GCSE Biology - Pyramids of Biomass #87
Summary
TLDRThis video explains biomass pyramids, illustrating the decreasing mass of organisms across trophic levels in a food chain. It uses an example with grass, rabbits, snakes, and hawks, highlighting how only about 10% of biomass and energy is transferred to the next level due to consumption inefficiencies, indigestibility, and energy use for respiration. The video concludes with a formula to calculate biomass transfer efficiency as a percentage.
Takeaways
- 🌿 Biomass pyramids represent the mass of living organisms at each trophic level in a food chain.
- 🐰 Grass is the producer, rabbits are primary consumers, snakes are secondary consumers, and hawks are tertiary consumers.
- 📊 The bars in the pyramid decrease in size as you move up the trophic levels, indicating a reduction in total mass of organisms.
- 🐍 Even though a snake is heavier than a rabbit, there are fewer snakes, leading to less total biomass.
- 🔄 Approximately 10% of biomass and energy is transferred to the next trophic level with each consumption.
- 🦅 Organisms don't consume every part of what they eat, leading to biomass loss.
- 💩 Consumed parts that aren't absorbed are excreted as waste, reducing the biomass passed on.
- 🔥 Most absorbed nutrients are used for energy release through respiration, not stored indefinitely.
- 📉 Biomass is often released as waste products like CO2 and urea, not retained by the organism.
- 📊 To calculate biomass transfer efficiency, use the formula: (biomass transferred / biomass available) * 100.
Q & A
What does a pyramid of biomass represent?
-A pyramid of biomass represents the total mass of living organisms at each trophic level in a food chain.
What is the significance of the bars in the biomass pyramid?
-The bars in the biomass pyramid get smaller as you go up the trophic levels, indicating that the total mass of organisms decreases with each level.
Why do the bars get smaller as you move up the trophic levels?
-The bars get smaller because only about 10% of the biomass and energy is transferred to the next trophic level when one organism is consumed by another.
What are the three main reasons that only about 10% of the biomass and energy gets passed on each time?
-The three main reasons are: 1) Organisms don't eat every part of their prey, 2) Some parts consumed are not absorbed and are excreted, and 3) Most nutrients absorbed are used for respiration and are released as waste products.
Why might a hawk not eat the entire snake it catches?
-A hawk might not eat the entire snake because it doesn't consume parts like the skeleton or teeth, which are not digestible.
What is meant by biomass being 'used for respiration'?
-Biomass being 'used for respiration' means that the nutrients are used to release energy, which is then released as waste products like carbon dioxide and urea, rather than being stored within the organism.
How is the efficiency of biomass transfer calculated?
-The efficiency of biomass transfer is calculated as the percentage of biomass that has passed on to the next trophic level, using the formula: (biomass transferred to the next level / biomass available at the previous level) * 100.
What is the efficiency of biomass transfer between rabbits and snakes in the given example?
-The efficiency of biomass transfer between rabbits and snakes is 10.4 percent, calculated as (15 kg / 144 kg) * 100.
What is the efficiency of biomass transfer between snakes and hawks in the given example?
-The efficiency of biomass transfer between snakes and hawks is 10.7 percent, calculated as (1.6 kg / 15 kg) * 100.
Why is it important to understand the efficiency of biomass transfer?
-Understanding the efficiency of biomass transfer is important because it helps us understand how energy and nutrients flow through an ecosystem and how much is lost at each trophic level.
Outlines
🌿 Understanding Biomass Pyramids
This paragraph introduces the concept of biomass pyramids, which visually represent the biomass at each trophic level within a food chain. The example given includes grass as the producer, rabbits as primary consumers, snakes as secondary consumers, and hawks as tertiary consumers. Biomass refers to the total mass of living organisms at each level. The paragraph explains that the bars in the pyramid decrease in size as you move up the trophic levels, indicating a reduction in total mass. This is due to the fact that energy and biomass are lost or used at each level, with only about 10% being transferred to the next level. The reasons for this inefficiency are outlined: organisms do not consume every part of their prey, not all consumed parts are absorbed, and most nutrients are used for respiration rather than growth.
