Biology Final Exam Study Guide

Which of the following is true of natural selection?

Which of the following is true of natural selection?

It requires genetic variation, results in descent with modification, and involves differential reproductive success

Which of the following types of cells utilize deoxyribonucleic acid (DNA) as their genetic material but do not have their DNA encased within a nuclear envelope?

Archaean

How does a scientific theory differ from a scientific hypothesis?

Theories are usually an explanation for a more general phenomenon; hypotheses typically address more specific issues

The temperature at which an alligator's egg is incubated will determine the sex of the offspring. The dependent and the independent variables in this experiment are?

The sex of the baby alligator (dependent) and temperature (independent) respectively

The application of scientific knowledge for some specific purpose is known as?

Technology

You are suffering from the Streptococcus (Strep) throat infection. You share the following with the bacteria that is responsible for your condition...

You are both made up of cells

Which of the following are qualities of any good scientific hypothesis?

It is testable and falsifiable

The process by which information in a gene directs the synthesis of a protein is called?

Gene expression

Which of these provides evidence of the common ancestry of all life?

Near universality of the genetic code

Why is a scientific topic best discussed by people of varying points of view, different subdisciplines, and diverse cultures?

Robust and critical discussion between diverse groups improves scientific thinking (also less bias imo)

What is the maximum number of covalent bonds that an oxygen atom with atomic number 8 can make with hydrogen?

2 covalent bonds

The atomic number of nitrogen is 7. Nitrogen-15 has a greater mass number than nitrogen-14 because the atomic nucleus of nitrogen-15 contains?

8 neutrons

What is the difference between covalent bonds and ionic bonds?

Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between charged atoms

If an atom has a charge of +1, which of the following must be true?

It has one more proton than it does electrons

Which bond or interaction would be difficult to disrupt when compounds are put into water?

Covalent bonds between carbon atoms

Nitrogen (N) normally forms 3 covalent bonds with a valence of 5. However, ammonium has 4 covalent bonds, each to a different hydrogen (H) atom (H has a valence of 1). What do you predict to be the charge on ammonium?

+1

Oxygen has an atomic number of 8 and, most commonly, a mass number of 16. Thus, what is the atomic mass of an oxygen atom?

Approximately 16 Daltons

A covalent bond is more likely to be polar when?

One of the atoms sharing electrons is more electronegative than the other atom

Which of the following is broken when water evaporates?

Hydrogen bonds

About 25 of the 92 natural elements are known to be essential to life. Which 4 of these 25 elements make up approximately 96% of living matter?

Carbon, hydrogen, nitrogen, and oxygen

Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?

Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers

Humans can digest starch but not cellulose because?

Humans have enzymes that can hydrolyze the α glycosidic linkages of starch but not the β glycosidic linkages of cellulose

Ibruprofen is a drug commonly used to relieve inflammation and pain. It is a mixture of two enantiomers, which are molecules that?

Are mirror images of one another

Which of the following functional groups confers the properties of an acid on amino acids?

Carboxyl

The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA___

Contains one less oxygen atom than the sugar in RNA

A nucleotide is composed of

A nitrogenous base, a phosphate group, and a pentose sugar

Which of the following statements concerning saturated fats is true?

They are generally solid at room temperature

Which bonds maintain the primary structure of a protein?

Peptide bonds

Collagen is a protein made of three identical polypeptides composed primarily of α helix structure. The α helix is an example of a?

Secondary structure stabilized by hydrogen bonds

One of the primary functions of RNA molecules is to?

Function in the synthesis of proteins

If 14C-labeled uracil is added to the growth medium of cells, what macromolecules will be labeled?

RNA

Which of the following statements is true regarding cellulose?

It is a primary structural component of plant cell walls

If a DNA sample were composed of 20% guanine, what would be the percentage of cytosine?

20%

Lactase is an enzyme composed of a single polypeptide that hydrolyzes the disaccharide lactose to produce monosaccharides. The optimal pH for lactase activity is 6. Transfer of lactase to pH 5 results in a substantial decrease in enzyme activity, likely due to the disruption of?

