Mrs. Isengard-Westside High School

AP BIOLOGY

Supplemental Assignment

Mrs. Isengard-Westside High School

This guide is used to review Atoms & Molecules, and Ecology. These are two units that are covered in your prerequisite Biology and Chemistry courses. Please use:

Chapters 2& 3 for Atoms & Molecules

Chapters 50-56 for Ecology & Animal Behavior

You may use your textbook and any online resources (please cite any you use) to answer the following questions. This assignment will be due the first day of school and the information will appear in a test that month. No LATE Assignments will be accepted

Answer the following questions in as much detail as possible and print out to turn in to me. This can be typed or written but must be legible. I will not accept email submissions for this assignment:

Name-______

Summer Assignment

1)“Life” is easy to recognize but difficult to define. The dictionary defines life as “the state or quality that distinguishes living beings or organisms from dead ones and from inorganic matter, characterized chiefly by metabolism, growth, and the ability to reproduce and respond to stimuli.” Biology textbooks usually elaborate slightly; for example, according to a popular text, living things:

1. Are highly organized compared to natural inanimate objects.
2. Display homeostasis, maintaining a relatively constant internal environment.
3. Reproduce themselves.
4. Grow and develop from simple beginnings.
5. Take energy and matter from the environment and transform it.
6. Respond to stimuli.
7. Show adaptation to their environment.

Score yourself, a car, and a cactus with respect to these characteristics. Is there any grey area? In the context of what you just did, why could defining life be an elusive business?

A human would display all of these characteristics for the characteristics of life. A cactus would also demonstrate these characteristics.

However,the car demonstrates e. and f. as it is responsive to changes and transforms chemical energy into mechanical energy (gasoline converts into movement through internal combustion). Therefore there are some grey areas in defining life. One primary example includes viruses; they are capable of reproduction but can’t live independently requiring a host cell. Another example of an elusive organism is the amoeba which amorphous and definitely not organized.

2)In 1944, at the beginning of the book, What is Life, the great physicist Erwin Schrödinger (of cat fame) asked the following question: “How can the events in time and space which take place within the spatial boundary of a living organism be accounted for by physics and chemistry?” What would be your answer today? Do you think there are peculiar properties of living systems that disobey the laws of physics and chemistry? Explain your answer.

There are some close connections between all sciences especially physics and chemistry. For example, organisms are controlled by metabolism; a sum of all chemical reactions in the body. Aerobic organisms also have elemental dependencies requiring atmospheric constants for respiration (partial percentage of gases, and physical parameters including STP (Standard Temperature and Pressure) volumes and pressure ratios). Conservation of matter and energy is also an important parameter in this process.

Without these environmental factors, they cannot maintain homeostasis. Also, physical & chemical properties can be accounted for with heat transfer, movement, growth. Some exceptions to this rule may include viroids and prions that replicate and thus may not maintain the same conservation of matter and energy.

It seems to be human nature to try and group living things into categories. These groupings have helped philosophers and naturalists better understand the living world around them. A taxon is the name given to any specific level of organization in our current classification system. Identify the taxonomic levels that biologists most frequently use. How are they organized? Can taxonomic systems be used to show phylogeny (aka evolutionary relationships) of organisms?

Biologists still categorize taxa in the following from most general to most specific: Domains, Kingdoms, Phyla, Class, Order, Family, Genus & Species. These taxa are derived from common characteristics and qualifiers. For example for the case of

Aristotle was one of the first to classify organisms into separate taxa or categories. However, many of these criteria were based on physical characteristics that failed to show any true evolutionary commonalities. For examples, Aristotle grouped butterflies and birds together as they are both take flight. However, we now know based on other characteristics (in the case of butterflies -chitinous wings, or in the case of a vertebrate bird possessing a yolk sac/amniotic/chorionic tissue that these are two distinct categories).

3)Chapter 1 includes heredity (i.e. DNA and genes) as well as evolution. Discuss the connection between heredity and evolution? There is a strong trend between Evolution and Heredity in that Natural Selection seems to drive inheritance in populations. For example, a microevolution scenario includes Kettlewell’s Peppered Moths; a study conducted before and following Industrial Revolution. As pollution increased, the lighter moths were selected against as they could no longer blend in with the graying lichen on trees. Consequently, these moths were selected against and therefore the selection curve median shifted towards the darker moths. Many geneticists have determined correlation in populations and have developed models. One main model is known as Hardy-Weinberg Equilibrium Principle. If there is no evolution there should be no fluctuation of dominant and recessive individuals in a population with a baseline 1:1 ratio. If there is a change in these genotypic frequencies, this reveals evolution.

4)What is meant by the term “descent with modification?”Descent with modification determines a change in a population indicating evolution. This is often an adaptive change that occurs in offspring which typically favors those members. In other words, the descendants are modified to best adapt to their environment.

5)Science is often described to work by a set of steps or by a specific method. Why is this not necessarily true? Science is constantly occurring and there are many theories that are not tested or can’t be proven through scientific method.

