Final Exam Biology 1201

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Each water molecule is joined to _____ other water molecules by ____ bonds.

four....hydrogen

The unequal sharing of electrons within a water molecule makes the water molecule _____.

polar

The tendency of an atom to pull electrons toward itself is referred to as its _____.

electronegativity

In the water molecule, what type of bond is found between the oxygen and hydrogens?

polar covalent

which bonds are the weakest?

hydrogen bonds are weaker than covalent bonds because they involve the sharing of electrons and they are weaker than ionic bonds because they involve the attraction of partial (not full) opposite charges

why can some insects float on the surface of water easily?

surface tension

hydrogen ion

H+

hydroxide ion

OH-

In a neutral solution the concentration of _____.

hydrogen ions is equal to the concentration of hydroxide ions

what affects the pH of a solution?

The more hydroxide ions present, the more basic a solution is. The more hydrogen ions present the more acidic a solution is.

atomic number

the number of protons in an element

mass number

total number of protons and neutrons in an element

atomic mass

approximately the mass number of an atom expressed in Daltons

isotope

elements with the same number of protons but a different number of neutrons

valence electrons

the chemical behavior of an atom depends mostly on these electrons which lie in the outermost shell

electronegativity

the attraction of a particular atom for the electrons of a covalent bond; the more electronegative an atom is, the more strongly it pulls shared electrons towards itself

non polar covalent bond

when an electrons are shared equally because the two atoms have the same electronegativity-this tug-of-war creates a standoff

polar covalent bond

when the electrons of the bond are not shared equally so that one atom is relatively more negative than the other

What bonds bind a molecule of water?

polar covalent bonds; very polar

ionic bond

formed between two atoms when one atom completely pulls an electron from the second atom and the two atoms are held together because one is now negatively charged (containing an extra electron) and the other is positively charge (because it has lost an electron)

cation

ion with a positive charge

anion

ion with a negative charge

examples of non polar covalent bonds

gaseous hydrogen (H2) or oxygen (O2)

examples of polar covalent bonds

H20

examples of ionic bonds

NaCl

what properties of water stabilize the temperature and lead to evaporative cooling?

As a result of hydrogen bonding among water molecules, it takes a relatively large heat loss or gain for each 1 degree C change in temperature.
The surface molecules with the highest kinetic energy are most likely to escape into gaseous form; the average kinetic energy of the remaining surface molecules is thus lower.

why does ice float?

ice is less dense than liquid water. as water freezes a crystal lattice is formed by hydrogen bonds joining all water molecules in the liquid. these hydrogen bonds keep the different water molecules at "arms length" from one another.

why is the idea of ice floating important for aquatic organisms living in temperate environments?

since ice floats, water freezes from the top down. organisms under ice are insulated from the freezing conditions above the water providing relatively warm and safe conditions.

cohesion

hydrogen bonds hold the substance together in a phenomenon called cohesion

mole

the number of grams of a substrate that equals its molecular weight in Daltons and contains Avogadro's number of number molecules

Avogadro's Number

6.02 X 10^23

molarity

the number of moles of solute per liter of solution (solute concentration)

how do you determine the molecular weight or mole weight of compound?

the molecular weight of the a molecule is equal to the sum of the atomic masses of the atoms making up the molecule

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

carbon, hydrogen, nitrogen, oxygen

The atoms of different phosphorus isotopes _____.

have different numbers of neutrons

The type of bonding and the numbers of covalent bonds an atom can form with other atoms is determined by _____.

the number of unpaired electrons in the valence shell

The atomic number of each atom is given to the left of each of the elements below. Which of the atoms has the same valence as carbon (12
6C)?

14Si Silicon

Hydrogen bonding is most often seen _____.

when hydrogen is covalently bonded to an electronegative atom

Which of the following correctly describes chemical equilibrium?

Forward and reverse reactions continue with no effect on the concentrations of the reactants and products.

Two atoms appear to have the same mass number. These atoms

must have the same number of protons + neutrons.

If an atom of sulfur (atomic number 16) were allowed to react with atoms of hydrogen (atomic number 1), which of the molecules below would be formed?

H-S-H

What is the maximum number of hydrogen atoms that can be covalently bonded in a molecule containing two carbon atoms?

6

Which statement is true of all atoms that are anions?

The atom has more electrons than protons.

Organic chemistry is currently defined as

the study of carbon compounds.

L-dopa is used to treat _____.

