Biology Genetics

Question 1

Mendel’s First Law: Law of Segregation posits that genes exist in alternative forms (now referred as alleles). A gene controls a specific trait in an organism.
An organism has two alleles for each inherited trait, one inherited from each parent.
The two alleles segregate during meiosis, resulting in gametes that carry only one allele for any given inherited trait.
If two alleles in an individual organism are different, only one will be fully expressed, and the other will be silent. A dominant allele only requires one copy present to be expressed whereas a recessive allele must have two copies present to be expressed. In genetics problems, dominant alleles are typically capital letters, and recessive alleles are assigned lowercase letters. organisms that contain two copies of the same allele are ___ for that trait; organisms that carry two different alleles are heterozygous. The dominant allele is expressed in the phenotype. This is known as Mendel’s Law of Dominance.

Answer 1

homozygous

Question 2

Because only one trait is being studied in this particular mating, it is referred to as a ___ cross

Answer 2

monohybrid

Question 3

The individuals being crossed are the parental or P generation; the progeny generations are the ___ or F generations, with each generation numbered sequentially

Answer 3

fillial

Question 4

A ___ square indicates all the potential progeny genotypes, and the relative frequencies of the different genotypes and phenotypes can be easily calculated

Answer 4

punnet

Question 5

Mendel also developed the testcross, a diagnostic tool used to determine the ___ of an organism

Answer 5

genotype

Question 6

Homozygous ___ organisms always breed true

Answer 6

recessive

Question 7

Generally, the closer the genes are on the chromosome, the more likely they are to be ___ together

Answer 7

inherited

Question 8

Dihybrid cross involves the analysis of two ___ of inheritance

Answer 8

traits

Question 9

An allele is incompletely dominant if the phenotype of the heterozygote is an ___ of the phenotypes of the homozygotes

Answer 9

intermediate

Question 10

Codominance occurs when ___ alleles exist for a given gene and more than one of them is dominant

Answer 10

multiple

Question 11

Only two alleles are present in any single individual (ABO blood groups) but the population contains ___ three alleles

Answer 11

all

Question 12

In codominance, however, both alleles in the genotype are expressed at the same time without a ___ of phenotype

Answer 12

blending

Question 13

In sexually differentiated species, most chromosomes exist as pairs of ___ called autosomes, but sex is determined by a pair of sex hormones

Answer 13

homologues

Question 14

All humans have 22 ___ of autosomes; additionally, women have a pair of homologous X chromosomes, and men have a pair of heterologous chromosomes, an X and a Y chromosome

Answer 14

pairs

Question 15

Genes located on the X or Y ___ are called sex-linked

Answer 15

chromosome

Question 16

Examples of sex-linked recessives in humans are the genes for ___ and color-blindness

Answer 16

hemophilia

Question 17

Sex-linked ___ generally affect only men; they cannot be passed from father to son, but they can be passed from grandfather to grandson via a daughter who is a carrier, thereby skipping a generation

Answer 17

recessives

Question 18

Mutations are changes in the genetic information ___ in the DNA of a cell

Answer 18

coded

Question 19

Mutagenic ___ induce mutations

Answer 19

agents

Question 20

Mutagenic agents are ___ also carcinogenic (cancer-causing)

Answer 20

sometimes

Question 21

In a point mutation, a nucleic acid is replaced by another ___ acid

Answer 21

nucleic

Question 22

As a result of a point mutation, the new codon may code for the same amino acid (___ mutation), the new codon may code for a different amino acid (missense mutation), the new codon may be a stop codon (nonsense mutation)

Answer 22

silent

Question 23

While point mutations may lead to proteins of a different length than the native protein, they do not affect the length of the genome itself as seen with ___ mutations

Answer 23

frameshift

Question 24

In a frameshift mutation, ___ acids are deleted or inserted into the genome sequence

Answer 24

nucleic

Question 25

In a frameshift mutation, the length of the ___ changes

Answer 25

genome

Question 26

Many bacteria also contain smaller circular rings of DNA called plasmids, which contain ___ genes

Answer 26

accessory

Question 27

Episomes are ___ that are capable of integration into the bacterial genome

Answer 27

plasmids

Question 28

Bacterial cells reproduce by ___ fission and proliferate

Answer 28

binary

Question 29

Although binary fission is an ___ process, bacteria have three mechanisms for increasing the genetic variance of a population: transformation, conjugation , and transduction

Answer 29

asexual

Question 30

Transformation is the process by which a foreign ___ fragment (plasmid0 is incorporated into the bacterial chromosome via recombination, creating new inheritable genetic combinations

