TLS Online TPP Program

#Question id: 7278


The following demonstrates the blastocoel formation in the mammals. Which of the following statement is correct?

#Unit 5. Developmental Biology
  1. The membranes of inner cell mass contain sodium pumps that pump Na+ into the central cavity. The subsequent accumulation of Na+ draws in water osmotically, creating and enlarging the blastocoel.
  2. The membranes of trophoblast cells contain sodium pumps  that pump Na+ into the central cavity. The subsequent accumulation of Na+ draws in water osmotically, creating and enlarging the blastocoel.
  3. The membranes of inner cell mass contain potassium pumps that pump K+ into the central cavity. The subsequent accumulation of K+ draws in water osmotically, creating and enlarging the blastocoel.
  4. The membranes of trophoblast cells contain potassium pumps that pump K+ into the central cavity. The subsequent accumulation of K+ draws in water osmotically, creating and enlarging the blastocoel.

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TLS Online TPP Program

#Question id: 11159

#Unit 9. Diversity of Life Forms

Which kind of DNA should provide the best molecular clock for gauging the evolutionary relatedness of several species whose common ancestor became extinct billions of years ago?

TLS Online TPP Program

#Question id: 11160

#Unit 9. Diversity of Life Forms

A phylogenetic tree constructed using sequence differences in mitochondrial DNA would be most valid for discerning the evolutionary relatedness of

TLS Online TPP Program

#Question id: 11161

#Unit 9. Diversity of Life Forms

The lakes of northern Minnesota are home to many similar species of damselflies of the genus Enallagma that have apparently undergone speciation from ancestral stock since the last glacial retreat about 10,000 years ago. Sequencing which of the following would probably be most useful in sorting out evolutionary relationships among these closely related species?

TLS Online TPP Program

#Question id: 11162

#Unit 9. Diversity of Life Forms

Which statement represents the best explanation for the observation that the nuclear DNA of wolves and domestic dogs has a very high degree of homology?

TLS Online TPP Program

#Question id: 11163

#Unit 9. Diversity of Life Forms

The reason that paralogous genes can diverge from each other within the same gene pool, whereas orthologous genes diverge only after gene pools are isolated from each other, is that

TLS Online TPP Program

#Question id: 11164

#Unit 2. Cellular Organization

Cellular membranes are self-sealing— if they are punctured or disrupted mechanically, they quickly and automatically reseal. What properties of membranes are responsible for this important feature?