Studied by 11 people
At each level of the biological hierarchy, we find a correlation of ___________ and _____________.
Structure and function.
Can a hypothesis ever be proven in science? Explain.
No. There will always be a certain extent of doubt as to whether the hypothesis is true. However, it is possible to increase confidence in a hypothesis by testing it several times.
Describe how your body regulates the amount of sugar in your blood stream.
Increases in blood glucose leads the pancreas to release insulin (stimuli) into the blood to store excess glucose in a large carbohydrate form called glycogen, reducing blood glucose to a stable level for bodily functioning (response).
Does a controlled experiment mean that all non-experimental variables are kept constant? Explain.
No. Doing so is practically impossible in all environments; control groups are used to cancel out the effects of non-experimental variables, though.
Explain what is meant by a scientific theory by giving the three ways your text separates a theory from a hypothesis or mere speculation.
1. Much broader than a hypothesis.
2. General enough to lead to many new, specific hypotheses.
3. Supported by a much greater amount of evidence.
List and define the levels of biological organization (from most complex to least).
The biosphere, ecosystem, community, population, organism, organ and organ systems, tissues, cells, organelles, and molecules.
What is a hypothesis? In science, hypotheses must be testable and falsifiable. What does this mean?
A tentative answer to a scientific question; must be able to be tested (experiment/additional observations) and disproved.
What is an organism's basic unit of structure and function?
The cell.
What is data? What is the difference between quantitative and qualitative data?
Data is recorded observations/information. Qualitative data is recorded in descriptions, while quantitative data is recorded in numbers/measurements.
What is feedback regulation?
Feedback regulation is a process where the product of a process regulates that process.
What are the 2 types of feedback regulation? Which one is more common? Provide examples of each.
The two types are negative (e.g. stabilizing blood glucose levels) and positive feedback (e.g. blood clotting), with negative feedback being more common.
What is the difference between an experimental group and a control group?
The experimental group receives the variable being altered, while the control group does not.
What are control groups used for?
Control groups are used to compare with the experimental group to make conclusions about the effects of the independent variable and rule out other factors as causes.
What is the difference between an independent and dependent variable?
The independent variable is the factor being altered in the experiment, and the dependent variable is the factor being measured and affected by the independent variable.
What is the difference between how energy flows through an ecosystem and how chemicals/matter flow through an ecosystem?
Energy flows in one direction (entering as light and exiting as heat after work is performed), while chemicals/matter are recycled within an ecosystem.
What is the myth of the scientific method?
The ideal process of the scientific method is not commonly followed due to the unpredictability of science.
Sketch a model of an atom of helium, showing the electrons, protons, neutrons, and atomic nucleus. What is the atomic number and atomic mass of helium?
The atomic number of helium is 2 and the atomic mass is approximately 4 amu.
Define neutron.
A neutrally charged subatomic particle.
Define proton.
A positively charged subatomic particle.
Define electron.
A negatively charged subatomic particle.
Define atomic number.
The # of protons an electron has; used to identify the atom.
Define atomic mass.
The total mass of an atom.
Define isotope.
Different forms (atomic masses) of the same element; # of neutrons is changed.
Define electron shells.
Energy levels with a certain distance from the nucleus that electrons stay on.
Define energy.
The capacity to cause change.
What is the only subatomic particle that is directly involved in the chemical reactions between atoms?
The electron.
What is energy?
The capacity to cause change; matter has a natural tendency to move toward the lowest state of potential energy.
When is an atom stable? How does this influence how atoms/elements react to each other?
An atom is stable when it has a full outer electron shell. Atoms/elements react with each other in order to reach that full outer shell.
Explain how electrons have various states of potential energy.
The amount of potential energy an electron has is determined by its distance from the nucleus. Atoms have multiple electron shells with certain average distances from the nucleus that electrons can jump up/down to.
Give an example of how light can influence the energy of an atom/an electron.
Light energy can “excite” an electron to a higher energy level (absorbed energy); shown as in photosynthesis, as plants use light energy to convert CO2 and H2O to sugar.
