From the Holy See

MESSAGE OF HIS HOLINESS
POPE BENEDICT XVI
FOR THE CELEBRATION OF THE
WORLD DAY OF PEACE

1 JANUARY 2007

THE HUMAN PERSON, THE HEART OF PEACE

1. At the beginning of the new year, I wish to extend prayerful good wishes for peace to Governments, leaders of nations and all men and women of good will. In a special way, I invoke peace upon all those experiencing pain and suffering, those living under the threat of violence and armed aggression, and those who await their human and social emancipation, having had their dignity trampled upon. I invoke peace upon children, who by their innocence enrich humanity with goodness and hope, and by their sufferings compel us all to work for justice and peace. Out of concern for children, especially those whose future is compromised by exploitation and the malice of unscrupulous adults, I wish on this World Day of Peace to encourage everyone to reflect on the theme: The Human Person, the Heart of Peace. I am convinced that respect for the person promotes peace and that, in building peace, the foundations are laid for an authentic integral humanism. In this way a serene future is prepared for coming generations.

The human person and peace: gift and task

2. Sacred Scripture affirms that “God created man in his own image, in the image of God he created them; male and female he created them” (Gen 1:27). As one created in the image of God, each individual human being has the dignity of a person; he or she is not just something, but someone, capable of self-knowledge, self-possession, free self-giving and entering into communion with others. At the same time, each person is called, by grace, to a covenant with the Creator, called to offer him a response of faith and love that no other creature can give in his place(1). From this supernatural perspective, one can understand the task entrusted to human beings to mature in the ability to love and to contribute to the progress of the world, renewing it in justice and in peace. In a striking synthesis, Saint Augustine teaches that “God created us without our aid; but he did not choose to save us without our aid(2).” Consequently all human beings have the duty to cultivate an awareness of this twofold aspect of gift and task.

3. Likewise, peace is both gift and task. If it is true that peace between individuals and peoples—the ability to live together and to build relationships of justice and solidarity—calls for unfailing commitment on our part, it is also true, and indeed more so, that peace is a gift from God. Peace is an aspect of God's activity, made manifest both in the creation of an orderly and harmonious universe and also in the redemption of humanity that needs to be rescued from the disorder of sin. Creation and Redemption thus provide a key that helps us begin to understand the meaning of our life on earth. My venerable predecessor Pope John Paul II, addressing the General Assembly of the United Nations on 5 October 1995, stated that “we do not live in an irrational or meaningless world... there is a moral logic which is built into human life and which makes possible dialogue between individuals and peoples(3) .” The transcendent “grammar”, that is to say the body of rules for individual action and the reciprocal relationships of persons in accordance with justice and solidarity, is inscribed on human consciences, in which the wise plan of God is reflected. As I recently had occasion to reaffirm: “we believe that at the beginning of everything is the Eternal Word, Reason and not Unreason(4).” Peace is thus also a task demanding of everyone a personal response consistent with God's plan. The criterion inspiring this response can only be respect for the “grammar” written on human hearts by the divine Creator.

From this standpoint, the norms of the natural law should not be viewed as externally imposed decrees, as restraints upon human freedom. Rather, they should be welcomed as a call to carry out faithfully the universal divine plan inscribed in the nature of human beings. Guided by these norms, all peoples —within their respective cultures—can draw near to the greatest mystery, which is the mystery of God. Today too, recognition and respect for natural law represents the foundation for a dialogue between the followers of the different religions and between believers and non-believers. As a great point of convergence, this is also a fundamental presupposition for authentic peace.

The right to life and to religious freedom

4. The duty to respect the dignity of each human being, in whose nature the image of the Creator is reflected, means in consequence that the person can not be disposed of at will. Those with greater political, technical, or economic power may not use that power to violate the rights of others who are less fortunate. Peace is based on respect for the rights of all. Conscious of this, the Church champions the fundamental rights of each person. In particular she promotes and defends respect for the life and the religious freedom of everyone. Respect for the right to life at every stage firmly establishes a principle of decisive importance: life is a gift which is not completely at the disposal of the subject. Similarly, the affirmation of the right to religious freedom places the human being in a relationship with a transcendent principle which withdraws him from human caprice. The right to life and to the free expression of personal faith in God is not subject to the power of man. Peace requires the establishment of a clear boundary between what is at man's disposal and what is not: in this way unacceptable intrusions into the patrimony of specifically human values will be avoided.

5. As far as the right to life is concerned, we must denounce its widespread violation in our society: alongside the victims of armed conflicts, terrorism and the different forms of violence, there are the silent deaths caused by hunger, abortion, experimentation on human embryos and euthanasia. How can we fail to see in all this an attack on peace? Abortion and embryonic experimentation constitute a direct denial of that attitude of acceptance of others which is indispensable for establishing lasting relationships of peace. As far as the free expression of personal faith is concerned, another disturbing symptom of lack of peace in the world is represented by the difficulties that both Christians and the followers of other religions frequently encounter in publicly and freely professing their religious convictions. Speaking of Christians in particular, I must point out with pain that not only are they at times prevented from doing so; in some States they are actually persecuted, and even recently tragic cases of ferocious violence have been recorded. There are regimes that impose a single religion upon everyone, while secular regimes often lead not so much to violent persecution as to systematic cultural denigration of religious beliefs. In both instances, a fundamental human right is not being respected, with serious repercussions for peaceful coexistence. This can only promote a mentality and culture that is not conducive to peace.

The natural equality of all persons

6. At the origin of many tensions that threaten peace are surely the many unjust inequalities still tragically present in our world. Particularly insidious among these are, on the one hand, inequality in access to essential goods like food, water, shelter, health; on the other hand, there are persistent inequalities between men and women in the exercise of basic human rights.

A fundamental element of building peace is the recognition of the essential equality of human persons springing from their common transcendental dignity. Equality on this level is a good belonging to all, inscribed in that natural “grammar” which is deducible from the divine plan of creation; it is a good that cannot be ignored or scorned without causing serious repercussions which put peace at risk. The extremely grave deprivation afflicting many peoples, especially in Africa, lies at the root of violent reactions and thus inflicts a terrible wound on peace.

7. Similarly, inadequate consideration for the condition of women helps to create instability in the fabric of society. I think of the exploitation of women who are treated as objects, and of the many ways that a lack of respect is shown for their dignity; I also think —in a different context—of the mindset persisting in some cultures, where women are still firmly subordinated to the arbitrary decisions of men, with grave consequences for their personal dignity and for the exercise of their fundamental freedoms. There can be no illusion of a secure peace until these forms of discrimination are also overcome, since they injure the personal dignity impressed by the Creator upon every human being(5).

The “ecology of peace”

8. In his Encyclical Letter Centesimus Annus, Pope John Paul II wrote: “Not only has God given the earth to man, who must use it with respect for the original good purpose for which it was given to him, but man too is God's gift to man. He must therefore respect the natural and moral structure with which he has been endowed(6).” By responding to this charge, entrusted to them by the Creator, men and women can join in bringing about a world of peace. Alongside the ecology of nature, there exists what can be called a “human” ecology, which in turn demands a “social” ecology. All this means that humanity, if it truly desires peace, must be increasingly conscious of the links between natural ecology, or respect for nature, and human ecology. Experience shows that disregard for the environment always harms human coexistence, and vice versa. It becomes more and more evident that there is an inseparable link between peace with creation and peace among men. Both of these presuppose peace with God. The poem-prayer of Saint Francis, known as “the Canticle of Brother Sun”, is a wonderful and ever timely example of this multifaceted ecology of peace.

