Module 5- Ecology and ecosystems Flashcards
What is an ecoystem?
An ecosystem includes all the organisms living in a particular area and all the non-living conditions.
What is a producer?
The organism that makes its own food
Where is energy and carbon dioxide gained from during photosynthesis?
Energy from sunlight
Carbon dioxide from the atmosphere or dissolved in water in aquatic habitats
What is a plant’s biomass?
The mass of living material or chemical energy stored in the plant
What are primary/secondary/tertiary consumers?
Primary = eat producers
Secondary = eat primary
Tertiary = eat secondary
How can biomass be measured in terms of…
The mass of the carbon that an organism contains or the dry mass of its tissue per unit.
How is biomass in an organism found when looking for dry mass?
A sample of an organism is dried. This is done by placing it into an oven at a low temperature and checking the weight at regular intervals. When the mass is constant, the mass is completely dry. The mass of carbon is taken by 50% of the dry mass.
How to measure biomass using a calorimeter?
A sample of dry biomass is burnt and energy is released which is used to heat a known volume of water. The change in temperature of water is used to calculate the chemical energy of dry biomass.
What is GPP?
The total amount of chemical energy converted from light energy by plants
What is respiratory losses?
50% of chemical energy is lost to the environment in heat when plants respire. This is known as respiratory losses.
After the respiratory losses, the chemical energy is called what?
NPP = Net primary production
What is NPP?
The energy available for a plant for growth and reproduction and the energy available to organisms in the next stage of the food chain.
Where is NPP stored?
The plants Biomass
What is primary productivity?
The total amount of chemical energy in a given area, in a given time
How do consumers collect energy?
When a consumer eats a producer or eats an animal that has eaten a producer
How much of the total energy available in the previous trophic level is lost ?
90%
Explain why some GPP is so low compared with the original light energy available
Some solar energy is lost because
* It is the wrong wavelength for photosynthesis
* Reflects off the leaf
* Passes straight through the leaf/misses chloroplasts
* Just heats the leaf
* Misses the leaf/strikes a non-photosynthetic part of the plant
What are the 3 reasons why not all energy is passed on to the next trophic level?
- Some parts of organisms are indigestible such as the bones etc.
- Some is egested through faeces
- Some is lost to the environment through respiration or urine excretion.
What is the total energy that is available to the next trophic level called?
Net production of consumers
How is net production of consumers calculated?
N = I - ( F + R )
How to calculate energy efficiency?
(Net productivity/total energy available) x 100
What are decomposers?
Decomposers break down dead or undigested material
What are two ways in which a farmer can increase the NPP?
simplifying the food web and reducing respiratory losses
What are 2 ways in which the food web can be simplified to increase NPP?
Insecticides which kill insect pests that eat and damage crops. Killing pests means less biomass is lost from crops
Herbicides kill unwanted weeds which reduces direct competition
What are biological agents and how do they increase the efficiency of energy transfer of humans?
Parasites which live or lay their eggs inside a pest and kill them.
Pathogenic bacteria and viruses also kill pests
How may a farmer reduce respiratory losses in an organism?
Reducing their movement so that they lose less through respiration
Kept indoors and warm so less energy is used to keep warm
What is the negative of farmers reducing respiratory losses in organisms?
Ethical concerns
What are the measurements used to measure primary and secondary productivity?
Biomass in a given area in a given time
KJ m-2 year-1
How can a student suggest how the mass of carbon for a particular organism could be estimated?
- Calculate the mean diameter of the organism
- Use this to determine the mean biomass
- Use this % water content to find the dried mass
- Use the dried density to calculate the mass of the organism
- Estimate the number of organisms in the given area and multiply by the mean carbon content to find the total carbon.
How to determine the chemical energy of a sample.
Dry the mass by placing in an oven at a low temp and checking at regular intervals until the mass is constant. Then burn the dry sample and allo the heat energy being released to heat up a known volume of water. The change in temperature of the water is the chemical energy
1 mark
Suggest appropriate units for gross producitvity
mass, per area, per year
2 marks
After 6 weeks, the scientists removed the plants from the soil and cut the roots from the
shoots. They dried the plant material in an oven at 90 °C for 3 days. They then determined
the mean dry masses of the roots and shoots of each group of pea plants.
Suggest what the scientists should have done during the drying process to be sure that all
of the water had been removed from the plant samples.
- Weigh samples at intervals during drying
- To see if weighings became constant by 3 days)
2 marks
In natural ecosystems, most of the light falling on producers is not used in photosynthesis. Suggest 2 reasons why
- Light is reflected
- Temperature or low CO2 concentration could be a limiting factor
- Light didnt hit chlorophyll
2 marks
The scientist determined the dry mass of the spinach plants. First, he heated each sample at 80 °C for 2 hours. Suggest what the scientist should do to ensure that he has removed all the water from the sample.
- Weigh and heat
- Until mass is constant
2 marks
Farming cattle for humans to eat is less efficient than farming crops because of energy transfer. Explain why
- Energy lost between trophic levels
- Energy lost via respiration/ excretion/ faeces
2 marks
Explain why determination of dry mass was an appropriate method to use
- Dry mass measures increase in organic material
- Water content varies
3 marks
Give three reasons for the low efficiency of energy transfer from secondary consumers to tertiary consumers in an ecosystem
- Heat loss from respiration
- Food not digested
- Excretion
2 marks
Suggest two reasons for conserving rainforests
- For biodiversity
- Conserve/protect habitats/niches
- Reduces climate change
- Source of medicines/drugs/wood
- Reduces eutrophication
- For tourism
In the following passage, the numbered spaces can be filled with biological terms. An ecosystem supports a certain size of population of a species, called the (1) capacity. There are often numerous habitats within an ecosystem. Within a habitat, a species occupies a (2) governed by an adaption to both (3) and biotic conditions. Populations of different species form a (4) .
Write the correct biological term beside each number below that matches the space in
the passage.
(1) carrying
(2) niche
(3) abiotic
(4) community
