AP Biology Midterm

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Which four elements make up appx. 96% of living matter?

Carbon, Oxygen, Hydrogen, Nitrogen

What is a trace element required by humans and other vertebrates?

Iodine

What indicates the number of protons in an atom's nucleus?

Atomic number

To find the mass number of an element, add _____ and _____.

Protons & neutrons

What is the appx. mass of an atom with 16 neutrons, 15 protons, and 15 electrons?

31 daltons

Calcium has an atomic number of 20 and an atomic mass of 40. Therefore, a calcium atom must have

20 protons

Different atomic forms of an element that contain the same number of protons but a different number of neutrons are called ...

isotopes

The atomic number of carbon is 6. Carbon-14 is heavier than carbon-12 because the nucleus of carbon-14 contains ______ neutrons.

6

Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that ...

an electron may move to an electron shell farther out from the nucleus.

The atomic number of neon is 10. Therefore, what is true about an atom of neon?

It has 8 electrons in its outer shell and is inert.

What does the reactivity of an atom depend on?

the number is unpaired electrons in its valence shell

Atoms whose outer shells contain 8 electrons tend to

be stable and chemically nonreactive, or inert.

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

2

What is the maximum number of electrons in a 2p orbital of an atom?

2

A molecule of CO2 is formed when one atom of carbon (atomic number ) is covalently bonded with two atoms of oxygen (atomic number 8). What is the total number of electron pairs that must be shared between the carbon atom and the oxygen atoms in order to complete the outer shell of all three atoms?

4

Nitrogen is much more electronegative than hydrogen. Which of the following statements is correct about the atoms in ammonia (NH3)?

Each hydrogen has a partial positive charge.

When two atoms are equally electronegative, they will react to form

nonpolar covalent bonds.

What results from an unequal sharing of electrons between atoms?

a polar covalent bond

Which of the following best describes chemical equilibrium?

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

If your blood pH is 7.8, what is the hydrogen ion concentration in your blood?

1.58 x 10^-8

How many grams of NaOH are needed to produce a 200 mL of a .1 M NaOH solution?

.8 grams NaOH

How do highly electronegative elements affect macromolecules' behavior?

Makes it polar and soluble

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by....

polar covalent bonds

The slight negative charge at one end of one water molecule is attraced to the slight positive charge of another water molecule to form a _____ bond.

hydrogen

What do cohesion, surface tension, and adhesion have in common with reference to water?

All are properties related to hydrogen bonding.

What happens when an ice cube cools a drink?

Kinetic energy in the drink decreases.

Water's high specific heat is mainly a consequence of the...

absorption and release of heat when hydrogen bonds break and form.

Which bonds must be broken for water to vaporize?

hydrogen bonds

Desert rabbits are adapted to the warm climate because their large ears aid in the removal of heat due to the

high heat of vaporization of water

The formation of ice during colder weather helps moderate the seasonal transition to winter. This is because

the formation of hydrogen bonds releases heat

Temperate usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon?

the release of heat by the formation of hydrogen bonds

At what temperature is water at its densest?

4*C

Hydrophobic substances such as vegetable oil are

nonpolar substances that repel water molecules

How many molecules of glucose (C6H12O6 molecular mass = 180 daltons) would be present in one mole of glucose?

6.02 x 10^23

Recall that when sodium chloride (NaCl) is placed in water the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently bonded molecules (e.g, glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest concentration of particles (molecules of ions)?

1.0 M MgCl2

The molecular mass of glucose is 180 g. To make a 1 M solution of glucose, you should do what?

Dissolve 180 g of glucose in water, and then ass more water until the total volume of the solution is 1 L.

Which of the following ionizes completely in solution and is considered to be a strong acid?

HCl

Which of the following ionizes completely in solution and is considered to be a strong base?

NaOH

If the pH of a solution is decreased from 9 to 8, its means that the...

concentration of H+ has increased 10 times what it was at pH 9 and the concentration of OH- has decreased 10 times what it was at pH 9.