9. The close connection between these two ecologies can be understood from the increasingly serious problem of energy supplies. In recent years, new nations have entered enthusiastically into industrial production, thereby increasing their energy needs. This has led to an unprecedented race for available resources. Meanwhile, some parts of the planet remain backward and development is effectively blocked, partly because of the rise in energy prices. What will happen to those peoples? What kind of development or non-development will be imposed on them by the scarcity of energy supplies? What injustices and conflicts will be provoked by the race for energy sources? And what will be the reaction of those who are excluded from this race? These are questions that show how respect for nature is closely linked to the need to establish, between individuals and between nations, relationships that are attentive to the dignity of the person and capable of satisfying his or her authentic needs. The destruction of the environment, its improper or selfish use, and the violent hoarding of the earth's resources cause grievances, conflicts and wars, precisely because they are the consequences of an inhumane concept of development. Indeed, if development were limited to the technical-economic aspect, obscuring the moral-religious dimension, it would not be an integral human development, but a one-sided distortion which would end up by unleashing man's destructive capacities.

Reductive visions of man

10. Thus there is an urgent need, even within the framework of current international difficulties and tensions, for a commitment to a human ecology that can favour the growth of the “tree of peace”. For this to happen, we must be guided by a vision of the person untainted by ideological and cultural prejudices or by political and economic interests which can instil hatred and violence. It is understandable that visions of man will vary from culture to culture. Yet what cannot be admitted is the cultivation of anthropological conceptions that contain the seeds of hostility and violence. Equally unacceptable are conceptions of God that would encourage intolerance and recourse to violence against others. This is a point which must be clearly reaffirmed: war in God's name is never acceptable! When a certain notion of God is at the origin of criminal acts, it is a sign that that notion has already become an ideology.

11. Today, however, peace is not only threatened by the conflict between reductive visions of man, in other words, between ideologies. It is also threatened by indifference as to what constitutes man's true nature. Many of our contemporaries actually deny the existence of a specific human nature and thus open the door to the most extravagant interpretations of what essentially constitutes a human being. Here too clarity is necessary: a “weak” vision of the person, which would leave room for every conception, even the most bizarre, only apparently favours peace. In reality, it hinders authentic dialogue and opens the way to authoritarian impositions, ultimately leaving the person defenceless and, as a result, easy prey to oppression and violence.

Human rights and international organizations

12. A true and stable peace presupposes respect for human rights. Yet if these rights are grounded on a weak conception of the person, how can they fail to be themselves weakened? Here we can see how profoundly insufficient is a relativistic conception of the person when it comes to justifying and defending his rights. The difficulty in this case is clear: rights are proposed as absolute, yet the foundation on which they are supposed to rest is merely relative. Can we wonder that, faced with the “inconvenient” demands posed by one right or another, someone will come along to question it or determine that it should be set aside? Only if they are grounded in the objective requirements of the nature bestowed on man by the Creator, can the rights attributed to him be affirmed without fear of contradiction. It goes without saying, moreover, that human rights imply corresponding duties. In this regard, Mahatma Gandhi said wisely: “The Ganges of rights flows from the Himalaya of duties.” Clarity over these basic presuppositions is needed if human rights, nowadays constantly under attack, are to be adequately defended. Without such clarity, the expression “human rights” will end up being predicated of quite different subjects: in some cases, the human person marked by permanent dignity and rights that are valid always, everywhere and for everyone, in other cases a person with changing dignity and constantly negotiable rights, with regard to content, time and place.

13. The protection of human rights is constantly referred to by international bodies and, in particular, the United Nations Organization, which set itself the fundamental task of promoting the human rights indicated in the 1948 Universal Declaration. That Declaration is regarded as a sort of moral commitment assumed by all mankind. There is a profound truth to this, especially if the rights described in the Declaration are held to be based not simply on the decisions of the assembly that approved them, but on man's very nature and his inalienable dignity as a person created by God. Consequently it is important for international agencies not to lose sight of the natural foundation of human rights. This would enable them to avoid the risk, unfortunately ever-present, of sliding towards a merely positivistic interpretation of those rights. Were that to happen, the international bodies would end up lacking the necessary authority to carry out their role as defenders of the fundamental rights of the person and of peoples, the chief justification for their very existence and activity.

International humanitarian law and the internal law of States

14. The recognition that there exist inalienable human rights connected to our common human nature has led to the establishment of a body of international humanitarian law which States are committed to respect, even in the case of war. Unfortunately, to say nothing of past cases, this has not been consistently implemented in certain recent situations of war. Such, for example, was the case in the conflict that occurred a few months ago in southern Lebanon, where the duty “to protect and help innocent victims” and to avoid involving the civilian population was largely ignored. The heart-rending situation in Lebanon and the new shape of conflicts, especially since the terrorist threat unleashed completely new forms of violence, demand that the international community reaffirm international humanitarian law, and apply it to all present-day situations of armed conflict, including those not currently provided for by international law. Moreover, the scourge of terrorism demands a profound reflection on the ethical limits restricting the use of modern methods of guaranteeing internal security. Increasingly, wars are not declared, especially when they are initiated by terrorist groups determined to attain their ends by any means available. In the face of the disturbing events of recent years, States cannot fail to recognize the need to establish clearer rules to counter effectively the dramatic decline that we are witnessing. War always represents a failure for the international community and a grave loss for humanity. When, despite every effort, war does break out, at least the essential principles of humanity and the basic values of all civil coexistence must be safeguarded; norms of conduct must be established that limit the damage as far as possible and help to alleviate the suffering of civilians and of all the victims of conflicts(7).

15. Another disturbing issue is the desire recently shown by some States to acquire nuclear weapons. This has heightened even more the widespread climate of uncertainty and fear of a possible atomic catastrophe. We are brought back in time to the profound anxieties of the “cold war” period. When it came to an end, there was hope that the atomic peril had been definitively overcome and that mankind could finally breathe a lasting sigh of relief. How timely, in this regard, is the warning of the Second Vatican Council that “every act of war directed to the indiscriminate destruction of whole cities or vast areas with their inhabitants is a crime against God and humanity, which merits firm and unequivocal condemnation(8).” Unfortunately, threatening clouds continue to gather on humanity's horizon. The way to ensure a future of peace for everyone is found not only in international accords for the non-proliferation of nuclear weapons, but also in the determined commitment to seek their reduction and definitive dismantling. May every attempt be made to arrive through negotiation at the attainment of these objectives! The fate of the whole human family is at stake!

The Church as safeguard of the transcendence of the human person

16. Finally, I wish to make an urgent appeal to the People of God: let every Christian be committed to tireless peace-making and strenuous defence of the dignity of the human person and his inalienable rights.

