Following statements are regarding to the mechanism of migration of pollen tube.

A. The embryo sac is the product of three mitotic divisions of the diploid megaspore; it comprises seven cells and eight haploid nuclei.

B. The two polar nuclei in the central cell will fuse with the second sperm nucleus and produce the endosperm that will nourish the egg. The other six cells, including the egg, contain one haploid nucleus each.

C. After compatible pollen germinates, the pollen tube grows toward the micropyle.

D. The three cells from the pollen are connected to one another at the tip of the tube, and waves of sodium ions play a key role in the growth of the tube.

Which of the following combinations are correct?

#Question id: 9249

#Unit 9. Diversity of Life Forms

Which of the following strategies would most rapidly increase the genetic diversity of a population in an extinction vortex?

#Question id: 9250

#Unit 9. Diversity of Life Forms

Of the following statements about protected areas that have been established to preserve biodiversity, which one is not correct?

#Question id: 9242

#Unit 9. Diversity of Life Forms

Eutrophication is often caused by excess limiting-nutrient runoff from agricultural fields into aquatic ecosystems. This process results in massive algal blooms that eventually die and decompose, ultimately depleting the dissolved oxygen, killing large numbers of fish and other aquatic organisms. Predict which of the following human actions would best address the problem of eutrophication near agricultural areas?

#Question id: 9240

#Unit 9. Diversity of Life Forms

Use the following figure to answer the question.

Looking at the figure, what can you conclude about the data?

#Question id: 9228

#Unit 9. Diversity of Life Forms

Use the following figure to answer the question

Looking at the figure showing the results of forest fragmentation, what can be said about edge effects?

#Question id: 9227

#Unit 9. Diversity of Life Forms

A land developer and several ecologists are discussing how a parcel of private land should be developed with housing while saving 20 hectares as natural habitat. The land developer suggests that the 20 hectares be divided into 20 separate 1-hectare areas, spread out across the area. The ecologists suggest that it would be better to have one intact parcel of 20 hectares on one side of the larger area. What is the significance of these different arrangements of the 20 hectares?