The Bombardier Beetle… “…the ability to eject from the anus a glandular fluid that vaporizes...

The Bombardier Beetle…The Bombardier Beetle…

“…“…the ability to eject from the anus a the ability to eject from the anus a glandular fluid that vaporizes with a glandular fluid that vaporizes with a popping sound when it hits the air, popping sound when it hits the air, blinding the victim and confusing it blinding the victim and confusing it with the noise.” with the noise.”

http://www.talkorigins.org/faqs/bombardier.html “Bombardier Beetles and the

Argument of Design”

by Mark Isaak

(a controversial argument…”The bombardier beetle would explode if the hydrogen peroxide and hydroquinone which produce their ejecta were mixed without a chemical inhibitor. Such a combination of chemicals couldn't have evolved.” (Creationist Argument)

““Poison arrow frogs, for instance, exude Poison arrow frogs, for instance, exude from their skin a potent cocktail of from their skin a potent cocktail of alkaloids called histrionicotoxins. This toxin alkaloids called histrionicotoxins. This toxin was first reported in 1823 by the western was first reported in 1823 by the western traveller Captain Charles Stuart Cochrane traveller Captain Charles Stuart Cochrane during an expedition around the lowland during an expedition around the lowland tropical rain forests of Colombia. He tropical rain forests of Colombia. He encountered tribes of native Indians who encountered tribes of native Indians who used it to coat the tips of their arrows and used it to coat the tips of their arrows and blow-darts in much the same way that the blow-darts in much the same way that the South American Indians useSouth American Indians use curaré curaré. “. “

http://www.pueblozoo.org/archives/apr00/feature.htm

http://www.thenakedscientists.com/HTML/Columnists/davinacolumn2.htm

Poison arrow frogs have 200 micrograms of poison in their system. It only takes 2 micrograms to kill a human.Currently research is being done on the development of a painkiller from the skin extract of Epipedrobates tricolor. Apparently it blocks pain 200 times more effectively than morphine…and without those known side effects (Nashville Zoo)“The Blue Poison Arrow frog's only predator is the frog-eating snake (Leimadophis epinephelus) which is apparently immune to the frog's poison.” –An astounding adaptation. Isn’t biology amazing?

EXAMPLE OF A CH EXAMPLE OF A CH 2 WARMUP:2 WARMUP:

1. The mass number of an element can 1. The mass number of an element can be easily approximated by adding be easily approximated by adding

together the number of:together the number of:

A) protons and neutronsA) protons and neutrons

B) electron orbitals in each energy B) electron orbitals in each energy levellevel

C) protons and electronsC) protons and electrons

D) neutrons and electronsD) neutrons and electrons

E) isotopes of the atomE) isotopes of the atom

Example of a Ch 2 Example of a Ch 2 Warmup Cont. Warmup Cont.

• 2. A covalent bond is polar when: 2. A covalent bond is polar when: A) one of the atoms sharing A) one of the atoms sharing

electrons is more electronegative electrons is more electronegative than the other atomthan the other atom

B) two atoms sharing electrons are B) two atoms sharing electrons are equally electronegativeequally electronegative

C) two atoms sharing electrons are C) two atoms sharing electrons are the same elementthe same element

D) it is between two atoms that are D) it is between two atoms that are both strong electron acceptorsboth strong electron acceptors

E) the two atoms sharing electrons E) the two atoms sharing electrons are different elementsare different elements

3. The atomic number of neon is 10. 3. The atomic number of neon is 10. Therefore it has Therefore it has

A) 8 electrons in the outer A) 8 electrons in the outer shellshell

B) 10 electrons in the outer B) 10 electrons in the outer shellshell

C) has an atomic mass of 10C) has an atomic mass of 10

D) only A and B are correctD) only A and B are correct

E) A, B, and C are correctE) A, B, and C are correct

• 4. When two atoms are equally 4. When two atoms are equally electronegative, they interact to electronegative, they interact to formform

A) equal number of isotopesA) equal number of isotopes

B) ionsB) ions

C) polar covalent bondsC) polar covalent bonds

D) nonpolar covalent bondsD) nonpolar covalent bonds

E) ionic bondsE) ionic bonds

5. A hydrogen atom has 1 electron. 5. A hydrogen atom has 1 electron. How many bonds can hydrogen How many bonds can hydrogen form?form?

A) 1A) 1

B) 2B) 2

C) 4C) 4

D) NoneD) None

• Nature is not neatly packaged into Nature is not neatly packaged into the individual life sciences.the individual life sciences.