Parkinson's disease

What kind of effect does R-dopa have on Parkinson's disease?

none

Enantiomers are molecules that _____.

are mirror images

Geometric isomers are molecules that _____.

differ in the arrangement of their atoms about a double bond

How do isomers differ from one another?

Isomers differ in the arrangement or bonding of atoms.

which of the functional groups behaves as a base?

the electronegativity of nitrogen means that amino groups tend to pick up hydrogen atoms

Which of the functional groups is characteristic of thiols?

Thiols are characterized by the presence of a sulfhydryl group.

Which of the functional groups plays a major role in energy transfer?

Phosphate groups are a component of ATP.

Which of the functional groups is characteristic of a ketone?

A carbonyl group in the middle of a carbon skeleton characterizes ketones.

Which of functional groups behaves as an acid?

By donating hydrogen ions, carboxyl groups act as an acid.

Which of the following hydrocarbons has a double bond in its carbon skeleton?

C2H4

Which action could produce a carbonyl group?

the replacement of the -OH of a carboxyl group with hydrogen

Which of the functional groups is most likely to gain a proton and become positively charged?

An amino group acts as a base and can pick up protons from the surrounding medium, becoming positively charged.

Which polymers are composed of amino acids?

proteins

Which of the following is not attached to the central carbon atom in an amino acid?

an oxygen

Which part of an amino acid is always acidic?

carboxyl functional group

Which monomers make up RNA?

nucleotides

Which of the following statements about the formation of polypeptides from amino acids is true?

A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid.

True or false? Enzymes in the digestive tract catalyze hydrolysis reactions.

true

Glycogen is _____.

a polysaccharide found in animals

glucose + glucose —> _____ by _____.

maltose+water.....dehydration synthesis

Which of these is a source of lactose?

milk

Which of these is a polysaccharide?

cellulose

_____ is the most abundant organic compound on Earth.

cellulose

Sucrose is formed when glucose is joined to fructose by a(n) _____.

glycosidic linkage

Plant cell walls consist mainly of _____.

cellulose

Which of these is NOT a lipid?

RNA

what is the product when the fatty acid tails lack double bonds?

an unsaturated fat

what are phospholipids composed of?

a phosphate group, a glycerol, and fatty acids

Which of these is rich in unsaturated fats?

olive oil

A function of cholesterol that does not harm health is its role _____.

as a component of animal cell membranes

Proteins are polymers of _____.

amino acids

What type of bond joins the monomers in a protein's primary structure?

peptide

what are characteristics of protein's secondary structure?

alpha helices and beta pleated sheets

The secondary structure of a protein results from _____.

hydrogen bonds

Tertiary structure is NOT directly dependent on _____.

peptide bonds

Which structure is not a component of a nucleotide?

Sulfhydryl Oxygen group

Which of the following statements about nucleotide structure is false?

The phosphate group is bonded to the nitrogenous base. (it is bonded to the sugar in actuality)

True or false? Guanine and uracil are examples of nitrogenous bases.

true

Which linkage forms the backbone of a nucleic acid?

sugar-phosphate linkage

Which of the following statements about DNA structure is true?

The nucleic acid strands in a DNA molecule are oriented antiparallel to each other.

What is the complementary DNA sequence to 5' ATGCATGTCA 3'?

5' TGACATGCAT 3'

Some regions of a polypeptide may coil or fold back on themselves. This is called _____, and the coils or folds are held in place by _____.

secondary structure ... hydrogen bonds

The flow of genetic information in a cell goes from _____.

DNA to RNA to protein

Which of the following statements concerning unsaturated fats is true?

They have double bonds in the carbon chains of their fatty acids.

In eukaryotic cells the first step in protein synthesis is the _____.

transferring of information from DNA to messenger RNA

which organelle contains most of the cell's DNA?

the nucleus

Which of these organelles carries out cellular respiration?

mitochondrian

The _____ is composed of DNA and protein.

chromatin

Ribosomal subunits are manufactured by the _____.

nucleolus

_____ are the sites of protein synthesis.

ribosomes

Which of these manufactures cellular membranes by adding membrane proteins and phospholipids to its own membrane?

rough endoplasmic reticulum

The _____ is a selective barrier, regulating the passage of material into and out of the cell.

plasma membrane

Where is calcium stored?

smooth endoplasmic reticulum

Which organelles stores, modifies, and packages products?

the golgi apparatus

Which of these are hollow rods that shape and support the cell?

microtubules

_____ is/are identical in structure to centrioles.

basal bodies

Which of these organelles produces H2O2 as a by-product?

peroxisome

which structure provides the cell with structural support?

microfilaments (they are components of the cytoskeleton)

Mitochondria are found in _____.

plant and animal cells

Which of the following are common traits of chloroplasts and mitochondria?

both have their own DNA and ribosomes

Which of these cell junctions form a barrier to the passage of materials?

tight junctions

The primary role of _____ is to bind animal cells together.

desmosomes (anchoring junctions)

_____ aid in the coordination of the activities of adjacent animal cells.

gap junctions (gap junctions allow for the passage of material between cells, thus facilitating communication between these cells.)