With gratitude to the Lord for having called him to belong to his Church, which is “the sign and safeguard of the transcendental dimension of the human person”(9) in the world, the Christian will tirelessly implore from God the fundamental good of peace, which is of such primary importance in the life of each person. Moreover, he will be proud to serve the cause of peace with generous devotion, offering help to his brothers and sisters, especially those who, in addition to suffering poverty and need, are also deprived of this precious good. Jesus has revealed to us that “God is love” (1 Jn 4:8) and that the highest vocation of every person is love. In Christ we can find the ultimate reason for becoming staunch champions of human dignity and courageous builders of peace.

17. Let every believer, then, unfailingly contribute to the advancement of a true integral humanism in accordance with the teachings of the Encyclical Letters Populorum Progressio and Sollicitudo Rei Socialis, whose respective fortieth and twentieth anniversaries we prepare to celebrate this year. To the Queen of Peace, the Mother of Jesus Christ “our peace” (Eph 2:14), I entrust my urgent prayer for all humanity at the beginning of the year 2007, to which we look with hearts full of hope, notwithstanding the dangers and difficulties that surround us. May Mary show us, in her Son, the Way of peace, and enlighten our vision, so that we can recognize Christ's face in the face of every human person, the heart of peace!

From the Vatican, 8 December 2006.

Ch. 1 of my Research Proposal

CHAPTER 1: INTRODUCTION

A. Background of the Study

"If a single word had to be chosen to describe the goals of science educators

during the 30-year period that began in the late 1950s, it would have to be

INQUIRY." (DeBoer, 1991, p. 206).

The Inquiry-based approach to teaching science seeks to engage the student in the investigative nature of science. Using this approach, more emphases are placed on the process of gathering information, converting data to scientific knowledge, and using scientific knowledge in the resolution of problems. In an article by Haury entitled, ‘Teaching Science Through Inquiry’ published in 1993, he observed that “some have emphasized the active nature of student involvement, associating inquiry with ‘hands-on’ learning and experiential or activity-based instruction. Others have linked inquiry with a discovery approach or with development of process skills associated with ‘the scientific method.’ Though these various concepts are interrelated, inquiry-oriented instruction is not synonymous with any of them.” In essence, what this approach does is to make the student an active participant in his or her education by learning science the way science is done.

The inquiry-based approach to teaching science takes on a new dimension though, when confined within the framework of a Transformative Science Curriculum like the curriculum adopted at Berea Arts and Sciences High School. In a dissertation proposal that Mr. Aurelio Ramos - the President of BASHS - wrote in 2005, he qualified the Berea Transformative Curriculum as one that “is centered on the learner and has three areas of concentration: Knowledge, character, and service. Transformation occurs as the individual learner moves from where he is – brought there by the level of knowledge acquired in grade school, the qualities and behavior developed in childhood, and the orientation to service (whether or not this exists) learned in his social environment – to where he has the potential to be. In all three areas, education is holistic. Thus, the curriculum content stimulates both analytic (left) and global (right) parts of the brain; values training is incorporated in all subjects; and service becomes a curricular as against wholly an extra curricular part of the academic program.”

The idea behind the integration of an inquiry-based approach to teaching science in the Berea transformative Curriculum is an attempt to provide the curriculum with a concrete platform on which the curriculum’s implementation can take effect. Traditionally, science is taught according to the Pragmatist approach propounded upon by Dewey. Students are made to work out a laboratory exercise that has been pre-designed with procedures that the students can just follow. After the exercise the students are asked what conclusions they can draw out from the activity. These are anticipated conclusions considering that the process of gathering interpretation is packaged by the pre-designed procedures to encapsulate a more or less predictable outcome. There is a gap here between the acquisition of scientific knowledge and the source from which such knowledge has emanated and was processed. To this end, adjustments can be reflected on, such that the students’ transformation is genuinely anchored on the actual practice of science. That is, they learn science through the scientific method.

As both the Inquiry-Based Approach to teaching science and the Berea

Model of Transformative Science Curriculum are recognizably multifaceted and

differently situated, it is considered that inquiry in this regard, which is taken as

an attempt to carry out the teaching of science in a manner with which it is

practiced through the scientific method, may take on a different dimension when

confined in the Transformative Science Curriculum. Thus considered, can the

Inquiry-Based Approach to teaching science - which saw widespread

implementation in the early ‘90s - be implemented and applied to the Berean

experience and still touch on the constructivist models of learning, complemented

to varying degrees by project-based teaching and problem-based instruction?

The key questions subsumed in this proposal are: (1) how can Inquiry-Based

Approach to science teaching be implemented in the framework of a

Transformative Curriculum in Science? (2) what are possible implications that

may arise from its implementation? and (3) how can Inquiry-Based Approach to

teaching science using the Transformative Curriculum translate more effectively

to scientific knowledge?

During the 1990s, a number of science education initiatives were undertaken to

reform high school science teaching to reflect strategies from the latest research and to enable more students to attain a higher level of scientific literacy. (Dean

Goodwin, 1996).

Science can be taught in a wide range of settings, from a regular classroom to a state-of-the-art facility dedicated to science instruction. All of these learning environments, though, should have several common features to facilitate quality science instruction. (Dan Butin, July 2000).

At PSHS, where Science is taught taking into consideration both depth and breadth, laboratory exercises play central role in the educative process and are complemented only by lectures or facilitations. At PSHS, Dewey’s Pragmatist approach defines, for the most part, the teaching of science. And there is no question as to its efficacy on the basis of student achievement. At Berea Arts and Science High School where I work now, much of the PSHS science curriculum is revised and incorporated in its Transformative Curriculum framework. At BASHS, Science is taught following a little of Dewey’s Pragmatist approach and a little of the Progressivist approach.

BASHS is only on its second year of operation. As it is a new school - and the

first of its kind in the country, we are still in the initial stages of conceptualizing

what features – in terms of special course offerings, are necessary to beef up our

curriculum with and with the end-in-view of improving student achievement within

the framework of a Transformative curriculum.

In this proposal, the idea of studying the implications of confining the teaching of science within a Transformative curriculum on student achievement is considered. The idea behind this proposal is that while right-brained students are achieving well in schools for the arts like the Philippine High School for the Arts and that the same level of achievement is noted with left-brained students who are enrolled in science schools like the PSHS, can holistic education for either left-brained or right-brained students, like that being offered at BASHS approximate the same or higher level of achievement?

B. Statement of the Problem

This study seeks to determine whether integrating an inquiry-based approach to teaching transformative science improve the performance of students. Also, this study aims to provide an insight into possible avenues of effectively implementing transformative science and enriching the curriculum. To which end, the following questions are considered: (1) how can Inquiry-Based Approach to science teaching be implemented in the framework of a Transformative Curriculum in Science? (2) what are possible implications that may arise from its implementation? and (3) how can Inquiry-Based Approach to teaching science using the Transformative Curriculum translate more effectively to scientific knowledge?

C. Significance of the Study

If the study is able to show that the integration of an inquiry-based approach to the teaching of science in a transformative curriculum framework results to a significantly higher student achievement and better performance, then new insights may be reintroduced to refine the transformative curriculum of Berea and make it more responsive to the needs of students who are endowed with both logical and global inclinations.

If proved that inquiry-based approach to teaching science is able to complement the Berean transformative curriculum, then students will be benefited hugely first, for the transformation that the curriculum seeks to equip them with in preparation for college life.

