ISE 362HOMEWORK SEVEN Due Date:Thursday 12/07

1.Water aeration is often required in water bodies that suffer from anoxic conditions, usually caused by adjacent human activities such as sewage discharges, agricultural run-off, or over-baiting a fishing lake. Aeration can be achieved through the infusion of air into the bottom of the lake or pond by surface agitation from a fountain (see below) or spray-like devices to allow for oxygen exchange at the surface and the release of noxious gasses such as carbon dioxide or methane.Natural aeration is a type of both sub-surface and surface aeration. It can occur through sub-surface aquatic plants. Through the natural process of photosynthesis, pond plants restore oxygen to the water, and thus aerate the pond, providing it with the oxygen necessary for fish to live and aerobic bacteria to break down excess nutrients.Arecent study reports data on the rate of oxygenation in streams at 20oC in the upstate New York regions.The sample mean and standard deviation were computed asx_bar = .173 ands = 0.066, respectively. Based on the accompanying frequency distribution, can it be concluded that the oxygenation rate is a normally distributed variable? Use the chi-squared goodness-of-fit test withα =0.05.

Rate (per day) / Frequency
Below .100 / 14
.100-below .150 / 24
.150- below .200 / 28
.200 –below .250 / 18
.250 or more / 16

ANS:

Fountains aerate the lakes…

8.Genetics has shown us that many of the differences between organisms are the result of differences in the genes they carry. The principles of heredity were first written by GregorMendal in the 1860s. (The importance of his findings was not recognized in his lifetime). The genetic material of all living organisms is DNA. DNA strandsare made of a sequence of ATCG. In a nucleus, genetic material is complexed with protein and is organized into a number of linear structures called chromosomes. Chromosome means colored body and is so named because these threadlike structures are visible under the microscope only after they are stained with dyes.Chromosomes are the essential unit for cellular division and must be replicated.Compaction of the duplicated chromosomes during mitosis and meiosisresults in the classic four-arm structure pictured below. Chromosomal recombination plays a vital role in genetic diversity. If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastropheand die, or it may unexpectedly evade apoptosis leading to the progression of cancer.In an experiment reported in Genetics, investigators looked at 300 metacentric chromosomes and then counted the number of sister-chromatid exchanges on each.(Sister-chromatids are ones that are identical).A Poisson model was hypothesized for the distribution of the number of exchanges. Test the fit of a Poisson distribution to the data by first estimating λ and then combining the counts for x = 8 and x = 9 into one cell.

X = number of exchanges> 0123456789

Observed Counts >6 24 42 59 62 44 41 14 62

Ans:

Diagram of a replicated and condensed metaphase eukaryotic chromosome. (1)Chromatid– one of the two identical parts of the chromosome after S phase. (2)Centromere– the point where the two chromatids touch, and where the microtubules attach. (3) Short arm. (4) Long arm. THE END