Download Notes - Educast

Environmental Biology
Content
•
Ecology
•
The Fundamental Steps
•
Components Of A Community
•
Energy Flow In An Ecosystem
•
Components Of A Pond Ecosystem
•
Cycling Of Materials
•
Carbon Cycle
•
Water Cycle
•
Nitrogen Cycle
•
Ecological Interdependence
•
External Environment
Ecosystem:
It is a science that deals with the relationships between groups of living things and their
environments.
Fundamental concept of Ecosystem
•
The term habitat refers to the kind of place where an organism normally lives. It includes the
arrangement of food, water, shelter and space that is suitable to meet an organism's needs.
•
Green plants (and some bacteria) are the only organisms that can directly capture the sun's
energy and change it into a form that other organisms can use.
•
Through the process of photosynthesis, plants use sunlight to change carbon dioxide and
water into sugar and oxygen.
•
The oxygen is given off into the air, where it is available to other organisms including humans.
•
Other organisms then eat the plants, or eat organisms that eat plants, and in doing so
indirectly gain the benefit of the sun's energy to run their bodies.
It takes a lot of grass to support one rabbit, and many rabbits to support one hawk(a diurnal bird of
prey). As a consequence, there are many, many green plants on the Earth, fewer animals that eat
plants, and even fewer animals that eat animals; this is known as the energy pyramid.
Components of a community
Producers: Photosynthesizing organisms
Producers are any kind of green plant. Green plants make their food
by taking sunlight and using the energy to make sugar. The plant uses
this sugar, also called glucose to make many things, such as wood,
leaves, roots, and bark. Trees are examples of producers.
Consumers: any organism that can’t make its own food
Consumers have to feed on producers or other consumers to survive.
Deer are herbivores, which means that they only eat plants
(Producers). Bears are another example of consumers. Black bears are
omnivores and scavengers (feeds on dead animal and plant material
present in its habitat), Black Bears will eat blueberries, bugs, acorns(a
large tree which bears acorns and typically has lobed deciduous
leaves. Oaks are dominant in many north temperate forests and are
an important source of durable timber used in building, furniture, and
(formerly) ships.), and many kinds of nuts.
Consumers: any organism that can’t make its own food
Consumers have to feed on producers or other consumers to survive.
Deer are herbivores, which means that they only eat plants
(Producers). Bears are another example of consumers. Black bears are
omnivores and scavengers (feeds on dead animal and plant material
present in its habitat), Black Bears will eat blueberries, bugs, acorns(a
large tree which bears acorns and typically has lobed deciduous
leaves. Oaks are dominant in many north temperate forests and are
an important source of durable timber used in building, furniture, and
(formerly) ships.), and many kinds of nuts.
Ecosystems
•
Examples of a biotic components are temperature, average
humidity, topography and natural disturbances.
Temperature
•
Temperature varies by latitude; locations near the equator are
warmer than are locations near the poles or the temperate
zones.
A biotic components
Humidity
• Humidity influences the amount of water and moisture in the air
and soil, which, in turn, affect rainfall.
Topography
• Topography is the layout of the land in terms of elevation.
A biotic components
Water
Plant and animal habitats vary from entirely aquatic environments to
very dry deserts. Water is essential for life and all organisms depend
on it to survive in especially desert areas.
Water requirements of plants
Plants can be classified into 3 groups according to their water
requirements:
A biotic components
Hydrophytes
Hydrophytes are plants which grow in water e.g. water-lilies and
rushes.
Mesophytes
Mesophytes are plants with average water requirements e.g. roses ,
sweet peas . Roses are mesophytes
Xerophytes
Xerophytes are plants which grow in dry environments where they
often experience a shortage of water e.g. cacti and often
succulents.Aloes are xerophytes
Biotic Components
The biotic components of an ecosystem are the life forms that inhabit
it. The life forms of an ecosystem aid in the transfer and cycle of
energy. They are grouped in terms of the means they use to get
energy. Producers such as plants produce their own energy without
consuming other life forms; plants gain their energy from conducting
photosynthesis via sunlight.
