North Hills Preparatory
Theory of Knowledge
Ms. Biela
Sample Extended Essay Introductions: Chemistry (p. 1), History (p. 4), and English (p. 5)
INTRODUCTION
Vitamin C, or L-ascorbic acid (C6H8O6), is mainly found in vegetables and fruits, though it can also be
obtained from animals such as lambs, goats, and cows. It is an essential vitamin that is an oxidized form
of the 6-carbon sugar glucose and the L-enantiomer of ascorbate.1 Due to its water-soluble nature,2
excesses of vitamin C cannot be stored in the body and will be urinated, causing a need for ascorbic acid
to be constantly ingested. Ascorbic acid is denatured by baking soda, copper, and iron, and is unstable at
warm temperatures and when exposed to oxygen.
In developing countries, the seasons usually determine the amount of available ascorbic acid. These
seasons give indication as to what fruits or vegetables are available to be harvested, along with how
much time and labor is available to harvest those sources of vitamin C. Although vitamin C is relatively
easily obtained, studies have shown that people in Latin America, India, China, Gambia, and other
developing countries intake less than the recommended amount for their age group. For example, in
Gambia, the average intake each month can range anywhere from 0 mg/day to 115 mg/day, depending
on the time of year.3 The peaks of intake coincide, as expected, with harvests of main sources of vitamin
C such as mangoes, oranges, and grapefruit.
In this essay, the different cooking methods and their effect on concentrations of ascorbic acid will be
investigated. Because ascorbic acid can be conserved, and therefore deficiencies can be reduced by
changing the cooking methods, I thought that it would be appropriate to investigate which cooking style
would preserve the most amount of ascorbic acid. By examining how cooking processes affect vitamin C,
developing countries can reduce deficiencies in vitamin C. This way to prevent deficiencies in vitamin C
thus led to the Research Question:
How do different dry cooking styles affect the concentration of vitamin C in Capsicum annuum (red
bell peppers)?
I chose to use red bell peppers because, based on literature values, they have a large concentration of
ascorbic acid, making it easier to test with accurate results. While other sources had higher
concentrations of vitamin C, red bell peppers were more accessible.
Two hydrogens in ascorbic acid are part of –OH groups. While one of these hydrogens causes the acidity
of ascorbic acid and forming semi-dehydroascorbate as shown by Equation 1,
H2Asc(s)
1
→
HAsc(aq)
+
H+(aq)
(Eq. 1)
World Health Organization. Vitamin C. 10 June 2005. PDF.
Higdon, Jane. "Vitamin C." Linus Pauling Institute at Oregon State University. Linus Pauling Institute, Jan. 2006.
Web. 15 Oct. 2010. <http://lpi.oregonstate.edu/infocenter/vitamins/vitaminC/>.
3
World Health Organization. Vitamin C
2
North Hills Preparatory
Theory of Knowledge
Ms. Biela
the other is the cause of the oxidation of the ascorbate ion to form dehydroascorbate as shown by
Equation 2:
HAsc(aq) →
Asc(aq)
+
H+(aq)
+
2e-
(Eq. 2).
To stress the importance of the hydrogens and make the reaction into ascorbate easier to see, ascorbic
acid is written as H2Asc.
Functions of Vitamin C
The ease with which ascorbate donates electrons causes it to function as a co-factor for several enzymes
containing copper or iron such as proline hydroxylase and lysine hydroxylase, which are crucial
producing collagen, the main protein present in connective tissues such as skin, cartilage, tendons,
ligaments, and blood vessels.4 Ascorbic acid keeps the iron in the enzymes in the reduced form and
maintains enzyme activity.
