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? 

#Question id: 11824

#Unit 6. System Physiology – Plant

Only two of the ethylene receptors in Arabidopsis have intrinsic histidine kinase activity, these receptors are_______

#Question id: 11825

#Unit 6. System Physiology – Plant

Ethylene receptors are localized into the______

#Question id: 11826

#Unit 6. System Physiology – Plant

Some given statements about ethylene signalling pathways are listed;

a) Ethylene receptors are interact with two downstream signaling proteins, CTR1 (CONSTITUTIVE TRIPLE RESPONSE1) and EIN3 (ETHYLENE-INSENSITIVE3)

b) CTR1 is a soluble serine/threonine kinase that is associated with ethylene receptors, while EIN2 is an ER transmembrane protein with a cytosolic C-terminal domain that is a target for CTR1 kinase activity

c) EIN2 is required to stabilize transcription factors of the EIN3 (ETHYLENEINSENSITIVE3) family, which activate the transcription of ethylene-responsive genes

d) EIN3 is required to stabilize transcription factors of the EIN2 (ETHYLENEINSENSITIVE2) family, which activate the transcription of ethylene-responsive genes

Which of the following is the correct statements  of auxin signalling pathway ?

#Question id: 11827

#Unit 6. System Physiology – Plant

Which of the following enzyme is involved in the rate-limiting step in ethylene biosynthesis?

#Question id: 11828

#Unit 6. System Physiology – Plant

Given some enzymes of ethylene biosynthetic pathway and its character;

A) ACC synthase                                                               i) It is an unstable, cytosolic enzyme. Its level is regulated by environmental and internal factors, such as wounding, drought stress, flooding, and auxin

B) ACC oxidase                                                                  ii) It catalyzes the last step in ethylene biosynthesis, the conversion of ACC to ethylene

                                                                                                iii) Its activity can be the rate-limiting step in ethylene biosynthesis

                                                                                                iv) That is encoded by a multigene family that is differentially regulated

                                                                                                v) It is present in such low amounts in plant tissues and is very unstable and also difficult to purify the enzyme  for biochemical analysis

                                                                                                vi) These enzymes belong to the Fe2+/ascorbate oxidase superfamily

Find out the correct combination from the given enzymes and its character?

#Question id: 11829

#Unit 6. System Physiology – Plant

The certain cyclic olefin compounds, have been shown to block ethylene breakdown without inhibiting ethylene action?