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: 291

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following types of non-covalent bonds or interactions is thought to be primarily responsible for driving the three-dimensional folding of a protein:

#Question id: 292

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following types of non-covalent bonds or interactions is responsible for forming the α helix and β sheet secondary structural motifs of a protein:

#Question id: 293

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following types of bonds or interactions between lipid hydrocarbon tails is responsible for lipids forming a membrane bilayer or membranous vesicles in water

#Question id: 294

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following pairs of amino acids would you predict to only participate in Van der Waals interactions in the three dimensional folding of a protein:

#Question id: 294

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following pairs of amino acids would you predict to only participate in Van der Waals interactions in the three dimensional folding of a protein:

#Question id: 295

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following pairs of amino acids could form a covalent disulfide bond to link two polypeptides together in a multi-subunit protein complex