Vitamin C also acts as a strong antioxidant by protecting the body from free radicals (oxidants). It is able
to donate a hydrogen atom while still forming a stable free radical form of ascorbate. Many oxidants are
highly reactive due to an unpaired electron, giving them the potential to dangerously interact with
lipids, proteins, and nucleic acids due to the fact that the interactions changes surrounding molecules
into free radicals in a chain reaction fashion.5 Through the oxidation of ascorbate, the free radicals gain
an electron and are neutralized. In addition, vitamin C helps in the stabilizing vitamin E, mainly the αtocopherol.6
Deficiencies of Vitamin C
While most mammals are able to synthesize vitamin C by converting glucose, humans cannot. Humans
lack the last step of the conversion from glucose into vitamin C in which D-mannose, a form of glucose,
is converted into ascorbic acid in the presence of gulonolactone oxidase. Due to this and the fact that
ascorbic acid is water-soluble, humans must constantly take in vitamin C. Humans lack gulonolactone
oxidase due to a mutation of the gene that codes the enzyme.7
4
Rebec, George V. "From Interferant Anion to Neuromodulator: Ascorbate Oxidizes Its Way to Respectability -Electrochemical Methods for Neuroscience -- NCBI Bookshelf." NCBI National Center for Biotechnology
Information. Taylor and Francis Group, LLC, 2007. Web. 15 Aug. 2010.
<http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=frelchem∂=ch9>.
5
Thomas, R. H., Bernards, M. A., Drake, E. E., & Guglielmo, C. G., Changes in the antioxidant activities of seven
herb- and spice-based marinating sauces after cooking, Journal of Food Composition and Analysis (2008),
doi:10.1016/j.jfca.2009.08.019
6
Dietary Antioxidants. World Health Organization, 10 June 2005. PDF.
Giovannoni, James J. "Completing a Pathway to Plant Vitamin C Synthesis — PNAS." Proceedings of the
National Academy of Sciences. 2007. Web. 26 Sept. 2010. <http://www.pnas.org/content/104/22/9109.full>.
7
North Hills Preparatory
Theory of Knowledge
Ms. Biela
With mild deficiencies of ascorbic acid, the connectives tissues of the body weaken, leading to joint
pains, poor wound healing, easy bruising, and a weakened immune system. Severe deficiencies cause
scurvy, causing loosened teeth, swollen gums, and bleeding of the skin in mild cases, while severe cases
can cause edema, ulcerations, and death.8 Lack of ascorbic acid causes difficulties in bone growth or
vascular tissues, possibly leading to anemia.
Recommended Intake
The average daily requirement for adults over the age of 19 years is 45 mg/day, with pregnant or
lactating women needing 55 and 70 mg/day, respectively. Children under the age of 10 years need
anywhere from 25-35 mg/day, while adolescents from ages 10 to 19 need 40 mg/day.9
Cooking Methods
Cooking methods can be classified into dry or moist categories. Moist cooking involves water, while dry
cooking occurs in the absence of water.10 Based on literature, moist methods do not maintain ascorbic
acid as well as dry cooking methods due to ascorbic acid’s water-soluble nature.11 Because I grew up
exposed to one type of cooking (sautéing), and my family has recently become interested in health, I
decided to investigate the different kinds of cooking that are common in the society that we live in as
compared to what type of cooking I am used to. Therefore, the cooking methods I will investigate are
sautéing, microwaving, roasting, grilling, and deep-frying.
8
World Health Organization. Vitamin C
World Health Organization. Vitamin C
10
Briggs, Taste of Home Cookbook: Timeless Recipes from Trusted Home Cooks.
11
Lesková, Emília, Jana Kubíková, Eva Kovácikvá, Martina Kosická, Janka Porubská, and Kristína Jolcíková. "Vitamin
Losses: Retention during Heat Treatment and Continual Changes Expressed by Mathematical
Models." Journal of Food Composition and Analysis (2006): 252-76. ScienceDirect. Web. 25 Feb. 2010.
9
North Hills Preparatory
Theory of Knowledge
Ms. Biela
Introduction
The history of Spain up until the establishment of Castilian as the official Spanish
language can be split into three parts: rule by the Romans and Visigoths, rule by the Muslims,
and the Reconquista, which began the establishment of the Christian empire (Pharies 23). At the
time of Muslim rule, Spain was a hodgepodge of different languages. In addition to introducing
Arabic, which “contributed several thousands of words to the Hispano-Romance vocabulary”
(Pharies 37) to the Iberian Peninsula, the Muslim invasion split the Visigoth Empire
linguistically into small areas in which different varieties of Hispano-Romance were spoken. The
Reconquista unified Spain linguistically; Castilian became the dominant language of Spain and
the official Spanish. The rise of Castilian and the rise of a Spanish, Christian identity fed off
other during the Reconquista, where Spain expelled Muslims and Jews, and also coincided with
the rise of Spain as an empire.
