biology 2 - unit 1: genetics lessons 1-5

which statement best describes a monohybrid cross?

a cross in which the traits of a single characteristic are studied

lesson 5

human genetics

lesson 2

punnett squares

what is an example of an environmental effect on phenotype?

the gender of sea turtles being affected by the temperature

x is the genetic makeup of an organism, as determined by the alleles, while y is the observable form.

x : genotype y : phenotype

a father is color blind, and a mother is homozygous dominant for normal vision. what is the probability that one of their offspring will be color blind?

0%

how many alleles are typically found for mitochondrial genes?

1

what is the probability that the offspring will have green seeds?

100 percent

what is the ratio of tall offspring to short offspring?

3:1

a female has a brother who is color blind and a mother who is not. what is the probability that the female is a carrier for the trait?

50%

a dihybrid cross experiment produces offspring of four different types in the f2 generation. what is the predicted ratio of the four phenotypes in the offspring?

9:3:3:1

if the allele for having dimples is represented with the letter D, what allele combinations can result in having dimples?

DD, Dd

what would happen if this experiment were run only once?

XXX the experiment would give a single purple-flowered plant. the conclusion would be that tall plants always produce purple-flowered plants. could be: the experiment would give the same results. the conclusion would not be changed from the original experiment.

what statement is true?

a diploid organism most often has two alleles for a trait.

what effects can epistasis have on polygenic inheritance? select all that apply

a gene can modify the effect of another gene a gene can mask the effect of another gene genes can combine to produce entirely new traits

which statement defines heterozygous?

a genotype composed of two different alleles

which of these statements about mutation are true? select all that apply

a mutation can be inherited from a parent's genetic material. a mutation changes the dna found in a cell. a mutation can occur when dna replicates during cell division.

blood type is an example of which of the following? select all that apply.

a situation in which a gene has three or more alleles a situation in which more than one allele for a trait is dominant

two parents both have homozygous genotypes. one parent has blood type a and the other has blood type b. what genotype can be expected in all of their children?

ab

lesson 4

abo blood type - a typical gene

a type of insect can be red or black. red is the dominant trait and is represented by a capital R. identify the punnett square that illustrates all offspring being homozygous recessive for a trait.

all lowercase r

which of the following facts was unknown to gregor mendel?

alleles for genes are found on chromosomes

multiple alleles for a gene exist in a population. which of these statements describes how alleles are inherited?

an individual can only inherit two alleles for a gene.

what is the difference between blood types in the abo blood type system?

antigens on red blood cells

parent a is homozygous dominant for curly hair, and parent b is homozygous recessive for straight hair. what is the expected phenotype of the offspring?

curly hair

a mutated cftr gene codes for an abnormal cftr protein. this protein alters the normal function of the cell, leading to the disorder cystic fibrosis. based on the statements, which of the following is true?

cystic fibrosis is caused by a mutated cftr gene.

fathers can only pass x-linked traits to their _[blank1]_, while mothers can pass x-linked traits to their _[blank2]_. what option correctly completes this sentence.

daughters; sons and daughters

lesson 1

discovery of a new science

which are sex-linked traits? select all that apply

duchenne muscular dystrophy red-green color blindness

which of the following statements about polygenic inheritance are true? select all that apply

each gene only contributes a small part to the phenotype when a high number of genes is involved, the number of possible phenotypes is also high

how can epistatic interactions affect the number of phenotypes that can appear? select all that apply

epistasis can modify existing phenotypes epistasis can create new phenotypes epistasis can mask genes and prevent them from affecting the phenotypes

which of these describe an inheritance pattern of autosomal genetic disorders? select all that apply.

for an autosomal dominant disorder to be expressed, just one copy of the abnormal allele must be inherited. for an autosomal recessive disorder to be expressed, two copies of the abnormal allele must be inherited.

in which situation are you likely to find a trait with only one allele?

genes found in the dna of the mitochondria

twenty-five percent of the possible offspring for a cross are homozygous dominant. what genotype do each of the parents have?

heterozygous

what statement is true about heterozygous organisms?

heterozygous organisms are more diverse than homozygous organisms.

which term defines a genotype composed of two identical alleles?

homozygous

how are human genetic disorders related to genetic mutations?

human genetic disorders are caused by genetic mutations that occur in human genetic material.

a lab technician observed that the red blood cells in a blood sample display codominance. what alleles does the person who provided the blood sample have?

iA and iB

a person has blood type b. what combination of alleles could she have to give her this blood type? select all that apply.

iBi iBiB

two people have the genotype iAiB. of the following options, what possible genotypes could their children have?

