Chapter Seven - Ecology Flashcards
What is community?
The relationships between all the living species in that area
What is an ecosystem?
The relationship between all living species in their environment
What is an environment?
The surroundings in which an organism lives
What is a habitat?
The place where each organism lives and breeds
What is population?
The number of organisms of a single species in a given habitat
Give an overview of how to study the environment?
A range of sampling techniques can be used. Some techniques use apparatus that can be used to measure biotic (living) data, e.g. Distribution of plant or animal species.
What is a pitfall trap? How is it used?
A jar or pot is sunk in a hole in the ground, stones are placed above to prevent rain flooding the trap or birds or other predators from removing trapped animals
How to use - a hole is dug to accommodate a container and a raised lid is places on top to prevent entry of rain/predators. The trap is then left for a period of time (e.g 24 hours). Useful for collecting small ground-living animals such as beetles.
What is a quadrat?
Square frame of sides 1m or 50cm that can be placed at a series of randomly chosen coordinates. The abundance of plant species is often measured in this way - if individual plants can’t be identified (grass) then percentage cover can be used.
What is a pooter?
Allows small animals to be sucked into an observation chamber so they can more easily be identified
What are abiotic factors?
To understand an ecosystem fully, the abiotic (non-living) factors in the environment must be measured.
Includes
1. light intensity - light meter to measure
2. Temperature - thermometer
3. Wind speed - anemometer
4. Water availability - rain gauge
5. pH - pH meter or soil testing kit
6. Extent of cultivation
Also - space, shelter, predators, mineral availability
Features of classifications of organisms you must know;
- Chordates - animals with backbones: mammals, reptiles, fish amphibians, birds MRFAB
- Insects - animals with an exoskeleton and body divided into three sections (head, thorax, abdomen) two pairs of wings, three pairs of jointed legs, body temp not constant
- Annelids - animals with a segmented body and hairlike structures called chaetae for grip, body temp not constant
- Flowering plants - plants with true roots, stems and a highly developed transport (vascular) system. Rely on flower, seed and fruit production to facilitate reproduction.
The five kingdoms of organisms
For each state; group, nutrition, cell wall and cellular organisation
Protoctista
Nutrition - saprophytic or photosynthetic
Cell wall - cellulose / no cell wall
Cellular organisation - single-called sigh nucleus/ algae that are not truly multicellular
Bacteria
Nutrition - saprophytic
Cell wall - non-cellulose
Cellular organisation - single celled, lacking nucleus
Fungi
Nutrition - saprophytic or parasitic
Cell wall - non-cellulose
Cellular organisation - single or multicellular, sometimes difficult to distinguish cells and so are referred to as acellular
Plants
Nutrition - photosynthetic
Cell wall - cellulose
Cellular organisation - multicellular
Animals
Nutrition - heterotrophic
Cell wall - none
Cellular organisation - multicellular
Explain the characteristics of protoctista
It is a kingdom containing organisms hard to classify e.g some contain plant and animal characteristics
What is saprophytic nutrition?
A form of external digestion - enzymes act outside the organism and the products of digestion are then absorbed
Why do viruses pose a problem for biologists?
They can only reproduce through invading host cells. For this reason they are hard to classify as true living organisms
How are similar species classified into different species?
If they can breed to produce fertile offspring and look similar then they are the same species. E.g a horse and a donkey look very similar and can breed to produce a mule but mules are infertile so therefore horses and donkeys are different species.
- Population equation
2. Equation if immigration is not involved
Change in population size = (birth rate + immigration) - (death rate + emigration)
- No pop. Change - birth rate = death rate
- pop. decrease - birth rate < death rare
- pop. increase - birth rate > death rate
- No pop. Change - birth rate = death rate
Explain transfer of energy.
As plants are capable of photosynthesis they are able to harness the Suns energy and use this to produce food for themselves and other organisms that consume them. The flow of energy to plants can be represented in food chains.
Give a food chain with examples and definitions
Tropic level 1–>tropic level 2–>tropic level 3–>tropic level 4
Producers> primary consumers>2nary consumers>tertiary c.
Plant ——> caterpillar ——> bird —-> bird of prey
Producers - make food by photosynthesis
Consumers - feed on other living things
What is a pyramid of numbers?
A simple diagram used to represent numbers of organisms at each tropic level. It is common that numbers decrease as the food chain progresses from producer to tertiary consumer.
Why would an atypical pyramid of numbers occur?
As one producer could provide food for many primary consumers. E.g. A single rose bush can sustain hundreds of aphids - greenflies.
What is a pyramid of biomass?
A diagram used to represent the mass of living material at each trophic level. The steps of the pyramid always become shorter as you progress through the food chain.
Guidelines for drawing a pyramid of biomass
- never change the order of the food chain - the producer is always at the bottom and the final consumer at the top
- keep it symmetrical
- bars should all have the same depth
- if required ensure you have an appropriate scale for the length of bars
- if converting from an atypical period of numbers to a pyramid of biomass remember pyramids of biomass are always proper pyramids
Why are food chains are so short?
Food chains never exceed four or five levels because not all energy from one trophic level is transferred to the next. Reasons for this are:
- respiration of organisms at each stage releases heat energy that cannot be passed through feeding
- excreted waste contains some energy
- faeces also contains energy that cannot be digested
- not all parts of an organism can be eaten
Why might countries suffering from famine only have one consumer?
