chapter 21: ecology Flashcards
1
Q
what does an abiotic environment consist of?
A
- it consists of physical, non-living factors such as light, water and pH of the soil and water
2
Q
what does a biotic environment consist of?
A
- it consists of all the living things that an organism interacts with
3
Q
what is habitat?
A
a place where an organism lives
4
Q
what is population?
A
it is a group of organisms of the same species that live together in a habitat
5
Q
what is a community?
A
it is made up of all the populations living and interacting with one another in a habitat
6
Q
what is ecosystem?
A
ecosystem is a community of organisms interacting with one another and with its abiotic environment
7
Q
how does light intensity affect organisms?
( the abiotic environment)
A
- light intensity affects the rate of photosynthesis and growth in plants
> affects the rate of growth of animals
> animals depend directly or indirectly on plants for food
8
Q
how does temperature affect organisms?
( the abiotic environment)
A
- temperature affects the rate of enzyme reactions
> affect the metabolic rate and the rate of growth of organisms
9
Q
how does water availability affect organism?
( the abiotic environment)
A
- water is important for survival of all living things
> the main component of protoplasm - some animals adapted to live in arid regions
- desert rats have comparatively long loops of Henle (where water is reabsorbed) in their kidneys
> most of the water filtered is reabsorbed by the kidneys
> the urine of desert rats is relatively concentrated
10
Q
how does oxygen content affect organisms?
( the abiotic environment)
A
- oxygen is needed for aerobic respiration
> aerobic respiration releases energy for cell activities such as active transport of mineral salts - plants living in oxygen-poor soil usually have special adaptations to obtain the amount of oxygen needed
- eg. mangroves plants (avicennia) have their roots buried in oxygen-poor mud
> have special breathing roots called pneumatophores
> that project above the mud surface
> the roots have openings for gas exchange
> oxygen diffuses into these root openings to the whole root system of the plant
11
Q
how does the salinity of soil and water affect organisms?
( the abiotic environment)
A
- it affects the water potential of a solution
> organisms living in freshwater constantly remove excess water that enter their bodies via osmosis
> those living in sea water have to conserve water
12
Q
how does the pH of soil and water affect organisms?
( the abiotic environment)
A
- organisms are sensitive to the pH of soil or water in which they live in
> pH of surroundings affect rate of enzyme reactions within bodies
> extreme changes in the pH will result in denaturation of these enzymes
13
Q
what is an ecological community?
A
- when different populations of plants and animals live together and interact within the same environment
> AN ECOLOGICAL COMMUNITY - the various populations in any community live interdependently
> a change in one population, affects the other populations of the community
14
Q
what are producers?
A
- producers can make their own food by photosynthesis
> like plants, algae and photosynthetic bacteria and organisms - the contain chlorophyll which traps and converts light energy into chemical energy
- they synthesise glucose from carbon dioxide and water and they produce oxygen as a by-product during photosynthesis
- producers affect the lives of other organisms
> they provide them with energy and oxygen
15
Q
what are consumers?
A
- consumers are organisms that are not able to make their own food
> they obtain energy and nutrients by feeding on other organisms
primary consumers: herbivores (plant eaters)
>they feed directly on plants
secondary consumers: carnivores (meat eaters)
>they feed on primary consumers
tertiary consumers: carnivores
> they feed on secondary consumers
16
Q
what are decomposers?
A
- decomposers feed on decaying organic matter
> bacteria and fungi - they break down dead bodies of organisms, faeces and excretory products
- their activities return nutrients to the environment
17
Q
explain the non-cyclic energy flow in an ecosystem
A
- the ultimate source of energy is the sun
> sun provides light energy - light energy absorbed by chlorophyll in producers is converted into chemical energy during photosynthesis
- energy in producers is passed from one trophic level to another by feeding
- the flow of energy through the ecosystem is non-cyclic
> energy lost as heat to the environment through respiration
> since heat energy does not return to the same system or the organisms that produce it
> it cannot be recycled in the ecosystem - egested and excreted materials and dead organisms contain trapped chemical energy
> the energy is released through the activity of decomposers
> decomposers use some of this trapped energy for their needs
> the rest of the energy is lost as heat
- living organisms cannot use heat energy to do work
> can only use light and chemical
> thus, light energy has to be constantly supplied to the ecosystem
18
Q
what is the pyramid of numbers used for?
