The document discusses key concepts in ecology. It defines ecology as the scientific study of interactions between organisms and their environment. It notes that ecology is an interdisciplinary field that includes biology and earth science. It also describes several core ecological concepts - ecosystems are composed of interacting living and non-living parts; species have various relationships including competition and cooperation; nutrients cycle through biotic and abiotic components.

1. BY: Ayushi – Mukherjee
CLASS: XI A

2. What is ecology?
. Ecology is the scientific analysis and study of interactions among
organisms and their environment. It is an interdisciplinary field that
includes biology and Earth science. Ecology includes the study of
interactionsorganisms have with each other, other organisms, and
with abiotic components of their environment. Topics of interest to
ecologists include the diversity, distribution, amount , and number of
particular organisms; as well as cooperation and competition between
organisms, both within and among ecosystems. Ecosystems are
composed of dynamically interacting parts including organisms, the
communities they make up, and the non-living components of their
environment. Ecosystem processes, such as primary production,
pedogenesis, nutrient cycling, and various niche construction
activities, regulate the flux of energy and matter through an
environment.

3. ENVIROMENT
• The biophysical environment is the biotic
and abiotic surrounding of an organism or
population, and consequently includes the
factors that have an influence in their
survival, development and evolution. The
biophysicalenvironment can vary in scale
from microscopic to global in extent.

4. DIFFRENCE B/W BIOTIC AND
ABIOTIC
• Based on their origin, natural resources are classified into
1)Biotic: Biotic resources are obtained from the biosphere (living
and organic material), such as forests, animals, birds, and fish and
the materials that can be obtained from them. Fossil fuels such
as coal and petroleum are also included in this category because
they are formed from decayed organic matter.
2)Abiotic: Abiotic resources are those that come from non-living,
non-organic material. Examples of abiotic resources include land,
fresh water, air and heavy metals including ores such
as gold, iron, copper, silver, etc.

5. NATURAL RESOURCES
• Natural resources occur naturally within environments that exist relatively
undisturbed by mankind, in a natural form.
• Some of them are essential for our survival while most are used for satisfying
our wants.
• They are present abundantly in nature.
• Natural resources are materials and components that can be found within the
environment. Every man-made product is composed of natural resources. A
natural resource may exist as a separate entity such as fresh water, and air, as
well as a living organism such as a fish, or it may exist in an alternate form
which must be processed to obtain the resource such as metal ores, oil, and most
forms of energy.

6. Organism
Population
Community
Biosphere
Ecosystem

7. Biosphere- The biosphere is the global sum of all
ecosystems. It can also be termed the zone of life on
Earth, a closed system (apart from solar and cosmic
radiation and heat from the interior of the Earth), and
largely self-regulating.

8. ECOSYSTEM-An ecosystem is a community of living
organisms in conjunction with the nonliving components of
their environment (things like air, water and mineral soil),
interacting as a system.

9. Community- several interacting
populations that inhabit a common
environment and are interdependent.

10. Population-a group of organisms of
one species living in the same place
at the same time that interbreed
and compete with each other for
resources (ex. food, mates, shelter)

11. Organism- any unicellular or
multicellular form exhibiting all of the
characteristics of life, an individual.
•The lowest level of organization

12. FEEDING RELATIONSHIP
• The three basic ways in which organisms get food are as
producers, consumers and decomposers.
• Producers (autotrophs) are typically plants or algae. Plants
and algae do not usually eat other organisms, but pull
nutrients from the soil or the ocean and manufacture their
own food using photosynthesis. For this reason, they are
calledprimary producers. In this way, it is energy from the
sun that usually powers the base of the food chain. An
exception occurs in deep-sea hydrothermal ecosystems,
where there is no sunlight. Here primary producers
manufacture food through a process

13. • called chemosynthesis.
• Consumers (heterotrophs) are species that cannot manufacture their
own food and need to consume other organisms. Animals that eat
primary producers (like plants) are called herbivores. Animals that eat
other animals are calledcarnivores, and animals that eat both plant and
other animals are called omnivores.
• Decomposers (detritivores) break down dead plant and animal material
and wastes and release it again as energy and nutrients into the
ecosystem for recycling. Decomposers, such as bacteria and fungi
(mushrooms), feed on waste and dead matter, converting it into
inorganic chemicals that can be recycled as mineral nutrients for plants
to use again.

14. Symbiotic Relationships
Symbiosis- two species living together
3 Types of
symbiosis:
1. Commensalism
2. Parasitism
3. Mutualism

15. Commensalism-
In ecology, commensalism is a class of relationships
between two organisms where one organism benefits
from the other without affecting it. This is in contrast
with mutualism, in which both organisms benefit from
each other, amensalism, where one is harmed while the
other is unaffected, and parasitism, where one benefits
while the other is harmed.

16. Parasitism-
Parasitism is a non-mutual symbiotic relationship between species, where one
species, the parasite, benefits at the expense of the other, the host.
Traditionally parasite referred primarily to organisms visible to the naked
eye, or macroparasites (such as helminths). Parasitenow includes
microparasites, which are typically smaller, such as protozoans,viruses and
bacteria. Some examples of parasites include the plants mistletoe and
cuscuta, and animals such as hookworms.