Answer 30

chromosome

Question 31

Only bacteria containing ___ called sex factors are capable of conjugating

Answer 31

plasmids

Question 32

A bacteriophage is a virus that infects its host bacterium by ___ to the bacterium, boring a hole through the bacterial cell wall, and injecting its viral DNA while its protein coat remains attached to the cell well

Answer 32

attaching

Question 33

Transduction occurs when fragments of the ___ chromosome become packaged into the viral progeny produced during such a viral infection

Answer 33

bacterial

Question 34

The closer two genes are to one another on a chromosome, the more likely they will be to ___ together; this fact allows geneticists to map genes to a high degree of precision

Answer 34

transduce

Question 35

Recombination occurs when linked ___ are separated

Answer 35

genes

Question 36

Recombination occurs by breakage and rearrangement of adjacent regions of DNA when organisms carrying different genes or ___ for the same traits are crossed

Answer 36

allelles

Question 37

The ___ is the noncoding sequence of DNA that serves as the initial binding site for RNA polymerase

Answer 37

promoter

Question 38

There is also a ___ gene, which codes for the synthesis of a repressor molecule that binds to the operator and blocks RNA polymerase from transcribing the structural genes

Answer 38

regulator

Question 39

Regulation may be via inducible systems or ___ systems

Answer 39

repressible

Question 40

In an inducible system, the repressor binds to the operator, forming a barrier that prevents RNA polymerase from transcribing the __ genes

Answer 40

structural

Question 41

For transcription to occur, an inducer must bind to the repressor forming an ___-repressor complex

Answer 41

inducer

Question 42

The ___ complex cannot bind to the operator, thus removing it as a barrier and permitting transcription

Answer 42

inducer-repressor

Question 43

The proteins synthesized from an inducible system are said to be ___

Answer 43

inducible

Question 44

In a ___ system, the repressor is inactive until it combines with the corepressor

Answer 44

repressible

Question 45

The repressor can bind to the operator and prevent transcription only when it has formed a ___ complex

Answer 45

repressor-corepressor

Question 46

Corepressors are often the ___ products of the biosynthetic pathways they control

Answer 46

biosynthetic

Question 47

The proteins (usually enzymes) are said to be repressible because they are normally being synthesized; transcription and translation occur until the ___ is synthesized

Answer 47

corepressor

Question 48

Operons containing mutations, such as deletions, or whose regulator genes code for defective repressors are incapable of being turned off; their enzymes, which are always being ___, are referred to as constitutive

Answer 48

synthesized

Question 49

In pedigrees, affected individuals (those who express a particular phenotype) are shaded in and ___ are not

Answer 49

unaffected

Question 50

If a trait is autosomal recessive, a person will only be affected if he or she possesses two copies of the recessive allele (homozygous ___)

Answer 50

recessive

Question 51

Only individuals who are homozygous recessive will be unaffected by an autosomal ___ trait

Answer 51

dominant

Question 52

If significantly more males are affected than females and two unaffected individuals produce an affected offspring, then a ___ is likely X-linked recessive

Answer 52

trait

Question 53

The change in the genetic ___ of a population with time is termed evolution

Answer 53

makeup

Question 54

A discredited theory proposed by Jean-Baptiste Lamarck posited that new organs or changes in existing ones arose because of the ___ of the organism

Answer 54

needs

Question 55

In Charles Darwin's theory, pressures in the ___ select for the organism most fit to survive and reproduce

Answer 55

environment

Question 56

In the evolutionary sense, ___ is the ability to survive and reproduce

Answer 56

fitness

Question 57

___ is when there are more offspring produced than can survive

Answer 57

overpopulation

Question 58

Offspring naturally show differences in their ___ compared to those of their parents (variations)

Answer 58

characteristics

Question 59

The developing ___ must compete for the necessities of life (competition)

Answer 59

population

Question 60

Some organisms in a species have variations that give them an advantage over other ___ of the species

Answer 60

members

Question 61

The individuals that survive (those with the favorable variations) live to adulthood to reproduce and thus ___ these favorable variations or adaptations to their offspring

Answer 61

transmit

Question 62

Over many generations of natural selection, the favorable changes (adaptations) are ___ in the species (evolution of new species)

Answer 62

perpetuated

Question 63

speciation is the evolution of new species, which are groups of individuals that can interbreed freely with each other but not with members of ___ species

Answer 63

other

Question 64

gene ___ is impossible between different species

Answer 64

flow

Question 65

Different selective pressures act upon the gene pools of each group, causing them to ___ independently

Answer 65

evolve

Question 66

Before speciation, small, local populations called ___ often form within a species