A
- it allows us to compare the number of organisms present in each trophic level at a particular time
19
Q
what is the pyramid of biomass used for?
A
- it allows us to compare the mass of organisms
> the dry mass of organisms in each trophic level at any one time
> the dry mass of an organism is the mass of the organism when all its water has been removed
20
Q
why are short food chains more efficient in energy transfer?
A
- since large amount of energy is lost at each trophic level (arnd 90%)
> less and less energy is available for the organisms at the next trophic level as we move along the food chain - the shorter the food chain, the greater amount the energy available to the final consumer because less energy is lost to the environment
21
Q
describe the carbon cycle.
A
- carbon is constantly being removed from and released into the environment as carbon dioxide
> the carbon dioxide concentration remains relatively constant
- PHOTOSYNTHESIS (removing CO2)
- plants absorb carbon dioxide and use it to synthesise carbohydrates
> some of the carbohydrates are converted into fats and proteins - FEEDING (removing CO2)
- animals obtain carbon compounds by feeding on plants or other animals - RESPIRATION (returning CO2)
- plants and animals respire, releasing carbon dioxide into the environment - DECOMPOSITION (returning CO2)
- decomposers: bacteria, microbes and fungi
> break down organic matter and release carbon dioxide - COMBUSTION (returning CO2)
- dead bodies of organisms buried in the earth for millions of years produce fossil fuels
> coal, natural gas and oil
> combustion of these fossil fuels releases carbon dioxide into the environment
22
Q
what is the importance of the carbon cycle?
A
- ensures that there is a continuous supply of carbon dioxide for plants to carry out photosynthesis
> photosynthesis converts light energy from the sun into chemical energy in food
> which non-photosynthetic organisms can use to stay alive - enables energy to flow through the ecosystem
> carbon compounds carry the stored energy from organism to organism in the food chains of an ecosystem - it maintains the correct concentration of carbon dioxide in the atmosphere
23
Q
what is a carbon sink?
A
- a carbon sink is an area that stores carbon compounds for an indefinite period
> stores more carbon than it releases
24
Q
why is the ocean a carbon sink?
A
- about one third of the carbon dioxide released by human activities is absorbed by the oceans
- the role of oceans as carbon sinks is driven by SOLUBILITY and PHOTOSYTHESIS
> the carbon dioxide that dissolves in the ocean’s water is absorbed and used by phytoplankton and algae in photosynthesis - a portion of the carbon compounds found in the oceans in buried in the seabed
> and is in the form of fossil fuels such as natural gas and oil - to increase the photosynthetic activity of phytoplankton
> add iron compounds such as iron oxide and iron sulfate into the ocean
> stimulates the growth of phytoplankton and increases the phytoplankton’s photosynthetic rate
25
Q
why are forests carbon sinks?
A
- atmospheric carbon dioxide is absorbed by the plants and used in photosynthesis
> large amount of carbon compounds is stored in trees
> when they die, their remains may be buried deep in the ground
> after millions of years, the remains form coal- a fossil fuel - the study of the asian , african and south american tropical forests show that forests absorb about 20% of all the carbon dioxide released by the burning of fossil fuels
indiscriminate deforestation has damaging effects
> effective forest management is important
- canada has about 10% of the world’s forest and it claims that less than 0.5% of its forests are harvested in a year
> harvested areas are allowed to regenerate again
26
Q
what is the kyoto protocol?
A
- it requires participating industrialised countries to reduce their carbon dioxide emission
eg. USA should reduce their carbon dioxide emission by 7%
> they would need to plant millions of fast-growing trees per year to reforest lands over a period of 40 years - in 2001, the US pulled out of the Kyoto protocol
> but most of the other industrialised nations still collectively agreed to reduce their greenhouse gases emissions by 5.2% for the period of 2008-2012 - singapore joined the kyoto protocol in 2006
> in SG, the primary greenhouse gas is carbon dioxide generated for energy consumption
>in trying to reduce energy consumption, singapore has made it compulsory for all air conditioners and refrigerators to be energy efficient