Less chance for energy to be lost
E.g rice –> human
Explain the process of decomposition
A key process in the recycling of carbon and nitrogen. The decay process releases the nutrients back into the soil. The bacteria and fungi responsible for this recycling feed on dead plant and animal material as well as waste materials released by egestion and excretion of animals.
What is biodiversity?
A measure of the range of different species of organisms living in an area
What is humus?
The result of decomposition. It is a component of the soil in which plants grow and from which they extract minerals. For this to happen, the bacteria and fungi involved release digestive enzymes on to the material. Following this extracellular digestion (meaning outside the body or cell) the soluble products are absorbed by the organism.
Draw a diagram of the carbon cycle.
Carbon cycle diagram in page 45 of revision guide.
Explain the carbon cycle.
The amount of c02 in our atmosphere should stay constant but if the amount of respiration and combustion of fossil fuels increases and the amount of photosynthesis decreases (due to deforestation for example) then levels of c02 will increase.
Why have carbon dioxide levels increased?
There is a vast amount of scientific research to suggest that human activities have resulted in increased c02 levels which have in turn led to the greenhouse gas effect and global warming.
Although there is much evidence to support this theory it should be remembered there are other possible explanations for some of the increase in global temps such as natural variations in temp due to solar activity
What factors are monitored of global warming and what have governments done in response to increase in co2 levels?
Abiotic data used to monitor global warming includes c02 levels, extent and size of polar ice fields, ice density and sea levels.
Govts have put in place policies at national and local levels to reduce c02 emissions through placing a greater emphasis on use of renewable energy sources and changes in agricultural practises.
Draw diagram of the nitrogen cycle including labels and explanations.
The nitrogen cycle diagram is on page 46 of revision guide.
- Animals feed on plants and covert plant protein to animal protein.
| - death and excretion
| - decay bacteria and fungi break down dead plant and animals to
| produce ammonia
\/ - Ammonia
| - nitrifying bacteria convert ammonia to nitrate (in process called
| nitrification) which can be absorbed by plants
\/ - Nitrate –>Denitrifying bacteria covert nitrates to nitrogen gas- denitrification occurs mainly in waterlogged soils –>4. Nitrogen in air
3 & 4
| | - nitrogen- fixing bacteria converts nitrogen gas to nitrates
| | - nitrogen fixation takes place in root nodules of legumes, the
V V plants use the nitrates for growth - Plants absorb nitrates and use them to make proteins–> 1.
What three major minerals are required for healthy growth in plants and what do they do?
Magnesium - for making chlorophyll
Calcium - for the production of new cell walls
Nitrogen - in the from of nitrates for the formation of protein
What are root hair cells?
These are cells with an extended cell wall that increases the surface area for effective absorption of minerals and water.
Why do farmers use fertilisers?
To improve growth of their crops. Fertilisers can be natural of artificial and argue designed to increase the levels of minerals magnesium, calcium and nitrogen and other minerals.
Give an overview of natural fertilisers.
E.g manure, compost
- low cost
- release nutrients throughout growing season and do not leach easily
- amount of minerals contained in them vary
- they can be difficult to store and spread
Give an overview of artificial fertilisers.
- more expensive than natural fertilisers
- more easily applied to fields
- more accurate level of each mineral can be applied
- soluble and can leach easily leading to pollution
- for food to be labelled organic, only natural fertilisers can be used during growing
Explain mineral absorption.
The absorption of minerals from the soil relies on a process called active uptake. This process uses energy to move the minerals from low concentration to high concentration (against the concentration gradient).
Energy required for active uptake is derived from respiration - oxygen is required. If soil becomes waterlogged oxygen levels are too low goal low sufficient energy to be released. Results in minerals are not being absorbed and poor plant growth.
What is eutrophication?
A form of water pollution and can be the result of sewage entering water ways. It’s a problem associated with incorrect use of fertilisers.
Draw diagram of results of eutrophication
Additional nutrients to water from sewage, slurry and fertilisers run-off.
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Leads to increased aquatic plant and algal growth. Many die due to shading
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When algae die they are decomposed by bacteria
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The bacteria use up the oxygen in the water
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Fish and other animals die without oxygen
Draw diagram summarising acid rain
Combustion of fossil fuels
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Sulphur dioxide released
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Sulfur dioxide dissolves in water vapour forming sulphuric acid
V
Water vapour forms clouds that are carried long distances
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When rain falls it can cause a range of problems
V V V
- river and lakes become acidic, can lead to fish poisoning
- trees can lose their leaves (defoliation) and therefore die
- stonework (statues and buildings) can be corroded
Where are the effects of acid rain seen? What is being done
The problems caused by acid rain are often not seen in the country that released the original pollutant as prevailing winds carry the rain clouds long distances before the rain falls.
International action is being taken to filter emissions from combustion of fuels and the increased used of renewable energy sources such as wind, solar and hydroelectric power has vastly reduced emissions of gases that cause acid rain.
How is environmental change best monitored by biologists?
Indicator species
1. Lichen - simple plants that cannot tolerate air pollution. Their presence on brick, stone and roofing indicates low levels of pollution. They are rarely found in towns and cities where air pollution is high
- Bloodworms - water-dwelling animals that can only survive when oxygen levels are low. They are therefore good indicators of instances of eutrophication