A biologist wants specifically to examine the surfaces of different types of cells in kidney tubules of small mammals. The cells in question can be distinguished by external shape, size, and 3-D characteristics. Which of the following would be the optimum method for her study?

scanning electron microscopy

Which of the following correctly matches an organelle with its function?

central vacuole....storage

Which statement correctly describes the nuclear envelope of a eukaryotic cell?

the nuclear envelope is continuous with the endoplasmic reticulum

Which of the following produces and modifies polysaccharides that will be secreted?

golgi apparatus

Which organelle often takes up much of the volume of a plant cell?

vacuole

Thylakoids, DNA, and ribosomes are all components found in

chloroplasts

A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from

nearly any eukaryotic oragism

Which of the following contain the 9 + 2 arrangement of microtubules, consisting of nine doublets of microtubules surrounding a pair of single microtubules?

both flagella and motile cilia

The smallest cell structure that would most likely be visible with a standard (not super-resolution) research-grade light microscope is

a mitochondrian

Vinblastine, a drug that inhibits microtubule polymerization, is used to treat some forms of cancer. Cancer cells given vinblastine would be unable to

separate chromosomes during cell division.

The diameter of a typical eukaryotic cell is approximately ten times the diameter of a typical prokaryote. What is the ratio of the volume of typical eukaryotic:prokaryotic cells?

1000:1

What do the cell walls of plants and the extracellular matrix of animal cells have in common?

They have functional connections with the cytoskeleton inside the cell.

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

gap junctions

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis

what does it mean when a cell is in a hypertonic solution?

There is a greater concentration of solute outside the cell.

how do you know when a cell has been placed into a hypotonic solution?

it will swell (it will gain water when placed into a hypotonic solution)

how do you know when a cell has been placed into a hypertonic solution?

the cell will shrink (it will lose water when placed in the hypertonic solution)

Based on Figure 7.21 in your textbook, which of these experimental treatments would increase the rate of sucrose transport into the cell?

decreasing extracellular pH

Which statement is correct?

The contents of a red blood cell are hypertonic to distilled water.

Which factors affect the rate of osmotic movement of water?

The rate of osmosis increases with increasing differences in solute concentrations between two solutions separated by a selectively permeable membrane.

What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium?

Water molecules move between the two solutions, but there is no net movement of water across the membrane.

In general, enzymes are what kinds of molecules?

proteins

Enzymes work by _____.

reducing activation energy

An enzyme _____.

organic catalyst

What name is given to the reactants in an enzymatically catalyzed reaction?

substrate

As a result of its involvement in a reaction, an enzyme _____.

is unchanged

What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?

hydrolysis

The reaction A --> B + C + heat is released in a(n) _____ reaction.

exergonic (energy is being released)

A(n) _____ reaction occurs spontaneously.

exergonic (the products have less potential energy than the reactants in these types of reactions)

Which of these reactions requires a net input of energy from its surroundings?

endergonic

In cells, what is usually the immediate source of energy for an endergonic reaction?

ATP

The reaction ADP + P --> ATP is a(n) _____ reaction.

endergonic

The energy for an endergonic reaction comes from a(n) _____ reaction.

exergonic

What is the fate of the phosphate group that is removed when ATP is converted to ADP?

It is acquired by a reactant in an endergonic reaction.

What is energy coupling?

the use of energy released from an exergonic reaction to drive an endergonic reaction

where does glycolysis occur?

the cytosol

which process transfers electrons to NADH and FADH2?

the citric acid cycle

what is the final electron acceptor of cellular respiration?

oxygen

How many NADH are produced by glycolysis?

2

In glycolysis, ATP molecules are produced by _____.

substrate-level phosphorylation (A phosphate group is transferred from glyceraldehyde phosphate to ADP.)

Which of these is NOT a product of glycolysis?

FADH2 (it is a product of the citric acid cycle)

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