The secondary and tertiary structures of the enzyme

Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates. How do these molecules differ from each other?

Testosterone and estradiol have different functional groups attached to the same carbon skeleton

Why are hydrocarbons insoluble in water?

The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages

How many molecules of water are needed to completely hydrolyze a polysaccharide that is 10 monomers long?

9

Which of the following organelles are enclosed by a double membrane?

Nuclei and chloroplasts

A researcher disrupts cells and separates subcellular components using centrifugation. Which of the following correctly lists the order in which cellular components will pellet when disrupted cell mixtures are centrifuged at increasingly higher speeds.

Nucleus, mitochondria, ribosomes

Which organelle occupies much of the volume of a plant cell?

Central vacuole

What is the primary reason that modern transmission electron microscope (TEM) can resolve biological structures as small as 2 nm, whereas 200 nm is the limit of resolution for a light microscope?

Electron beams have much shorter wavelengths than visible light

Which of the following molecules or structure may be found in eukaryotic cells but not in bacteria?

Endoplasmic reticulum

Which of the following statements concerning cells of bacteria and archaea is correct?

Chromosomes in both archaea and bacteria contain DNA

The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and therefore abundant in liver cells?

Smooth ER

A mutation that inactivates an enzyme involved in the modification of sugars associated with glycoproteins is most likely to affect the function of which of the following cellular structures?

Cisternae of the Golgi apparatus

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules

Proteins

Proteins that will be exported from the cell are synthesized by which of the following cellular components?

Rough ER

Extracellular matrix proteins are produced by ribosomes in which part of a eukaryotic cell?

Rough ER

Which of the following molecules is required to build cilia or flagella?

Tubulin

Which of the following structures plays a major role in making skin tissues watertight?

Tight junctions

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through?

Gap junctions

Plastids are only found in which of the following types of cells or organisms?

Plant cells

Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells?

Gap junctions

Following activation of a receptor, which sequence below represents the correct order in which components will be involved in a signaling pathway that utilizes the second messenger cAMP?

G protein → adenyl cyclase → cAMP → protein kinase

Which of the following statements about diffusion is correct?

It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration

The electrochemical gradient across a membrane would generally be increased by which of the following membrane proteins?

A hydrogen ion pump

The fluid mosaic model of membrane structure suggests that membranes?

Are composed of protein molecules imbedded in a fluid bilayer of phospholipids

What kinds of molecules pass through a cell membrane most easily?

Small hydrophobic

Submerging a red blood cell in distilled water will result in

Lysis of the cell

The primary function of G proteins in signal transduction is to?

Transmitting the signal from an activated receptor to the next protein in the pathway

The primary function of kinases in signal transduction is to?

Activate protein kinases or other relay molecules in a series

A protein that spans the phospholipid bilayer one or more times is?

A transmembrane protein

Based on the fluid mosaic model of cell membranes, which of the following statements about membrane phospholipids is true?

They can move laterally along the plane of the membrane

Based on the first law of thermodynamics, which of the following statements about a living organism is true?

The organism ultimately must obtain all of the necessary energy for life from its environment

A non-competitive inhibitor decreases the rate of an enzymatic reaction by

Changing the shape of the enzyme active site

Which of the following statements is a logical consequence of the second law of thermodynamics?

Every chemical reaction must increase the total entropy of the universe/Heat is produced as a product of moving energy from one place to another. This is entropy

A chemical reaction that has a positive AG is best described as

Endergonic/Not spontaneous

The ΔG for a particular enzyme-catalyzed reaction is -20 kcal/mol. If the amount of enzyme in the reaction is doubled, what will be the ΔG for the new reaction?

-20 kcal/mol (enzyme amount changes don't affect the ΔG)

ATP hydrolysis in a test tube releases only about half as much energy as ATP hydrolysis in the cell. Which of the following statements is the best explanation for this observation?