6)What is the difference between a hypothesis and a theory? A hypothesis is a guess based on observations and environmental phenomena. A theory is a proposal based from a hypothesis tested multiple times. However, a theory is still not as concrete as a scientific law because there have been exceptions. Some examples include the Theory of Evolution, Gene Theory and the Endosymbiotic Theory. Very few scientific laws exist and often are within the physics field (Laws of Gravity, Inertia, Thermodynamics).

7)What is the arrangement of protons, neutrons and, electrons in an atom? Describe this verbally then diagrammatically.Positively charged protons and neutrally charged neutrons are found within the nucleus of the shell providing an overall positive charge to internal atom. Negatively or oppositely charged subatomic particles known as electrons are found in shells that constantly orbit the outer layer of the atom.

8)A carbon atom contains six protons and six neutrons.

1. Without looking at a periodic table what is carbons atomic number and atomic weight? How did you know this?6; 12 The proton # denotes the atomic # while the mass number is the sum of protons and neutrons.
2. How many electrons does it have? How many valence electrons does it have? How did you know this? The C atom would have 6 electrons with 4 valence electrons. Carbon is in the 4th group which indicates the # of valence electrons.
3. How many additional electrons must it add to fill its outermost shell? 4
4. How does this affect carbon’s chemical behavior? Carbon is tetravalent (forming 4 bonds and thus serves as the backbone of organic compounds).
5. Carbon with an atomic weight of 14 is radioactive. How does it differ in structure from nonradioactive carbon? How does this difference affect its chemical behavior? Carbon 14 isotope is structurally different because it possesses two additional electrons. It is chemically unstable and emits radioactive particles for this purpose.

9)Sketch the electron shell configuration of a sodium atom. According to the octet rule, what would be the simplest way for a sodium atom to achieve electron stability?Because sodium only has one valence electron, the simplest way for sodium to achieve is to bond with a halogen possessing 7 valence electrons. One common exam

10)Many elements have isotopes, which are rare variants of the element with additional neutrons in the nucleus. Deuterium is an isotope of hydrogen that has one neutron. Does the neutron change the chemical reactivity of deuterium, compared with normal hydrogen? Explain why or why not.

Generally, the amount of neutrons determines its chemical stability. However, in the case of deuterium, the isotope remains stable because there is a negligible mass difference between protons and neutrons.

11)The concepts of chemical bonding and electronegativity allow us to predict whether a molecule will be polar or nonpolar, and how it will interact with water. Typically, a difference in electronegativity greater than 0.5 will result in polarity. For each of the bonds below indicate:

a) Whether the bond is polar or nonpolar

b) If polar which end is + end

c) How a molecule with the bond will interact with water (hydrophilic or hydrophobic).

N-HPolar (+Hydrogen)Hydrophilic / C-HNonpolar
Hydrophobic / C=OPolar (+Carbon) / C-N(Polar)
(+Nitrogen) Hydrophilic
O-H Polar (+Hydrogen) Hydrophilic / C-CNonpolar
Hydrophobic / H-HNonpolar
Hydrophobic / O-P(Polar)
(+Oxygen) Hydrophilic

12)Compare electron behavior in ionic, covalent, and hydrogen bonds. Which is strongest, and why?Ionic bonds have the strongest electron bonds because they have the greatest electronegativity.

13)What is the difference between a covalent and a non-covalent bond?Covalent bonds equally share electrons while the non-covalent bonds do not.

14)Hydrogen bonds and van der Waals attractions are important in the interactions between molecules in biology.

1. Describe the differences and similarities between van der Waals attractions and hydrogen bonds.Van der Waals and Hydrogen Bonds both occur between hydrogen atoms. However, Van der Waals are more temporary reactions forming and breaking continuously. Van Der Waals are often found between DNA molecular bonds.
2. Which of the two types of interactions would form (1) between two hydrogens bound to carbon atoms, (2) between a nitrogen atom and a hydrogen bound to a carbon atom, and (3) between a nitrogen atom and a hydrogen bound to an oxygen atom?

1)This would form a hydrocarbon non polar bond (often found in lipids)

2)N-H-C would form a non polar bond

3)Nitrogen, hydrogen and oxygen would form a polar bond.

15)How do variations in electronegativity result in the unequal sharing of electrons in polar molecules?

Since electronegativity levels vary, this often causes dipole or various intermolecular reactions causing a partial positive or negative charge.

16)Consider the molecule carbon dioxide. Are the bonds between the C and the O atoms ionic or covalent? Is this molecule hydrophobic or hydrophilic? Explain your answers.Bonds between C and O are covalent because their electronegativity is less than in a hydrophilic molecule.

17)Here is the structure of the molecule glycine:

a) Is this molecule hydrophilic or hydrophobic? Amino acid charges vary/ are hydrophilic or hydrophobic resulting from whether hydrogen bonds occur. In the case of glycine it is hydrophobicand does not have a side chain or charge indicating which bond it can form.

b) Draw two glycine molecules and show how they can be linked by dehydration synthesis.

Amino Acids are formed with Peptide Bonds (Between Amine Groups)

18)What is the difference between a solute and a solvent?Solutes are solid particles that are dissolved into a solvent (liquid). A good example would be iced tea powder (solute) stirred into a pitcher of water (solvent). Combined, these form the solution.