Consumers exist on the next level of the food hain. There are three
main types of consumers: herbivores, carnivores and omnivores.
Herbivores feed on plants, carnivores get their food by eating other
carnivores or herbivores, and omnivores can digest both plant and
animal tissue
Energy flows in ecosystem
1. The energy flow in the ecosystem is unidirectional. Sun is the
main source of energy.
2. Some part of the energy is used by the producers or autotrophs.
3. They not only make their food but also for the other organisms.
4. They absorb the energy from sun and convert into the chemical
energy. They release oxygen.
5. The organic compounds release energy during respiration. The
organic compounds which are formed play an important role in
the building of bodies and help in the release of energy which
helps to overcome the entropy.
6. There are herbivorous which feed on the plants. They are not
able to eat the whole of plant.
7. There is a non usage of food energy which passes into the
decomposers.
8. The phytoplankton in the aquatic food chain is mainly eaten by
the herbivore.
9. The herbivores act on the ingested food which gets aggregated.
It releases the energy later on and helps in the respiration.
10.
The energy lost in this case is not much and the remaining
is used to overcome the entropy.
Energy flows in ecosystem
11.
The primary carnivore feed on the herbivore which is
feeded by the secondary carnivore. In the food chain when the
food is broken energy is released. The small part of energy is
utilized and so the rest of energy is dissipated.
Pond Ecosystem
The pond is a small body of standing water and the pond ecosystem
is complex interactions between its biotic and abiotic components.
Abiotic component of pond ecosystem
Abiotic component of pond ecosystem are: Environmental factors:
light, temperature, water The edaphic factors: Soil Inorganic
Components are: O2, CO2, N2, nitrates, phosphates, carbonates
etc. Organic components are: carbohydrates, proteins, amino acids,
fats, nucleic acids
Producers
The producers are the aquatic green plants, which may be divided
into two groups.
Microphytes (phytoplanktons) : They are microscopic autotrophs,
which fix solar energy. eg. Spirogyra, Zygnema, Volvox,
Oedogonium.
Macrophytes : They are large plants, which manufacture complex
food. They are of following types
Submerged plants: those, which are submerged in water, are
submerged plants eg Hydrilla and Utricularia
Floating plants: those, which float freely in water surface, are called
floating plants eg. Pistia, Nymphea and Azolla
Immerged plants: those, which are rooted but emergent, are called
immerged plants eg Ranunculus, Sagittaria and Typha .
Consumers
The consumers are those heterotrophic organisms, which consume
producers as food. They are also following types
Primary consumers: These herbivorous animals depend upon
autotrophic organisms such as microscopic plant eaters or
zooplanktons, Mollusks, Beetles, Cyclops, and Daphnia etc.
Secondary consumers: These are primary carnivores, which depend
upon herbivorous animals for food eg. Insects, fishes, frogs, crab
etc.
Tertiary consumers: These are second grade of carnivores. They feed
upon plants or animals (secondary consumer) therefore are called
omnivores. for eg. Large fishes and frogs.
Top consumers: These are third grade of carnivores, which feed
upon primary, secondary, and tertiary consumers eg. Water snake,
water birds etc.
Decomposers
These include heterotrophic microorganisms such as bacteria fungi,
which break down the organic complex food from dead producers
and consumers into simple inorganic compounds made available to
the producers.
Pond stratification: On the basis of water depth, light penetration
and types of vegetation and animals there may be three zones
Littoral zone: This is the shallow water region, which is usually
occupied by rooted plants. This region is warmer and rich in oxygen.
In this region, there is high intensity of light penetration so called
epolomentic zone
Limnetic Zone: this is the central part of pond upto where there is
the penetration of effective light water level, oxygen content and
tem[perature varies time to time in this zone. here the light
penetration is lesser so called thermocline.
