Erma and Harvey were a compatible barnyard pair, but a curious sight. Harvey's tail was only 6 cm long, while Erma's was 30 cm. Their F₁ piglet offspring all grew tails that were 18 cm. When inbred, an F₂ generation resulted in many piglets (Erma and Harvey's grandpigs), whose tails ranged in 4-cm intervals from 6 to 30 cm (6, 10, 14, 18, 22, 26, and 30). Most had 18-cm tails, while 1/64 had 6-cm tails and 1/64 had 30-cm tails.
If one of the 18-cm-tail F₁ pigs is mated with one of the 6-cm-tail F₂ pigs, what phenotypic ratio will be predicted if many offspring resulted? Diagram the cross.

The narrow-sense heritability of the number of seeds per flower is 0.9. The mean of the population is 6.0 seeds per flower. A flower breeder crosses one flower with 7 seeds to another plant with 9 seeds. What is the expected number of seeds per flower in the offspring of this cross?

Heritability calculations were calculated for a variety of different traits. Which of the following traits would respond best to selection?

How do we know that monozygotic twins are not identical genotypically as adults?

Define the following:

(a) Polygenic

(b) Additive alleles

(c) Correlation

(d) Monozygotic and dizygotic twins

(e) Heritability

(f) QTL

(g) Continuous variation

Erma and Harvey were a compatible barnyard pair, but a curious sight. Harvey's tail was only 6 cm long, while Erma's was 30 cm. Their F₁ piglet offspring all grew tails that were 18 cm. When inbred, an F₂ generation resulted in many piglets (Erma and Harvey's grandpigs), whose tails ranged in 4-cm intervals from 6 to 30 cm (6, 10, 14, 18, 22, 26, and 30). Most had 18-cm tails, while 1/64 had 6-cm tails and 1/64 had 30-cm tails.

Explain how these tail lengths were inherited by describing the mode of inheritance, indicating how many gene pairs were at work, and designating the genotypes of Harvey, Erma, and their 18-cm-tail offspring.

In the following table, average differences of height, weight, and fingerprint ridge count between monozygotic twins (reared together and apart), dizygotic twins, and nontwin siblings are compared: 

Based on the data in this table, which of these quantitative traits has the highest heritability values?

What kind of heritability estimates (broad sense or narrow sense) are obtained from human twin studies?

Corn plants from a test plot are measured, and the distribution of heights at 10-cm intervals is recorded in the following table: 

 Height (cm)   Plants (no.)    

100          20    

110          60    

120          90    

130         130    

140         180   

 150         120    

160          70    

170         50    

180         40 

Calculate 

(a) the mean height, 

(b) the variance, 

(c) the standard deviation, and 

(d) the standard error of the mean. 

Plot a rough graph of plant height against frequency. Do the values represent a normal distribution? Based on your calculations, how would you assess the variation within this population?