Answer 66

demes

Question 67

Members of the same deme are subject to similar ___ factors and thus are subject to the same selection processes

Answer 67

environmental

Question 68

If these demes become ___, speciation may occur

Answer 68

isolated

Question 69

over time, isolated demes may become so different that ___ may be impossible

Answer 69

mating

Question 70

evolutionary history of ___ alive today is termed phylogeny

Answer 70

species

Question 71

All of the descendants from the common ancestor form what is known as a ___ in phylogenies

Answer 71

clade

Question 72

When two species from different ancestors develop similar traits, this is known as ___ evolution

Answer 72

convergent

Question 73

___ evolution is similar to convergent evolution but ocurs when a more recent ancestor can be identified

Answer 73

parallel

Question 74

In contrast, divergent evolution occurs when ___ with a shared ancestor develop differing traits due to dissimilarities between their environments

Answer 74

species

Question 75

___ radiation is the emergence of a number of lineages from a single ancestral species

Answer 75

adaptive

Question 76

A single species may diverge into a number of distinct species; the differences between them are those adaptive to a ___ lifestyle or niche

Answer 76

distinct

Question 77

A ___ includes all members of a particular species inhabiting a given location

Answer 77

population

Question 78

The ___ pool of a population is the sum total of all the alleles for any given trait in the population

Answer 78

gene

Question 79

Gene ___ is the decimal fraction representing the presence of an allele for all members of a population that have this particular gene

Answer 79

frequency

Question 80

p plus q is ___ to one

Answer 80

equal

Question 81

Hardy Weinberg principle states an ideal situation as: The population is very large No mutations affect the gene pool Mating between individuals in the population is random There is no net migration of individuals into or out of the population The genes in the ___ are all equally successful at reproducing

Answer 81

population

Question 82

Hardy Weinberg equation where p is the frequency of allele T and q is the frequency of __ t

Answer 82

allele

Question 83

p squared plus 2 times p times q plus q squared is ___ to one

Answer 83

equal

Question 84

Hardy Weinberg equation holds that p squared is the frequency of TT (dominant ___), 2 times p times q is the frequency of Tt (heterozygotes), q squared is tt (recessive homozygotes)

Answer 84

homozygotes

Question 85

Genotypes with low ___ values tend to disappear

Answer 85

adaptive

Question 86

Gene mutations can either be ___ or detrimental for the offspring

Answer 86

favorable

Question 87

If mates are not randomly chosen but rather selected according to criteria such as phenotype and proximity (sexual selection), the relative ___ ratios will be affected and will depart from the predictions of the Hardy-Weinberg equilibrium

Answer 87

genotype

Question 88

Large die off events can also cause genetic drift and are called a ___ bottleneck

Answer 88

genetic

Question 89

Migration of individuals between populations will result in a loss or gain of ___, thus changing the composition of a population's gene pool

Answer 89

genes

Question 90

Homologous structures have the same basic ___ features an evolutionary origins

Answer 90

anatomical

Question 91

Analogous structures have similar functions but may have different evolutionary origins and entirely different ___ of development

Answer 91

patterns

Question 92

Similarity of developmental stages suggests a common ___ and development history

Answer 92

ancestry

Question 93

Vestigial structures have ___ known current function but apparently had some ancestral function

Answer 93

no

Question 94

Species multiplication is generally accompanied by migration to lessen ___ competition

Answer 94

intraspecific

Question 95

Among the first forms of life were ___ which depended on outside sources for food

Answer 95

heterotrophs

Question 96

Colloidal protein molecules tend to clump together to form coacervate droplets (a cluster of ___ molecules surrounded by a shell of water

Answer 96

colloidal

Question 97

The primitive heterotrophs slowly evolved complex ___ pathways, enabling them to use a wider variety of nutrients

Answer 97

biochemical

Question 98

Autotrophs are able to produce ___ compounds, including energy-containing molecules, from substances in their surroundings

Answer 98

organic

Question 99

Once molecular oxygen became a major component of the Earth's atmosphere, both heterotrophs and ___ evolved the biochemical pathways of aerobic respiration

Answer 99

autotrophs

Question 100

Autotrophic anaerobes include chemosynthetic bacteria. Autotrophic aerobes include the green plants and photoplankton. The heterotrophic anaerobes include yeasts. The heterotrophic aerobes include ___, earthworms, and humans

Answer 100

amoebas

Question 101

___ is the system by which organisms are classified

Answer 101

Taxonomy

Question 102

Every organism fits into eight categories, or ___, each one increasingly specific based on traits or common ancestors

Answer 102

taxa

Question 103

Cladograms do not represent the ___ of change between ancestor and descendant

Answer 103

amount