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Visit the websites titled, “Exponential Growth”(http://www.otherwise.com/population/exponent.html)and “Logistic Growth”. (http://www.otherwise.com/population/logistic.html) Run theapplet (for both websites) at birth rates of 1.2, 1.5 and 2. Makesure to view the graph results of all growth rates.

Describe the effects of birth rate on the exponential andlogistic growth curves.

Answer in100 words or less.

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Collen Von
Collen VonLv2
28 Sep 2019

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In your opinion, what strategies would be most effective incontrolling population growth in undeveloped countries? Answer in500 words or less.

Is the low rate of population growth a problem in the U.S.? Whyor why not? Answer in 500 words or less.

Cystic Fibrosis (CF) is an autosomal recessive genetic disease that is characterized by the secretion of thick, abnormal mucous in the lungs. The mutated gene that leads these symptoms is the CF transmembrane conductance regulator (CFTR gene). The encoded protein is a chloride channel that moves chloride ions out of epithelial cells. In a homozygous individual, the lack of this chloride channel function in a mutant slows the flow of water into extracellular spaces. This lack of water export leads to the heavy mucus in the lungs of CF patients. Although children with CF would die in childhood, current treatments provide life expectancies into the 30’s.

CF is the most frequently inherited genetic disorder among American children. It affects 1 of every 2,500 children; 30,000 currently have the disease. Although its frequency is higher in European populations, it affects all human populations. Heterozygous carrier frequencies in the US are estimated to be 1 out of 29 Caucasians, 1 out of 46 Hispanics, 1 out of 61 African Americans and 1 out of 90 Asians. There are genetic screens for carriers of CF but they are not routinely performed despite this high frequency of carriers. At least all states in the US proscribe testing of newborns to identify children with CF early so that treatment can be started. Newborn tests for CF: http://www.cff.org/AboutCF/Testing/NewbornScreening/ScreeningforCF/ . If CF is such a common genetic disease, and such a simple Mendelian trait, why is genetic screening of parents not done more frequently? Is it just economic, a pain to do, or is it more complex such that the results of genetic testing are not just positive or negative?

Answer the following questions:
1. If two parents are heterozygous carriers of CF, show a pedigree with four children showing the incidence of carriers and afflicted children. If each unafflicted child (carrier or not) mates with another person, who has a 1 out of 30 chance of being a carrier of CF, what is the expected incidence CF disease in the third generation (frequency of CF in any one of grandchildren of the original couple)?

2. Pleiotropy of Cystic Fibrosis. Watch the two videos on the left at:

http://www.cftrscience.com/MOD-animation
or, if you can not view these, read the short NIH Genetics Home Reference for Cystic Fibrosis http://ghr.nlm.nih.gov/condition/cystic-fibrosis

Connect the description with one of the following videos, or related ones (there are many) you see:
video (10 minutes) of daily life of a child with Cystic Fibrosis http://www.youtube.com/watch?v=WUsuGKzdDg8
Laura’s (20 year old) video diary of life with CF http://www.youtube.com/watch?v=Pgrf8qJXhpc&feature=related

In your own words, describe the range of CF phenotypes. List the other organs besides lungs that are affected and how does it affects those organs.

3.The DNA sequence of the CFTR gene is 170,000 base pairs in length and encodes the CFTR protein that is 1480 amino acids long. Open the accompanying text file (in Canvas/Files/Discussion folder) “CFTR gene DNA sequence”. You will see an alignment of the NIH human genome sequence of the CFTR gene – called “Reference” rather than “wild-type”- against a gene sequence containing a common mutation in CFTR. Look at the alignment and determine how the DNA sequence differs between them. What is the position number where they differ? How many and what nucleotides do they differ in? A “-“ mark in one sequence in the alignment means that that base sequence is missing the corresponding bases in the other sequence. The sequence is a long one but the differences are in bolded bright red text. Matching sequence is marked with a | linking the two sequences. Look near the sequence AAATATCATC if you use FIND tool in Word.

In another file, you will an alignment of the reference translated into a protein sequence, compared to the mutant allele translated into protein sequence. The differences are again in red whereas the areas where the proteins match are in black. Look at the alignment. How do these two proteins differ? Again, find the position number and describe how they differ at that location. A “-“ mark in the alignment means that amino acid is missing when compared to the other sequence.

4. Given that the CFTR gene can be analyzed for a mutation that causes CF, couples interested in being tested as carriers face several choices given the results.
What could be a consequence of a false positive result (couple is identified as carriers but they would not produce any children with symptoms)?

What could be a consequence of a false negative result (a test indicates the couple is not both carriers but they would produce some children with CF)?

5. The sensitivity of the test can vary with ethnic group. The following is a chart from the NCBI Genetic testing site. A sensitivity less than 100% would be likely to produce false negative results from an inability to determine that someone is carrier.