Buffers are substances that help resist shifts in pH by

donating H+ to a solution when they've been depleted and accepted H+ when they are in excess.

Who refuted the concept of vitalism?

Miller's experiments with ancient atmospheres

Which properties of the carbon atom give it compatability with a greater number of different elements than any other type of atom?

Carbon has a valence of 4.

What type of bonds does carbon have a tendency to form?

Covalent

What is the major reason why hydrocarbons are not soluble in water?

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

Research suggests that side effects from ritalin may be caused my contamination of enentiomers, or molecules that are

mirror images of one another.

Hydroxyl groups

make molecule polar

What is a carbonyl group?

a carbon atom joined to an oxygen by a double covalent bond

What is a carboxyl group?

a carbon atom double bonded to an Oxygen and single bonded to an OH

Which is a false statement concerning amino groups?

They are nonpolar.

Which two functional groups are always found in amino acids?

carboxyl and amino

Amino acids are acids because they always posess what functional group?

carboxyl

A chemist wishes to make an organic molecule less acidic. Which of the following functional groups should be added to the molecule in order to do so?

amino

Which functional groups can act as acids?

Carboxyl and phosphate

What functional group helps stabilize proteins?

Sulfhydryl (thiol)

What is a hydroxyl group?

-OH (alcohols)

What do phosphate groups do?

transfer energy between organic molecules

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

catabolism

Which of the following statements correctly describes catabolic pathways?

They release energy as they degrade polymers to monomers.

Which of the following is true of anabolic pathways?

They are highly regulated and consume energy to build polymers from monomers.

Where does the Calvin Cycle take place?

the stroma of the chloroplast

During photosynthesis, visible light has enough energy to..

excite electrons.

Why are the absorption spectrums for photosynthesis different?

Other pigments absorb light in addition to chlorophyll a.

In the thylakoid membranes, what is the main role of the antenna pigment molecules?

harvest photons and transfer light energy to the reaction center chlorophyll

The reaction center chlorophyll of photosystem I is known as p700 because

this pigment is best at absorbing light w a wavelength of 700 nm

What does not occur in the light reactions of photosynthesis?

Carbon dioxide is incorporated into PGA

Which statement regarding the events of photosystem II is false?

The p680 chlorophyll donates a pair of protons to NADPH

All of the following are directly associated with photosystem II except

NADP+ reductase

What are the products of noncyclic photophosphorylation?

ATP and NADPH

What does cyclic electron flow in the chloroplast product?

ATP

Assume a thylakoid is somehow punctured. This damage will have the most direct effect on

the synthesis of ATP (electron transport chain)

What does the chemiosmotic process in chloroplasts involve?

establishment of a proton gradient

Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transderred in the dark to a ph-8 solution. What would be likely to happen?

The isolated chloroplasts will make ATP.

In a plant cell, where are the ATP synthase complexes located?

thylakoid & inner mitochondrial membranes

In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrance space, whereas in chloroplasts, chemiosmosis translocates protons from

the stroma into the thylakoid space

When does the synthesis of ATP by the chemiosmotic mechanism occur?

both photosynthesis and respiration

When does the reduction of oxygen to form water occur?

respiration

When does the generation of proton gradients across membranes occur?

both photosynthesis and respiration

What is required in the Calvin Cycle?

CO2, ATP, RuBP

What is a chromatid?

a replicated chromosome

If there are 20 chromatids in a cell, how many centromeres are there?

10

Two centromeres are arranged at opposite poles of the cell.

prometaphase

Centrioles begin to move apart in animal cells

prophase

Longest mitotic stage

metaphase

Centromeres uncouple, sister chromatids are seperated, and two new chromosomes move to opposite poles of the cell

anaphase

If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, which stage will mitosis be arrested?

metaphase

All of the following occur during prophase of mitosis in animals except:

chromosomes are duplicated

It there are 20 centromeres in a cell at anaphase, how many chromosomes will there be in each daughter cell following cytokinesis?

20

Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?

centrosome

If a cell has 8 chromosomes at metaphase of mitosis, how many will it have during anaphase?

