For each biological level, write a sentence that includes the next "lower" level. Example" "A community consists of populations of the various species inhabiting a specific area."
A molecule consists of atoms bonded together. Each organelle has an orderly arrangement of molecules. Photosynthetic plant cells contain organelles called chloroplasts. A tissue consists of a group of similar cells. Organs such as the heart are constructed from several tissues. A complex multi-cellular organism, such as a plant, has several type of organs, such as leaves and roots. A population is a set of organisms of the same species. A community consists of populations of various species inhabiting a specific area. An ecosystem consists of a biological community along with the nonliving factors important to life, such as air, soil, and water. The biosphere is made of all of Earth's ecosystems.
For each theme discussed in Section 1.1, give an example mentioned in the book.
Evolution: All plants have chloroplasts, indicating their descent from a common ancestor. Emergent Properties: The ability of a human heart to pump blood requires an intact heart; it is not a capability of any of the heart's tissues or cells working alone. Exchange of Matter and Energy with the environment: A mouse eats food, and then uses the nutrients for growth and the generation of energy for its activities; some of the food material is expelled in urine and feces, and some of the energy returns to the environment as heat. Structure and Function: The strong, sharp teeth of a wolf are well-suited to grasping and dismembering its prey. Cells: The digestion of food is make possible by chemicals (chiefly enzymes) made by cells of the digestive tract. DNA: Human eye color is determined by the combination of genes inherited from the two parents. Feedback Regulation: When your stomach is full, it signals your brain to decrease your appetite.
What theme or themes are exemplified by
a) the sharp spines of a porcupine,
b) the cloning of a plant from a single cell, and
c) a hummingbird using sugar to power its flight?
a) Structure and function are correlated.
b) Cells are an organism's basic units, and the continuity of life is based on heritable information in the form of DNA.
c) Organisms interact interact with their environments, exchanging matter and energy.
How is a mailing address analagous to biology's hierarchial taxonomic system?
An address pinpoints a location by tracking from broader to narrower categories - a state, city, zip, street, and building number. This is analgous to the groups - subordinate-to-groups structure of a biological taxonomy.
Explain why "editing" is an appropriate metaphor for how natural selection acts on a population's heritable variation.
Natural selection starts with the naturally occurring variation (heritable) in a population and then "edits" the population as individuals with heritable traits better suited to the environment survive and reproduce more successfully than others.
Contrast inductive reasoning with deductive reasoning.
Inductive reasoning derives generalizations from specific cases;
Deductive reasoning predicts specific outcomes from general premises.
Why is natural selection called a theory?
Compared to a hypothesis, a scientific theory is usually more general and substantiated by a much greater amount of evidence. Natural selection is an explanetory idea that applies to all kinds of organisms and is supported by vast amounts of evidence of various kinds.
Suppose you extended the snake mimicry experiment to an area of Virginia where neither type of snake is known to live. What results would you predict at your field site?
You might predicts that the colorful artificial snakes would attacked more often than the brown ones, simply because they are easier to see. This prediction assumes that the area in Virginia where you are working has predators that attack snakes but no poisonous snakes that resemble the colorful artificial snakes.
What is a correct sequence of levels in life's hierarchy proceeding down from an individual animal?
What is NOT on observation or inference on which Darwin's theory of natural selection is based?
Poorly adapted individuals never produce offspring.
Protists and bacteria are grouped into different domains because
protists have a membrane - bound nucleus, which bacterial cells lack.
What describes the logic of hypothesis-based science?
If my hypothesis is correct, I can explain certain test results.
A controlled experiment is one that
may include experimental groups and control groups tested in parallel.
What statement distinguishes hypothesis from theories in science?
Hypothesis usually are relatively narrow in scope;
Theories have broad explanatory power.
With rough sketches, draw a biological hierarchy using a coral reef as the ecosystem, a fish as the organism, its stomach as the organ, and DNA as the molecule. Include all levels in the hierarchy.
Your figure should show:
1) For the biosphere, the Earth with an arrow coming our of a tropical ocean
2) For the ecosystem, a distant view of a coral reef
3) For the community, a collection of reef animals and algae, with corals, fish, some seaweed, and any other organisms you can think of
4) For the population, a group of fish of the same species
5) For the organism, one fish from your population
6) For the organ, the fish's stomach, and for the organ system, the whole digestive tract
7) For a tissue, a group of similar cells from the stomach
8) For a cell, one cell from the tissue, showing its nucleus and a few other organelles
9) For an organelle, the nucleus, where most of the cells' DNA is located
10) For a molecule, a DNA double helix
Explain how table salt has emergent properties.
