Additions to reading 16th edition Ecology and Connections.
In 3-1 “What is Ecology” Under the section “In Cells Are the Basic Units of Life” add the information
about the characteristics of life, which seems odd that a section about life doesn’t include. Just add it
at the end of this short section
What is Life? All life shares a set of basic characteristics that enable growth, survival, and reproduction:
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Living organisms are made of cells that have highly organized internal structures and functions.
The cell is the basic unit of life. Each cell is bounded by an outer membrane or wall and contains
genetic material (DNA) and other structures needed to perform its life functions.
Living organisms have characteristic types of deoxyribonucleic acid (DNA) molecules in each cell.
DNA is the stuff of which genes, the basic units of heredity, are made. These self-replicating
molecules contain the instructions for making new cells and for assembling proteins and other
molecules each cell needs for survival and reproduction.
Living organisms capture and transform matter and energy from their environment to supply
their needs for survival, growth, and reproduction. The complete set of chemical reactions that
carries out this role in cells and organisms is called metabolism.
Living organisms maintain favorable internal conditions, despite changes in their external
environment through homeostasis, if not over stressed.
Living organisms perpetuate themselves through reproduction: the production of offspring by
one or more parents. Asexual reproduction generally occurs by simple cell division and is
common in single-cell organisms. In this case, the mother cell divides to produce two identical
daughter cells that are clones or replicas of the mother cell. Sexual reproduction occurs in
organisms thar produce offspring by combining sex cells or gametes (such as ovum and sperm)
from both parents. This produces offspring that have combinations of traits from each of their
parents. Sexual reproduction usually gives the offspring a greater chance of survival under
changing environmental conditions than the genetic clones produced by asexual reproduction.
Living organisms adapt to changes in environmental conditions through the process of evolution.
Evolution involves changes in the genetic composition of organisms through time. When
evolution continues long enough, it can result in new species. Ongoing processes of extinction
and evolution, in response to environmental changes over millions of years, have led to the
diversity of life-forms found on the earth today. This biodiversity, a vital part of earth capital,
sustains life and provides the genetic raw material for adaptation to future environmental
changes.
In 3-2 “What Keeps Us and Other Organisms Alive?” in the first section ”The Earths Life-Support
System has Four Major Components” make sure you look at and take some notes on Fig 3-6 there is
significant material in the figure not explained in the text.
Also in 3-2 “What Keeps Us and Other Organisms Alive?” in the section “Three Factors Sustain Life on
Earth” after the information there also include notes on the following:
First in the section that describes the cycling of nutrients our curriculum needs to differentiate between
different nutrient types. Some elements (such as carbon, oxygen, hydrogen, nitrogen, phosphorus,
sulfur, potassium, calcium, magnesium, and iron) called macronutrients, are needed in fairly large
amounts, whereas others (such as sodium, zinc, copper, chlorine, and iodine), called micronutrients, are
needed in small or even trace amounts.
In real life there are two types of systems: closed and open. In a closed system, energy – but not
mater—is exchanged between the system and its environment. The Earth is a closed system that can
receive energy from the sun but loses essentially no matter into space and receives almost negligible
amounts of matter from space (mostly cosmic dust and occasional meteorites that strike the Earth).
Because the Earth is closed to significant inputs of matter, essentially all of the nutrients used by
organisms are already present on Earth and must be recycled again and again for life to continue.
In an open system, such as a living organism, both matter and energy are exchanged with the
environment. You are an open system. You take matter (air, water, food) and energy into your body
and transform and use these inputs to stay alive and healthy. At the same time, you put waste matter
(urine, feces, dead skin cells, exhaled air, evaporated perspiration) and low-quality heat into the
environment. You and other organisms remain alive and healthy only if the input of certain types of
matter and energy is balanced by an output of certain types of matter and energy.
Thus, where life on Earth as a whole is maintained by energy flow and matter cycling, the life of an
individual organism is maintained by the processes of energy flow and matter flow.
In 3-3 “What Are the Major Components of an Ecosystem?” in the section “Ecosystems on Living and
nonliving components” make sure you look at and take some notes on Fig 3-10 there is significant
material in the figure not explained in the text.
On page 59 of the file in 3-3 “What Are the Major Components of an Ecosystem?” in the section
“Producers and Consumers are the Living Components of Ecosystems” there is good information on
decomposers and detritivores but I wanted to add a piece of information that might help clarify the
difference because they are different.
Detritivores (also known as detritus feeders) take detritus or dead organic material into their bodies or
guts and breakdown that material, for example a worm or carpenter ant. Decomposers secret enzymes
and have an external breakdown of dead organic material and perform these tasks on a molecular level.
In section 3-4 “What Happens to Energy in an Ecosystem?” in the section “Energy Flows through
Ecosystems in Food Chains and Food Webs” after the paragraph defining food webs you should add
the following information, there are two types of food webs that are in the AP curriculum the author
left out.
In most ecosystems, energy and nutrients typically move through two interconnected types of food
webs. In grazing food webs, energy & nutrients move from plants to herbivores (grazers), then through
an array of carnivores, and eventually to decomposers. In detrital food webs, organic waste material or
detritus is the major food source, and energy flows mainly from producers (plants) to decomposers &
detritivores. In many terrestrial ecosystems (such as forests) and in aquatic ecosystems (such as streams
and marshes), detrital pathways predominate.