19)What is meant by the terms osmosis and diffusion? Are they the same thing? How are they related to the concepts or hypertonic, isotonic, and hypotonic? Osmosis refers to the diffusion of water down its concentration gradient. Diffusion refers to any particles moving from an area of high concentration to low concentration. Hypertonic solutions contain more solute than their surrounding environment, isotonic solutions are in equilibrium with their environment and hypotonic cells would contain less solute than their environment. A good example includes mass changes with a grape placed in a

Hypertonic (concentrated salt) solution, -Grape Shrivels

Isotonic (limited salt tap water solution)Grape’s mass remains constant

Hypotonic (deionized, tap water solution). Grape takes in water (increases mass)

20)Transpiration is the name given to how water travels up a plant, from its roots to its leaves. Discuss how this happens in the context of waters special properties.

Transpiration involves the uptake of water through xylem canals. This applies two important water properties, including adhesion (water connecting to the sides of plant or another surface). The second main property is cohesion where water molecules stick to one another and draw each other up the plant.

21)The organic chemistry of living cells is said to be special for two reasons: it occurs in an aqueous environment and it accomplishes some very complex reactions. But do you suppose it’s really all that much different from the organic chemistry carried out in the top laboratories in the world? Why or why not?

I don’t believe so. Dehydration synthesis & condensation reactions are occurring in the environment all the time. However, top labs will use pre-existing organic compounds to synthesize new synthetic compounds from these base reactions.

22)What is pH? What does the pH scale represent? How do you calculate pH?

pH is a logarithm of hydrogen protons found in a given solution. The pH scale represents the ratio of hydroxide (OH ions) and (H protons) found in a substance to base 10. You can calculate pH in a number of ways; by subtracting the hydrogen protons from 1x 10 -14 this will provide the approximate concentration of H protons thus giving you pH.

23)Why is pH important to the functioning of biological systems?pH is an essential part of most systems because it provides a buffer for chemical reactions. For example, human blood is alkaline must not vary much outside of 7.4. Anything lower or higher than that number can cause enzymatic failure, illness and even death.

24)How are two monomers linked together? Broken down?P. 50 Monomers are linked with a condensation reaction (removing a water molecule to form a polymer).

They are broken down through (hydrolysis) reactions that release water into the environment.

25)Draw the chemical structure of a disaccharide formed by two glucose monosaccharides.

26)Examine the glucose molecule shown in your textbook. Identify the functional groups on the molecule.Glucose (a hexose sugar-monosaccharide) is collectively known as an aldehyde possessing a double bond between C & O. It also holds a hydroxyl (-OH group).

27)What are the structural differences between alpha-glucose and beta-glucose? How does this difference affect the structure of a string of alpha-glucose molecules in comparison to a string of beta- glucose molecules? Explain why this happens.Alpha and Beta glucose are two differences in monomer structure based on the location of –OH or hydroxyl group relative to the side chain. If OH is on the same side it is known as a Beta glucose; it is an alpha Glucose if on opposing ends.

28)Some sugars have other functional groups in addition to those typically present. Draw the structure of the amino sugar glucosamine, which has an amino group bonded at carbon #2 of glucose. Would this molecule be more or less polar than glucose? Explain why.

This polymer would be less polar than glucose based on its new electronegativity associated with the additional amine group (NH2).

29)The molecular formula for glucose is C6H12O6. What would be the molecular formula for a polysaccharide made by linking ten glucose molecules together by dehydration reactions?Initially you would multiply each compound by 10 giving you 60 Carbons, 120 Hydrogens, and 60 Oxygens. However, you would need to remove 9 H20 molecules to link the compound together. This results in subtracting18 Hydrogen (9x 2= 18) and 9 Oxygen molecules to form the polysaccharide. This would give you C60H102O51

30)What is the difference between fats and oils?

Fats are solids, but may liquefy at room temperature.This is solidity is based on saturation levels as most fats have very few available unbonded carbons. Oils are always liquid-based at room temperature.

31)Why are phospholipids amphipathic, and how does this result in a lipid bilayer membrane?Since phospholipids have differing polarities on opposing sides of the molecule, this renders the lipid bilayer selectively permeable. This allows the membrane to filter or channel proteins, toxins and other molecules based on polarity.

32)If fatty acids are carefully put onto the surface of water, they will form a single molecular layer. If the mixture is then shaken vigorously, the fatty acids will form round structures called micelles. Why does this happen? Explain.Micelles form as a way to gather nonpolar molecules in a spherical form. This same process allows us to extract DNA (a polar molecule) with liquid detergent (nonpolar substance).

33)List the key differences between DNA and RNA and between purines and pyrimidines.DNA is double ringed whereas RNA is single ringed. Both molecules include purines and pyrimidines just in different chemical forms.

34)How can DNA molecules be so diverse when they appear to be structurally similar?The unique nitrogen bonding sequence is what produces genetic diversity. One nitrogenous base substitution could produce a completely different amino acid sequence and thus an entirely different protein. This is why polygenic traits are so diverse such as eye color and hair color.