Table salt is made up of sodium and chlorine. We are able to eat the compound, showing that it has different properties from those of a metal and a poisonous gas.
Iron, (Fe), is a trace element required for the proper functioning of hemoglobin, the molecule that carries oxygen in red blood cells. What might be the effects of an iron deficiency?
A person with an iron deficiency will probably show effects of low oxygen in the blood, such as fatigue. (The condition is called anemia and can also result from too few red blood cells or abnormal hemoglobin.)
If two or more elements are in the same row (of the periodic table), what do they have in common? If two or more elements are in the same column, what do they have in common?
The elements in a row all have the same number of electron shells.
In a column, all the elements have the same number of electrons in their valence shells.
Is a trace element an essential element? Explain.
Yes, because an organism requires trace elements, even though only in small amounts.
A nitrogen atom has 7 protons, and the most common isotope of nitrogen has 7 neutrons. A radioactive isotope of nitrogen has 8 neutrons. Write the atomic number and mass number of this radioactive nitrogen as a chemical symbol with a subscript and superscript.
How many electrons does flourine have? How many electron shells? Name the orbitals that are occupied. How many electrons are needed to fill the valence shell?
2 electron shells
1s, 2s, 2p (3 orbitals)
1 electron needed to fill the valence shell
Why does the following structure fail to make sense chemically?
Each carbon atom has only 3 covalent bonds instead of the required 4
Explain what holds together the atoms in a crystal or magnesium chloride (MgCl2).
The attractions between oppositely charged ions forms ionic bonds.
If you were a pharmaceutical researcher, why would you want to learn the three dimensional shapes of naturally occurring signaling molecules?
If researchers can synthesize molecules that mimic these shapes, they may be able to treat diseases or conditons caused by the inability of affected individuals to synthesize such molecules.
Which types of chemical reactions occur faster at equilibrium, the formation of products from reactants, of reactants from products?
At equilibrium, the forwards and reverse reactions occur at the same rate.
Write an equation that uses the products of photosynthesis as reactants and that uses the reactants as products. Ad energy as another product. This new equation describes a process that occurs in your cells. Describe this equation in words. how does this equation relate to breathing?
C6 H12 O6 + 6O2 --> 6CO2 + 6 H2O + Energy. Glucose and oxygen react to form carbon dioxide, water, and energy. We breathe in oxygen because we need it for this reaction to occur, and we breathe out carbon dioxide because it is a by-product of this reaction. By the way, this reaction is called cellular respiration.
Atoms can be represented by simply listing the number of protons, neutrons, and electrons - for example, 2p +; 2n 0; 2e-; for helium. Which one of the following lists represents the 18O isotope of oxygen?
The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound.
Which statement is true of all atoms that are anion?
The atoms has more electrons than protons, and has a negative charge.
Which of the following statements correctly describes any chemical reaction that has reached equilibrium?
The rates of the forward and reverse reactions are equal
What coefficients must be placed in the following blanks so that all atoms are accounted for in the products?
C6 H12 O6 --> ___ C2 H6 O + ____ CO2
What is electronegativity, and how does it affect interactions between water molecules?
Electronegativity is the attraction of an atom for the electron of a covalent bond. Because oxygen is more electronegative than hydrogen, the oxygen atom in H2O pulls electrons towards itself, resulting in a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atoms. Oppositely charged ends of water molecules are attracted to each other, forming a hydrogen bond.
Why is it unlikely that two neighboring water molecules would be arranged like this?
(The oxygens are each attached to two hydrogens)
The hydrogen atoms of one molecule, with their partial positive charges, would repel the hydrogen atoms of the adjacent molecules.
What would be the effects on the properties of the water molecule if oxygen and hydrogen had equal electronegativity?
Water molecules would not be polar, and they would not form hydrogen bonds with each other.
Describe how properties of water contribute to the upward movement of water in a tree?
Hydrogen bonds hold neghboringi water molecules together. This cohesion helps the water molecules resist gravity. Adhesion between water molecules and the walls of water-conducting cells also counters gravity. As water evaporates form leaves, the chain of water molecules in water-conducting cells moves upward.
