Punnett Squares 1
What is a Punnett square?
A tool for calculating probability of traits in offspring.
What do the letters on the inside of the Punnett square represent?
Offspring genotypes
Who came up with the theory of natural selection?
Charles Darwin
Is red eyes an example of genotype or phenotype?
phenotype
What is heredity?
The passing of traits from parent to offspring.
What do the letters on the outside of the Punnett Square represent?
Parent's alleles
(View Punnett Square 1) What is the probability of getting heterozygous offspring?
50% or 2/4
Where did Darwin travel to when he was studying animals before coming up with his theory?
The Galapagos Islands
Is Ee an example of genotype or phenotype?
genotype
How much DNA do you inherit from each parent?
Half from each parent.
(View Punnett Square 2) What percentage of the offspring will be homozygous recessive?
25% or 1/4
(View Punnett Square 1) What percentage of offspring will show the recessive phenotype?
0%
What is necessary in a population for natural selection to occur?
There has to be differences in traits (ex. fur color)
Traits have to be passed down from parents to offspring.
One trait has to be advantageous over the other trait.
Would an individual with the genotype we have the dominant phenotype or recessive phenotype?
recessive phenotype
Traits are passed from parents to offspring as ____.
genes
(View Punnett Square 2) What percentage of the offspring will show the recessive trait?
25% or 1/4
In larkeys, red eyes (E) is dominant to gray eyes (e). A gray eyed female is crossed with a heterozygous male. What is the female's genotype?
ee
In a snowy environment, would you expect brown rabbits or white rabbits to survive better? Why?
White because they are harder for predators to detect
Is it possible for an individual with a recessive phenotype to have a heterozygous genotype (Ee)? Why?
No, because you need two copies of a recessive allele to have the recessive phentype.
Different forms of a gene are called ____.
alleles
Draw the Punnett square for a TT female and a tt male.
100% Tt
In larkeys, red eyes (E) is dominant to gray eyes (e). A gray eyed female is crossed with a heterozygous male. Draw the Punnett Square for this cross.
50% Ee
50% ee
Is every adaptation suitable for every environment? Explain.
No; certain traits are only beneficial in certain environments (ex. sickle cell)
If two homozygous dominant individuals were crossed, is there a possibility of producing offspring that is homozygous recessive?
No.
In larkeys, red eyes (R) are dominant to gray eyes (r). Is it possible for an individual that is Rr to have a gray eyed offspring? What would need to happen?
Yes; they need to be crossed with a larkey that is either rr or Rr.