What are the two strongest types of chemical bonds within a molecule? Which one forms when electrons are shared?
Covalent bonds and ionic bonds. Covalent bonds form when electrons are shared.
What is meant by electronegativity?
Electronegativity is the attraction of an atom for electrons in a covalent bond.
Make an electron distribution diagram of water. Which element is most electronegative? Why is water considered a polar molecule? Label the regions that are more positive or more negative.
Oxygen is the most electronegative. Since oxygen is more electronegative, oxygen pulls the electrons towards its own nucleus, as it has a greater attraction for electrons than hydrogen; this imbalance makes water polar.
What is a covalent bond?
The sharing of electrons between two atoms.
What is a non polar covalent bond?
Covalent bonds where electronegativity is balanced.
What is a polar covalent bond?
Covalent bonds where electronegativity isn’t balanced; one atom pulls the shared electrons towards itself.
What is an ionic bond?
The attraction between two oppositely charged atoms, where the high electronegativity atom takes an electron from the low electronegativity atom.
What is a hydrogen bond?
The attraction between the partial positive charge of hydrogen and the partial negative charge of another atom (F, O, N).
Place hydrogen bonds, van der Waals interactions, covalent bonds, and ionic bonds in order from strongest to weakest.
Ionic bonds, covalent bonds, hydrogen bonds, van der Waals interactions.
Why does the following structure fail to make sense chemically? H-C=C-H
It does not make sense because each carbon atom only has 3 bonds, though 4 bonds are needed for carbon to have a full outer shell.
What is a polar molecule?
A polar molecule is a molecule whose overall change isn’t balanced and has polar covalent bonds between atoms.
Why is water considered polar?
Oxygen’s higher electronegativity leads electrons in the covalent bonds to be attracted and move closer to it, creating a polar covalent bond (water’s V shape also pulls the molecule in oxygen’s direction)
Explain hydrogen bonding.
The partial negative charge of oxygen in one water molecules is attracted to the partial positive charge of hydrogen in another water molecules, thus forming a weak bond.
The calorie is a unit of heat. Define calorie.
A calorie is the amount of heat it takes to raise the temperature of 1g of water by 1C.
Water has a high specific heat. What does this mean?
Water requires a very large amount of heat to absorb/lose 1C of heat, leading it to change temperatures less than other substances.
How does water’s specific heat compare to alcohol’s specific heat?
Water's specific heat is 1 cal/g x C, while ethyl alcohol's specific heat is 0.6 cal/g x C, therefore less heat is needed to absorb/lose 1C of heat for 1g of ethyl alcohol.
Taking into consideration the polarity of a water molecule, explain why the specific heat of water is so high.
Water’s high specific heat is due to hydrogen bonds. When absorbing 1 cal of heat, water’s temperature only marginally changes, as most of the heat is first used to break H-bonds to allow water molecules to move freely. Alongside that, when the temperature decreases slightly, more H-bonds form, releasing heat energy while doing so.
Why is water an extremely good solvent?
Water’s polarity allows the partial charges of oxygen and hydrogen to attract and surround the ionic/polar regions of the solute.
Describe what it means to be hydrophobic versus hydrophilic.
Hydrophilic describes ionic/polar substances that have an affinity for water and typically dissolve in water, while hydrophobic describes nonionic and nonpolar substances that don’t have an affinity for water and typically repel from water.
Water, which is neutral with a pH of 7, has a equal number of H+ and OH- ions. Now, define acid and basic.
An acid is a substance that increases the hydrogen ion concentration of a solution, while a base is a substance that reduces the hydrogen ion concentration of a solution.
Because the pH scale is logarithmic, each numerical change represents a 10x change in ion concentration. How many times more acidic is a pH of 3 compared to a pH of 5?
10^-3 / 10^-5 = 100
How many times more basic is a pH of 12 compared to a pH of 8?
10^-2 / 10^-6 = 10000
Even a slight change in pH can be harmful. How do buffers moderate pH change?