• While biologists specialize in the While biologists specialize in the study of life, organisms and the study of life, organisms and the world they live in are natural world they live in are natural systems to which the basic concepts systems to which the basic concepts of chemistry and physics apply.of chemistry and physics apply.

• Biology is a multidisciplinary Biology is a multidisciplinary science, drawing on the insights science, drawing on the insights from other sciences.from other sciences.

Introducing Ch 2…Introducing Ch 2…

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

• Life can be Life can be organized into organized into a hierarchy of a hierarchy of structural structural levels.levels.

• At each At each successive successive level level additional additional emergent emergent properties properties appear.appear.Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 2.1

• Organisms are composed of Organisms are composed of mattermatter..– Matter is anything that takes up space Matter is anything that takes up space

and has mass.and has mass.

• An An elementelement is a substance that is a substance that cannot be broken down to other cannot be broken down to other substances by chemical reactions.substances by chemical reactions.– There are 92 naturally-occurring There are 92 naturally-occurring

elements.elements.– Each element has a unique symbol, Each element has a unique symbol,

usually from the first one or two letters usually from the first one or two letters of the name, often from Latin or of the name, often from Latin or German.German.

1. Matter consists of 1. Matter consists of chemical elements in pure chemical elements in pure form and in combinations form and in combinations

called compoundscalled compounds


• A A compoundcompound is a substance is a substance consisting of two or more elements consisting of two or more elements in a fixed ratio.in a fixed ratio.– Table salt (sodium chloride or NaCl) is a Table salt (sodium chloride or NaCl) is a

compound with equal numbers of compound with equal numbers of chlorine and sodium atoms.chlorine and sodium atoms.

– While pure sodium is a metal and While pure sodium is a metal and chlorine is a gas, their combination chlorine is a gas, their combination forms an edible compound, an emergent forms an edible compound, an emergent property.property.


Fig. 2.2

• About 25 of the 92 natural elements About 25 of the 92 natural elements are known to be essential for life.are known to be essential for life.– Four elements - carbon (C), oxygen Four elements - carbon (C), oxygen

(O), hydrogen (H), and nitrogen (O), hydrogen (H), and nitrogen (N) - make up 96% of living (N) - make up 96% of living matter. matter. COHN!COHN!

– Most of the remaining 4% of an Most of the remaining 4% of an organism’s weight consists of organism’s weight consists of phosphorus (P), sulfur (S), calcium phosphorus (P), sulfur (S), calcium (Ca), and potassium (K).(Ca), and potassium (K).

2. Life requires about 25 2. Life requires about 25 chemicalchemicalelementselements


• Trace elementsTrace elements are required by an are required by an organism but only in minute organism but only in minute quantities.quantities.– Some trace elements, like iron (Fe), are Some trace elements, like iron (Fe), are

required by all organisms.required by all organisms.– Other trace elements are Other trace elements are

required only by some species.required only by some species.• For example, a daily intake For example, a daily intake

of 0.15 milligrams of iodine of 0.15 milligrams of iodine is required for normal is required for normal activity of the human activity of the human thyroid gland.thyroid gland.


Fig. 2.4

• Each element consists of unique Each element consists of unique atoms.atoms.

• An An atomatom is the smallest unit of is the smallest unit of matter that still retains the matter that still retains the properties of an element.properties of an element.– Atoms are composed of even smaller Atoms are composed of even smaller

parts, called subatomic particles.parts, called subatomic particles.– Two of these, Two of these, neutronsneutrons and and protons,protons,

are packed together to form a dense are packed together to form a dense core, the atomic nucleus, at the center core, the atomic nucleus, at the center of an atom.of an atom.

– ElectronsElectrons form a cloud around the form a cloud around the nucleus.nucleus.

1. Atomic structure 1. Atomic structure determines the behavior determines the behavior

of an elementof an element


• Each electron has one unit of Each electron has one unit of negative charge.negative charge.

• Each proton has one unit of positive Each proton has one unit of positive charge.charge.

• Neutrons are electrically neutral.Neutrons are electrically neutral.• The attractions between the positive The attractions between the positive

charges in the nucleus and the charges in the nucleus and the negative charges of the electrons negative charges of the electrons keep the electrons in the vicinity of keep the electrons in the vicinity of the nucleus.the nucleus.


Fig. 2.5

• All atoms of a particular element All atoms of a particular element have the same number of protons in have the same number of protons in their nuclei.their nuclei.– Each element has a unique number of Each element has a unique number of

protons, its unique protons, its unique atomic numberatomic number..– The atomic number is written as a The atomic number is written as a

subscript before the symbol for the subscript before the symbol for the element (for example, element (for example, 22He).He).

