.

The high heat capacity of water means it takes a lot of ____ to change its temp.

energy

In nonpolar covalent bonds electrons are shared ____ between the two atoms & the two atoms have similar ____ values

equally electronegativity

controlled experiment

experiment in which only one variable is changed

Molecules that contain covalent bonds are ____ structures and change their ____ when the atoms rotate around covalent bonds

flexible shape

High heat evaporation of water means it takes a large amount of ____ for molecules to separate and enter the ____ phase.

heat gas

standardized variable

held constant for all subjects in an experiment

A partially positive and partially negative atom pair is required for a ____ bond to form; oxygen can't be both

hydrogen

Water can ionize into ____ protons and ____ ions

hydrogen hydroxide

In a(n) _____ reaction, water is used to break apart another molecule.

hydrolytic

The ____ associated with the theory have been tested rigorously and have never been ____.

hypothesis falsified

An atom that has net electric charge due to the gain or loss of electrons is called a(n) _____.

ion

An atom with a net electric charge is called a(n):

ion

When a cation binds to an anion, a(n) _____ bond forms.

ionic

What type of bond occurs when a cation binds to an anion?

ionic bond

A covalent bond is one in which a pair of electrons:

is shared between 2 atoms

An atom or ion is most stable when?

its outermost shell is occupied by its full complement of electrons

Ions are formed when an atom ____ or ____ electrons

loses or gains

Amphipathic molecules are

molecules that have both hydrophilic and hydrophobic regions

Larger atoms have ___ electron shells than smaller atoms

more

pH is defined as the _____ _____ to the base 10 of the _____ ion concentration.

negative logarithm hydrogen (H+)

Electrons

negatively charged particles. found outside the nucleus in orbitals

Bonds between atoms with similar electronegativities?

nonpolar covalent bond

In a water molecule (H2O), the _____ atom has a partial negative charge, and the _____ atom has a partial positive charge.

oxygen hydrogen

By mass, the most abundant element in living organisms is:

oxygen (reason: Hydrogen makes up 9% of human body mass, and oxygen makes up 65%.)

The _____ of a solution is the negative base 10 logarithm of the H+ concentration of the solution.

pH

Protons

positively charged particles inside the nucleus

Pure water can ionize into:

positively charged protons (H+) and negatively charged hydroxide (OH-) ions.

A water molecule has two partially ____ Hydrogen atoms and one partially ____ Oxygen atom.

postive negative

Within an atom, _____ and neutrons have nearly equal masses, while _____ have a much smaller mass

protons electrons

Neutral atoms contain equal numbers of

protons and electrons

Why would the nonpolar region of an amphipathic molecule be oriented toward the center of a micelle?

reason: to minimize interactions with water molecules b/c its hydrophobic

The concentration of a liquid is defined as the amount of ______ dissolved in a unit volume of solution

solute

Substances dissolved in liquid are known as:

solutes

Water's cohesive properties are responsible for?

surface tension (tendency of a liquid's surface to resist rupture when placed under tension)

Dogs are happier when they are walked regularly is a ____ hypothesis

testable

A hypothesis must be ____ or ____

testable or falsifiable

Neutrons

the particles of the nucleus that have no (neutral) charge

Atoms

the smallest units of matter. can't be broken down into other substances.

Solvent

the substance in which the solute dissolves.

Water, within the chemical formula H2O, contains _____ hydrogen atoms(s) and _____ oxygen atom(s)

two one

Molecule

two or more atoms bonded together

The two sides of DNA are held together by

weak hydrogen bonds

Octet Rule

when forming a chemical bond atoms gain, lose or share valence electrons until they have 8 electrons in their valence shell, making them stable