CF Carrier Test Sensitivity by Ethnic Group
http://www.ncbi.nlm.nih.gov/projects/GeneTests/static/concepts/primer/ptscarr5.shtml

Ethnic Group 1

Population Frequency of CF

Sensitivity of Carrier Detection 2

Caucasian

1 in 29

90%

Ashkenazi Jewish

1 in 29

97%

Native American

1 in 32

94%

Latino

1 in 46

57%

African-American

1 in 60

75%

Asian

1 in 90

30%

Why might different ethnic populations differ in the ability of the genetic test to identify carriers of CF?

Question:

Organisms living in Antarctica are thought to be particularly susceptible to change in climatic conditions. How might future climate changes affect the distribution of Antarctic organisms?

Describe the current Antarctic climate and factors that are likely to affect environmental change. Make predictions about future changes to the environment and how this might impact the distribution of organisms in the region.

Below has the format that it could be answered.

below the template, it has exampler template with different topic.

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------ template

What do you think is the answer to the question? / What is your perspective on the topic? This is your stance or thesis.

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Why do you think this? Give at least three supporting reasons (main points)

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Use your stance and supporting points to build your plan. For each main point give a brief explanation, some evidence and/or examples you will use to support it. Provide references where appropriate.

I. Introduction

Possible ideas for the introduction:

(What does the reader need to know to understand the essay? Write as a statement rather than a question or keyword)

-

Proposed thesis statement:

-


II. Body - The number of body paragraphs will vary from essay to essay, you choose how many you need.

- Topic sentence:

(Include the main point making it clear how it supports your stance)

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Explanations /Evidence/ Examples (include references with each fact (author, date)):

Write as a statement of fact not as a question, heading or keyword

-

- Topic sentence (include the topic and how it supports your stance):

-

Explanations /Evidence/ Examples (include references (author, date)):

Write as a statement of fact not as a question, heading or keyword

-

-Topic sentence (include the topic or how it supports your stance):

-

Explanations /Evidence/ Examples (include references (author, date)):

Write as a statement rather than a question or keyword

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III. Conclusion:

(What are the broad implications of the essay?)

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DRAFT WRITING

Introduction and first body paragraph

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------- exampler template with different topic

-

I. Introduction

Possible ideas for the introduction

Climate change

Process of OA

Somehow lead to SO

Thesis Statement : All organisms living bathed in an acidic environment will incur a metabolic cost as a result of the energy expended to maintain functioning cell chemistry this results in reduced growth and reproductive outputs. As a consequence population numbers will drop with a flow on reduction in overall ecosystem biomass and diversity.

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II. Body

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Main Point: OA has a metabolic cost for all marine organisms and affects growth, reproduction and nutrient value as a food source.[CA2]

Examples/Details/Explanations (include references (author, date)) :

Most pronounced in small organisms but is variable and dependant on pH

e.g. krill, gill & haemolymph regulation issues (Flores et al, 2012) ;

e.g. phytoplankton, reduced nutritional value;

e.g. shell forming organisms dissolution of CaCO3 shells e.g. pteropods

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Main Point: The metabolic cost on the individual results in lower numbers of individuals in a population.

Examples/Details/Explanations (include references (author, date)):

This cost results in reduced fertilisation, extended larval development time, deformities

e.g. seastar (Gonzalez-Bernat et al, 2014) detail effects at different pH levels;

e.g. urchin (Sewell et al 2014)

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Main Point: A reduction in biomass of any one species has flow on effects up and down the food chain and could be especially pronounced in the unique Southern Ocean ecosystem.

Examples/Details/Explanations (include references (author, date)):

SO characterised by high nutrient low productivity, ‘wasp-waist’ structure and short food chains

e.g. phytoplankton as primary producers

e.g. krill as important food source

e.g. pteropods as nutrient cyclers

-

Main Point: Reduced food availability will likely alter interspecific interactions and may result in some species being driven to extinction.

Examples/Details/Explanations (include references (author, date)):

a. competition will increase as a result of less food e.g. between larger birds and mammals as a flow on from loss of krill

b. shell forming species will be at greater risk of predation due to weaker shells

c. e.g. seastars as keystone species maintaining diversity

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III. Conclusion

Effects at organism level will impact on total biomass of that species and those that depend on it for food, therefore the overall productivity and biomass of the SO ecosystem will be reduced and loss of species diversity is expected.

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Other Ideas to Conclude:

Effects growth and reproduction and is especially costly for shell forming organisms.

Will see changes as a result of effects on organisms with key functions within the SO ecosystem.

-

Ideas to leave the reader with (clincher):

Global significance of effects of OA on SO (something related to carbon sink and sequestering of Carbon) or perhaps reminding reader that OA is only one consequence of climate change and that organisms will also be at risk from rising sea temps, melting ice, and invasive species.

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