BIO Unit Test #1

Gene pool

-all alleles from all gametes in each generation go into a single group -pairs of gametes are picked randomly, many times, and each pair combines to produce theoretical offspring

The Modern Synthesis

-an era in the early 1900s where evolutionary biologists, mathematicians, and geneticists collaborated to quantify evolution -product of this era was a model, known as the Hardy-Weinberg principle

Exponential growth

1) a few individuals colonize a new habitat with plentiful resources 2) a population has been devastated by a storm or some other type of catastrophe and then begins to recover, starting with a few surviving individuals

Conditions needed for natural selection

1) phenotypic variation 2) phenotypic variation is inherited 3) reproductive excess 4) non-random (differential) reproduction of genotypes

Evolution is driven by four processes

1. natural selection: increases the frequency of alleles that contribute to reproductive success in a particular environment 2 genetic drift: causes allele frequencies to change randomly 3. gene flow occurs when individuals leave one population, join another, and breed 4. mutation modifies allele frequencies by continually introducing new alleles

Hardy-Weinberg model has 5 assumptions

1. random mating: no mate choice; gametes combine randomly 2. no natural selection: all individuals contribute equally to gene pool 3. no genetic drift: no random allele frequency changes 4. no gene flow: no new alleles added or lost from gene pool 5. no mutation: no new alleles introduced into gene pool

Model organism

Mendel used peas to work a model of inheritance

Density dependent

When population density gets very high, the population's per capita birthrate decreases and the per capita death rate increases

X-linkage

a gene being on the X chromosome

Y-linkage

a gene being on the Y chromosome

Homologous pair

a pair of homologs

Gene

a section of DNA that influences one or more hereditary traits

Population growth relies on many factors including a) births, deaths, immigration, emigration b) phenotypic variation, inheritance, reproductive excess, differential genotypes c) phenotype, genotype, size, shape d) births, death, population growth rate, genetic variation

a) births, deaths, immigration, emigration

A mouse with white fur breeds with a mouse with black fur, all of their offspring have a phenotype of gray fur. What does the gene for fur color in these mice appear to be an example of? a) incomplete dominance b) codominance c) complete dominance d) partial inheritance

a) incomplete dominance

Which of following is true about inbreeding? a) it increases the rate by which natural selection removes deleterious alleles from the population b) it increases the number of heterozygotes in the population c) it often leads to rapid evolutionary changes on its own d) it leads directly to changes in allele frequencies

a) it increases the rate by which natural selection removes deleterious alleles from the population

Locus

address, where physically on the neighborhood of chromosome is the gene that codes for that trait

Parental generation

adults in monohybrid cross

Codominance

alleles of a gene are not always dominant or recessive

Recessive

an allele that is masked when a dominant allele is present

Dominant

an allele whose trait always shows up in the organism when the allele is present

Phenotype

an individual's observable features

Diploid

an organism or cell having two homologous chromosomes or two alleles of each gene

Trait

any characteristic of an individual

Apomixis

asexual production via seeds, where embryo in seed forms without meiosis and offspring are genetically identical to parent

The population of squirrels in Boston common in 2006 was 85, the population increases by 12% each year, how many squirrels are there in 2014? a) 762 b) 210 c) 295 d) 750

b) 210

If a phenotype is due to an autosomal recessive allele, individuals that display this phenotype must: a) be heterozygous b) be homozygous c) have parents that express the phenotype d) have one parent that has the recessive allele

b) be homozygous

Which of the following is a density dependent form of population control? a) freezing temperatures b) disease c) drought d) wildfire

b) disease

Which of the following evolutionary mechanisms always increases the prevalence of alleles associated with increased fitness? a) gene flow b) natural selection c) genetic drift d) mutation

b) natural selection

Individuals of a plant with the genotype Rr have red and white flowers, individuals with RR have red flowers and rr have white flowers. Which of the following is true of the allele(s) that control flower color in this species? a) R is dominant b) the alleles display codominance c) the trait for flower color is likely controlled by several alleles d) the alleles show incomplete dominance

b) the alleles display codominance

Sister chromatids

before meiosis, each chromosome in the parent cell is replicated, the resulting identical copies of each chromosome are called

