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TLS Online TPP Program

#Question id: 8926

Sponges and cnidarians are among the fossilized animals found in both the Ediacara Hills and the Burgess Shale from the Rocky Mountains of British Colombia. This observation requires that

#Unit 9. Evolution & Diversity of Life Forms
  1. ancestral sponges and cnidarians had formerly been terrestrial animals.
  2. North America and Australia were united to each other about 550 million years ago (mya).
  3. land that now comprises the Ediacara Hills and the Rocky Mountains was underwater about 550 million years ago.
  4. only sponges and cnidarians existed at the time the sediments were deposited.
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TLS Online TPP Program

#Question id: 15594

#Unit 8. Inheritance Biology

In an unordered tetrad with the parental ditype:
TLS Online TPP Program

#Question id: 15595

#Unit 8. Inheritance Biology

How might the function of extracellular endonucleases help protect the bacterium from infection by viruses?
TLS Online TPP Program

#Question id: 15660

#Unit 8. Inheritance Biology

Tetrad analysis automatically includes the centromere as an additional point in mapping crosses, because
TLS Online TPP Program

#Question id: 15665

#Unit 8. Inheritance Biology

In deletion mapping, mutations can be localized to a region of the gene because:
TLS Online TPP Program

#Question id: 15667

#Unit 8. Inheritance Biology

You set up the following dihybrid mapping cross in fruit flies. 
P e+e+ roro cq cq x ee ro+ro+ cq+cq+. After backcrossing F1 males to ee roro cq cq females, you get the following results: gray body, rough eyes, claret eyes 576; ebony body, smooth, red eyes 564. How can you explain this result?
TLS Online TPP Program

#Question id: 15834

#Unit 8. Inheritance Biology

You are interested in a new type of autosomal dominant mutation that gives purple eyes in Drosophila. You have a true-breeding purple-eyed line carrying a mutation that you call pr-1. You have isolated a second purple-eyed mutation that you call pr-2, which you have established in a true-breeding line that also carries a recessive marker st, which gives stubby legs. You cross a fly from the pr-1 line to a fly from the st, pr-2 line producing F1 females which you then cross to males from a true breeding st line (normal eyes). From this cross, 1000 progeny flies can be categorized into four different phenotypic classes:
                             
Normally, 3-factor crosses give eight different phenotypic classes, why does this particular cross give only four?