5o6 Organisms Are Products of Heredity cwd Environment unit ix 



Exercises 



1. If the genetic make-up of a plant is HI (H stands for high oil con- 

 tent; / stands for low oil content, assuming that the character is due to a 

 single pa:r of genes) and it is self-pollinated, what offspring might vou 

 expect? IHustracc bv diagram. How could vou get a pure strain of plants 

 with high oil content? 



2. For some purposes corn should be low in oil content; for others it 

 should be high. If a breeder had an otherwise desirable variety whose 

 grains vielded \\hat is considered a medium amount of oil (from 3.84% 

 to 6.02 °o), what s':cps would vou recommend that he take to obtain corn 

 with a high and corn with a low content? 



3. If \ ()u were raising strawberries on the verv best kind of soil and 

 under the best conditions of moisture, temperature, and light, what would 

 ymi trv to do next to improve \our plants? State specificallv \\'hat vou 

 M-ould consider desirable characters in a strawberrv plant. 



4. Between 1880 and 1942 the record milk production advanced from 

 18,004 to 41,943 pounds per vear largelv through careful selection. What 

 would vou expect the record milk production to be in i960 if similar 

 methods were used? Read again carefullv the paragraph on "The first 

 method." Then explain your answer. 



5. Can vou demonstrate with two living flowers how the breeder 

 would cross-pollinate them artificially? What precautions must be taken? 



6. Show h\ diagram what might happen in the hybridization of Texas 

 and Brahman cattle. Assume that qualitv of meat and susceptibilit\- to 

 disease are each due to a single pair of genes (which thev probablv are 

 not) and that good meat is dominant to poor meat and resistance is domi- 

 nant to susceptibility. Let At stand for good meat (dominant) and 7// stand 

 for poor meat (recessive). Let R stand for resistance to disease (domi- 

 nant) and r for lack of resistance or susceptibilitv (recessive). What then 

 would be the genetic make-up of the Texas cattle? Of the Brahman cattle? 

 Of the offspring in the F,? What qualities would be shown bv this off- 

 spring? What would the breeder do next? What offspring might he 

 expect? 



7. If your class were divided into committees vou might obtain much 

 interesting information about the work done by your State Agricultural 

 Experiment vStation, about the Department of Agriculture at Washington. 

 the Bureau of Animal Industry, the Bureau of Plant Industrv. and the 

 Cattle or Poultry Breeders' Association of vour state. 



8. Let your imagination create some plant or animal type that would 

 be desirable in the future. Give several reasons w^hy such a form mi^ht 

 be made to order now when it would have been impossible a hundred 

 years ago. 



9. Luther Burbank gave the world a variety^ of new and improved 

 plant forms but left no valuable records. How would you rate him as a 