17. • Mutualism is the way two organisms of different species
exist in a relationship in which each individual benefits
from the activity of the other. Similar interactions within a
species are known as co-operation. Mutualism can be
contrasted with interspecific competition, in which each
species experiences reduced fitness, and exploitation, or
parasitism, in which one species benefits at the expense of
the other. Mutualism is a type of symbiosis. Symbiosis is a
broad category, defined to include relationships that are
mutualistic, parasitic, orcommensal. Mutualism is only
one type.

18. Trophic Levels
The trophic level of an organism is the position it occupies in a food chain.
The word trophic derives from the Greek τροφή (trophē) referring to food
or feeding. A food chain represents a succession of organisms that eat
another organism and are, in turn, eaten themselves. The number of steps an
organism is from the start of the chain is a measure of its trophic level. Food
chains start at trophic level 1 with primary producers such as plants, move
to herbivores at level 2, predators at level 3 and typically finish with
carnivores or apex predators at level 4 or 5. The path along the chain can
form either a one-way flow or a food "web". Ecological communities with
higher biodiversity form more complex trophic paths.

19. Trophic Levels
Producers- Autotrophs
Primary consumers- Herbivores
Secondary consumers-
small carnivores
Tertiary
consumers-
top carnivores
E
N
E
R
G
Y

22. Trophic Levels
Food chain- simple model that
shows how matter and energy
move through an ecosystem

24. Toxins in food chains-
While energy decreases as it moves up
the food chain, toxins increase in
potency.
•This is called biological magnification
Ex: DDT & Bald Eagles

25. Trophic Levels
Food web- shows all possible
feeding relationships in a
community at each trophic level
• Represents a network of
interconnected food chains

30. NUTRIENT CYCLE
• The nutrient cycle is nature's recycling system. All forms
of recycling have feedback loops that use energy in the
process of putting material resources back into use.
Recycling in ecology is regulated to a large extent during
the process of decomposition. Ecosystems employ
biodiversity in the food webs that recycle natural
materials, such as mineral nutrients, which includes water.
Recycling in natural systems is one of the many ecosystem
services that sustain and contribute to the well-being of
human societies.

31. WATER CYCLE
• The water cycle, also known as the hydrologic cycle or the H2O
cycle, describes the continuous movement of water on, above and
below the surface of the Earth. The mass of water on Earth remains
fairly constant over time but the partitioning of the water into the
major reservoirs of ice, fresh water, saline water and
atmospheric water is variable depending on a wide range of
climatic variables. The water moves from one reservoir to another,
such as from river to ocean, or from the ocean to the atmosphere, by
the physical processes of evaporation, condensation, precipitation,
infiltration, runoff, and subsurface flow. In doing so, the water goes
through different phases: liquid, solid (ice), and gas (vapor).

33. CARBON CYCLE
• The carbon cycle is the biogeochemical cycle by which carbon is exchanged
among the biosphere,pedosphere, geosphere, hydrosphere, and atmosphere of
the Earth. Along with the nitrogen cycleand the water cycle, the carbon cycle
comprises a sequence of events that are key to making the Earth capable of
sustaining life; it describes the movement of carbon as it is recycled and
reused throughout the biosphere.
• The global carbon budget is the balance of the exchanges (incomes and
losses) of carbon between the carbon reservoirs or between one specific loop
(e.g., atmosphere ,biosphere) of the carbon cycle. An examination of the
carbon budget of a pool or reservoir can provide information about whether
the pool or reservoir is functioning as a source or sink for carbon dioxide.
• The carbon cycle was initially discovered by Joseph Priestley and
Antoine Lavoisier, and popularized by Humphry Davy.

35. NITROGEN CYCLE
• The nitrogen cycle is the process by which nitrogen is converted between its
various chemical forms. This transformation can be carried out through both
biological and physical processes. Important processes in the nitrogen cycle
include fixation, ammonification, nitrification, and denitrification. The
majority of Earth's atmosphere (78%) is nitrogen, making it the largest pool of
nitrogen. However, atmospheric nitrogen has limited availability for biological
use, leading to a scarcity of usable nitrogen in many types of ecosystems. The
nitrogen cycle is of particular interest to ecologists because nitrogen
availability can affect the rate of key ecosystem processes, including
primary production and decomposition. Human activities such as fossil fuel
combustion, use of artificial nitrogen fertilizers, and release of nitrogen in
wastewater have dramaticallyaltered the global nitrogen cycle.

36. NITROGEN FIXATION
• Atmospheric nitrogen must be processed, or "fixed", to be used by
plants. Some fixation occurs in lightning strikes, but most fixation is
done by free-living or symbiotic bacteria known as diazotrophs. These
bacteria have the nitrogenase enzyme that combines gaseous nitrogen
with hydrogen to produce ammonia, which is converted by the
bacteria into other organic compounds. Most biological nitrogen
fixation occurs by the activity of Mo-nitrogenase, found in a wide
variety of bacteria and some Archaea. Mo-nitrogenase is a complex
two component enzyme that has multiple metal-containing prosthetic
groups

37. Atmospheric
nitrogenLightning
Nitrogen
fixing bacteria
Ammonium
Nitrification
by bacteria
Nitrites Nitrates
Denitrification
by bacteria
Plants
Animals
Decomposers
Nitrogen Cycle