Buffers minimize changes in the concentrations of H+ and OH- by taking the H+ in a solution if there is too much and donating H+ to a solution if there is too little.
Exercise will result in the production of CO2, which will acidify the blood. Explain the buffering system that minimizes blood pH changes.
If pH rises, H2CO3, created by CO2 reaction with H2O in blood, dissociates to form HCO3- and H+, which drops the pH, and if pH drops, HCO3- and H+ react to reform H2CO3, rising the pH.
How do natural buffers play a role in living systems?
Many buffers contribute to stabilizing pH in many biological substances, such as human blood.
Illustrate how bicarbonate acts as a buffer under basic and acidic conditions.
If pH rises: H2CO3 → HCO3- + H+
If pH drops: HCO3- + H+ → H2CO3
Illustrate the partial charges and hydrogen bonds in water.
How many valence electrons does carbon have?
Carbon has 4 valence electrons.
How many bonds can carbon form?
Carbon can form 4 bonds.
What type of bonds does carbon form with other elements?
Carbon forms covalent bonds with other elements (in organic molecules), mostly single and double bonds.
What property of carbon accounts for the molecular complexity snd diversity that characterizes living things?
Carbon’s ability to form 4 forms with the electrons of the 6 major elements’ (CHNOPS) atoms allows for very simples and very complex molecules to be made, as each bond acts like a branch for more atoms to be placed in the molecule.
What is a hydrocarbon? Are hydrocarbons hydrophobic or hydrophilic?
A hydrocarbon is an organic molecule that only consists of carbon and hydrogen. Hydrocarbons are hydrophobic due to carbon hydrogen binds being nonpolar.
“Change the structure, change the function.” Label each molecule in the sketch below and circle the differences. Describe the function of each molecule.
Estradiol (left) is the female sex hormone, and testosterone (right) is the male sex hormone. They only differ in the chemical groups attached to their carbon skeleton, but these slight differences produce the contrasting features of men and women.
What is a functional group?
Functional groups are chemical groups with different properties that cause it to take part in certain reactions and have a different function.
Identify three functional groups in this molecule.
Carboxyl group, hydroxyl group, amino group
Characteristics of a hydroxyl group.
Polar due to electronegative oxygen; forms hydrogen bonds w/ water, helping dissolve compounds like sugars.
Characteristics of a carbonyl group.
Sugars with ketone groups (carbonyl group is within a carbon skeleton) are called ketoses, while sugars with aldehyde groups (carbonyl group is at the end of a carbon skeleton) are called aldoses.
Characteristics of a carboxyl group.
Acts as an acid (can donate H+) because the oxygen hydrogen bond is so polar.
Characteristics of an amine group.
Acts as a base (can pick up an H+ from the surrounding solution)
Characteristics of a sulfhydryl group.
Two sulfhydryl groups can react to form a cross-link that helps stabilize protein structure
Characteristics of a phosphate group.
Contributes a negative charge (1- when positioned inside a chain of phosphates, 2- when at the end); when attached, gives the molecule the ability to react with water and release energy (ATP)
Characteristics of a methyl group.
Affects the expression of genes when on DNA or on proteins bound to DNA; affects the shape/function of male and female sex hormones.
What is a polymer? What is a monomer? Which of the classes of macromolecules are polymers?
Polymer: a large molecule consisting of several similar/identical molecules chained together by covalent bonds.
Monomer: a smaller molecule used as a building block to form polymers when linked together
Carbohydrates, proteins, and nucleic acids are polymers
What is a dehydration reaction?
A dehydration reaction occurs when two molecules covalent bond with each other, forming a longer polymer, through the loss of a water molecule.
How does a dehydration reaction form? What facilitates this process?
When two monomers react, they contribute a part of an H2O molecule from the end of their own molecule (-OH and H), allowing the H2O to form and the monomers to bond.
Enzymes facilitate and speed up this process.
How are polymers disassembled to monomers?
