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?

TLS Online TPP Program

#Question id: 15673

#Unit 2. Cellular Organization

A urine sample with more than 100,000 organisms is considered indicative of infection. A urine sample containing 5,000 bacteria, with a generation time of 30 minutes, sits for 3 hours before finally being assayed. How many bacteria will then be present within the sample?

TLS Online TPP Program

#Question id: 15674

#Unit 2. Cellular Organization

During which phase of the bacterial growth curve does the total number of viable cells decline?

TLS Online TPP Program

#Question id: 15675

#Unit 2. Cellular Organization

Shake tubes are used to determine the

TLS Online TPP Program

#Question id: 15676

#Unit 2. Cellular Organization

The dairy industry also sometimes uses ultrahigh-temperature (UHT) sterilization. Milk and milk products are heated at

TLS Online TPP Program

#Question id: 15677

#Unit 2. Cellular Organization

Ultraviolet (UV) radiation around 260 nm is quite lethal but does not penetrate

1. glass 

2. dirt films 

3. Water

March the correct answer

TLS Online TPP Program

#Question id: 15678

#Unit 2. Cellular Organization

Alcohols are among the most widely used disinfectants and antiseptics. They act by