Bio Test Six Review Flashcards
Which statement does not describe a classical assumption most scientists and the general public had before the experiments of Kolreuter (1760s), T.A. Knight (1832) and Mendel?
Heredity can be mixed amongst species
Ex. Greek mythology (bull + man = minotaur)
Not every species can mix
Species never change, will always remain the same, no such things as mutations
Ex. moths (the phenotype of moth’s changed with coal dust, lack of light)
Species to evolve and change
Traits are transmitted directly
Marking evolution (ex. If mom has no leg baby has no leg)
Certain physical traits like the ex. cannot be inherited
What were the findings of Josef Kolreuter (1760s) regarding patterns of inheritance?
Hybridization:
Kolreuter’s Experiment: Took different stains of tobacco plants. He cross fertilized them and got fertile species. Sometimes you will get a genetic deadend if the offspring is non-fertile.
Fertile: it can reproduce
The different strains aren’t different species just different breeds (like dogs)
Cross Fertilization: mixing different breeds of the same species
Began to question why missing pink flowers for
example would lead to white offspring
flowers??
What were the findings of T.A. Knight (1832) regarding patterns of inheritance?
True-breeding:
Knight’s experiment: The offspring produced from self fertilization, remained uniform throughout. Crossed two pea plants with yellow pods only, first gen had a few green mixed in.After that everything was yellow for a period of time. This could suggest that the recessive gene in the yellow pods could lead to a 25% chance of being green. Truebreeding is trying to reach only homozygous (having the same genes either dominant or recessive).
Self fertilization: taking female and male reproductive organs of the same individual plant and creating a zygote with it. Most plants have both female and male reproductive organs, they’re called angiosperms. This can be observed in the stigma and its reproduction leads to multiple of the same plants grown, for many generations. However the excessive self fertilization makes heterozygous disappear. (for Knight’s experiment he eventually got a dominant that was homozygous for green and one that is homozygous for yellow)
First gen. Characteristics: can remain the same
color from parents
Second gen. Characteristics: will begin to differ, as
well in upcoming generations
What is the definition of true-breeding?
The offspring produced from self-fertilization remained uniform from one generation to the next
Mendel, through his pea experiments, came up with the terms segregation, character, and traits. How are these words related to one another?
They all contribute and determine aspects of your genetic characteristics
Male and female sexual organs are enclosed within a pea flower which Mendel used. He would self-pollinate and cross-pollinate to obtain his results. What is the difference between self-pollination and cross-pollination?
Self: male and female creating a zygote from the same plant
Cross: different plants from same species creating zygote
Which statement does not describe how Mendel found his phenotype and genotype results for the F1 and F2 generations? (know the experimental design and which genotype and phenotypes he breed)
He did some cross and self fertilization for his design.
1) Make sure to it can do enough self fertilization to get true/purebreed
- Easy cause he had them or they are also easily bread
- Genetically one trait available pure D or pure R
- Worked with one of each
2) Crosses between alternative forms of characters
- Results: should be the same unless there is a mutation. Complete set of heterozygotes. always the results, always 100% yellow
- Phenotype: physically representation 3
3) Do self fertilization
- Ratio is different but its same genetics if its from same plant
- Genotypic ratio 1:2:1 should add the the amount you see inside
- Phenotypic ratio 3:1 three yellow and 1 green
4) Figured out the ratios
- What is the probability of being yellow or green (75% and 25%)
- 75% dominant or 25 true breed and 50% a hetero zygote
Which statement describes the results of Mendel’s experiments (i.e. what did we learn from them being completed)?
F1: yellow and hetero zygote
F2: 75% purple 25% white (called a disguised ratio)
What is the difference between a dominant and recessive trait?
Dominant: main trait you see
Recessive: trait you see if dominant is not present
What is the (a) genotypic and (b) phenotypic ratio of the offspring of a monohybrid cross of a heterozygous male and heterozygous female plant? H = tall and h = short
Genotypic: 1:2:1
Phenotypic: 3:1
What is the (a) genotypic and (b) phenotypic ratio of the offspring of a monohybrid cross of a homozygous short male and a heterozygous female plant? H = tall and h = short
Genotypic: 1:1
Phenotypic: 1:1
What does it mean that Mendel discovered a “disguised ratio?”
F1 did not show white but F2 did when they were not original shown
- Helps with detecting diseases and incorrect genetics, so disused ration not physically shown in the parent
What is the definition of a gene?
particular DNA Nucleotide Sequence (Long or short on a particular part of the chromosomes)
What is the definition of an allele?
varying genetic traits (varying phenotypic things) will still be on the same location of the gene and chromosomes
What is the definition of a locus?
where the gene is located on the chromosome
What is the difference between a homozygous and heterozygous individual?
Homozygous: two of the same alleles (ex. HH or hh)
Heterozygous: two different alleles (ex. Hh)
What is the difference between a genotype and phenotype?
Genotype: the gene / alleles (hh)
Phenotype: the physics trait (not hairy)
What does it mean that Mendelian genetics are considered “discrete” genetics?
They can only have one or the other; two possibilities
- The recessive allele will not show unless there are two
there
- Both alleles will not be shown proportionally in a
heterozygous individual
Which statement does not describe Mendel’s First Law of Heredity: Segregation?
Alternative alleles of character segregate from each other in heterozygous individuals and remain distinct
What is the difference between completing a monohybrid vs dihybrid test cross?
Monohybrid: one trait
Dihybrid: two traits
Which statement does not describe how Mendel found his phenotype ratio for the and generations from dihybrid crosses? (know all experimental design and which genotypes he breed)
Which statement describes the results of Mendel’s experiments for dihybrid crosses?
If short did cross fertilization, got 100% then took those offspring did self fertilization and got a 9:3:3:1 ratio phenotypically
What do the letters on the outside of the Punnett square stand for?
Parent alleles
What do the letters on the inside of the Punnett square stand for?
Possible genotypes of their offspring
What is the (a) genotypic and (b) phenotypic ratio of the offspring of a dihybrid cross of a homozygous tall and green male and homozygous short and yellow female plant? H = tall, h = short, G = green, and g = yellow
Genotype & Phenotype both 16:0
What is the phenotypic ratio of the offspring of a dihybrid cross of a heterozygous male and a heterozygous female plant? H = tall, h = short, G = green, and g = yellow
Phenotypic: 10:2:3:1
Hornless (H) in cattle is dominant over horned (h). A homozygous hornless bull mated with a homozygous horned cow. What will be the genotype and phenotype of the first generation?
1:3
In tomatoes, red fruit (R) is dominant over yellow fruit (r). A plant that is homozygous for red fruit is crossed with a plant that has yellow fruit. What would be the genotypes and phenotypes of the P1 and F1 generations?
1:1
In humans, being a tongue roller (R) is dominant over non-roller (r). A man who is a non-roller marries a woman who is heterozygous for tongue rolling. What is the probability of this couple having a child who is a tongue roller?
50%
Brown eyes in humans are dominant over blue eyes. A brown-eyed man, whose mother was blue-eyed, marries a brown-eyed woman whose father had blue eyes. What is the probability that this couple will have a blue-eyed child?
25%
