Practice Questions

  1. Home
  2. Free Resources
  3. Practice Questions
  4. 953
TLS Online TPP Program

#Question id: 971

What is the source of the nitrogen atoms 3 and 9 during the de novo biosynthesis of purines?

#Unit 1. Molecules and their Interaction Relevant to Biology

  1. aspartate 

  2. glycine

  3. arginine

  4. glutamine

More Questions
TLS Online TPP Program

#Question id: 16140

#Unit 13. Methods in Biology

Many mouse genes are “tissue-specific,” that is, they are present throughout the body but are expressed in only one of the animal’s many tissue types. (Other mouse genes are expressed throughout the body, or in multiple tissues.) Geneticists can study the regulation of a mouse gene by fusing the gene’s promoter region to the LacZ coding sequence and injecting the construct to create a transgenic mouse. Fusion of the mouse amylase promoter to LacZ yielded a Pamylase-LacZ construct.
You are surprised to observe that mice homozygous for the transgene insertion display a serious heart defect. (Heterozygotes have normal hearts.) which one is a  possible explanation?
a) LacZ overexpression (with two copies of the transgene) causes the defect.
b) the insertion disrupted a gene that is haploinsufficient.
c) the insertion disrupted a gene that is haplosufficient.
d) LacZ expression inhibition (with two copies of the transgene) causes the defect.
Which of the following statements is correct  predict about the  heart defect?
TLS Online TPP Program

#Question id: 28322

#Unit 5. Developmental Biology

In mammalian cell, second slow block to polyspermy comes from___
TLS Online TPP Program

#Question id: 29504

#Unit 6. System Physiology – Plant

Idioblasts cells are involved in the synthesis of
TLS Online TPP Program

#Question id: 31125

#Unit 2. Cellular Organization

At low temperatures, bilayer lipids are highly ordered, forming a gel phase with the acyl chains nearly perpendicular to the plane of the membrane plane. This state, called: 
TLS Online TPP Program

#Question id: 13130

#Unit 10. Ecological Principles

Biologists performed an experiment with flies to examine the effects of population size on the maintenance of genetic variation  and  on  egg-to-adult survival.  From  a  large  source  population, they  randomly  assigned  eggs  to  three experimental  populations  of  size  N,  equal  to  20,  60,  and0100.  For  later  generations,  they  collected  N  eggs  from each  population  and  moved  them  into  identical  vials  that  co0ntained  f2re0sh  me4d0ium.  Th6e0y  coun8te0d  the  number  of adult flies that emerged and used tissue samples from the adults for genetic analyses. Genetic variation was measured by  scoring  alleles  at  several  polymorphic  loci  and  expressed  as  the  average  number  of  alleles  at  those  loci.  The results are summarized in Figure 1 and Figure 2 below.


Which process best explains the dynamics of genetic variation observed in this experiment?