Ultrastructural studies have led to the characterization of two distinctive cytological

pathways of PCD in plants;

I) Vacuolar-type PCD

II) Hypersensitive response-type (HR-type) PCD

a) cytosol and all its organelles, including the plasma membrane, are completely brokendown

b) The vacuole loses water, resulting in marked cell shrinkage, contraction from the cell wall,

and nuclear DNA degradation

c) PCD occurs in leaves in response to microbial attack

d) cell wall is either partially or completely digested as well, as in endosperm tissue

e) Continued water loss from the cytosol leads to the breakdown of the plasma membrane

and the release of residual cellular contents into the apoplast

Given characterization of PCD pathway match with its type PCD?

#Question id: 3274

#Unit 9. Evolution & Diversity of Life Forms

The common edible frog of Europe is a hybrid between two species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when they mate among themselves, they are rarely successful in producing offspring. What can you infer from this information?

#Question id: 3275

#Unit 9. Evolution & Diversity of Life Forms

When imbalances occur in the sex ratio of sexual species that have two sexes (that is, other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of ________.

#Question id: 3276

#Unit 9. Evolution & Diversity of Life Forms

Which of these conditions are always true of populations evolving due to natural selection?

Condition 1: The population must vary in traits that are heritable.

Condition 2: Some heritable traits must increase reproductive success.

Condition 3: Individuals pass on most traits that they acquire during their lifetime.

#Question id: 3277

#Unit 9. Evolution & Diversity of Life Forms

Which of the following describes the most likely order of events in allopatric speciation?

#Question id: 3278

#Unit 9. Evolution & Diversity of Life Forms

What does the biological species concept use as the primary criterion for determining species boundaries?

#Question id: 3279

#Unit 9. Evolution & Diversity of Life Forms

Which two of the following have operated to increase divergence between mosquito fish populations on island?

a. improved gene flow

b. bottleneck effect

c. sexual selection

d. founder effect

e. natural selection