Profundal Zone: This is the deep-water region where there is no
effective light penetration. There the microscopic plants and
decomposers are present.
Cycling of Materials in Ecosystems
 Cycles within an Ecosystem
 Water Cycle
 Carbon Cycle
 Phosphorous and Nitrogen Cycle
 Almost everything within an ecosystem is recycled.
 Water, carbon, nitrogen & phosphorus pass from the nonliving
environment to living organisms & then back to the
environment.
Water Cycle
Water is the most important, non-living component of the
ecosystem.
Nonliving cycle: involves condensation, precipitation, &
evaporation.
Living cycle: involves plants in a process called transpiration.
Nonliving portion:
Water vapor, as it cools, condenses in the form of clouds and falls
to the Earth’s surface as precipitation (as rain, snow, etc)
Then water evaporates (turning from a liquid to a gas) and reenters the atmosphere
Living portion:
Water is absorbed by roots of plants
After passing through the plant, the water evaporates from the
leaves in a process called transpiration.
Carbon Cycle
Carbon dioxide in the air (or dissolved water) is used by
photosynthesizing plants, algae and bacteria as raw material to build
organic molecules.
What does that mean? Autotrophs take in carbon dioxide to help
make food in order to grow and survive
Involves:
Respiration (breathing where CO2 is a by product)
Combustion (burning)
Erosion (limestone)
Phosphorous and Nitrogen Cycle
• You need phosphorous and nitrogen to build proteins and
nucleic acids (part of DNA)
• Since more organisms are unable to use nitrogen gas (N2),
nitrogen fixing bacteria bind nitrogen with hydrogen to form
ammonia (NH3)
• What does that mean? We need nitrogen, but we can’t use pure
nitrogen gas (N2) so certain bacteria convert N2 into a usable
forms (ammonia)
• Stages:
• Assimilation (absorption of nitrogen gas,N2, by plants)
• Ammonification (production of ammonia, NH3, by bacteria
during organism decay)
• Nitrification (production of nitrate from ammonia)
• Denitrification (conversion of nitrate to N2)
Types of interactions
Symbiosis
• Symbiosis describes the way in which two different species living
together in the same community, interact with each other over a
long time period. This can occur in the form of parasitism,
mutualism or commensalism.
• Parasitism: Parasitism is when the one species benefits or gains
something from the relationship and the other species is harmed
in some way. The host may die in some interactions.
In some interactions between individuals from
different species, the one species benefits, while the other one is
unaffected by the relationship.
Unlike parasitism, in commensalism the other
species is not harmed or benefited in any way.
Mutualism
Mutualism occurs between any two species where both of the
individuals benefit from the interaction. Both species gain something
from the other, so we can say it is mutually beneficial.
Competition
Feeding:
Different species in an ecosystem are related and interact
when one species can use the other species as a food
source. For example, in predator-prey relationships, the
one species (predator) will hunt another species (prey).
Extreme Environments
Extreme environments are places where"normal" life finds it hard to survive.
That doesn't mean that there isn't any life in extreme environments. Certain
creatures can live and grow in extreme environments. Scientists have a
special name for creatures that live in extreme environments. They are
called "extremophiles".
What kinds of environments are "extreme"? Some
extreme environments that you may know about
are deserts, mountain peaks, caves, and frozen
places like the Arctic and Antarctic. Some
environments are very hot or very cold, extremely dry,
or both. Other extreme environments are filled with
acids, are blasted with radiation, are under high
pressure, or are tough places for most living things in
various other ways. Some environments are extreme in more than
one way. Most deserts are both hot and dry. The Dry Valleys
in Antarctica are very cold and dry. Some hot springs are acidic as well as
Being nearly boiling hot. Hydrothermal vents on the sea floor don't receive
any sunlight, spew out hot water filled with harsh chemicals, and are
weighed down by the crushing pressure of the deep oceans.