In angiosperms, the megasporangium goes through several stages as it develops into an embryo sac. The sac protects the egg cell and several supporting cells, but it does not completely enclose it. What is the opening in the embryo sac that allows the pollen tube to enter called?
a. integument
b. microspore
c. micropyle
d. exine
c. micropyle
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How can freeze-fracture be used to determine the orientation of a protein in a membrane?
A. Freeze-fracture allows a cell to be cleaved in between the lipid bilayer, splitting the plasma membrane into two layers. B. Freeze-fracture allows a cell to be cleaved in such a way as to preserve the embedded proteins. C. Freeze-fracture cuts the membrane in protein-sized components for viewing under an electron microscope.
______ is a process of nuclear division which reduces the number of chromosomes per cell from 2 sets to 1 set.
A. Mitosis B. Meiosis C. Binary fission D. Syngamy
Variation arises in asexually reproducing populations by ________
a. mutation b. all of the choices c. natural selection d. recombination
Respond to the following statements in reference to the four kinds of reception listed below that are used by social animals.
A. This sensory modality is used by honeybees during the waggle dance. B. C. The elaborate posturing displays of male birds-of-paradise utilize this sense in the female. D. The sex pheromone emitted by a female gypsy moth relies upon this sense in the male. E. The primary signal sent out by receptive female primates is likely to be this. F. The alarm signal one snail sends to another is most likely to be this.