From the perspective of someone living during Muslim-ruled Spain, it would seem odd
that the Castilian language, an isolated and peripheral dialect during the Muslim rule, would
become the dominant language spoken by a majority of the Peninsula after the Reconquista.
During the Reconquista, this dialect spread from the outskirts of northern Spain towards the
south and replaced the provincial languages throughout the Iberian Peninsula. In these areas
where Castilian became dominant, languages such as Aragonese and Leonese totally vanished
and were definitively superseded by Castilian. On the other hand, more prominent languages
such as Catalan and Portuguese, although weakened by the spread of Castilian, survived (Penny
17).
What were the primary factors that contributed to and limited the proliferation of
Castilian during the Reconquista, and to what extent did these factors contribute to and limit the
proliferation of Castilian? Castilian’s displacement of the other Ibero-Romance languages can be
contributed to four factors. These are Castilian’s religious neutrality, Castilian’s literary
standardization that other Ibero-Romance languages did not have, nationalism associated with
the language, and its status as the language of the reconquerers of Toledo, the capital of the
Visigoths. Geographical barriers, however, limited Castilian’s spread through the Iberian
Peninsula (Penny 11-15). Also, the established cultural literature of other languages prevented
Castilian from completely displacing these languages (Pharies 37-44).
North Hills Preparatory
Theory of Knowledge
Ms. Biela
II. Introduction
The literary vampire has entertained the masses for centuries. From Bram Stoker’s infamous
Dracula to Stephenie Meyer’s Edward Cullen, this character has been presented by authors in a variety
of lights. The past several years have witnessed a surge in vampire media extending not only to books
and movies, but also to television shows, magazines, and general merchandise. The popularity of the
literary vampire has not simply risen; it has soared. This leads some to wonder: why now?
The answer lies in the vampires themselves, or, rather, in how they are presented. Authors
through the years have shifted in their portrayals of the literary vampire, depicting the vampires with
increasingly human traits. This shift has reinvented the vampire as a character, allowing authors more
creative scope and inspiration. This trend is studied through the works by three authors from different
time periods: J. Sheridan LeFanu, Anne Rice, and John Ajvide Lindqvist. Analysis of these authors’
portrayals of the literary vampire helps in understanding the growth of the literary vampire through
the works Carmilla by Sheridan LeFanu, Interview with the Vampire by Anne Rice, and Let Me In by
John Ajvide Lindqvist.
The vampires studied are LeFanu’s Carmilla, Rice’s Claudia, and Lindqvist’s Eli. They are
nineteen, five, and twelve years of age, respectively. Additional characters may be referenced;
their relations to the vampires are included in the footnotes. The settings of Carmilla, Interview
with the Vampire, and Let Me In are listed in order as follows: Styria, a rural part of Austria;
western and eastern Europe; and Blackeberg, a suburb of Stockholm. Styria is historically
Catholic, most of Europe during the novel’s time period is Christian, and Blackeberg is notably
free of any religious influences. The term “Vampire” in the essay may be used in place of
“literary vampire.”
North Hills Preparatory
Theory of Knowledge
Ms. Biela
B: Introduction
Achievement level
0
1
2
This criterion assesses the extent to which the introduction makes clear how the
research question relates to existing knowledge on the topic and explains how the
topic chosen is significant and worthy of investigation.
Descriptor
Little or no attempt is made to set the research question into context. There is little or
no attempt to explain the significance of the topic.
Some attempt is made to set the research question into context. There is some
attempt to explain the significance of the topic and why it is worthy of investigation.
The context of the research question is clearly demonstrated. The introduction
clearly explains the significance of the topic and why it is worthy of investigation.