Mindmap
Keywords
💡Pyramids of Biomass
💡Trophic Levels
💡Biomass
💡Producers
💡Primary Consumers
💡Secondary Consumers
💡Tertiary Consumers
💡Energy Transfer
💡Efficiency of Biomass Transfer
💡Respiration
💡Waste Products
Highlights
Pyramids of biomass represent the mass of living organisms at each trophic level in a food chain.
The example food chain includes grass (producer), rabbits (primary consumer), snakes (secondary consumer), and hawks (tertiary consumer).
Biomass refers to the total mass of living organisms at each level.
The pyramids show a decrease in total mass as you move up the trophic levels.
Although individual snakes may weigh more than rabbits, there are fewer snakes, resulting in lower total biomass.
Only about 10% of biomass and energy is transferred to the next trophic level.
Organisms do not consume every part of what they eat, leading to biomass loss.
Consumed parts that are not absorbed are excreted as waste.
Most absorbed nutrients are used for respiration rather than growth.
Biomass is released as waste products like carbon dioxide and urea.
The efficiency of biomass transfer is calculated as a percentage.
Efficiency is calculated by dividing the biomass transferred to the next level by the biomass available at the previous level.
The example calculation shows 10.4% efficiency between rabbits and snakes.
The example calculation also shows 10.7% efficiency between snakes and hawks.
Understanding biomass transfer efficiency is crucial for studying food chains and ecosystems.
The video provides a clear explanation of biomass and its transfer in food chains.
The video concludes with a call to action for viewers to like and subscribe for more content.
Transcripts
in this video we're looking at pyramids
of biomass
which show the biomass of each trophic
level in a food chain
so this pyramid here could represent a
food chain like this
with grass as the producer
rabbits as the primary consumer
snakes as the secondary consumer
and hawks as a tertiary consumer
now the term biomass just means the mass
of living organisms
so this bar at the bottom
represents the total mass of all of the
grass in the food chain
whereas this next bar represents the
total mass of all the rabbits
then the next one represents the total
mass of all the snakes
and so on
the important thing to notice is that
the bars get smaller as you go up the
trophic levels
which means that the total mass of the
organisms in each level is decreasing
so even though each individual snake
might weigh more than each rabbit
there would be a lot fewer snakes than
rabbits
so the total mass of snakes is much
lower than the total mass of rabbits
the reason for this is that every time
one organism is consumed by another and
remove upper trophic level
most of the biomass and energy is either
lost or used
only about 10 of it actually gets
transferred up to the next level
so if we think about all the biomass of
the grass
only about 10 of it will be passed on to
the rabbits
and then only 10 of that rabbit biomass
will be passed on to the snakes
and so on
now there are a whole bunch of reasons
why only 10 of the biomass and energy
gets passed on each time
but there are three main reasons that
you need to know
the first is that organisms don't
normally eat every single part of the
organism they're consuming
for example the hawks wouldn't eat the
snake skeleton or teeth
the second is that even the bits that
they do eat might not be absorbed if
they can't break them down properly
such as the scales or something so those
beds just get adjusted as feces
which is the technical way of saying
pooped out
the most important reason though is that
most of the nutrients that animals do
absorb are used to release energy
through respiration rather than for
growth
this means that the biomass gets
released as waste products like carbon
dioxide and urea
rather than being stored within the
organism forever
so when the organism ends up being eaten
by something
it doesn't pass on all the biomass that
is consumed throughout its life
because it's been using most of it for
everyday functions
the last thing we need to cover is how
to calculate the efficiency of biomass
transfer
which is basically just the percentage
of the biomass that has passed on each
time and for this we'll need some actual
values for the biomass in each trophic
level
the equation is that efficiency equals
the biomass transferred to the next
level
divided by the biomass that was
available at the previous level
and we have to times the whole thing by
100 to turn it into a percentage
so if we wanted to find the efficiency
between snakes and rabbits
were to just do 15 kilos
which is the biomass that must have been
transferred to the snakes
divided by 144 kilos
which is the biomass that was available
in the form of rabbit biomass
we just multiply that by 100
to get an efficiency of 10.4 percent
which means that 10.4 percent of the
rapid biomass got passed on to the
snakes
or for the efficiency between snakes and
hawks
would just do 1.6
divided by 15 times 100
which gives us 10.7 percent for the
efficiency
anyway that's everything for this video
so if you found it useful then please do
give us a like and subscribe
and we'll see you again soon
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