A population of annual plants had 125 individuals in year 1, 106 individuals in year 2 and 129 individuals in year 3. What are the net reproductive rates for years 1 to 2 and years 2 to 3 respectively? a) 0.85, 1.03 b) 1.03, 1.03 c) 0.85, 1.22 d) 1.03, 1.22

c) 0.85, 1.22

The ability to taste phenylthiocarbamide (PTC) is a trait controlled by a single gene with two alleles (PTC taster and PTC non-taster). Suppose 36% of a remote mountain village cannot taste PTC and must, therefore, be homozygous recessive (aa) for the PTC non-taster allele. If this population conforms to Hardy-Weinberg expectations for this gene, what percentage of the population must be homozygous (AA) for the PTC taster allele? a) 48% b) 40% c) 16% d) 32%

c) 16%

Tail fluffiness for the fictions species Fluffus maximus is controlled by a single gene, where the allele for fluffy tails is dominant to the allele for smooth tails. A litter of 8 babies is born, it contains 2 smooth tailed and 6 fluffy tailed individuals. Assuming these babies are representative, what are the most likely genotypes of the parents? a) both parents are homozygous smooth b) one parent is homozygous fluffy, the other is heterozygous c) both parents are heterozygous d) one parent is homozygous smooth, the other is homozygous fluffy

c) both parents are heterozygous

The influx of individuals from other populations increases genetic diversity. This is an example of: a) a bottleneck b) genetic drift c) gene flow d) dispersion

c) gene flow

Which of the following is not a way that sex generates genetic variation? a) independent assortment during gamete formation b) crossing over during gamete formation c) higher mutation rates in sexually reproducing organisms d) combination of parental genetic information during fertilization

c) higher mutation rates in sexually reproducing organisms

Offspring that result from many generations of inbreeding are expected to have a) heterozygous alleles b) higher fitness than outcrossed offspring c) homozygous alleles and lower fitness d) large genetic variation

c) homozygous alleles and lower fitness

What is the principle by which individuals with favorable inherited traits are more likely to survive and reproduce? a) the origin of species b) decent with modifications c) natural selection d) mendelian genetics

c) natural selection

Mendel crossed plants with round seeds with plants with wrinkled seeds. F1 offspring all had round seeds. The most likely explanation is... a) seed wrinkles are not genetically determined b) wrinkled seeds are dominant c) round seeds are dominant d) seed shape is an example of blended inheritance

c) round seeds are dominant

Density-dependent factors

change in intensity as a function of population size and are usually biotic

Discrete traits

characteristics that are clearly different

Paternal chromosomes

chromosomes from the father

Maternal chromosomes

chromosomes from the mother

Homologous

chromosomes of the same type

Phenotype

collection of physical traits

Evolutionary processes give rise to diversity at the level of a) species b) individuals c) DNA d) all of above

d) all of the above

Which of the following is the best null hypothesis for the research question: Does playing music for a dog during a storm decreases its stress response?

d) dogs that listen to music during a storm will have the same stress level as those who don't

If a population is diploid and has 2 alleles at one locus, and genotype frequencies like the one below, what can we infer about this population and/or its history? TT = 0.81, Tt = 0.18, tt = 0.01 a) in relation to locus T, this population has experienced genetic drift b) in relation to locus T, this population has a long (multiple generations) history of random mating c) in relation to locus T, this population has high mutation rates d) in relation to locus T, the parents of this observed generation mated at random

d) in relation to locus T, the parents of this observed generation mated at random

