# Biology chapter 7 revision

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• Created by: Harvey_H
• Created on: 10-01-22 08:45
what is the smallest part of an eco-system
individual organisms
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what makes up a single species
population
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what are communities made up of
populations of different species
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what is a biotic factor
an ecosystem made up of living organisms
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what is an abiotic factor
an ecosystem made up of non-living organisms
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what do animals compete for
food, mates and territory
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what do plants compete for
water, minerals, light and space
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what is a transect line
transects are used to investigate the effect of a factor on the distribution of species
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Quadrats are square frames that can be used to estimate population sizes
placed in regular intervals across the transect line
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what is the mode
the most common value in a series
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how do you use quadrats to estimate a population size
Divide the habitat up into a series of quadrat-sized cells.
Randomly select a given number of cells, then go out into the habitat and place the quadrat in these positions.
To evaluate the quadrat contents, either count the number of individual organisms o
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How do you calculate the population
population = number counted x (total survey area / area sampled)
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How do you calculate the area of a quadrat
10 x quadrat length x quadrat height
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what are the 2 cycles
the water cycle - describes how the water moves on between different locations by changing state
the carbon cycle - carbon is present in all living organisms so when the living organisms die the carbon is recycled for future generations
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describe the carbon cycle
Carbon is removed from the atmosphere by producers (e.g. algae) who use it in photosynthesis to make glucose
By consuming plant matter, animals obtain carbon compounds.
Carbon is returned into the atmosphere (as carbon dioxide) because of the respiration
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describe the water cycle
Water evaporates from the Earth’s surface, before rising up into the atmosphere.
Once in the atmosphere, the water vapour cools and condenses into either rain or snow. This eventually returns to the Earth’s surface.
The rain or snow will either become sur
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how is carbon removed from the atmosphere
by producers e.g. algae
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what is biodiversity
the variety of different species in a given space
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how have humans affected a decline in biodiversity
industrial revolution
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how is pollution affecting us
water - sewage and toxic chemicals
land - toxic herbicides and pesticides in farming
air -smoke and gases are being added into the atmosphere constantly particulary by power stations and cars
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Why do you think the human population has been rapidly expanding in recent decades
Why do you think the human population has been rapidly expanding in recent decades
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describe the levels of the food chains
level 1 - the producers that use light energy from the sun to synthesise their own food e.g. algae and green plants
level 2 - herbivores that eat the producers (primary consumers)
level 3 - carnivores that eat the herbivores are called the secondary cons
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what are predators and prey
a predator is a consumer that eats other animals and the prey are the animals that are eaten
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what are decomposers
decomposers are responsible for recycling organic matter within an eco-system and are the final stop for all food chains by breaking down dead material by secreting enzymes. the enzymes partly digest the waste products producing small soluble food molecul
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what are 2 decomposers
bacteria , fungi
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what is a pyramid of biomass
represents the relative amount of biomass at each trophic level in a food chain.
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how much light energy does producers trap from the sun
1%
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how much energy from a given trophic level will be able to the next trophic level
10%
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what are the reasons for inefficient transfer of biomass
excretion - some material is excreted CO2 in H2O, urea and water in urine
body temperature - warm-blooded animals need energy to sustain a suitable body temp
digestion - not all food is digested (faeces being egested)
movement - glucose are used in respi
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what is biomass
the total mass of living material in an organism multiplied by the number of organisms.
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Why may removing one species from an ecosystem make it unstable?
There is interdependence between different species (rely on species for food, shelter, pollination and seed dispersal)
or
could remove a key predator/prey which would increase population sizes
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when is a community stable
A community is stable when populations stay more or less constant.
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why do predator prey graphs population increase and decrese
An increase in the hare numbers means more food is available for the lynx, so lynx numbers also increase.
The increase in lynx numbers means that the hares have more predators, so the hare numbers decrease.
The lynx then have less food available so their
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what do predator prey graphs show
they show the cyclical nature of predator and prey populations in stable communities
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what is the rate of decay dependant on
high temperature
high oxygen availability
high moisture availability
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when does anaerobic decay occur
when the oxygen supply is insufficient (not enough), and results in the production of biogas, which is mainly methane.
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why are biogas generators useful
produces methane which is used as fuel and also produces slurry which is used as a ferilisers
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how do you make sure that the temperatures in biogas generators are sustained
Bury the generators underground.
Cover them in insulating jackets.
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what is crucial for bio gases
the temperatures are maintained and no oxygen enters the site of fermentation
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small and large scale generators
small scale generators used by houses and farm and inputted by human and animal egested material and garden waste
large scale generators take waste from factories or sewage works
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## Other cards in this set

### Card 2

#### Front

what makes up a single species

population

### Card 3

#### Front

what are communities made up of

### Card 4

#### Front

what is a biotic factor

### Card 5

#### Front

what is an abiotic factor