MCAT Bio Genetics and Evolution

Question 1

The two nonidentical copies of a chromosome are called____

Answer 1

homologous chromosomes

Question 2

Different versions of a gene are called ___

Answer 2

alleles

Question 3

___ in males undergo meiosis

Answer 3

Spermatogonia

Question 4

___ in females undergo meiosis

Answer 4

Oogonia

Question 5

The product of meiosis in males occurs in testes with production of ____

Answer 5

haploid spermatozoa

Question 6

In females meiosis occurs in the ovaries producing ___

Answer 6

ova

Question 7

In meiosis ___ occurs between homologous chromosomes

Answer 7

Recombination

Question 8

During prophase 1 of meiosis ____ pair

Answer 8

Homologous chromosomes

Question 9

The longest phase of meiosis is ___

Answer 9

prophase because of the complexity of crossing over

Question 10

Meiotic recombination occurs between ____

Answer 10

homolgous chromosomes, NOT sister chromatids

Question 11

____ states that two alleles of an individual are separated and passed on to the next generation singly

Answer 11

Law of segregation

Question 12

At what stage during meiosis are different alleles of a gene separated?

Answer 12

During meiosis 1 at the time when homologous chromosomes separate

Question 13

During this stage the replicated homologous chromosomes are pulled to opposite sides of the cell

Answer 13

Anaphase 1

Question 14

During ___ stage, the sister chromatids are finally separated at their centromeres and pulled to opposite sides of the cell

Answer 14

Anaphase 2

Question 15

A situation in which a heterozygote displays the phenotype associated with each of the alleles

Answer 15

Codominance

Question 16

A form of evolution in which different organisms are placed into the same environment and exposed to the same selection pressures. This causes the organisms to evolve along similar lines. As a result, they may share functional, but not structural similarity (because they possess different starting material)

Answer 16

Convergent evolution

Question 17

The exchange of DNA between paired homologous chromosomes (tetrads) during prophase 1 of meiosis

Answer 17

Crossing over

Question 18

A form of evolution in which the same organism is placed into different environments with different selection pressures. This causes the organisms to evolve differently; The resulting (new) species may share structural similarity

Answer 18

Divergent evolution

Question 19

___produces homologous structures

Answer 19

Divergent evolution

Question 20

The frequencies of alleles in a given gene pool do not change over time

Answer 20

Hardy-Weinberg Law

Question 21

What are the five assumptions of Hardy-Weinberg?

Answer 21

• No mutations
• No natural selection
• No migration
• Random Mating between individuals
• Large population

Question 22

Experiments with phage and bacteria that definitively determined DNA to be the genetic information of the cell

Answer 22

Hershey-Chase experiments

Question 23

___states that genes found very far apart on the same chromosome sort independently of one another during gamete formation

Answer 23

Law of Independent Assortment

Question 24

States that the two alleles of a given gene will be separated from one another during gamete formation (meiosis)

Answer 24

Law of segregation

Question 25

The failure of two separate genes to obey the Law of Independent Assortment, as might occur if the genes were found close together on the same chromosome

Answer 25

Linkage

Question 26

During ___ the paired homologous chromosomes (tetrads) align at the center of the cell (the metaphase plate)

Answer 26

Metaphase 1

Question 27

During __ replicated chromosomes align at the center of the cell (metaphase plate)

Answer 27

Metaphase

Question 28

___ is identical to mitotic metaphase except the number of chromosomes was reduced by half during meiosis

Answer 28

Metaphase 2

Question 29

The failure of homologous chromosomes or sister chromatids to separate properly during cell divison. This could occur during anaphase 1 of meiosis (homologous chromosomes),or during anaphase 2 of meiosis or anaphase of mitosis

Answer 29

Nondisjunction

Question 30

The percentage of individuals with a particular genotype that actually display the phenotype associated with that genotype

Answer 30

Penetrance

Question 31

A subset of a species consisting of members that mate and reproduce with one another

Answer 31

Population

Question 32

During __ the replicated chromosomes condense, homologous chromosomes pair up, crossing over occurs between homologous chromosomes, the spindle is formed, and the nuclear envelope breaks apart into vesicles.

Answer 32

Prophase 1

Question 33

__ is identical to mitotic prophase, except that the number of chromosomes was reduced by half during meiosis 1

Answer 33

Prophase 2

Question 34

The RF value is the percentage of recombinant offspring resulting from a given genetic cross.

Answer 34

Recombination frequency

Question 35

The ___ is proportion to the physical distance between two genes on the same chromosome

Answer 35

Recombination frequency

Question 36

If the recombination frequency is low, the genes under consideration may be __

Answer 36

linked

Question 37

Pairing of homologous chromosomes in a diploid cell, as occurs during prophase 1 of meiosis

Answer 37

Synapsis

Question 38

A structure that forms in early prophase 1 that mediates synapsis (pairing of homologous chromosomes)

Answer 38

Synaptonemal complex

Question 39

__ is identical to mitotic telophase, except that the number of chromosomes is now reduced by half. After this phase the cell is considered to be haploid. The chromosomes still replicated, and the sister chromatids must still be separated during meiosis 2

Answer 39

Telophase 1

Question 40

Identical to mitotic telophase, but that chromosome number was reduced by half during meiosis 1

Answer 40

Telophase 2

Question 41

A genetic cross between an organism displaying a recessive phenotype (homozygous recessive) and an organism displaying a dominant phenotype, done to determine the unknown genotype

Answer 41

Testcross

Question 42

A pair of replicated homologous chromosomes. Formed during prophase 1 of meiosis so that homologous chromosomes can exchange DNA in a process known as "crossing over"

Answer 42

Tetrads

Question 43

Gene is said to have __ if its expression alters many different, seemingly unrelated aspects of the organism's total phenotype

Answer 43

Pleiotropism

Question 44

A mutation in a gene may cause altered development of heart, bone, AND inner ears, it altered many unrelated aspects of the organism's total phenotype

Answer 44

Pleitropism

Question 45

Expression of alleles for one gene is dependent on a different gene. For example, a gene for curly hair cannot be expressed if a different gene causes baldness

Answer 45

Epistasis

Question 46

___ are ligands that bind to receptors and elicit responses

Answer 46

Receptor agonist

Question 47

__ are ligands that bind to the receptor but elicit no response, blocking receptor agonists from binding.

Answer 47

Receptor antagonist

Question 48

A right shift on the oxyhemoglobin curve indicates ____

Answer 48

Decreased hemoglobin-oxygen binding affinity

Question 49

What things will cause a decrease in the hemoglobin-oxygen binding (right shift on ODC)

Answer 49

- Low (acidic) pH of plasma - Increased levels of CO2 - 2,3 bisphosphoglycoric acid (2,3-BPG)

Question 50

With decreasing temperatures, air is able to hold ___

Answer 50

less H20

Question 51

During elongation, ribosomes read the mRNA in the ____

Answer 51

5' to 3' direction

Question 52

During synthesis of proteins, the direction of addition of amino acids is in the ___

Answer 52

N terminus to C- terminus direction

Question 53

__ are sugars that differ at only one stereocenter

Answer 53

Epimers

Question 54

Arachidonic acids are an important precursor molecule of __,__and __

Answer 54

Prostaglandins, thromboxanes, and leukotrienes

Question 55

__ are a large family of lipids derived from arachidonic acids, they give rise to prostaglandins

Answer 55

Eicosanoids