iBiB iAiA iAiB

a lab technician observes that the red blood cells in a blood sample have surface antigen b. what alleles does the person who provided the blood sample have?

iBiB or iBi

how is inbreeding related to the expression of human genetic disorders?

inbreeding increases the chances that a human genetic disorder will be expressed by the offspring.

what valuable information was gained from mendel's dihybrid crosses? select all that apply

inheritance of one trait does not affect inheritance of another. statistical and probability methods can be used to determine how likely an offspring is to inherit certain traits.

multiple alleles for a gene make populations more diverse. what are the benefits of this? select all that apply

it makes it more likely that a population will survive environmental changes. if a population encounters a new disease, some of the individuals may be immune to it.

why are linked traits inconsistent with mendel's laws?

linked traits are likely to be inherited together. this is not consistent with mendel's law of independent assortment.

which statements about the inheritance of color blindness are true? select all that apply

males are more likely to be color blind than females. females can inherit the color blindness allele from their fathers.

why are males more likely than females to have an x-linked disorder?

males have only one x chromosome; thus, if a recessive allele is inherited, it is always expressed.

what are characteristics of polygenic traits? select all that apply

on a histogram, traits distribute on a bell-shaped curve traits are continuous across a range

what is an effect that results when two genes are located side by side on the same chromosome?

punnett squares can give incorrect predictions of inheritance.

which statement is true about recessive traits?

recessive traits can only be expressed with recessive alleles.

which factor determines if someone has brown eyes or green eyes?

several genes acting together

which of these diseases are examples of autosomal recessive human genetic disorders? select all that apply.

sickle cell anemia tay-sachs disease cystic fibrosis

which is an example of the environment affecting gene expression?

some genes being turned off in warm temperatures

which of these are genes that have more than two alleles?

the c gene for melanin production in rabbit coats

a few genes are responsible for melanin pigmentation in human skin. each gene has one allele that codes for melanin production and one allele that does not. which of the following are true? select all that apply.

the combination of alleles determines how pigmented the skin will be each allele only contributes a small amount to the phenotype

a dihybrid cross experiment is carried out in pea plants. which statements are true? select all that apply

the f1 generation will all have both dominant phenotypes. the f2 generation will be a mixture of four different phenotypes.

what can be shown by a dihybrid cross experiment?

the inheritance of one trait does not affect the chance of inheriting another.

dihybrid cross experiments led mendel to propose his law of independent assortment. which statement best describes this law?

the law of independent assortment states that alleles of different genes are inherited independently of each other.

what statement would be true according to the theory of blending inheritance?

the offspring of a tall parent plant and a short parent plant will all have a height in the middle.

if both parents are unaffected carriers of an autosomal recessive disorder, which one of the following statements is true?

the offspring will have a 25% chance of having the disorder.

why might a punnett square predicting the results of a dihybrid cross give incorrect results?

the two genes are on the same chromosome, making some combinations less likely than others.

when mendel crossed a purple-flowered pea plant with a white-flowered pea plant, the offspring always had purple flowers. when mendel crossed the offspring with each other, the second-generation offspring had some white-flowered plants. what conclusion can be drawn from this observation?

there is a chance that any second-generation plant will be a white-flowered one.

a scientist is studying two traits on a fruit fly. she discovers that these are most often inherited together. what can be said about these traits?

they are on the same chromosome and are linked together.

which statement is true about model organisms?

they help scientists understand biological processes.

what is epistasis?

traits where one gene interferes with the effect of another

mendel crossed a tall pea plant with a short pea plant. all the offspring in the first generation were tall pea plants. how did mendel explain why all the offspring were tall pea plants?

two factors affect the height trait of pea plants. one of the factors is dominant over the other.

lesson 3

what genes are really like

a pea plant that is tall has a dominant trait. which statements are true about the genotype/phenotype relationship of the plant? select all that apply

when the phenotype is tall, the genotype can either be TT or Tt. the genotype Tt always results in a phenotype that is tall.

a dihybrid cross experiment is carried out in pea plants. the traits being observed are flower color and stem length. in the f2 generation, 81 plants have purple flowers and long stems, 27 plants have purple flowers and short stems, 27 plants have white flowers and long stems, and 3 plants have white flowers and short stems. which traits are recessive?

white flowers, short stem

when mendel crossed a purple-flowered pea plant with a white-flowered pea plant, the offspring were always x. when mendel crossed the offspring with each other, the distribution was about y purple and z white. the more experiments mendel did with pea plants, the closer they approached these percentages. which option correctly replaces x, y, and z in the statement?

x: purple y: 75% z: 25%