16

If a cell completed mitosis but not cytokinesis, the result would be a cell with

two nuclei.

How do the daughter cells at the end of mitosis and cyotkinesis compare with their parent cell when it was in G1 of the cell cycle?

The daughter cells have the same number of chromosomes and same amound of DNA.

Which of the following are primarily responsible for cytokinesis in plant cells?

Golgi-derived vesicles

Chromosomes first become visible during _____ of mitosis.

prophase

In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis?

dinoflagellates & diatoms

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3-6 picograms per nucleus. in which stage of the cell cycle was the nucleus with 6 picograms of DNA?

G2

By examining a karyotype, it is possible to determine

which is a gametophyte/sporophyte and the sex of an animal.

At which stage of mitosis are chromosomes photographed in preparation for a karyotype?

metaphase

If a liver cells of an animal have 24 chromosomes, how many does its sperm have?

12

Which of the following is true of a species that has a chromosome number of 2n = 16?

There are 8 homologous pairs.

Which of the following is the term for a human cell that contains 22 pairs of autosomes and two X chromosomes?

a female somatic cell

In animals, meiosis results in gametes, and fertilization results in

zygotes

Referring to a plant sexual life sycle, which of the following terms describes the process that leads directly to the formation of gametes?

gametophyte mitosis

Which of the following is an example of alternation of generations?

A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain.

Which of the following is missing from the life cycle progression shown below? sporophyte-meiosis-spore-________-gametophyte-mitosis-gametes-fertilization-zygote

mitosis

After telophase I of meiosis, the chromosomal makeup of each daughter cell is

halpoid, and the chromosomes are composed of two chromatids

How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?

they have half the number of chromosomes and 1/4th the DNA

When does the synaptonemal complex disappear?

late prophase of meiosis I

Which of the following terms belongs with the words synapsis, tetrads, and chiasmata?

crossing over

Tetrads of chromosomes are aligned at the center of the cell, independent assortment soon follows.

Metaphase I

Synapsis of homologous pairs occurs, crossing over may occur.

Prophase I

Centromeres of sister chromatids uncouple and chromatids seperate.

Anaphase II

Homologous chromosomes synapse and crossing over occurs.

Prophase I

Which of the following occurs in meiosis but not in mitosis?

synapsis and alignment of tetrads at metaphase plate

When T2 phages infect bacteria and make more viruses in the presence of radioactive sulfur, what is the result?

The viral proteins will be radioactive

Chargaff's analysis of the relative base composition of DNA was significant because he was able to show that

the relative proportion of each of the four bases differed among species, and the amount of A=T and C=G

What kind of chemical bond is found between paired bases of the DNA double helix?

hydrogen

Which of the following statements is false when comparing prokaryotes with eukaryotes?

Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not.

Which enzyme catalyzes the elongation of a DNA strand in the 5'-3' direction?

DNA polymerase

removed the RNA nucleotides from primer and adds DNA nucleotides to the 3' end of okazaki fragments

DNA polymerase I

seperates the DNA strands during replication

helicase

synthesizes short RNA segments

primase

DNA-cutting enzymes used in the repair of DNA damage

ligase/nuclease

The leading/lagging strands differ in that

The leading strang is synthesized in the same direction as the movement of the replication fork, and the lagging strang it synthesized in the opposite direction. the leading strand is also synthesized continuously

What is primer made of?

RNA

A eukaryotic cell lacking telomerase would

undergo a reduction in chromosome length.

What is a similarly between DNA and RNA?

nucleotides consisting of a phosphate, sugar, and nitrogenous base

Using RNA as a template for protein synthesis is advantageous because

RNA is an expendable copy, and many mRNA molecules can be transcribed from a single gene

Which of the following are transcribed from DNA

exons & rRNA

Which of the following is not a part of the eukaryotic transcription initiation complex?

snRNP

RNA polymerase moves along the template strand in the _____ direction and adds nucleotides to the ____ end.

3'---5'; 3'

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