Organisms and their environment (chapter 13)

Ecology meaning

The study of interactions among organisms and their environment.

• The living or Biotic Environment comprises of all living things that an organism interacts with.

• The populations in a community live independently.

• A change in one population would affect the other populations in the community.

• The equilibrium in a community is like a web, breaking a single strand will affect the whole system.

Habitat

place where an organism lives.

Population

A group of organisms of the same species living in a particular habitat

Community

All the population of organisms living and interacting with one another in a particular habitat.

Ecosystem

A community of organisms interacting with one another and its abiotic environment.

Producers

• Organisms which convert light energy from the sun into chemical energy. The chemical energy is used to synthesize carbohydrates from water and carbon dioxide.

• By the process of Photosynthesis in Chloroplasts

Consumers

• Organisms that are not able to photosynthesize, depends on producer/other consumers

• Obtain energy by feeding on organisms

Decomposers

• Obtain energy by feeding on decaying organic matter

• The decomposition process releases inorganic nutrients, such as carbon and nitrogen for nutrient cycling.

Food chain

A series of organisms, beginning with the producer, through which energy and nutrients are transferred.

Trophic level

The position an organism occupies in a particular food chain

Non-cyclic energy flow in an ecosystem

• the sun is the main energy source in an ecosystem

• Light energy is converted to chemical energy by producers via photosynthesis.

• Energy from producers are passed from one trophic level via feeding.

• The transfer of energy in an ecosystem is non-cyclic

• Energy is lost to the environment and heat as it floes through the ecosystem.

Pyramid of number

• allows the comparison of the number of organisms presently in each trophic level at a particular time

• Constructed based on the number of organisms at each trophic level

• Limitation: Does not take into consideration the size/mass of the organisms & if the organism is at adult/young stage

A pyramid of Number can be inverted:

• Organisms in one trophic level are parasitic on organisms of another trophic level

• many small organisms feed on a large organism

Pyramid of Biomass

• Allows the comparison of Biomass of organisms presently in each trophic level at a particular time

• Constructed based on the Dry Mass of organisms in each at a particular time

• Use oven to dry/remove the water constantly, leaving only organic material.

• This representation is more accurate than the Pyramid of numbers as the size and mass of organisms are considered.

Limitations:

• The organisms needs to be killed to obtain the pyramid of biomass.

• It needs to be constructed at a particular time.

Pyramid of Energy

• Energy is lost to the environment as energy is transferred from one trophiuc level to another.

Energy is lost to the environment:

• as heat during respiration

• in uneaten body parts

• through undigested material and excretory products

• Due to inefficient transfer of energy between trophic levels, it limits the amount of energy in a trophic level, hence limiting the number of organisms in that trophic level.

• Hence there is insufficient energy to support a longer food chain

Carbon cycle

• Carbon is constantly removed from and released into the atmosphere in the form of carbon dioxide

• Hence, the concentration of carbon compounds carbon dioxide in the environment is fairly constant.

IMPORTANCE:

• It ensures a continuous supply of carbon dioxide for photosynthesis.

• It enables energy to flow through the ecosystem. Carbon compounds carry the stored energy from one organisms top another in the food chain

• Regulates the amount of carbon dioxide in the atmosphere.

Carbon sinks

• A carbon sink is an area that stores carbon compounds for an indefinite period and stores more carbon than it releases.

• Remove carbon dioxide gases and helps reduce the rate of global warming

Oceans:

• Carbons dioxide dissolves in the ocean water as it is soluble.

• Dissolved carbon dioxide is used by phytoplankton band plants in photosynthesis

• A portion of carbon compounds is found in the oceans is buried in the seabed and is in the form of fossil fuels such as natural gas and oil

• Many organisms use carbon to make calcium carbonate, a building material of shells and skeletons

Forests:

• Atmospheric carbon dioxide is absorbed by plants and used in photosynthesis

• A large amount of carbon compounds is stored as cellulose

• Remains of dead trees form coal- type of fossil fuels

Sewage and Fertilisers pollution

• Sewage refers to waste matter from homes and industries.

• Untreated sewage may contain harmful bacteria and that can result in epidemics if discarded into water bodies. An epidemic is an outbreak of disease that affects a large population of humans in a given period.

• Untreated sewage also contains nitrates and phosphate that can also lead to Eutrophication

• Chemical fertilisers that contain nitrates and phosphates used to increase crop yield. which cam lead to eutrophication.

Eutrophication

When a body of water becomes overly enriched with minerals and nutrients that induce excessive growth of algae, which forms a bloom over water surface.

Inorganic waste & pesticide

• Inorganic waste includes poisonous metals, some type of pesticides.

• Poisonous metals that are dumped into rivers or lakes are extremely harmful to humans

• Can result in BIOACCUMULATION Bioamplification

Bioaccumulation vs Bioamplification

• Chemicals are NOT excreted, as they are not soluble in water, and are stored in the body especially in fats/lipids/adipose tissues of an organism and will build up over time in the organism. The chemicals are also non-biodegradable

• The chemical are then passed on to next organism in the food chain and become concentrated in thr bodies of the top consumers. (bioamplification)

• Bioaccumulation refers to the build up of a toxic chemical in the tissue of a particular organism.

• Bioamplification refers to the increased concentration of a toxic chemical along the food chain.

Non-biodegradable Plastic waste

• Plastic waste may physically harm organims such as cuts and suffocation

• Harmful chemicals in plastic, buried in landfills, may leach into rivers and seas and poison the wildlife

• Animals die from feeding on plastic waste as it is indigestible and can lead to blockages in their alimentary canal

• Plastic may be broken down into microplastics and indigested by organims. These will accumulate in their bodies and lead to bioamplification/ biomagnification along the food chain.

• Burning of plastic waste increase carbon dioxide concentration in the atmosphere, leading to global warming.