D. Scope and Delimitations of the Study

This proposed study touches only on the relationship between an inquiry-based approach to teaching science and the Berea transformative curriculum. The object of this study is to determine whether such relationship impacts significantly on the science performance of the students. As such, this proposal is limited only to the Berean experience with no reference at any attempt to compare the efficacy of an inuiry-based approach to teaching science used in different schools with different curricular offerings.

Atypical Berea

I went to Berea today and found it to be atypical. Of course, the students were not made to report yet. They were asked to make use of the day to rest. They have practically been on a range of activities for the past two weeks or so. Beginning from the concert to the retreat then up to this week's PressCon (for some students). I found Berea atypical not because there were no classes nor is it because I just missed the noise coming from the students' interactions. It is not also because I learned today that TJ broke his lips and lost a tooth. But that would be atypical as well. There's more to it that emanates from a weird feeling - that up to this writing, I just can't figure still. But next time that I do, I will write again about it.

Theory of Nullity

Hi kids... Here is an article that you will find either amusing or amazing. But it gives you a little cerebral stimulation somehow. A certain Dr. James Anderson claims that he has solved a 1200-yr old problem in math that neither Newton nor Pythagoras has solved. He has tried to prove that any number divided by zero is equal to nullity... Nullity is a new term he coined... Read this article and give it a little reflection...

My Research Proposal

RESEARCH PROPOSAL (An Overview)

Michael Anthony B. Mantala

Educ 293 - December 5, 2005

"If a single word had to be chosen to describe the goals of science educators during the 30-year period that began in the late 1950s, it would have to be INQUIRY." (DeBoer, 1991, p. 206).

This research proposal centers on the area of Inquiry-Based Approach to teaching science. This is an approach that seeks to engage the student in the investigative nature of science. Emphasis using this approach is placed more on the process of gathering information, converting data to scientific knowledge, and using scientific knowledge in the resolution of problems. In essence, what this approach does is to make the student an active participant in his or her education by learning science the way science is done. It takes on a new wind though, when confined within the framework of a Transformative Science Curriculum like that adopted at Berea Arts and Sciences High School. In this curriculum, students are trained to be equally adept in both the sciences and the arts. Therefore, the sciences have to be taught in a manner that integrates certain artistic activities like visual arts, music, and creative movements.

As both the Inquiry-Based Approach to teaching science and the Berea Model of Transformative Science Curriculum are recognizably multifaceted and differently situated, it is considered that inquiry in this regard, which is taken as an attempt to carry out the teaching of science in a manner with which it is practiced through the scientific method, may take on a different dimension when confined in the Transformative Science Curriculum. Thus considered, can the Inquiry-Based Approach to teaching science - which saw widespread implementation in the early ‘90s - be implemented and applied to the Berean experience and still touch on the constructivist models of learning, complemented to varying degrees by project-based teaching and problem-based instruction?

The key questions subsumed in this proposal are: (1) how can Inquiry-Based Approach to science teaching be implemented in the framework of a Transformative Curriculum in Science? (2) what are possible implications that may arise from its implementation? and (3) how can Inquiry-Based Approach to teaching science using the Transformative Curriculum translate more effectively to scientific knowledge?

The House of Con-Ass's

I have always believed that hope springs eternal... until today when the con-ass's of the lowest house rammed through our collective throats the despicable and self-serving con-ass resolution to convene the house for cha-cha... these really are the bleak times when even hope is cursed. Albay has just recently been devastated by a super typhoon... And these brilliant con-ass's have this fix-it-all solution to the typhoon victims' misery... to have them dance the cha-cha... Is this not yet the abyss of desperation?

Air Pollution and Chemistry Notes

Hi kids and littluns... Pls find on my multiply site the power point presentation of my lecture on air pollution. This is the lecture file that we failed to open last time because our computers were all bugged. I've also posted some chemistry notes that cover past and future topics in chemistry. I hope it will be of help to all of you. But first, you've got to read them.

Air Pollution

Hi freshies... As I've promised, I have already posted on my multiply blog, the files on air pollution... Do check them out now.

Nobel Prize Announcements

Hi kids and littluns... I want you to read the announcements on this year's winners of the prestigious Nobel Prize.

Notice

Hi April-o and schoolmates... As promised, here is now my multiply site with some berea pics that you can copy for your own multiply site. But pls do browse only on the berea pics, ok.

Hi kids and littluns... What do you think about today's suspension of classes?

The Miracle Of Science

I've come across this very interesting article titled, "The Miracle Of Science". I thought it made a point. Read it and then tell me what you think about it...

Notice

Hi Sophies and Freshies...
Pls. be reminded that your next LTs are scheduled on the week of October 9... Do start studying...

Stem Cell Debate

Hi sophies... i've added a new link, "Science and Theology News" which you can visit to while away a stormy day... click on it and find on the home page an interesting, if not enlightening, debate on stem cell research... happy reading!

Covalent and Ionic Bonds

Berea Arts and Sciences High School
Covalent and Ionic Bonds Problem Set

Notes

Ionic bond – a strong attractive force holding ions together. An ionic bond can
form between two atoms by the transfer of electrons from the valence shell of one atom to the valence shell of the other

Covalent bond – a strong attractive force that holds two atoms together by their
sharing of electrons. These bonding electrons are attracted simultaneously to both atomic nuclei, and they spend part of the time near one atom and part of the time near the other

Electronegativities – the unequal abilities of the atoms to draw bonding electrons
to themselves

Lewis electron-dot formulas – simple representations of the valence-shell
electrons of atoms in molecules and ions and are useful for describing the covalent bonding in substances

Problem Set.

1. For each of the following pairs of elements, state whether the binary compound formed is likely to be ionic or covalent. Give the formula and name of the compound.

a. Sr,O b. C,Br c. Ga, F d. N, Br

2. Give the Lewis formula for the arsenate ion, AsO3-4. Write the formula of lead(II) arsenate.

3. Iodic acid, HIO3, is a colorless, crystalline compound. What is the electron dot formula of iodic acid?

4. Write electron dot formulas for the following:

a. SeOCl2 b. CSe2 c. GaCl-4 d. C2-2

5. Why do most monoatomic cations of the main-group elements have a charge equal to the group number? Why do most monoatomic anions of these elements have a charge equal to the group number minus 8?

6. Describe the formation of a covalent bond in H2 from atoms. What does it mean to say that the bonding electrons are shared by the two atoms?

Nuclear Chemistry

Berea Arts and Science High School
Nuclear Chemistry Notes and Problem Set

Notes
Radioactive decay – the process in which a nucleus spontaneously disintegrates, giving
off radiation

Nuclear bombardment reaction – a nuclear reaction in which a nucleus is bombarded, or
struck, by another nucleus or by a nuclear particle

Types of Radioactive Decay
a. Alpha emission – emission of a 42He nucleus, or alpha particle, from an unstable
nucleus. An example is the radioactive decay of radium-22, written as

22688Ra 22286Rn + 42He

The product nucleus has an atomic number that is two less, and a mass number
that is four less, than that of the original nucleus.

b. Beta emission – emission of a high-speed electron from an unstable nucleus. Beta
emission is equivalent to the conversion of a neutron to a proton.

