Practice Questions

TLS Online TPP Program

#Question id: 7099

A fate map of a Xenopus blastula, just before gastrulation begins, shows that the top portion of the embryo will become ectoderm (skin and nerve), the central portion will become mesoderm (bone, muscle, and blood), and the lowest portion will become endoderm (gut). How is it that the endoderm and mesoderm, shown on the outside in the fate map, end up on the inside in the embryo after gastrulation?

#Unit 5. Developmental Biology

The endoderm ends up inside through a process that can be visualized as if one pokes their finger into the bottom of a soft ball until the lowest endodermal portion ends up deep inside, the marginal zone mesoderm also ends up inside, and the ectoderm now encloses the entire outer surface.
The endodermal cells begin first to move into the embryo through the blastopore, displacing the blastocoel and forming a gut; as gastrulation proceeds, the blastopore spreads sideways and the mesoderm follows the endoderm in, ending up between the endoderm and the ectoderm.
The ectodermal cells divide and spread down over the rest of the embryo, so that the endoderm ends up on the bottom, ventral, surface of the embryo, and the mesoderm ends up around the middle, just as is shown in the fate map.
The three germ layers adopt their final positions through, first, the growth of the mesodermal marginal zone down over the endoderm, followed by, secondly, the growth of ectoderm down and over the mesoderm.

More Questions

TLS Online TPP Program

#Question id: 3485

#Unit 9. Evolution & Diversity of Life Forms

Optimal foraging involves all of the following except

A) maximizing energy gained by the forager.

B) minimizing energy expended by the forager.

C) securing essential nutrients for the forager.

D) minimizing the risk of predation on the forager.

E) maximizing the population size of the forager

TLS Online TPP Program

#Question id: 3486

#Unit 9. Evolution & Diversity of Life Forms

Which of the following might affect the foraging behavior of an animal in the context of optimal foraging?

A) risk of predation

B) prey size

C) prey defenses

TLS Online TPP Program

#Question id: 3487

#Unit 9. Evolution & Diversity of Life Forms

Which of the following is true of innate behaviors?

A) Genes have very little influence on the expression of innate behaviors.

B) Innate behaviors tend to vary considerably among members of a population.

C) Innate behaviors are limited to invertebrate animals.

D) Innate behaviors are expressed in most individuals in a population across a wide range of environmental conditions.

E) Innate behaviors occur in invertebrates and some vertebrates but not in mammals.

TLS Online TPP Program

#Question id: 3488

#Unit 9. Evolution & Diversity of Life Forms

According to Hamiltonʹs rule,

TLS Online TPP Program

#Question id: 3489

#Unit 9. Evolution & Diversity of Life Forms

In a bird species A, the male alone builds the nest, incubates the eggs and feeds the nestling. In bird species B, it is the female that does all that. In bird species C, both sexes contribute equally to the above activities. In species A and B, the uninvolved partner may fly away and mate again. Which sex among A, B and C is most likely to develop colorful plumage during breeding season?

TLS Online TPP Program

#Question id: 3490

#Unit 9. Evolution & Diversity of Life Forms

Given below are some behaviors strategies.

A) Fixed action pattern, complex sequence of behavior, Once released and continuous to completion, even when there is change in surrounding environment

B) natural selection select that territorial behavior that is benefit is greater than cost

C) Imprinting, a form of learning in which a very young animal fixes its attention on the first object with which it has visual, auditory, or tactile experience

D) Donor benefits at a cost to the recipient, the behavior is altruistic; when the recipient benefits at a cost to the donor, the behavior is selfish.

Which one of the following correct combination of true and false?