• Unless otherwise indicated, atoms Unless otherwise indicated, atoms have equal numbers of protons and have equal numbers of protons and electrons - no net charge.electrons - no net charge.– Therefore, the atomic number tells us Therefore, the atomic number tells us

the number of protons and the number the number of protons and the number of electrons that are found in a neutral of electrons that are found in a neutral atom of a specific element.atom of a specific element.


• Most isotopes are stable; they do not Most isotopes are stable; they do not tend to loose particles.tend to loose particles.– Both Both 1212C and C and 1313C are stable isotopes.C are stable isotopes.

• The nuclei of some isotopes are The nuclei of some isotopes are unstable and decay spontaneously, unstable and decay spontaneously, emitting particles and energy.emitting particles and energy.– 1414C is a one of these unstable or C is a one of these unstable or

radioactive isotopesradioactive isotopes..– In its decay, an neutron is converted to a In its decay, an neutron is converted to a

proton and electron.proton and electron.– This converts This converts 1414C to C to 1414N, changing the N, changing the

identity of that atom.identity of that atom.


• Radioactive isotopes are also used to Radioactive isotopes are also used to diagnose medical disorders.diagnose medical disorders.– For example, the rate of excretion in the For example, the rate of excretion in the

urine can be measured after injection urine can be measured after injection into the blood of known quantity of into the blood of known quantity of radioactive isotope.radioactive isotope.

– Also, radioactive tracers can be used Also, radioactive tracers can be used with imaging instruments to monitor with imaging instruments to monitor chemical processes in the body.chemical processes in the body.


Fig. 2.7

• The chemical behavior of an atom The chemical behavior of an atom depends mostly on the number of depends mostly on the number of electrons in its outermost shell, the electrons in its outermost shell, the valence shellvalence shell..– Electrons in the valence shell are known Electrons in the valence shell are known

as as valence electronsvalence electrons..

• Atoms with the same number of Atoms with the same number of valence electrons have similar valence electrons have similar chemical behavior.chemical behavior.

• An atom with a completed valence An atom with a completed valence shell is unreactive.shell is unreactive.

• All other atoms are chemically All other atoms are chemically reactive because they have reactive because they have incomplete valence shells.incomplete valence shells.


• The attraction of an atom for the The attraction of an atom for the electrons of a covalent bond is called electrons of a covalent bond is called its its electronegativity.electronegativity.– Strongly electronegative atoms attempt Strongly electronegative atoms attempt

to pull the shared electrons toward to pull the shared electrons toward themselves.themselves.

• If electrons in a covalent bond are If electrons in a covalent bond are shared equally, then this is a shared equally, then this is a nonpolar covalent bondnonpolar covalent bond..– A covalent bond between two atoms of A covalent bond between two atoms of

the same element is always nonpolar.the same element is always nonpolar.– A covalent bond between atoms that have A covalent bond between atoms that have

similar electronegativities is also similar electronegativities is also nonpolar.nonpolar.• Because carbon and hydrogen do not differ Because carbon and hydrogen do not differ

greatly in electronegativities, the bonds of greatly in electronegativities, the bonds of CHCH44 are nonpolar. are nonpolar.


• If the electrons in a covalent bond If the electrons in a covalent bond are not shared equally by the two are not shared equally by the two atoms, then this is a atoms, then this is a polar covalent polar covalent bond.bond.– The bonds between oxygen and The bonds between oxygen and

hydrogen in water are polar covalent hydrogen in water are polar covalent because oxygen has a much higher because oxygen has a much higher electronegativity than does hydrogen.electronegativity than does hydrogen.

– Compounds with a polar Compounds with a polar covalent bond have regions covalent bond have regions that have a partial negative that have a partial negative charge near the strongly charge near the strongly electronegative atom and a electronegative atom and a partial positive charge near partial positive charge near the weakly electronegative the weakly electronegative atom.atom.


Fig. 2.13

• An An ionic bondionic bond can form if two atoms can form if two atoms are so unequal in their attraction for are so unequal in their attraction for valence electrons that one atom valence electrons that one atom strips an electron completely from strips an electron completely from the other.the other.– For example, sodium with one valence For example, sodium with one valence

electron in its third shell transfers this electron in its third shell transfers this electron to chlorine with 7 valence electron to chlorine with 7 valence electrons in its third shell.electrons in its third shell.