10n 11p + 0-1e

An example of beta emission is the radioactive decay of carbon-14.

146C 147N + 0-1e

the product nucleus has an atomic number that is one more than that of the
original nucleus. The mass number remains the same.

c. Positron emission – emission of a positron from an unstable nucleus. Positron emission
is equivalent to the conversion of a proton to a neutron.

11p 10n + 01e
d. Electron capture – the decay of an unstable nucleus by capturing, or picking up, an
electron from an inner orbital of an atom. In effect, a proton is changed to a neutron as in positron emission

11p + 0-1e 10n

e. Gamma emission – emission from an excited nucleus of a gamma photon,
corresponding to radiation with a wavelength of about 10-12 m. in many cases, radioactive results in a product nucleus that is in an excited state. Often, gamma emission occurs very quickly after radioactive decay

Metastable nucleus – a nucleus in an excited state with a lifetime of at least one
nanosecond (10-9 s). In time, the metastable nucleus decays by gamma emission. An example is metastable technetium-99, denoted 99m43Tc, which is used in medical diagnosis.

99m43Tc 9943Tc + 00

he product nucleus is simply a lower-energy state of the original nucleus, so there is no change of atomic number or mass number.

Radioactive decay series – a sequence in which one radioactive nucleus decays to a
second, which then decays to a third, and so forth. Eventually, a stable nucleus is reached. For the natural radioactive decay series, this stable nucleus is an isotope of lead.

Particle accelerator – a device used to accelerate electrons, protons, and alpha particles
and other ions to very high speeds.

Cyclotron – a type of particle accelerator consisting of two hollow, semicircular metal
electrodes, called dees (because the shape of a dee resembles the letter D) in which charged particles are accelerated by stages to a higher and higher kinetic energies.

Nuclear force – a strong force of attraction between nucleons that acts only at very short
distances (about 10-15 m)

Problem Set
1. Of the following nuclides, two are radioactive. Which are radioactive and which is
stable?
a. 11850Sn b. 7633As c. 22789Ac

2. Potassium-40 is a naturally occurring radioactive isotope. It decays to calcium-40 by
beta emission. When a potassium-40 nucleus decays by beta emission, it emits one beta particle and gives a calcium-40 nucleus. Write the nuclear equation for this decay.

3. Plutonium-239 decays by alpha emission, with each nucleus emitting one alpha
particle. What is the other product of this decay?

4. Cobalt-60, used in cancer therapy, decays by beta and gamma emission. The decay
constant is 4.18 x 10-9/s. what is the half-life in years?

5. A nuclear power plant emits into the atmosphere a very small amount of krypton-85, a
radioactive isotope with a half-life of 10.76 y. What fraction of this krypton-85 remains after 25.0 y?

Four Questions for EnviSci

Hi sophies… I have here four questions for you… I also have provided the answers which you can reflect on as you prepare for your next exam in envisci…

1. Discuss the fate of energy in terrestrial communities. Discuss it on the perspective of the laws of thermodynamics.

My Answer

The first law of thermodynamics is also referred to as the Law of Conservation of Energy. This law purports that energy is neither created nor destroyed. Implicit to this is the principle that energy is simply transferred from one system to another through various forms. As such, the total energy in the universe is constant and will remain constant ad infinitum.

Ecologically, life on this planet is given to be ultimately driven by radiant energy. The energy coming from the sun is trapped in the chlorophyll pigments of chloroplasts prior to getting converted to chemical energy in the form of ATP’s or adenosine triphosphates. This process takes on the complementary roles of both thylakoidal and stromal reactions of photosynthesis among photoautotrophic organisms. Utilization and assimilation of this energy decreases invariably from one trophic level in the food chain to another trophic level.

Among heterotrophs, chemical energy is released from the food and assimilated in the system through aerobic cellular respiration. This process involves the cytoplasmic reactions of the glycolytic pathway where sugar is broken down into pyruvate molecules and the mitochondrial reactions of the tricarboxylic acid cycle and the electron transport chain. Much of the energy assimilated by organisms are released in the form of heat during cellular respiration. A certain fraction also gets locked in the soil during decomposition. It is noted that only about 10% of the total energy in the organism is passed on to the succeeding organisms occupying higher trophic levels in the food chain. This means that the highest amount of energy is assimilated by the photoautotrophs or chemoautotrophs. This assertion is better understood using the following illustrations.

The energy pyramid is an illustration of energy transfer that is representative of the fate of energy as it flows from one system to another. And in the energy flow, one form of energy gets converted to another form as one organism makes use of it to carry out its metabolic requirements.

Implicit to the First Law of Thermodynamics, the energy that gets passed on from one organism to another is the same energy that originated from the sun. They just have assumed different configurations like heat and come in diminishing concentrations like the 10% Rule illustrated above. No new energy is incorporated in the succeeding trophic levels after the direct assimilation of radiant energy by photosynthetic organisms.

Energy and mass (materials) are related concepts. In Einstein’s famous equation E=mc2, a direct relationship between energy and mass is noted. Implicit to this is the fact that the more mass a certain body has, the more energy it possesses. Unlike energy however which is linear, mass can go through cycles. At a certain point, the material that makes up an abiotic system may, at another point make up a living system.
Geographically, different topologies and latitudinal locations on the surface of the earth are invariably heated up. This implies that some areas receive more sunlight than do other areas. This uneven distribution of sunlight effects to a certain extent, different climatic conditions that bring about different effects on the other factors that affect climate like rainfall, humidity, and wind systems. Such differences in the abiotic component of the environment entail differences in primary productivity in different ecosystems. Here is another way of looking at energy flow as pertaining to the amount of primary productivity in ecosystems.

From the premises raised, it can be inferred that the ecosystems with highest average net Primary Productivity are the estuaries and the tropical rainforests. Logically, they are also the ecosystems that exhibit the highest species diversity.

2. Explain the top-down and bottom-up controls of food webs. Identify the factors related to each of these controls.

My Answer

The top-down and bottom-up controls of food webs pertain to the interaction of consumer (top-down) and resource (bottom-up) effects on species composition and abundance. The objectives of identifying these controls are to investigate how species and populations are distributed within food webs and what factors determine biomass and productivity within a trophic level.

It is noted that the biomass of organisms in food webs based on primary productivity is controlled simultaneously by resources (bottom-up) and consumers (top-down).

It is a matter of consequence that the population of certain species is checked either by predatory feeding relationships with other organisms that they share a common functional group with or by the availability (abundance or scarcity) of resources in their respective ecospaces.

In a study conducted by Power and Dietrich of the UC Berkeley titled, “Food Webs in River Networks”, they described food webs as complex adaptive systems with diverse components that are linked by flows and interactions. It was Robert Paine however, who pointed out that “energy flows from more basal resources up to consumers at higher trophic positions (bottom-up) while chains of population control link consumers to the resource populations they regulate or limit (top-down), if these consumers are not suppressed by their own predators.

Given these assertions, how then does a food web illustrate the flow of energy across trophic levels? Power and Dietrich offered that conditions, resource fluxes and biotic interactions all play pivotal role in the determination of functional food chains in food web systems, the length of energy flow paths and the controls on both. They have identified these controls as dependent on two environmental factors: Productivity/Efficiency and Disturbance/Stability; and one evolutionary factor – that of design constraints.