Hydrolysis, where the bond between two monomers breaks through the addition of a water molecule, disassembles polymers.
What occurs at the molecular level in hydrolysis?
A hydrogen atom attaches to one monomer while a hydroxyl group attaches to the other, breaking the bond between the two monomers.
How can differences and similarities in the variety of macromolecules provide an indication of relatedness between species?
Macromolecules differ for different cells and organisms due to different functions being needed, with closer related organisms having more similar macromolecules in their cells.
Relate the following terms: monomer, polymer, sugars, monosaccharides, polysaccharides, and disaccharides.
A monosaccharide is the monomer for all sugars, used to build larger polymers, such as disaccharides (2 monosaccharides bonded together) and polysaccharides (multiple monosaccharides bonded together)
What sugar is a major nutrient needed by cells?
Glucose is a major nutrient needed by cells.
What are the 2 main functions of polysaccharides?
Either storing sugar for later use (storage polysaccharides) or used as building material for structures to protect the organism/cell (structural polysaccharides)
What organism produces starch? What type of polysaccharides is starch?
Plants produce starch. Starch is a storage polysaccharide.
How can humans gain glucose from eating starchy foods?
Starch, a polymer of glucose molecules, once consumed, can be hydrolyzed, separating individual glucose molecules, and used as fuel.
Humans are unable to make starch, instead excess glucose is stored as _________, which is usually stored in the ________________.
Glycogen, stored in the liver and muscle cells.
How long does glycogen storage last in the body?
Glycogen storage lasts around a day, unless replenished via consumption of food.
What carbohydrate is used by plants as a structural component?
Cellulose, which is used to build cell walls.
Why are humans able to hydrolyze plant starch (and therefore obtain nutrition from it) but unable to hydrolyze plant cellulose?
Many organisms have enzymes that can hydrolyze/digest starch, but not cellulose, due to the different structures of each (starch is built of alpha glucose, cellulose is built of beta glucose); cellulose is often called insoluble fiber due to this.
Lipids have very little to no affinity for __________.
Water.
What molecules join to form a fat? What is the joining process called?
A fat is built from a glycerol molecule and three fatty acids joined to it via ester links.
Fats are also known as ____________ molecules.
Triacylglycerol molecules.
How do fatty acids vary?
Fatty acids can either be saturated or unsaturated (or trans).
Describe on a macro and molecular scale the differences between saturated and unsaturated fats.
Saturated fatty acids have no double bonds between carbon atoms and have as many H atoms as possible, while unsaturated fatty acids have one or more double bonds between carbon atoms, causing a bend in the hydrocarbon chain when they appear.
The major function of fats is ________ ________.
Energy storage.
What two macromolecules function in energy storage?
Carbohydrates and lipids (fats).
What is glucose used for and how is it used?
Glucose is a simple sugar that is quickly converted into energy (via powering ATP for immediate use of energy) for muscles/tissues/brain.
What is glycogen used for and how is it used/produced?
Glycogen is a type of starch that takes longer to convert into energy than glucose due to needing to digest it via hydrolysis. Excess glucose is converted/stored as glycogen in the muscles/liver.
What are fats used for and how are they used/produced?
Fats are used for long term energy storage and are produced when extra glucose is not stored as glycogen, and instead as triglycerides/fats. They are used for energy if glucose and glycogen storage is depleted.
Describe the structure of phospholipids.
Made up of 2 fatty acids attached to a glycerol molecule, with the last hydroxyl group of glycerol attached to a phosphate group (which commonly also has a small charged/polar group attached to the end of it)
How do the components of the phospholipid interact with water?
The tails (fatty acids) are hydrophobic, while the head (phosphate group, glycerol, attachment) is hydrophilic, so when placed in water, phospholipids from a structure called a bilayer, with the hydrophobic tails shielded from water.
What is the function of the phospholipid bilayer in cells?
Acts as a boundary between the inside and outside environment of a cell, with the hydrophilic heads in contact with each.
Note
Flashcard