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TLS Online TPP Program

#Question id: 7121

How do the endodermal cells of the sea urchin embryo carry out gut formation during gastrulation?

#Unit 5. Developmental Biology
  1. They move inside the blastocoel, and form the skeletal structures that will support the adult animal.
  2. They move into the blastocoel as mesenchyme and crawl ventrally, to mark the location of the future mouth.
  3. Changes in cell shape initiate the invagination; convergent extension extends the sheet of cells into the blastocoel, and finally, filopodia make contact with the future mouth region and pull the tip of the gut to that point.
  4. They enter the interior of the embryo through the dorsal lip of the blastopore and, through a combination of cell movements and convergent extension, form the gut.
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TLS Online TPP Program

#Question id: 12252

#Unit 10. Ecological Principles

In a study of interactions between plants, ants and caterpillars, the following experimental treatments were imposed: i) Control (both ants and caterpillars are present); ii) Ant removal; iii) Caterpillar removal; iv) Ant and caterpillar removal. Plus (+) indicates presence and minus (-) indicates absence on plants. The results for plant performance (growth) from this experiment  are shown in the figure below. Plant performance in all treatments were significantly different from each other. Based on these results, which of the following inferences is correct?
TLS Online TPP Program

#Question id: 12780

#Unit 10. Ecological Principles

The producers in aquatic ecosystems include organisms in which of the following groups?
TLS Online TPP Program

#Question id: 19380

#Unit 12. Applied Biology

Glyphosate results primarily from starving the cells of aromatic amino acids, which leads to
TLS Online TPP Program

#Question id: 28400

#Unit 5. Developmental Biology

Which of the following is the major candidate for the factor that forms the Nieuwkoop center ? 
TLS Online TPP Program

#Question id: 18786

#Unit 13. Methods in Biology

Flow cytometry is based on light scattering and fluorescence, in which two types of scattering are used Forward light scattering and side scattering, in which forward determines……………while side determines the………….