Which of the following is true about genetic drift? a) it only happens in small populations b) it decreases the genetic variability among populations c) it never results in allele fixation or loss d) it can cause the prevalence of deleterious alleles to drift up and down

d) it can cause the prevalence of deleterious alleles to drift up and down

Which of the following is not needed for natural selection to occur? a) phenotypic variation b) more individuals are produced than can survive c) some genotypes reproduce more than others d) rapid growth of the population

d) rapid growth of the population

Which of the following would result in organisms with the lowest level of genetic variation? a) self-fertilization b) parthenogenesis c) sexual reproduction d) vegetative reproduction

d) vegetative reproduction

Mode of transmission

describes a trait as autosomal or sex-linked and the type of dominance

Alleles

different versions of a specific gene

Zygote

diploid cell

Parthenogenesis

form of asexual reproduction where growth and development of an embryo happens without fertilization

Chromosome theory of inheritance

genes are located on chromosomes, at a locus, and separation of alleles during meiosis I responsible for principle of segregation

Particulate inheritance

hereditary determinants do not blend or change through use; they act as discrete, unchanging particles

Genes

hereditary determinants for a trait

Incomplete dominance

heterozygotes have an intermediate phenotype

Carriers

heterozygous individuals who do not have a disease but carry a recessive allele for it

Gametogenesis

in animals, the process in which daughter cells become eggs or sperm

Density independent

in exponential population growth, population size does not limit growth rate

Homozygous

individuals with two copies of the same allele

Heterozygous

individuals with two different alleles

Hardy-Weinberg principle

mathematical null hypothesis for study of evolutionary processes that predicts the genotype frequencies and allele frequencies in the next generation

Inbreeding

mating between relatives is an intensively studied form of nonrandom mating, with self-fertilization being the most extreme form

Monohybrid cross

mating parents with two different phenotypes for a single trait

Hybrids

mating two different pure lines that differed in one or more traits

Reduction division

meiosis I reduces the policy

Meiosis

nuclear division that leads to halving of chromosome #

Hardy-Weinberg equation

p^2 + 2pq + q^2 = 1

Pure lines

produce identical offspring when self-pollinated

Asexual reproduction

produces clones that are genetically identical to one another and to the parent

Crossing over

produces new combinations of alleles on the same chromosome

Sexual reproduction

produces offspring with unique chromosome combinations

Polygenic traits

products of more than one gene

Gametes

reproductive cells (sperm and eggs in animals)

Fertilization

reproductive cells unite to form a new individual

Self-fertilize

self-pollinate

Pleiotropic

some genes influence many traits

Genetics

the branch of biology that focuses on inheritance

Evolution

the change in the heritable characteristics of populations over successive generations or the change in allele frequency in population over time

Genotype

the combination of alleles found in an individual

Gene-by-environment

the combined effects of genes and environment

Inbreeding depression

the decline in average fitness that takes place when homozygosity decreases in a population

Natural selection

the differential survival and reproduction of individuals due to differences in phenotype

Sex linkage

the general term for genes being on either sex chromosome

Carrying capacity, K

the maximum # of individuals in a population that can be supported in a particular habitat over a sustained period of time

Genetic variation

the number and relative frequency of alleles that are present in a particular population

F1 generation

the offspring of two parental (P generation) individuals; F1 stands for first filial

Independent assortment

the random separation of homologous chromosomes during meiosis that results in a variety of combinations of maternally and paternally inherited chromosomes

Heredity

the transmission of traits from parents to their offspring

Meiosis I

the two homologs of each chromosome pair separate into two daughter cells

Principle of segregation

the two members of each particle (gene) pair must segregate and separate into different gamete cells during gametogenesis

Meiosis II

the two sister chromatids of each chromosome separate into two daughter cells

Alleles

these different versions of a gene

Quantitative traits

traits that vary continuously (such as height)

Polygenic trait

two or more genes work together to control a single trait

Cross

using the pollen from one flower to fertilize another

Density-independent factors

variation in weather patterns, are usually abiotic; they change birthrates and death rates irrespective of population size