How can the freezing of water crack boulders?
As water freezes, it expands because water molecules move farther apart in forming ice crystals. When there is water in a crevice of a boulder, expansion due to freezing may crack the rock.
If you were a pharmacist, how would you make a 0.5 molar solution of sodium chloride (NaCl)? (The atomic mass of Na is 23 daltons and that of Cl is 35.5 daltons.)
The molecular mass of NaCl is 58.5 daltons. A mole would have a mass of 58.5 grams, so you would measure out 0.5 moles, or 29.3 grams, of NaCl and gradually add water, stirring until it is dissolved. You would add water to bring the final volume to 1 liter.
A water strider's legs are coated with a hydrophobic substance. What might be the benefit? What would happen if the substance were hydrophilic?
The hydrophobic substance repels water, perhaps helping to keep the ends of the legs from becoming coated with water and breaking through the surface. If the legs were coated with a hyrophilic substance, water would be drawn up them, possibly making it more difficult for the water strider to walk on water.
Explain the saying, "It's not the heat, it's the humidity."
High humidity hampers cooling by suppressing the evaporation of sweat.
Compared with a basic solution at pH 9, the same volume of an acidic solution at pH 4 has ___ times as many hydrogen ions (H+).
10^5, or 100,000
HCl is a stron acid that dissociates in water. HCl--> H+ + Cl-
What is the pH of 0.01 M HCl?
[H+] = 0.01 M = 10^-2, so
pH = 2
Acetic acid, (CH3 COOH), can be a buffer, similar to carbonic acid. Write the dissociation reaction, identifying the acid, base, H+ acceptor, and H+ donor.
CH3 COOH <--> CH3 COO- + H+
CH3 COOH is the acid (the H+ donor)
CH3 COO- is the base (the H+ acceptor)
Given a liter of pure water and a liter solution of acetic acid, what would happen to the pH if you added 0.01 mol of a strong acid to each? Use the reaction equation to explain the result.
The pH of the water should go fro 7 to about 2; the pH of the acetic acid solution will only decrease a small amount, because the reaction shown in the question above will shift to the left, with CH3 COO- accepting the influx of H+ and becoming CH3 COOH.
Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temeperature?
The absorption of heat by the breaking of hydrogen bonds.
A slice of pizza has 500 kcal. If we could burn the pizza and use all the hear to warm a 50-L container of cold water, what would be the appropriate increase in the temperature of the water? (Note: a liter of cold water weights about 1 kg)
We can be sure that a mole of table sugar and a mole of vitamin C are equal in their
number of molecules
How many grams of acetic acid (C2 H4 O2) would you use to make 10 L of a 0.1 M aqueous solution of acetic acid? (Note: the atomic masses in daltons are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen.)
Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?
What conclusion did Stanley Miller draw when he formed amino acids int eh products of his experiments?
Amino acids are essential molecules for living organisms. Their synthesis from gases of the primitive atmosphere on Earth demonstrated that life's molecules could initially have been synthesized from nonliving molecules.
When Miller tried the experiment without the electrical discharge, no organic compounds were found. What might explain this result?
The spark provides energy needed for the inorganic molecules in the atmosphere to react with each other.
Can propane (C3 H8) form isomers?
No. There is not enough diversity in the atoms. It can't form structural isomers because there is only one way for three carbons to attach to each other (in a line). There are no double bonds, so geometric isomers are not possible. Each carbon has at least two hydrogens attached to it so the molecule is symmetrical and cannot have enantiometric isomers.
What does the term amino acid signify about the structure of such a molecule?
It has both an amino group (-NH2), which makes it an amine, and a carboxyl group (-COOH), which makes it a carboxylic acid.
What chemical change occurs when ATP reacts with water and releases energy?
The ATP molecule loses a phosphate, becoming ADP.
Suppose you had an inorganic molecule such as glycine and you chemically remove the -NH2 group and replaced it with -COOH. Draw the structural formula for this molecule and speculate about its chemical properties.
HO H OH
A chemical group that can act as a base has been replaced with a group that can act as am acid, increasing the acidic properties of the molecule. The shape of the molecule would also change, likely changing the molecules with which it can interact.
Choose the term that correctly describes the relationship between these two sugar molecules.