Reactant and product concentrations in the cell are different from the standard conditions used in a test tube/The enzymes that hydrolyze ATP are not working properly because the environment is not right

An aminoacyl-tRNA synthetase is the enzyme that catalyzes the attachment of a particular amino acid to its corresponding tRNA. This reaction requires energy from ATP. The enzyme initially binds the amino acid and ATP, but it is unable to bind the tRNA at this point. Which of the following would be a likely next step in the reaction by which the enzyme ultimately binds the tRNA and attaches the amino acid?

Hydrolysis of ATP phosphorylates the amino acid, which results in a conformational change in the active site that allows the tRNA to bind

Anabolic pathways share which of the following characteristics?

They consume energy to synthesize polymers from monomers/They take in energy to produce larger molecules from smaller molecules

Zinc, an essential trace element for most organisms, is required in the active site of the enzyme carboxypeptidase in order for the enzyme to function properly. The zinc most likely functions as a(n)

Cofactor necessary for enzyme activity

Which of the following is the most comprehensive definition of metabolism in living organisms?

Metabolism consists of all the energy transformation reactions in an organism/Metabolism is a combination of anabolic reactions plus catabolic reactions

A competitive inhibitor decreases the rate of an enzymatic reaction by

Binding to the active site of the enzyme

Based on the first law of thermodynamics, which of the following statements about a living organism is true?

All organisms must get their energy from somewhere else. No organism can make its own energy, not even plants

Where does glycolysis occur in animal cells?

Cytosol

Which of the following terms describes metabolic pathways that break down complex molecules to release stored energy?

Catabolic pathways

Which of the following metabolic pathways generates a proton gradient?

The electron transport chain

Which of the following describes the result of transferring an electron from a less electronegative atom to a more electronegative atom?

The more electronegative atom is reduced, and energy is released

In addition to ATP, what are the products of glycolysis?

NADH and pyruvate

Which of the following metabolic pathways occur(s) in mitochondria?

Oxidation of pyruvate to acetyl CoA and the citric acid cycle

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms

The oxygen consumed during cellular respiration is involved directly in which process of event?

Accepting electrons at the end of the electron transport chain

Why are carbohydrates and fats considered high-energy foods?

They have a large number of electron associated with hydrogen

What is the proton-motive force?

The energy provided by a transmembrane hydrogen ion gradient

Yeast cells with defective mitochondria are incapable of cellular respiration. Catabolism of which of the following energy sources would allow these to grow?

Glucose

Which of the following statements about NAD+ is true?

NAD+ is reduced to NADH during glycolysis

What is the source of the energy used to generate the proton gradient across the inner mitochondrial membrane?

Redox reactions in the electron transport chain

In an oxidation-reduction reaction, how is the reducing agent changed?

It loses electrons and loses potential energy

How many carbon atoms from one molecule of pyruvate enter the citric acid cycle?

2

Assuming glucose is the only energy source for a cell, what fraction of the carbon dioxide produced by aerobic respiration is generated by the reactions of the citric acid cycle?

2/3

Which of the following indicates a primary path by which electrons travel downhill energetically during aerobic respiration?

Glucose → NADH → electron transport chain → oxygen

Which chemical process generates the ATP produced in glycolysis?

Substrate-level phosphorylation

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the glucose molecule becomes?

Oxidized

Approximately what percentage of the ATP formed by the reactions of glycolysis is produced by substrate-level phosphorylation?

100%

What is the primary function of cyclic electron flow?

To produce additional ATP

What is the relationship between wavelength of light and the quantity of energy per photon?

They are inversely related

In mitochondria, the electron transport chain pumps protons from the matrix into the intermembrane space. In what direction are protons pumped by the electron transport chain in chloroplasts?

From the stroma to the thylakoid space

Which of the following molecules are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

ATP and NADPH

P680+ is often considered the strongest biological oxidizing agent. Given its function, why is this necessary?

It obtains electrons from the oxygen atom in a water molecule, so it must have a greater affinity for electrons than oxygen has