TLS Online TPP Program

#Question id: 2593


How do actin filaments appear when viewed by negative stain electron microscopy?

#Unit 2. Cellular Organization
  1. When viewed by negative stain electron microscopy, an actin filament appears as a twisted string of beads with a diameter of 7-9 nm.

  2. When viewed by negative stain electron microscopy, an actin filament appears as a straight string of beads with a diameter of 7-9 nm.

  3. When viewed by negative stain electron microscopy, an actin filament appears as a protofilamentous form with a diameter of 7-9 nm.

  4. When viewed by negative stain electron microscopy, an actin filament appears as a twisted string of beads with a diameter of 25 nm.

More Questions
TLS Online TPP Program

#Question id: 12097

#Unit 10. Ecological Principles

The herbaceous plant Achillea lanulosa is widespread in the Northern Hemisphere. Phenotypic variation in the species has been extensively studied along an altitudinal gradient from sea level to over 3,000 meters. In California there is conspicuous variation in  height; alpine plants are only several centimeters tall  while  those in  the San Joaquin Valley may reach a height of 1.8 meters. Adaptation to different local environments also results in variation in physiological processes such as photosynthetic rate, resistance to cold, and the timing of dormancy.


Which of the following methods would be best to determine whether the phenotypic variation in Achillea lanulosa is due to genotypic variation?

TLS Online TPP Program

#Question id: 5613

#Unit 5. Developmental Biology

Female mice with the CD9 gene knocked out are infertile because

TLS Online TPP Program

#Question id: 3840

#Unit 3. Fundamental Processes

The mechanism of DNA replication is studied in an E. coli replication fork. When will this fork stop replicating DNA?

TLS Online TPP Program

#Question id: 3490

#Unit 11. Evolution and Behavior

Given below are some behaviors strategies.

A) Fixed action pattern, complex sequence of behavior, Once released and continuous to completion, even when there is change in surrounding environment

B)  natural selection select that territorial behavior that is benefit is greater than cost 

C) Imprinting, a form of learning in which a very young animal fixes its attention on the first object with which it has visual, auditory, or tactile experience

D) Donor benefits at a cost to the recipient, the behavior is altruistic; when the recipient benefits at a cost to the donor, the behavior is selfish.

Which one of the following correct combination of true and false?

TLS Online TPP Program

#Question id: 23660

#Unit 13. Methods in Biology

In a cDNA library the probability of finding the desired clone depends on ________.