Power and Dietrich argued that in terms of productivity or efficiency, functional food chains should “lengthen as fluxes of limiting resources or energy to food webs increase, or as consumers increase their efficiency of resource capture or conversion”. In terms however, of disturbance or stability, it should follow that functional food chains are shorter in situations that are characterized by frequent disturbance. Conversely, a more stable situation should be able to host a longer functional food chain. Lastly, on the evolutionary factor of design constraints, they argued that “it is impossible for evolution to build a Pterodactyl predator”, for example, because an organism large enough to subdue one could not fly to catch it. While at this, it is important to note that the length of functional food chains in complex adaptive systems is directly related to the length of energy flow paths.

3. What is a “keystone species”? How does its absence affect the stability of the community where it is once found?

My Answer

Robert D. Davic in his correspondence with the Ohio Environmental Protection Agency titled, “Linking Keystone Species and Functional Groups: A New Operational Definition of the Keystone Species Concept”, redefined the concept of keystone species as one that “is held to be a strongly interacting species whose top-down effect on species diversity and competition is large relative to its biomass dominance within a functional group.” The premise behind this redefinition is anchored on the fact that from 1969, when the term “keystone species” was first defined by Paine up to the present, the concept has gone through linguistic metamorphosis to a point of controversy.

At issue in the keystone species controversy is whether abundance of the keystone relates significantly to impact within its functional group. This is on top of the controversy on how to measure abundance and impact, and where to delineate between abundance and impact.

In 1969 when the concept was first coined, Paine defined keystone species as “a species of high trophic status whose activities exert a disproportionate influence on the pattern of species diversity in a community”. But because it is a given ecological tenet that species in a keystone set are invariably interrelated to each other, it becomes difficult to tell which species is the keystone species. In the case for example of the mycorrhizae and certain species of trees, it is clear that the keystone species is the mycorrhiza – in spite of its low trophic status – for upon whose death depends the survival of the trees.

In Davic’s redefinition of the concept of keystone species, he noted the narrow food-web context that Paine used in his definition of keystone species and provided a divergent line of thought. His redefinition presupposes that the influence of a keystone species should be considered in light of the species’ biomass relative to its functional group. This implies that a keystone species is not necessarily the dominant species or the species of higher trophic status within a biotic community. Further, this also implies that a keystone species may be considered from across a wider width of feeding niches. But while at this, Davic’s premise however, does not preclude nor deviate from the predator-prey relationship model of Paine.

Regardless however of the blurry line that divides between biomass and impact, it is clear that for a species to qualify as a keystone species, it’s presence within a functional group in an ecospace must have an influence on the population of other species that belong to the same functional group and that such influence is taken to mean as a large top-down effect on biodiversity and competition relative to the keystone species’ biomass within a functional group.

Thus said, it is for the same argument that the impact of a keystone species’ absence to the stability of a community must be gleaned.

In a study conducted by the University of Washington on the delicate balance between and among marine organisms inhabiting the coastal areas extending from Baja, California to Alaska, they have figured a species of starfish as a prospective keystone species whose removal from the community may lead to disruption of ecological equilibrium there. The starfish Pisaster ochracues is said to influence negatively on the population of other marine organisms that it shares a functional group with through predatory relationships. If the starfish is taken out of its functional group, it is noted that a skewed population growth of other species, some of which are secondary predators, ensues as a consequence. Such trend in the other species is not noted as a result of their absence.

In Costa Rica, a species of shore crabs is noted to feed primarily on tree saplings. There is however, a tree sapling that is distasteful to the shore crabs. This tree sapling is what eventually grows in number and dominates the entire landscape. The proliferation of these trees makes the landscape an open-space forest that caters to a host of local animals like howler monkeys, tapirs, and coatis. If the shore crabs were to be taken out of this community, the open space forest will revert back to the level of heterogeneity of the off-coast forest and may threaten the extinction of the said local animals with particular preference to the open-type forest.

The examples cited above illustrate two typical influence of keystone species on other species within a functional group. The case of the starfish typifies what a top predator does to skew the population trend negatively. The case of the shore crabs on the other hand typifies an indirect check on the population of the other organisms within its functional group through drastic changes in the community.

4. Discuss the two ecological theories of island communities. Explain supporting evidences of these theories.

My Answer

The concept of “Island” can be broadly defined as patches of land that are, to some extent, isolated from the mainland. In the classical sense, islands are terrestrial habitats that are isolated from continental habitats either by freshwater or marine areas that represent a certain degree of geologic barrier to dispersal between the island and the mainland.

There are two ecological theories of island communities: the Habitat Diversity Theory and the Equilibrium Theory.

The Equilibrium Theory centers on the balance between the rate at which allochthonous organisms (species new to the island) colonize the islands and the rate at which autochthonous organisms (species that are residents/native to the island) go extinct on the islands.

There are three basic characteristics to the Equilibrium Theory of Island Biogeography: species-area relationship; species-isolation relationship; and species turnover. It is given that a larger area works to the advantage of resident species because there will be more resources available for them and therefore, intraspecific competition is less likely. But eventually, when other organisms migrate to the place, the resident species will have to compete with the new species for available resources. To mitigate the effects of intraspecific competition among the resident species, either dispersal ensues among them or niche differentiation is resorted to. In the case of turnover, a study conducted by Jared Diamond on the turnover of birds on California Channel Islands, established that “turnover tends to be lower on larger islands and increases with generation time of the organisms”. This follows the logic that a larger area will play host to a more diverse collection of resources that can be utilized by a wider array of species. Moreover, in an experimental defaunation conducted on arthropods by Wilson and Simberloff, where they exterminated an entire population of arthropods, it was established that turnover tends to increase with rapid colonization that followed the killing of the arthropods. This illustrates the likely scenario that when populations leave a place either for reasons of dispersal or extinction, they leave behind their respective niches which eventually gets assumed by colonizing species that share the same environmental niche.

The Habitat Diversity Theory on the other hand, hubs on the “suitability of islands as habitats for various species”.

In a study conducted by Ricklefs and Lovette titled, “The Roles of Island Area, per se and Habitat Diversity in the Species-Area Relationships of Four Lesser Antillean Faunal Groups”, they have established strong positive correlations between area and habitat diversity and between elevation and habitat diversity. It was observed that large elevated islands tend to host a more diverse habitat that matches species richness among faunal groups. These correlations however applied differently to other species included in their study like certain species of butterflies and bats. Species richness observed in some species of butterflies and certain groups of bats tend to be correlated to strong habitat-diversity effects. These species are said to exhibit “high degrees of habitat specialization”, large population sizes, high fitness rate, life-cycles that include a resistant resting stage that reduces vulnerability to catastrophic extinction and such other adaptive biological traits.

In other words, habitat diversity is rendered appropriate to a certain group of species only if it translates to species richness. But studies point out that while there may exist strong correlations between habitat diversity and habitat area, and between habitat area and species richness on account of resource availability, the same strong correlation cannot be applied to habitat diversity and species richness. Certain match between geographic features and biological traits must first be established as indeed resulting to or may result to species richness.

