Chapter 5-8 Life Science Review
A human baby has one X chromosome and one Y chromosome. Its sex is
male
As an egg or sperm cell forms, the number of chromosomes in the cell is reduced by half during the process of
meiosis
If you crossed a white flower with a red flower and got a pink flower, this would be an example of
incomplete dominance
when a group of gene pairs acts together
polygenic inheritance
the chance something will occur
probability
The primary job of genes is to control the making of
proteins
A farmer crosses two plants that have large fruit to try to produce a new plant that has even larger fruit. The farmer produces the new plant using the process of
selective breeding
red-green color blindness and hemophilia are examples
sex linked genes
a genetic mutation
sickle-cell anemia
the different forms a gene has for a trait
alleles
organisms with two different alleles for a trait
heterozygous
The universal blood recipient is blood type
AB blood, IAIB
when there are two alleles that are exactly the same
homozygous
What other factor must match, other than blood type, for a successful transfusion?
Rh factor
physical appearance of an organism
Phenotype
a trait that covers up another trait
dominant
A scientist cross-pollinates two plants, each with the genotype Tt. Each plant has one gene for tallness (T) and one gene for shortness (t). The seeds that are produced grow, giving three tall plants and one short plant. How many plants have the genotype tt? How many plants have the genotype Tt? How many plants have the genotype TT?
25% TT: 50% Tt: 25% 1 tt, 2 Tt, 1 TT
The somatic cells of a certain animal contain 12 chromosomes. How many chromosomes will appear in each of the animal's sex cells?
6
study of heredity
genetics
Blood type in humans is controlled by ___ alleles.
3
List the three principles of heredity that build on Gregor Mendel's work. (6)
1. traits are controlled by alleles on chromosomes 2. an allele's effect is dominant or recessive 3. when a pair of chromosomes separates during meiosis, the different alleles for a trait move into separate sex cells
Eight eggs combine with eight sperm during fertilization in a cat. Five sperm carry an X chromosome and three sperm carry a Y chromosome. How many of the offspring produced will be male? Female?
3 male (# of Y sperm) 5 female (# of X sperm)
If two people are heterozygous for a sickle-cell anemia, what are the chances that their children will have the disease? Write the parents' genotypes. Do a Punnett square to help determine the answer. Be sure to write a sentence explaining the genotypic and phenotypic results. (6)
A a A AA Aa a Aa aa Phenotypic ratio: 3 normal: 1 sickle cell Genotypic ratio: 1 normal: 2 carrier: 1 sickle cell There is a 25% chance of the child being affected with sickle cell disease, and 50% chance of the child being a carrier, and a 25% chance of being normal and not a carrier.
If in a certain species of animal, black fur is dominant over brown fur, what would be the possible genotypes and phenotypes of the offspring from a cross of the following parents: heterozygous for black fur and homozygous for brown fur? Write the parents' genotypes. Do a Punnett square to help determine the answer. Be sure to write a sentence explaining the genotypic and phenotypic results. (6)
B b b Bb bb b Bb bb Phenotypic ratio: 2 black fur: 2 brown fur Genotypic ratio: 2 heterozygous black fur: 2 homozygous brown fur There is a 50% chance of the offspring having black fur and 50% chance of the offspring having brown fur
In a Punnett square, a capital letter stands for a ___ allele. A lower case letter stands for a ___ allele.
Dominant, recessive
a normal allele is placed in a virus which then delivers it to its target cell
Gene therapy
changing the arrangement of DNA that makes up a gene
Genetic Engineering
If two heterozygous pea plants, with green pods and yellow seeds, were crossed, determine the possible offspring using a Punnett square. Explain the phenotypic ratio and genotypic ratio for the cross. (Hint: There are four possible gametes from each parent; each of the four gametes will have one allele for each of the two traits - pod color and seed color. Look up "dihybrid crosses".)
GgYy x GgYy Each parent will have the following gametes: GY, Gy, gY, gy The Punnett square will be a four by four array Offspring should be written with the Dominant allele first within the pair However, pod color should always be written before seed color, just as in the parents
A yellow pea plant crossed with a homozygous green pea plant produces the following offspring: yellow, yellow, green, green. The yellow pea plant parent's genotype would be ___ for color.
Heterozygous or Yy
when more than two alleles control a trait
Multiple alleles
The universal blood donor is blood type
O blood type, ii
If two pea plants are heterozygous for height, what are the chances that their offspring will be tall? What are the chances that their offspring will be short? Write the parents' genotypes. Do a Punnett square to help determine the answer. Be sure to write a sentence explaining the genotypic and phenotypic results. (6)
P p P PP Pp p Pp pp Phenotypic ratio: 3 tall:1 short Genotypic ratio: 1 homozygous tall: 2 heterozygous: 1 homozygous short There is a 75% chance of the plant offspring will be tall and 25% chance of the plant being short
The crossing of plants or animals with the most useful traits to produce offspring that have the combined useful traits of the parents is called
Selective Breeding
Why do scientists want to locate all of the genes on the human chromosomes? Identify the term described to prepare for matching.
To identify genes responsible for specific traits To begin treatment of disorders while children are young To save lives of people at risk
If the mother has type O blood and the father has type AB blood, what are the possible blood types of the offspring? Write the parents' genotypes. Do a Punnett square to help determine the answer. Be sure to write a sentence explaining the genotypic and phenotypic results. (6)
Use the IAIB or ii version on the test. O. O A AO AO B BO BO Phenotypic and genotypic ratios: both 1:1, AO:BO, type A:type B There is a 50% chance of the child having type A blood and 50% chance of having type B blood. All offspring are heterozygous.
A scientist crosses a homozygous white-flowered plant with a plant that is homozygous for red flowers. She crosses another homozygous white-flowered plant with a plant that is homozygous for yellow flowers. All the offspring of both of the crosses have white flowers. Which flower color is a dominant trait?
White or whatever color the question says that the offspring are
A child's mother carries one gene for normal blood clotting and one gene for hemophilia. The mother's genotype is XHXh. The child's father carries one gene for normal blood clotting. The father's genotype is XHY. What is the child's genotype if the child has hemophilia?
XhXh or XhY are the only two genotypes to produce hemophilia. Only XhY is possible from these parents.
A chart that shows all the possible combinations of traits among the offspring of a cross is called
a Punnett Square
a tool used to help predict the pairing of alleles
a Punnett Square
A Punnett square shows you all the ways in which ___ can combine.
alleles
when both alleles are expressed in offspring
codominance
A human baby has two X chromosomes. Its sex is
female
A section of a chromosome that carries the information for a specific trait is called
gene
Every trait you have is governed by ___ expressing themselves.
genes
The actual genetic make-up of an organism is called
genotype
genetic makeup of an organism
genotype
passing of traits from parents to offspring
heredity
The inherited appearance of an organism is calledThe primary job of genes is to control the making of
phenotype
a trait that seems to disappear
recessive
insertion of a useful segment of DNA into a bacterium
recombinant DNA
In sickle-cell anemia, blood cells don't move through blood vessels easily because they are
sickle-shaped, or folded, and not round, so they get stuck in the blood vessels (misshapen)