TLS Online TPP Program

#Question id: 5667


There may be an important connection between sperm translocation and capacitation. Which of the following option is correct explanation of above statement?

#Unit 5. Developmental Biology
  1. The influx of bicarbonate ions (and possibly other ions) alkalinizes the sperm, raising its pH.

  2. before entering the ampulla of the oviduct, the uncapacitated sperm bind actively to the membranes of the oviduct cells in the narrow passage (the isthmus) preceding it.  This binding is temporary and appears to be broken when the sperm become capacitated.

  3. The cholesterol efflux from the sperm cell membrane is thought to change the location of its “lipid rafts,” isolated regions that often contain receptor proteins that can bind the zona pellucida and participate in the acrosome reaction.

  4. Capacitation is a transient event but translocation is not

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TLS Online TPP Program

#Question id: 13186

#Unit 10. Ecological Principles

The following figure is a model of seedling establishment as a function of distance from a parent tree. Initial seed density measures the number of seeds falling to the ground. Seed survivorship measures the proportion of seeds that survive to the adult stage at each distance

This model predicts that recruitment of new individuals into the population should be

TLS Online TPP Program

#Question id: 13187

#Unit 10. Ecological Principles

The following figure is a model of seedling establishment as a function of distance from a parent tree. Initial seed density measures the number of seeds falling to the ground. Seed survivorship measures the proportion of seeds that survive to the adult stage at each distance


Which of the following factors is most likely to generate the seed density curve shown? 

TLS Online TPP Program

#Question id: 13188

#Unit 10. Ecological Principles

The following figure is a model of seedling establishment as a function of distance from a parent tree. Initial seed density measures the number of seeds falling to the ground. Seed survivorship measures the proportion of seeds that survive to the adult stage at each distance


Which of the following factors is most likely to generate the seed survivorship curve shown? 

TLS Online TPP Program

#Question id: 13189

#Unit 10. Ecological Principles

The relative abundance of C plant species increases with latitude because of the associated temperature gradient. A study in North America found that at  42°  North,  C3  plants  become more  abundant than  C4  plants. Given  an  increase in  mean global  temperatures by  10°C and no  other changes in  environmental conditions,  the latitude at which C3 plants become more abundant:

TLS Online TPP Program

#Question id: 13190

#Unit 10. Ecological Principles

During the evolution of life on Earth, the photosynthetic organisms initially responsible for raising atmospheric oxygen concentrations from less than 1 percent to about 20 percent were

TLS Online TPP Program

#Question id: 13191

#Unit 10. Ecological Principles

Which of the following statements about circadian rhythms is correct?