Ricklef and Lovette have established that these “taxon-specific differences demonstrate that both biological characteristics of organisms and geographical features of island groups” control the relative influence of island area and habitat diversity to differences in species richness.

References

Bak, P. 1996. How nature works: the science of self-organized criticality.
Springer-Verlag, New York, New York, USA.
Berger, W. H., and F. L. Parker. 1970. Diversity of planktonic Foraminifera in
deep sea sediments. Science 168:1345-1347
Primack, Richard B. Essentials of Conservation Biology
Ricklefs, R. E. et al., Island Biology Illustrated by the Land Birds of Jamaica
The Keystone-Species Concept in Ecology and Conservation," L. Scott Mills,
Michael E. Soule, and Daniel F. Doak, BioScience
"The Keystone Cops Meet in Hilo," Mary E. Power and L. Scott Mills, TREE

Notice

Hi sophies... I've just uploaded my lectures for EnviSci next week. Be sure to check them out at Mikology Correspondence under Sir Miko's Uploads before Tuesday. There are 6 new files for EnviSci in all...

Subic Escape

Hi kids and littluns.... I've posted some pics from our Subic Field Trip.... Check them out! You can also visit Flickr and use "berea pics" as your search words.... And there's Justin's Collection as well... some really good pics there!

Two Versions on the Central Dogma

If you find these illustrations quite small, you can click here to access the reference texts on the Central Dogma of Molecular Biology....

The Water Cycle

Cellular Respiration

Photosynthesis

The Carbon Cycle

Linkage Problems

Solving Linkage Problems

Tip: The most important part is to determine which progeny resulted from parental type gametes, and which from recombinant types.

In a plant, leaf color and leaf shape are controlled by two linked genes. Leaves of the wild-type plant are red. A recessive mutation in this gene causes white leaves. Wild-type leaves are pointed, and a recessive mutation in this gene causes them to be smooth. The following crosses were performed:

pure breeding white, smooth X pure breeding wild type

gives F1: all red, pointed

Now, the next cross:

red, pointed X pure breeding white, smooth

gives F2:
40 white, curly
36 red, pointed
10 white, pointed
14 red, curly

What is the recombination frequency between the gene for color and for shape?

Solution:

First, assign genotype symbols. Since the mutations are recessive to wild-type, use + for the wt allele and lower case letters for the mutant alleles:
w = recessive color allele for white
s = recessive shape allele for smooth
The first cross is: X giving progeny: (red, pointed)

The second cross is: X giving progeny where the genotypes can be unambiguously interpreted from their phenotypes.
The parental gamete types will be: and , resulting in [white, smooth] and [red, pointy] progeny.
The recombinant gamete types will be: and , resulting in [white, pointy] and [red, smooth] progeny.

Therefore, the recombination frequency is:

Mendelian Genetics

Sophies, why don't you give this a try...

Solving Problems: Practicing Crosses

A wild population contains red-eyed and white-eyed flies. A scientist crosses two white-eyed flies and gets all white eyed progeny (cross 1). She crosses two red eyed flies and gets all red-eyed progeny (cross 2). When she crosses a different pair of red-eyed flies, she gets 22 white eyed progeny and 78 red-eyed progeny (cross 3). Explain her observations, giving the most probable genotypes of the parents and progeny of each cross.

- try making a model where white is dominant to red. Appropriate symbols would be:

W - dominant white allele

w - recessive red allele

White eyed flies are either Ww or WW, red eyed flies must be ww.

- cross 1: to get all white progeny, the parents must be WW and WW. The data are compatible with this model.

- cross 2: ww X ww would give all ww - red eyed. This is also compatible with the data.

- cross 3: ww X ww would give no white eyed progeny

This is not compatible with the data. Therefore white cannot be dominant.

- try making a model where red is dominant to white. Appropriate symbols would be:

R - dominant red allele

r - recessive white allele

White eyed flies are rr, red flies are RR or Rr.

- cross 1: to get all white progeny, the parents must be rr and rr. OK.

- cross 2: as above, if the parents were RR and RR, all the progeny would be RR - red. This is also OK.

- cross 3: RR X RR would give all red progeny

RR X Rr would give all red progeny

Rr X Rr would give 75% red, 25% white - this prediction matches the data.

Therefore, the model that red is dominant to white fits the cross data best.

cross 1: rr X rr gives only rr progeny

cross 2: RR X RR gives only RR progeny

cross 3: Rr X Rr gives 75% R_ (RR or Rr), 25% rr

For problems with more than one trait (if the problem involved red and white eyes and short and long wings, for instance), treat each trait independently (work with eye color alone by counting red-eyed/short-winged and red-eyed/long-winged as simply red-eyed) to break the problem into two smaller problems.

GenSci Competency No. 4

Competency No. 4
Second Quarter

Name: Date:
Directions: Read the selection carefully and answer the items that follow.

The Selection

Metallic Meal

By Incognito

Aurisaur is a golden lizard that is autochthonous or native to the planet Metallandia. It is a gentle creature that feeds mainly on Cupripterans which are winged copper-toned insects that resemble a dragonfly. Both the Aurisaur and the Cupripterans live under an Argentophyte tree whose silver leaves serve as food to the winged creatures. The winged creatures in turn provide fertilizer to the tree through their copper droppings. One morning in autumn, as the Aurisaur clings from one branch of the Argentophyte to another, a beastly Wolframicarpus predator bird arrived and attacked the golden lizard. The predator bird has a tungsten beak that readily reacts and melts with the golden secretions of the dying Aurisaur. As the tungsten bird gobbled on the golden lizard, little did it know that it has already lost its beak and has thereby lost its lethal predatory weapon. The feasting did not escape the attention of a radioactive leaden snake called Plumboa. Without the bird’s weapon, it proved to be vulnerable to the precision-ambush of the snake. The Tungsten bird yielded its last gasp of metallic air to the leaden snake. But the Plumboa is not without its weakness. Its fissile constitution eventually gave way to the reaction caused by the copper droppings of the starving Cupripterans. The autumn season has shed off almost all the leaves of the Argentophyte leaving very little for the winged creatures to eat, and making their copper droppings most reactive. Ultimately, Natribacters - the bacteria that metabolize sodium - have then started decomposing the Plumboa.

I. List all the alien organisms mentioned in the selection. (12 pts)

II. Diagram a complete food chain for the selection. (12 pts)

III. Illustrate energy assimilation by the organisms using an energy pyramid. (12 pts)

IV. In what type of biome did the story take place? Substantiate your answer. (10 pts)

V. Which organisms exhibited a mutualistic relationship? Substantiate your answer (6 pts)

VI. Which organism(s) exhibited predatory instincts? (6 pts)

VII. Which organism(s) occupied the first trophic level? (5 pts)

VIII. What nutritive function did the Natribacters perform in the food chain? (5 pts)

IX. Assuming that 112,233 KJ of energy has been assimilated by the Wolframicarpus, determine the amount of energy invariably assimilated by the other organisms in the food chain. (10 pts)

Start answering here…

Life History Patterns

Explain the concept of life history. What are its various components?