– Now, sodium has a full valence shell (the Now, sodium has a full valence shell (the second) and chlorine has a full valence second) and chlorine has a full valence shell (the third).shell (the third).


Fig. 2.14

• Even molecules with nonpolar Even molecules with nonpolar covalent bonds can have partially covalent bonds can have partially negative and positive regions.negative and positive regions.– Because electrons are constantly in Because electrons are constantly in

motion, there can be periods when they motion, there can be periods when they accumulate by chance in one area of a accumulate by chance in one area of a molecule. molecule.

– This created ever-changing regions of This created ever-changing regions of negative and positive charge within a negative and positive charge within a molecule.molecule.

• Molecules or atoms in close proximity Molecules or atoms in close proximity can be attracted by these fleeting can be attracted by these fleeting charge differences, creating charge differences, creating van der van der Waals interactionsWaals interactions. .

• While individual bonds (ionic, While individual bonds (ionic, hydrogen, van der Waals) are weak, hydrogen, van der Waals) are weak, collectively they have strength.collectively they have strength.


• In In chemical reactionschemical reactions chemical chemical bonds are broken and reformed, bonds are broken and reformed, leading to new arrangements of leading to new arrangements of atoms.atoms.

• The starting molecules in the The starting molecules in the process are called process are called reactantsreactants and and the end molecules are called the end molecules are called products.products.

• In a chemical reaction, all of the In a chemical reaction, all of the atoms in the reactants must be atoms in the reactants must be accounted for in the products.accounted for in the products.– The reactions must be “balanced”.The reactions must be “balanced”.

5. Chemical reactions make 5. Chemical reactions make and break chemical bondsand break chemical bonds


• Photosynthesis is an important Photosynthesis is an important chemical reaction.chemical reaction.

• Green plants combine carbon dioxide Green plants combine carbon dioxide (CO(CO22) from the air and water (H) from the air and water (H22O) O) from the soil to create sugar molecules from the soil to create sugar molecules and molecular oxygen (Oand molecular oxygen (O22), a ), a byproduct.byproduct.

• This chemical reaction is powered by This chemical reaction is powered by sunlight.sunlight.

• Humans and other animals depend on Humans and other animals depend on photosynthesis for food and oxygen.photosynthesis for food and oxygen.

• The overall process of photosynthesis The overall process of photosynthesis isis– 6CO6CO22 + 6H + 6H22O -> CO -> C66HH1212OO66 + 6H + 6H22O O

• This process occurs in a sequence of This process occurs in a sequence of individual chemical reactions.individual chemical reactions.


• Eventually, the rate of formation of Eventually, the rate of formation of products is the same as the rate of products is the same as the rate of breakdown of products (formation of breakdown of products (formation of reactants) and the system is at reactants) and the system is at chemical chemical equilibriumequilibrium..– At equilibrium, products and reactants are At equilibrium, products and reactants are

continually being formed, but there is no net continually being formed, but there is no net change in the concentrations of reactants and change in the concentrations of reactants and products.products.

– At equilibrium, the concentrations of reactants At equilibrium, the concentrations of reactants and products are typically not equal, but their and products are typically not equal, but their concentrations have stabilized.concentrations have stabilized.


Moving into…Ch 3!Moving into…Ch 3!


• Because water is the substance that Because water is the substance that makes possible life as we know it on makes possible life as we know it on Earth, astronomers hope to find Earth, astronomers hope to find evidence of water on newly evidence of water on newly discovered planets orbiting distant discovered planets orbiting distant stars.stars.

• Life on Earth began in water and Life on Earth began in water and evolved there for 3 billion years evolved there for 3 billion years before spreading onto land.before spreading onto land.

• Even terrestrial organisms are tied to Even terrestrial organisms are tied to water.water.– Most cells are surrounded by water and Most cells are surrounded by water and

cells are about 70-95% water.cells are about 70-95% water.• Water exists in three possible states: Water exists in three possible states:

ice, liquid, and vapor.ice, liquid, and vapor.

• In a water molecule two hydrogen In a water molecule two hydrogen atoms form single polar covalent atoms form single polar covalent bonds with an oxygen atom.bonds with an oxygen atom.– Because oxygen is more electronegative, Because oxygen is more electronegative,

the region around oxygen has a partial the region around oxygen has a partial negative charge.negative charge.

– The region near the two hydrogen atoms The region near the two hydrogen atoms has a partial positive charge.has a partial positive charge.

• A water molecule is a polar molecule A water molecule is a polar molecule with opposite ends of the molecule with opposite ends of the molecule with opposite charges.with opposite charges.