OH O OH
O OH OH
H H H
Identify the asymmetric carbon in this molecule
O OH H H H
H H H H H
o oh h h h
h h h h h
Some scientists believe that life elsewhere in the universe might be based ont eh element silicon, rather than on carbon, as on Earth. Look at the electron distribution diagram for silicon and draw the Lewis dot structure for silicon. What properties does silicon share with carbon that would make silicon-based life more likely than say, neon-based life or aluminum-based life?
Si has four valence electrons, the same number as carbon. Therefore, silicon would be able to form long chains, including branches, that could act as skeletons for organic molecules. It would clearly do this much better than neon (with no valence electrons) or aluminum (with three valence electrons).
Which functional group is not present inthis molecule?
HO H H
Which action could produce a carbonyl group?
The replacement of the -OH of a carboxyl group with hydrogen
Which chemical group is most likely to be responsible for an organic molecule behaving as a base?
What are the four main classes of large biological molecules?
How many molecules of water are needed to completely hydrolyze a polymer that is ten monomers long?
Nine, with one water required to hydrolyze each connected pair of monomers.
Suppose you eat a serving of green beans. What reactions must occur for the amino acid monomers in the protein of the beans to be converted to proteins in your body?
The amino acids in the green beans' proteins are released in hydrolysis reactions and incorporated into other proteins in dehydration reactions.
A dehydration reaction joins two glucose molecules to form maltose. The formula for glucose is C6 H12 O6. What is the formula for maltose?
C12 H24 O11
What would happen if a cow were given antibiotics that killed all the prokaryotes in its stomach?
The absence of these prokaryotes would hamper the cow's ability to obtain energy from food and could lead to weight loss and possible death.
Why are human sex hormones considered lipids?
Human sex hormones are steroids, a type of hydrophobic compound.
Compare the structure of a fat (triglyceride) with that of a phospholipid.
Both have a glycerol molecule attached to fatty acids. The glycerol of a fat has three fatty acids attached, where as glycerol of a phospholipid is attached to two fatty acids and one phosphate group.
Suppose a membrane surrounded an oil droplet, as it does in the cells of plant seeds. Describe and explain the form it might take.
The oil droplet membrane could consist of a single layer of phospholipids rather than a bilayer, because an arrangement in which the hydrophobic tails of the membrane phospholipids were in contact with the hydrocarbon regions of the oil molecules would be more stable.
What parts of a polypeptide chain participate in the bonds that hold together secondary structure? What parts participate in tertiary structure?
Secondary structure involves hydrogen bonds between atoms of the polypeptide backbone.
Tertiary structure involves bonding between atoms of the R groups of the amino acid subunits.
Why does a denatured protein no longer function normally?
The function of a protein is a consequence of its specific shape, which is lost when a protein becomes denatured.
If a genetic mutation changes primary structure, how might it destroy the protein's function?
Primary structure, the amino acid sequence, affects the secondary structure, which affects the tertiary structure, which affects the quaternary structure (if any). in short, the amino acid sequence affects the shape of the protein. Because the function of a protein depends on its shape, a change in primary structure can destroy a protein's function.
In a DNA double helix, a region along one DNA strand has this sequence of nitrogenous bases: 5'-TAGGCCT-3'. Write down this strand and its complementary strand, clearly indicating the 5' and 3' ends of the complementary strand.
a) Suppose a substitution occurred in one DNA strand of the double helix, resulting in
Draw the two strands; circle and label the mismatched bases.
b) If the modified top strand is replicated, what would its matching strand be?
Which term includes all others in the list?
The molecular formula for glucose is C6 H12 O6. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions?
C60 H102 O51
The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the a form. Which of the following could amylase break down?
glycogen, starch, and amylopectin
Which of the following statements concerning unsaturated fats is true?
They have double bonds in the carbon chains of their fatty acids.
Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?
5'-ATGC-3' with 5'-GCAT-3'
Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?
The phosphodiester linkages between deoxyribose sugars would be broken.
Construct a table that organized the following terms, and label the columns and rows.
Monomers or Polymer or Type of
Components Larger Linkage
Sugars Monosacch. Polysacch. Glycosidic Links
Lipids Fatty Acids Triacylglycerols Ester
Proteins Amino Acids Polypeptides Peptide Bonds
Nucleic Nucleotides Polynucleotides Phosphodiester