Biology - Ecology

Organism

A living system

Population

Organisms of the same species in a given area

Community

All the populations of organisms in a given area

Ecosystem

All the organisms and the habitat

Biotic

Living components of an ecosystem that affect organisms, eg. food, predators, disease, competitors

Abiotic

The non living components of an ecosystem that affects organisms, eg. light, temp, pH

Omnivore

Animals that eat other animals and plants

Herbivore

Animals that eat plants

Carnivore

Animals that eat other animals

Producer

Organisms that can make their own nutrients

Consumer

An organism that gets its energy from eating other organisms

Predator

An animal that preys on others

Adaptation

Special features that make an organism particularly well suited to its environment

Xerophyte

Plants adapted to living in dry conditions

Extremophile

Organisms adapted to living in extreme conditions

Interdependence

One organism needing another

Food Chain

Shows feeding relationships and the flow of energy

Prey

An organism that is eaten by a predator

Decomposer

Microorganisms involved in decay, that break down dead matter

Detritivore

Animal that feeds on dead organic material, breaking it into smaller pieces and then decomposers finish the decay process.

What does a pyramid of numbers show?

The number of organisms at each trophic level

Why is a pyramid of biomass > than a pyramid of numbers?

It shows the mass of organisms at each trophic level, while still showing the feeding relationships, and more clearly shows the loss of mass at each level.

What are the ways that energy can be lost from the food chain?

Movement, faeces, urine, heat, gases, not all parts eaten, not all parts digested, sunlight reflected or transmitted

Equation to calculate energy efficiency

Energy after transfer/energy before transfer x 100

Decay/decomposition

The breakdown of dead matter

Difference between detritivores and decomposers?

Detritivores break down large pieces of dead matter into smaller pieces, they increase the SA for decomposers, as decomposers, bacteria and fungi finish breaking down the material, being responsible for rot and decay

Extracellular digestion/saprophytic feeding

Extracellular = out of the cell —> they secrete enzymes onto dead matter, which is then broken down and digested by these enzymes, and the products can then be absorbed.

Why are microorganisms and the process of decay so important?

In any organism there are cells and tissues made of biological molecules, which are useful and should not be wasted, so bacteria and fungi break them down. As they are broken down and used, they release CO2 from respiration and release nitrates back into the soil. Plants reabsorb these and they re-enter the food chain.

Oxygen

Needed by microorganisms for respiration

Warmth

Allows enzyme controlled reactions to occur more rapidly, allows microorganisms to reproduce rapidly

Moisture

Allows chemical reactions to take place

What does lipase break down?

Lipids

When lipase is added to milk, why will the cresol turn from purple to yellow?

Milk is neutral, so the cresol will be purple or red. When the lipase is added, it will break down the lipids in the milk to form glycerol and fatty acids. As the acids accumulate, the pH will lower, so the cresol will turn yellow.

What important function do detritus feeders perform?

Break down large particles of dead material into smaller pieces, increasing the SA for enzymes from microorganisms

2 types of decomposer

Bacteria, fungi

Why do decomposers need oxygen?

For aerobic respiration to release energy, needed for growth and reproduction

How do terrariums work?

Water, carbon and nitrogen are all recycles, and plants need these in order to grow, so energy is passed up the food chain. Our planet uses the same principles.

Pathway of water from soil into the plant and out again

Into root hair cells by osmosis, through the plant via the xylem vessels and is then taken to the leaves (palisade cells), acting as a reactant in photosynthesis. Water then leaves the leaves through the stomata by evaporation/transpiration.

Biological compounds in which carbon can be found

DNA, carbohydrates, proteins + amino acids, lipids

How does carbon move through the food chain?

Feeding

Which group of organisms is important in nutrient cycling?

Decomposers

How do plants get their carbon?

CO2 in the atmosphere fixed during photosynthesis

2 processes that lead to carbon as CO2 being released into the atmosphere

Aerobic respiration, combustion

How do aquatic plants get their CO2?

CO2 in atmosphere dissolves in the water, and oceans act as carbon sinks

Why is the carbon cycle so important?

It recycles carbon and returns it to the atmosphere as CO2, which can be used for photosynthesis. Without it, nutrients would run out.

Why is SA:V ratio important for animals in extreme conditions?

Larger ration = lose more heat, so colder climates mean it is better to have a smaller ratio in order to conserve heat