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?

TLS Online TPP Program

#Question id: 15618

#Unit 13. Methods in Biology

Wild type E. coli metabolizes the sugar lactose by expressing the enzyme ß-galactosidase. You have isolated a mutant that you call lac1-, which cannot synthesize ß-galactosidase and cannot grow on lactose (Lac-). During an condition  isolate  a second Lac– mutation, which you designate lac2-. Using P1 phage on this strain and use the resulting phage lysate to infect the lac2- strain, selecting for   Kanr   transductants. In this case, all 100   Kanr   transductants that are examined are Lac–. What does this result tell you about the relationship between the lac1- and lac2- mutations?

TLS Online TPP Program

#Question id: 14987

#Unit 4. Cell Communication and Cell Signaling

Which type of cell contains variety of proteins with distinct function; some damage pathogens directly, some regulate trafficking and activity of other WBCs, including lymphocytes, and some contribute to the remodelling of tissue at the site of infection?

TLS Online TPP Program

#Question id: 23071

#Unit 12. Applied Biology

Which of the following process using microbes to convert toxic industrial wastes to less toxic or non-toxic compounds is

TLS Online TPP Program

#Question id: 2463

#Unit 2. Cellular Organization

 In the operational model for movement of myosin along an actin filament, the power stroke occurs during:

TLS Online TPP Program

#Question id: 28238

#Unit 5. Developmental Biology

 At what state stem cell exist, when stem cells become positioned farther from the niche?