Chemical/physical barriers in the first line of defense do NOT include ______.
A. stomach acid
B. mucus in the trachea
C. macrophages
D. tears
Answer: C. macrophages
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Non-disjunction is the failure of homologous chromosomes to separate during meiosis I, or the failure of sister chromatids to separate during meiosis II or mitosis. As a result, both homologous chromosomes or both sister chromatids migrate to the same pole of the cell. This produces daughter cells with an imbalance of chromosomes. If 18 pairs of sister chromatids segregate normally during meiosis II in cats (n=19) but we have non-disjunction of 1 pair, then at the end of meiosis II we will have
A. 3 cells with 20 chromosomes and 1 cell with 18. B. 2 cells with 20 chromosomes and 2 cells with 18. C. 2 cells with 19 chromosomes, 1 with 20, and 1 with 18. D. 3 cells with 18 chromosomes and 1 cell with 20. Clarify Question · What is the key concept addressed by the question? · What type of thinking is required? · What key words does the question contain and what do they mean? Gather Content · What do you know about non-disjunction? How does it relate to the question? Consider Possibilities · What other information is related to the question? Which information is most Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? Reflect on Process · Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
The presence of genes that encode many types of hemoglobin in mammals, but not in other vertebrates that evolved
earlier, is evidence of ____ of genetic material.
a. an inversion b. the duplication c. reciprocal translocation d. the deletion e. both duplication and deletion
In Drosophila, an individual female fly was observed to be of the XXY chromosome complement (normal autosomal complement) and to have white eyes as contrasted with the normal red eye color of wild type
The female's father had red eyes, and the mother had white eyes. Knowing that white eyes are X-linked and recessive, present an explanation for the genetic and chromosomal constitution of the XXY, white-eyed individual. It is important that you state in which parent and at what stage the chromosomal event occurred that caused the genetic and cytogenetic abnormality.
In all plants, the zygote and earliest stages of the developing embryo are
A) enclosed within a seed. B) enclosed within a pollen grain. C) attached to and nourished by the parent plant. D) able to disperse in a tough-walled spore.