Ecology interactions among organisms part 3 - 30th and 31st July

Food Chain

What is a food chain? 

It is a series of organisms through which energy is transferred in material form. Carbon compounds move through the foodchains.

 

Each feeding level in the food chain is called a trophic level.

Note: Ultimately, all the energy in the ecosystem comes from the SUN.

Food Web

What is a food web?

A food web is interconnected food chains in ecosystem

Example of a food web:

(image taken from: http://chatt.hdsb.ca/~fosterk/FOV1-00097FBE/FOV1-000AD76C/S07453EB5)

Non-cyclical Nature of Energy Flowing Biological Systems

Energy flows in one-direction (non-cyclical). It is either utilised or lost into the surroundings but cannot be recycled.

Unidirectional flow of energy

The amount of available energy in a food web decreases with each trophic level.
 

Food consumed = growth + respiration + heat + egesta+ excreta
 

Only about 10% of the energy is stored as new tissues and is available for transfer to next feeding level. 90% of the energy is lost due to some food may not be eaten, or passes through the body without being digested and a lot of the energy is used in respiration.

Hence, the shorter the food chain, the greater the amount of food energy is available.

Detritivores 

Decomposers are detritivores that recycle organic matter back to inorganic nutrients (carbon, nitrates) in ecosystems. E.g. fungi, bacteria.

Detritus feeder acquire nutrients from dead animals/ plants or animal waste products. E.g.
certain beetles, earthworm, termites, bacteria, fungi.

Ecology interactions among organisms part 2 - 30th and 31st July

Abiotic Factors

Light 

– Affects many living organisms, not just plants
 

Temperature

– Affects physiological activities of all living organisms
 

Water

– Essential for life
– Organisms may have specially adapted features for survival in places with a lot of or very little water

Oxygen

– Most organisms are aerobes
 

Salinity

–Important factor for aquatic organisms
– Also a factor for other organisms
 

pH (Note! Must be small letter 'p' and capital letter 'H'. )

–May be influenced by photosynthetic activity of aquatic plants

Some Chemistry...

pH level is the measure of acidity of a certain substance. 

Acid (pH 1.0 - 6.9)

Alkaline (pH 7.1 - 14.0) 

Neutral - not acid or alkaline (water) 

Biotic Factors 

1. Symbiosis a long-term relationship between two different species “living together”. The relationship varies in population, can be mutualism, commensalism & parasitism.

Mutualism

Each population benefits. The interaction is necessary for the survival and growth of each species
+/+ 

Commensalism

One population benefits; the other is unaffected 

+/o

Parasitism

One population benefits (parasite) while the other is harmed (host). The interaction is necessary for the survival of the parasite.
+/-

2. Competition - Both population compete with each other for limited resources in the same ecosystem; both species are adversely affected by the relationship.
Interspecific (a form of symbiosis) or intraspecific (same species) competition
-/-

3. Predation - One population feeds on the other. The interaction is necessary for the survival of the predator

+/-

Ecology interactions among organisms part 1 - 30th and 31st July

 Ecology is the study of how living things interact with each other and with their environment.

 Biosphere...

 ...is the life supporting zone where the 3 zones meet, interact & make life possible

Lithosphere, hydrosphere & atmosphere are non-living components of the environment and
are called Abiotic.

Lithosphere is the surface of the earth, including aquatic systems, which contains most of the life. It is the lower atmosphere.

Biotic components include plants, fungi, animals and microbes living on earth.
Constant interaction between the abiotic & biotic components enables the transfer of food and energy, making it a stable and dynamic system.

Important terms to note!

A habitat is the physical place where a plant or animal (population) lives. It must supply the needs of organisms, such as food, water, temperature, oxygen, and minerals. A population is a group of living organisms of the same kind living in the same place at the same time. All of the populations in the same habitat interact and form a community.

The community of living things interacts with the non-living world around it to form the ecosystem.

A niche is the role and position of an organism (species) in the community. No two species can occupy exactly the same niche.

Ecosystems is a complex interaction of living and nonliving processes e.g. as small as a puddle or as huge as the Earth.

It consists of a community of living organisms interacting with each other and their environment to form a self-sustaining unit.

The environment consists of the abiotic and biotic components.

Habitats that have similar climate and plants are called biomes.

Note that: Living things cannot exist alone, there must be a relationship between them. Living things are adapted to the environment where they live.

Evolution - Specialised Cells

1. Red Blood Cells (erythrocytes)

·        It is flat and has a biconcave shape which increases the surface area to volume ratio, resulting in an increase in the diffusion of oxygen in and out of the cell. 

·        Has no nucleus so as to store more Haemoglobin, a red pigment that combines with oxygen to form oxyhaemoglobin. This also allows the Red Blood Cell to transport more oxygen.

·        Has a greater surface area for gas exchange, thus increasing the surface area to volume ratio for diffusion.

·        Red Blood Cell can change shape to a great extent, without breaking, as it squeezes single file through the capillaries.

Function: Transports oxygen from lungs to other parts of the body.  

 (image taken from: http://www.rkm.com.au/cell/red-blood-cells.html)

2. Xylem Cells   

·        Cells are arranged end to end.

·        Long narrow tubes with a continuous space (lumen).

·        Consists of dead cells with no protoplasm and cross walls. This enables water and dissolved mineral salts to move more easily.

·        They have lignified cell wall and the secondary walls of vessels are filled with lignin, a kind of hard glue. The lignin is deposited on the cell walls to strengthen them and provide mechanical support.

·        Three different types of cells: Xylem parenchyma cells and xylem fiber cells, which simply provide structural support for the most important xylem cells, the tracheary elements (TE). The TE are completely dead at maturity and act like popes to allow water and dissolved minerals to flow through them.

·        A key feature of their structure are secondary cell wall thickenings. These thickenings form in distinctive patterns, frequently rings, to provide maximum structural support. 

Function: 1) To transport water and mineral salts from the roots to the other parts of the plant. 2) To support the plant.

 

(image taken from: http://pharamcytimes.wordpress.com/tag/plants-tissues/)

3. Root Hair Cells

·      The Root Hair Cells have a long and narrow protruding end which increases the surface area to volume ratio, enabling the root hair cells to absorb more water and mineral salts from the soil. 

Function: Absorb water and mineral salts from the surrounding soil. 

(taken from: http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/cells/cells2.shtml)

4. Intestinal cells (Epithelial cells)

·      Epithelial cells in the small intestine are a type of brush border cell (covered in microvilli)

·      These cells are covered in microvilli to increase their absorptive surface area. 

Observation of Hydrilla Plant Cell Under 400X magnification - 19 July 2012

Observation of Hydrilla Plant Cell Under 100X magnification - 19 July 2012

Observation of Hydrilla Plant Cell Under 40X magnification - 19 July 2012