My Answer:

The concept of life history refers to the time spanning the initial origination of species that are now extinct and takes into consideration the process of change in species that are still extant, either through evolutionary mechanisms or ecological influences or through the indispensable interaction between the two forces. For the most part however, life history pertains to the story of how life first came into existence on this planet and how life went through the ramifications of evolution to bring about the level of complexity that characterizes living systems at present. Of course, the assertions inherent in the history of life based on evolutionary claims, take validity on account of the premises of evolution.

Peter J. Bryant of the University of California at Berkeley, in his book titled, “Biodiversity and Conservation”, described the concept of life history as “a complicated series of geological, climatic and biological events that have led up to the present day situation.” He speculated that the history of life and for that matter, the history of global biological diversity is best seen in marine habitats on account of the premise that the first life forms emerged from the bodies of water.

In support of Bryant’s presupposition, the geologic time scale describes the dawn of life as having started from the pre-cambrian phagocytic unicells. Henceforth, it is believed that this primitive life form went through the different evolutionary mechanisms to bring about the level of complexity characteristic of the many species that survived the tests of time.

The underlying premise here is that different species have evolved different structural mechanisms to enable them to shift their reproductive strategies in such a way that they are better able to cope with ecological pressures arising from scarcity of available resources or uncertainty of existing environmental conditions. The species’ continuous interaction with their environment created in them, the needed changes in their gene-pool that either will prepare their generation for changes in their ecospaces or will evolve new generations with new levels of fitness.

Begon in his book titled, “Ecology: Individuals, Populations, and Communities”, enumerated seven of the more apparent components of life history patterns: size, growth rate, pattern of development, reproduction, resource capture and allocation, and dispersal. The underlying premise here is that, variations to this components will have corresponding trade-offs if only to make the individual members of a species better able to utilize available resources or to compete for such resources.

In the case of the trade off between size and fitness for example, the energy used to compensate for an increase in the size of organisms is traded off with the energy that is thought to compensate for reproductive functions. This is consistent with the r/K Selection Theory. According to this theory, organisms that have capitalized on the advantages of reproduction (r-selection) will have to bear a multitude of offprings even if in the end, only quite a few of them survive. Organisms that have adapted to this evolutionary predisposition will have to reproduce at a fast-tracked rate and at the soonest time possible in their life cycle. This is an apparent trade off in terms of fitness relative to organisms that have capitalized on body size. This evolutionary predisposition takes on the advantage of bearing “fitter” offsprings (K-selection) even if to trade off the advantage that comes with reproducing in multitude.

In the case of developmental patterns, it is presupposed that the phenotypic attributes of individuals in a population must establish an “appropriateness of fit” with the environment that they will grow into later on in life to make them cope better by adapting a function that corresponds to the habitat’s intrinsic stresses and pressures. Phenotypic plasticity figures significantly in this component of life history. Through phenotypic plasticity, a genotype common among individual organisms of the same species will have variable phenotypic expressions. This is achieved in part through the physiologic response of the organism to fluctuations in environmental conditions and in part through the behavioral match that an organism will have to adapt itself to in order to accommodate a particular environmental setting.

Advisory

Hi kids and littluns... be reminded of your sched for next week:

Sept. 19 - Envi Sci Long Test
Sept. 20 - Gen Sci Long Test
Sept. 21 - Bio Long Test

Do study hard and God bless you in your studies....

Phenotypic Plasticity

What is phenotypic plasticity? How does it affect life history patterns?

My Answer:

Carl D. Schlichting of the University of Connecticut defined Phenotypic Plasticity as “the property of a genotype to produce different phenotypes when exposed to different environments. Phenotypic Plasticity can occur in the morphology and behavior of organisms.”

Thus defined, phenotypic plasticity recognizes individual organisms as complex “genetic and epigenetic” systems that respond according to the different stresses and constraints that figure in the dynamics of a continuously evolving environment. Because no super adapted species exist relative to the heterogeneity of environmental systems, the premise behind phenotypic plasticity is that, certain “incompleteness” in the genotype of organisms is compensated by variations in phenotypic expressions arising from the same genotype. In other words, phenotypic plasticity enables many organisms at different stages of growth and development to adaptively match trait expression to particular environmental settings.

How then does phenotypic plasticity affect life history patterns? It must be recognized that phenotypic plasticity is but a factor in a myriad of other factors that are central to the determination of life history patterns. Therefore, where phenotypic plasticity figures in life history patterns, its function should be taken as correlative to other evolutionary functions such as speciation, acclimatization, heterochrony, and allometry. Thus said, if phenotypic plasticity comes as a consequence of an organism’s juggling of its options to match existing environmental settings through variable expression of phenotypes, life history patterns should logically reflect these variations in the distribution of organisms across all possible geologic ecospaces. Following is an illustration of a trade off in the larvae of echinoids. (At left is an echinoid larva that was starved. Compared to the well-fed larva on the right that developed new adult structures, the starved larva developed feeding structures instead like the elongated ciliated arms.

Kathleen K. Smith of Duke University asserted in her article titled, “Heterochrony Revisited: The Evolution of Developmental Sequences”, the idea that evolutionary innovations can occur at any stage in the life history of organisms. She anchored this premise on the observation that a certain amount of change in developmental timing can produce evolutionary change. Having thus correlated developmental change – which in some cases may constitute phenotypic plasticity, to evolutionary change – which for the most part is about a survey of life history patterns, it bears noting where and how phenotypic plasticity can in fact, effect change in organisms belonging to the same taxonomic category, if not the same phyletic origin.

Stephen Jay Gould of Harvard University recognizes the idea “that morphological diversity among taxa arises from diversity underlying developmental processes responsible for ‘building’ morphological features.” Paul Magwene of Yale University in his article titled, “Comparing Ontogenetic Trajectories Using Growth Process Data”, substantiated this assertion on the correlation between developmental change and diversity among taxa by analyzing variation in phenotypic plasticity, its effect on morphology and behavior, and its influence in ontogenetic trajectories.

The aforesaid studies have shown that life history patterns may have in fact been driven by phenotypic plasticity through the mechanisms of heterochronic developmental changes. But as to whether phenotypic plasticity taken as a process independent of developmental mechanisms have direct influence on life history patterns remains uncertain. This is because phenotypic plasticity is largely on account of an organism’s response to a certain environmental stress or constraint but does not imply change in the genetic makeup of the organism. As such, it may be implied that no amount of genetic modification is introduced into the gene-pool of the population. Therefore, this hardly qualifies as a veritable evolutionary mechanism for organismic change.

Phenotypic Plasticity’s significance figures prominently in the discourse on life history patterns. It may even be made a discourse unto itself that is independent of the discourse in evolution. Is phenotypic plasticity then, to a certain level of validity, an alternative to evolution in mapping out life history patterns? Dr. Lee Spetner has this to say: “A change in phenotype in the fossil record is recognized as evolution. There is no way to tell from the fossils whether the observed changes in continuous records were caused by variation appearing in the genotype or only in the phenotype”

In other words, it cannot be deduced from the premises of evolution whether or not “apparent transitional features of a fossil are truly the results of changes in the genotype (i.e. random mutations)” or are simply the consequence of certain species adapting to varied environmental settings as a result of phenotypic plasticity.