BIOLOGY B – PRIMAVERA
which statement is true about recessive traits ? - Answer- Recessive traits can only be expressed with recessive alleles
replace X and Y with the correct answers
x is the genetic makeup of an organism , as determined by the alleles , while Y is the observable form - ...
BIOLOGY B – PRIMAVERA
which statement is true about recessive traits ? - Answer- Recessive traits can only
be expressed with recessive alleles
replace X and Y with the correct answers
x is the genetic makeup of an organism , as determined by the alleles , while Y is the
observable form - Answer- x : genotype
y : phenotype
read the statement :
When Mendel crossed a purple-flowered pea plant with a white-flowered pea plant ,
the offspring always gad 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 ? - Answer- there is a chance
that any second-generation plant will be a white-flowered one .
which statement defines heterozygous ? - Answer- a genotype composed of two
different alleles
some people have dimples ; other people do not . Having dimples is dominant over
not having dimples .
if the alleles for having dimples is represented with the letter D , what allele
combinations can result in having dimples - Answer- DD , Dd
which statement is true about model organisms ? - Answer- they help scientists
understand biological processes
Read the statement :
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 ? - Answer- x : purple
y : 75%
z : 25%
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 . - Answer- - The genotype Tt always results in a phenotype that
is tall .
- When the phenotype is tall , the genotype can either be TT or Tt .
What statement would be true according to the theory of blending inheritance ? -
Answer- The offspring of a tall parent plant and a short parent plant will all have a
height in the middle .
,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 ? - Answer- Two
factors affect the height trait of pea plants . One of the factors is dominant over the
other .
In some situations , when two purple-flowered pea plants reproduce , the offspring
can have purple or white flowers . When this experiment is run repeatedly , it is
discovered that three-fourths of the offspring have purple flowers and one-fourth of
the offspring have white flowers .
What would happen if this experiment were run only once ? - Answer- The
experiment would result in a plant with either purple or white flowers . The conclusion
would depend on this single result and would not be accurate .
What statement is true about heterozygous organisms ? - Answer- Heterozygous
organisms are more genetically diverse than homozygous organisms.
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 . - Answer- all lowercase r
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 ? - Answer- curly hair
What can be shown by a dihybrid cross experiment ? - Answer- The inheritance of
one trait does not affect the chance of inheriting another .
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 ? -
Answer- 9:3:3:1
Which statement best describes a monohybrid cross ? - Answer- a cross in which
traits of several different characteristics are studied
Twenty-five percent of the possible offspring for a cross are homozygous dominant .
What genotype do each of the parents have ? - Answer- heterozygous
In pea plants , green seeds are dominant (Y) , and yellow seeds are recessive (y) .
The following Punnett square shows a cross for seed color . - Answer- 100 percent
What is the ratio of tall offspring to short offspring ? - Answer- 3:1
What valuable information was gained from Mendel's dihybrid crosses ?
Select all that apply . - Answer- 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 .
,Dihybrid cross experiments led Mendel to propose his law of independent
assortment .
Which statement best describes this law ? - Answer- the law of independent
assortment states that alleles of different genes are inherited independently of each
other .
Read the following statement .
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 ? - Answer- white flowers , short stem
A dihybrid cross experiment is carried out in pea plants . Which statements are
true ?
Select all that apply . - Answer- the f1 generation will all have both dominant
phenotypes .
the f2 generation will be a mixture of four different phenotypes .
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 ? - Answer- They are on the same chromosome
and are linked together .
why might a Punnett square predicting the results of a dihybrid cross give incorrect
results ? - Answer- The two genes are on the same chromosome, making some
combinations less likely than others .
which is an example of the environment affecting gene expression ? - Answer- some
genes being turned off in warm temperatures
In which situation are you likely to find a trait with only one allele ? - Answer- genes
found in the DNA of the mitochondria
Multiple alleles for a gene exist in a population . Which of these statements
describes how alleles are inherited ? - Answer- An individual can only inherit two
alleles for a gene .
Which of the following facts was unknown to Gregor Mendel ? - Answer- alleles for
genes are found on chromosomes
Why are linked traits inconsistent with Mendel's laws ? - Answer- linked traits are
likely to be inherited together. this is not consistent with mendel's law of independent
assortment.
What is an effect that results when two genes are located side by side on the same
chromosome ? - Answer- Punnett squares can give incorrect predictions of
inheritance.
, What statement is true ? - Answer- a diploid organism most often has two alleles for
a trait.
What is epistasis ? - Answer- traits where one gene interferes with the effect of
another
What is an example of an environmental effect on phenotype ? - Answer- the gender
of sea turtles being affected by the temperature
How many alleles are typically found for mitochondrial genes ? - Answer- 1
Which of these are genes that have more than two alleles ? - Answer- the c gene for
melanin production in rabbit coats
Multiple alleles for a gene make populations more diverse .
What are the benefits of this ? Select all that apply . - Answer- 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 .
Which of the following statements about polygenic inheritance are true ?
Select all that apply . - Answer- 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 .
What effects can epistasis have on polygenic inheritance ? Select all that apply . -
Answer- 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
A lab technician observes that the red blood cells in a blood sample display
codominance . What alleles does the person who provided the blood sample have ?
- Answer- iA and iB
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 ? -
Answer- iBiB or iBi
What are characteristics of polygenic traits ?
Select all that apply . - Answer- on a histogram , traits distribute on a bell-shaped
curve
traits are continuous across a range
Which factor determines if someone has brown eyes or green eyes ? - Answer-
several genes acting together
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 .
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