-- card: 44003 from stack: in
-- bmap block id: 49062
-- flags: 0000
-- background id: 2665
-- name: 


-- part 1 (button)
-- low flags: 00
-- high flags: 8003
-- rect: left=271 top=222 right=244 bottom=309
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: 25%
----- HyperTalk script -----
on mouseUp
  global it
  add 1 to it
  if it = 1 then
    hide card field "cover III"
  end if
  if it = 2 then
    hide card field "cover IV"
  end if
  if it >=2 then
    put 0 into it
  end if
end mouseUp



-- part 2 (button)
-- low flags: 00
-- high flags: 8003
-- rect: left=271 top=246 right=268 bottom=309
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: 50%
----- HyperTalk script -----
on mouseUp
  hide card field "cover I"
  hide card field "cover II"
end mouseUp



-- part 3 (button)
-- low flags: 00
-- high flags: 8003
-- rect: left=272 top=270 right=292 bottom=310
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: 75%


-- part 4 (button)
-- low flags: 00
-- high flags: 8003
-- rect: left=272 top=294 right=316 bottom=310
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: 100%


-- part 5 (button)
-- low flags: 00
-- high flags: 8003
-- rect: left=340 top=253 right=276 bottom=431
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: RESTORE
----- HyperTalk script -----
on mouseUp
  SHOW CARD FIELD "COVER I"
  SHOW CARD FIELD "COVER II"
  SHOW CARD FIELD "COVER III"
  SHOW CARD FIELD "COVER IV"
end mouseUp



-- part 6 (field)
-- low flags: 00
-- high flags: 0001
-- rect: left=293 top=86 right=120 bottom=329
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 0
-- font id: 3
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: COVER I


-- part 7 (field)
-- low flags: 00
-- high flags: 0001
-- rect: left=293 top=122 right=152 bottom=329
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 0
-- font id: 3
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: COVER II


-- part 8 (field)
-- low flags: 00
-- high flags: 0001
-- rect: left=334 top=86 right=120 bottom=370
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 0
-- font id: 3
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: COVER III


-- part 9 (field)
-- low flags: 00
-- high flags: 0001
-- rect: left=334 top=123 right=153 bottom=370
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 0
-- font id: 3
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: COVER IV


-- part 10 (button)
-- low flags: 00
-- high flags: 8003
-- rect: left=151 top=314 right=336 bottom=251
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: SUB HEADINGS
----- HyperTalk script -----
on mouseUp
  go to card id 36585
end mouseUp




-- part 11 (button)
-- low flags: 00
-- high flags: 8003
-- rect: left=340 top=312 right=334 bottom=454
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: NONDISJUNCTION
----- HyperTalk script -----
on mouseUp
  go to card id 70843
end mouseUp




-- part contents for background part 1
----- text -----
SEX LINKAGE

-- part contents for background part 2
----- text -----
Let us take one of the females from the cross in which the original male parent was white eyed (The cross on the far right of the previous 
card) and mate her with a normal eyed male. This cross is shown at the right. Again, click on the button which describes the percentage of offspring in that generation displaying the phenotype in question. Make sure you proceed in an orderly fashion from the top of the question list to the bottom. That way the program will run without problems.
If the phenotype is not to be found in the generation, then do not click on any button. After viewing this card and the previous card, what can you say about sex-linked inheritance? Place your answer in the space below and then click on the scroll arrow to bring further information into view after you have run through the exercise.
COMMENT:










Note that the white eye condition only appears in the males. Half of the females are carriers of the trait and half are not. However, no female displays the trait. It appears only in males and hence is sex-linked. The only way a sex-linked trait can appear in a female is for a carrier female to be mated with a male displaying the characteristic. Then 50% of the female F1 from such a cross would show the sex-linked trait. Since the frequency of such mutant genes is so low... the occurrence of females displaying sex-linked traits is very rare. However, an unusual type of inheritance was discovered by Bridges who crossed a white-eyed male fly with a true breeding normal female and obtained a white-eyed male in the F1. Trace back through the previous cards and see if this is possible. The data  seemes to contradict the accepted theories of sex-linkage or sex determination in Drosophila. It involves a phenomenon called nondisjunction and can be studied by clicking on the NONDISJUNCTION button at the right.

-- part contents for background part 8
----- text -----
166