1. The polarity of water 1. The polarity of water molecules results from molecules results from

hydrogen bondinghydrogen bonding


• The hydrogen bonds joining water The hydrogen bonds joining water molecules are weak, about 1/20molecules are weak, about 1/20thth as as strong as covalent bonds.strong as covalent bonds.

• They form, break, and reform with They form, break, and reform with great frequency.great frequency.

• At any instant, a substantial At any instant, a substantial percentage of all water molecules are percentage of all water molecules are bonded to their neighbors, creating a bonded to their neighbors, creating a high level of structure.high level of structure.

• Hydrogen bonds hold the substance Hydrogen bonds hold the substance together, a phenomenon called together, a phenomenon called cohesioncohesion..

2. Organisms depend on the 2. Organisms depend on the cohesion of water moleculescohesion of water molecules


• Cohesion among water molecules Cohesion among water molecules plays a key role in the transport of plays a key role in the transport of water against gravity in plants.water against gravity in plants.– Water that evaporates from a leaf is Water that evaporates from a leaf is

replaced by water from vessels in the replaced by water from vessels in the leaf.leaf.

– Hydrogen bonds cause water molecules Hydrogen bonds cause water molecules leaving the veins to tug on molecules leaving the veins to tug on molecules further down.further down.

– This upward pull is transmitted to the This upward pull is transmitted to the roots.roots.

– Adhesion,Adhesion, clinging clinging of one substance to of one substance to another, contributes another, contributes too, as water adheres too, as water adheres to the wall of the to the wall of the vessels.vessels.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin CummingsFig. 3.2

• Surface tension,Surface tension, a measure of the a measure of the force necessary to stretch or break force necessary to stretch or break the surface of a liquid, is related to the surface of a liquid, is related to cohesion.cohesion.– Water has a greater surface tension Water has a greater surface tension

than most other liquids because than most other liquids because hydrogen bonds among surface water hydrogen bonds among surface water molecules resist stretching or breaking molecules resist stretching or breaking the surface.the surface.

– Water behaves as if Water behaves as if covered by an invisible covered by an invisible film.film.

– Some animals can stand, Some animals can stand, walk, or run on water walk, or run on water without breaking the without breaking the surface.surface.


Fig. 3.3

• Water is an effective solvent because Water is an effective solvent because it so readily forms hydrogen bonds it so readily forms hydrogen bonds with charged and polar covalent with charged and polar covalent molecules. molecules. – For example, when a crystal of salt For example, when a crystal of salt

(NaCl) is placed in water, the Na(NaCl) is placed in water, the Na++ cations cations form hydrogen bonds with partial form hydrogen bonds with partial negative oxygen regions of water negative oxygen regions of water molecules.molecules.

– The ClThe Cl-- anions form anions form hydrogen bonds with hydrogen bonds with the partial positive the partial positive hydrogen regions of hydrogen regions of water molecules.water molecules.Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 3.7

• Any substance that has an affinity for Any substance that has an affinity for water is water is hydrophilichydrophilic..– These substances are dominated by ionic These substances are dominated by ionic

or polar bonds.or polar bonds.

• This term includes substances that do This term includes substances that do not dissolve because their molecules not dissolve because their molecules are too large and too tightly held are too large and too tightly held together.together.– For example, cotton is hydrophilic For example, cotton is hydrophilic

because it has numerous polar covalent because it has numerous polar covalent bonds in cellulose, its major constituent. bonds in cellulose, its major constituent.

– Water molecules form hydrogen bonds in Water molecules form hydrogen bonds in these areas.these areas.


• Substances that have no affinity for Substances that have no affinity for water are water are hydrophobichydrophobic..– These substances are dominated by non-These substances are dominated by non-

ionic and nonpolar covalent bonds.ionic and nonpolar covalent bonds.– Because there are no consistent regions Because there are no consistent regions

with partial or full charges, water with partial or full charges, water molecules cannot form hydrogen bonds molecules cannot form hydrogen bonds with these molecules.with these molecules.

– Oils, such as vegetable oil, are Oils, such as vegetable oil, are hydrophobic because the dominant hydrophobic because the dominant bonds, carbon-carbon and carbon-bonds, carbon-carbon and carbon-hydrogen, exhibit equal or near equal hydrogen, exhibit equal or near equal sharing of electrons.sharing of electrons.

• Hydrophobic molecules are major Hydrophobic molecules are major ingredients of cell membranes.ingredients of cell membranes.Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

The Bombardier Beetle… “…the ability to eject from the anus a glandular fluid that vaporizes...

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