Ecosystems are composed of interacting biotic and abiotic factors. Biotic factors include species, habitats, populations, and communities. Autotrophs produce their own food through photosynthesis, while heterotrophs consume food obtained from other organisms or matter. Food chains and food webs show the transfer of energy and matter between trophic levels. As the human population increases, concentrations of greenhouse gases like carbon dioxide and methane are also increasing, intensifying the natural greenhouse effect and potentially disrupting ecosystems through impacts like rising sea levels and changes in climate and photosynthesis rates. Population growth can be described using concepts like carrying capacity, exponential growth phase, mortality, and transition phase. Evolution occurs through mechanisms like genetic variation,

1. 5.1
Ecosystems are made up of the interacting biotic and abiotic factors composed of the following: The
biotic factors are composed of the following: species, habitat, population, community. Autotroph
produce their food. Heterotroph’s consume it. Heterotrophs are made up of consumer, detrivores,
saphrotrophs. Auto’s are eaten by consumer, which are eaten by other consumers, and so on until the
decomposers decompose the consumer back into the base components which are sucked up by the
autotrophs again. A single line tracing animal consumption is called a food chain. Multiple food chains
make a food web. Light is the original source of all energy. Not even close to 100% efficient. 90% of the
energy is lost per trophic level. Plant to consumer is one trophic level. That consumer to another is
another trophic level. Energy enters and leaves, nutrients recycled. Saphrotrophs recycle the nutrients.
The abiotic factors are made up of the: hydrosphere ,atmosphere, lithosphere,. They interact with the
biosphere at the pedosphere
Topic 5.2
As humans population and activity increases the amount of concentrations of Carbon dioxide, Nitrous
dioxide and methane. All three of those gases have high potential for absorbing heat and climate
experts are concerned that gases are intensifying earth’s natural green house effect to a point where it
is being thrown off balance. As global temperature changes these things might happen
An increase in Photosynthetic rates
Changes in climate with varying effects on ecosystems
Extinction of certain species
Melting glaciers
Rise in sea levels which can cause flooding in some coastal areas
Topic 5.3
Population growth is described with Plateau Phase, Exponential Phase, Mortality, and Transition Phase.
Plateau Phase- Is also the carrying capacity. Carrying Capacity is the maximum size a population can
hold. Mortality is greater than natality.
Exponential Phase- Rate of population growth is rapid as recourse is abundant and competition and
mortality are low.
Morality- The death rate
Transition Phase- Natality is greater than Mortality but the difference begins to tighten. Birth rate is also
decreasing.

2. Random Sample- When you take a sample from an environment in different areas to take account of
different population which is accounted randomly to make sure every specie gets accounted for a fair
estimate of population.
-Capture and Release Method: Allows animals to be captured and marked in order to find out
the population. It is a method that can be done mathematically when you take into account of the
marked animals the first and second time to compare how many are actually marked for the second
sample. The Calculation is the # of animals initially caught, marked and released multiplied by the total
# of animals caught 2md time, and divided by the 3 of marked animals in the 2nd sample, to allow the
estimate of the population size in an environment.
-Quadrant Method- Used for plant population can be done quickly by gathering areas and
counting the # of plants and multiplying the area of the multiple quadrants. Accurate estimates can be
obtained more quickly than if every plant in population is counted.
Chapter 5.4- Evolution
Definition: The process of cumulative change in the heritable characteristics of a population
This was developed by Charles Darwin.
Evidence for Evolution:
Fossil records-
Life existed 500 million years ago, very different from today
Fish fossils have been found in rocks

3. Top predators today are bears, orca, whales, big cats, wolves; all of which did not exist
before dinosaurs
Sharks, cockroaches and ferns did not have identifiable forms in fossil form
Artificial selection:
Breeding helps scientists understand evolution. Animals such as cattle, horses, dogs, sheep,
pigeons provide records of recent changes of heritable changes
From breeding hundreds of times, all heritable traits could be found and later combined in
combinations that did not exist before; this is all driven by human force.
Homologous anatomical structures:
Structures that are similar between several different species can also help us show that we had
original ancestry. For example whales have a similar fin structure to human hands.
Mechanisms for evolution-
Too many offspring:
Because of the vast number of offspring being produced, resources would become limited and
only the best would survive. Organisms would make adaptations to become better and gain
access to those resources easier to help them survive.
Variation with populations:
When animals sexually reproduce, billions of different combinations can be made thus
facilitating variation such as different beaks or larger feathers.
Variation and success:
The amount of variation caused relates to how successful those variations were. If the variations
caused success those variations will continue to occur and be kept in the gene pool.
Causes of variety-
Mutations in DNA
Sexual reproduction promoting variation in species
DNA replication can cause DNA to slightly change in certain areas.
In sexual reproduction, meiosis and fertilization cause variation because DNA is exchanged and
only have of each organism’s DNA is contributed.
Natural selection:

4. Overproduction of offspring results in variation in order to keep the organism alive for
generations. Things such as size are affected.
Organisms with poor traits do not survive and do not pass their genes out, in a way
perfecting the organism from poor traits
Individuals with good adaptations survive longer and pass on their genes
Those organisms gather more resources and have a better chance of reaching maturity
Examples:
Bacteria become resistant to certain antibiotics from going through treatments. Certain resistant
bacteria survive and thus replicate and create a population of antibiotic resistant bacteria.
Topic 5.5
Taxonomy: is a practice and science of classification
Kingdom, phylum, class, order, family, genus, species
Species: group of organisms that can interbreed and produce fertile offspring
Homo sapien (first genus, then
species. Genus capitalized,
species lower cased. Italicized)