Outline the events that take place between exposure of the oocyte to spermatozoa and formation of the first blastomere pair
What will be an ideal response?
Powerful acrosomal hydrolases released from the sperm head create openings between adherent granulosa cells (the corona radiata) and penetrate the zona pellucida. A solitary sperm penetrates to the oocyte membrane to which it fuses, sending its nucleus into the oocyte. This is the moment of fertilization. This triggers maturation of the haploid maternal pronucleus, followed by development of the male pronucleus. These then fuse in the act of amphimixis, the true combining of maternal and paternal haploid chromosome sets to form a unique diploid set of 46. Spindle fibers organize the chromosomes on the metaphase plate after the nuclear envelopes break down. After mitosis is complete, cytokinesis takes place, dividing the original zygote into two daughter cells or pair of blastomeres. This takes more than 30 hours to complete.
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Antigen-displaying cells are infected by pathogens so they can display the antigens.
Answer the following statement true (T) or false (F)
Lateral inhibition
1.is an effect of the brain on sensory receptors.
2.is inhibition of the most strongly stimulated receptor by neighboring receptors.
3.increases the sensitivity of a receptor.
4.is especially significant in receptors for chemical senses (olfaction and taste).
5.increases the acuity of a receptor.
Name the layer from which fingernails and toenails are derived.
A. Dermis B. Subcutaneous tissue C. Epidermis
Mr. Huff and Puff is getting ready to blow up a pool float because he can't find the air pump. He takes a big breath in after exhaling normally. The air he takes in is the
A. inspiratory reserve volume. B. vital capacity. C. inspiratory capacity. D. tidal volume.