Transcript Revision B4

Biome
•The biosphere is made up of several types of
biome.
• These are classified due to their major
vegetation types, for example TUNDRA or
TROPICAL RAINFOREST.
• An Ecosystem is a part of a biome.
• Biomes themselves are far too large to study
Ecosystem so ecology work tends to be based around a
particular ecosystem.
• Each ecosystem has a characteristic set of
plants, animals and microbes.
• The organisms in an ecosystem form a selfsufficient unit in balance with their environment.
Community
• This is a group of species that occurs at the
same place at the same time.
• The word is often used to refer to organisms
of a particular kind, such as the plant
community on a lawn.
Population
• Ecosystems and communities contain
populations of species.
• A population is made up of all the members of
a species living together in the same place at
the same time.
• An example would be all the ash trees in a
wood.
Individual
• Finally each population is made up of many
individuals.
• The genetic and physiological adaptations of
an individual organism to its environment is
an important aspect of ecology.
Natural vs. Artificial
Natural
Artificial
• Low biodiversity
• Food supplies limited
• Small number of plants
and animals
• Artificial pesticides and
fertilizers used to limit
biodiversity
• Large biodiversity
• Wide variety of food
supplies
• Large number of plants
and animals
• No pesticides & fertilizers
used so nature finds its
own level for the
population of each
species.
All ecosystems have to be self supporting apart from an energy
source which is usually the sun.
Distribution of Living Organisms
• A transit line is used to map the
distribution of organisms.
• A line like a tape measure or a path is
laid out.
• Quadrates are distributed either along
the line or away from the line at set
intervals.
• The population of each species is then
counted.
• A kite diagram is then produced from
the data collected.
Zonation
• Zonation is the gradual
change in the
distribution of species
across the habitat.
• Gradual changes in
abiotic factors (nonliving) can result in
zonation
Sampling & Identifying
Organisms
1. How could you correctly identify the different
species collected in a sample?
2. How would you sample an area?
3. What would the advantages and disadvantages of
doing this?
4. What is the reasoning behind sampling an area?
5. What size would you make the sample and why?
6. Would you sample at random or would you sample
in a specific and logical way?
7. How are organisms distributed though a habitat?
8. How would you make the sampling accurate?
Counting Animals – Capture-Recapture
• The capture-recapture method is used to estimate the size
of a population
• Populations can be difficult to sample because animal
species move around all the time
• Population size =
No. in 1st sample (all marked) x no.
of 2nd sample (marked & unmarked)
No. in 2nd sample which were
previously marked
Assumption of CaptureRecapture
• No organisms have died or born or migrated or
emigrated between sampling
• Make sure identical sampling methods are used from 1
visit to the next
• Make sure the marking, tagging does not adversely
affect the organism
• The larger the sample size the more accurate the
population estimate size
Photosynthesis vs respiration
• All living organisms respire
• You should all know the word equation for aerobic
respiration…
• Glucose is needed for plants to respire, as well as oxygen
• Therefore plants need to respire as well as photosynthesise
to survive
• The 2 processes have many differences but a few
similarities…
C grade
What 3 things do
plants need to
survive?
Other than low
amounts of light and
carbon dioxide, what
else could cause a
plant to die?
Plants don’t have
blood, veins or
arteries – so how
does water and sugar
move around the
plant?
B grade
A grade
Give the word equation
for photosynthesis
Explain why plants have
leaves and suggest
adaptations of the leaves
that enable this to happen
What is it inside a plant
that absorbs sunlight
and what is done with
the light energy
absorbed?
Describe the term
‘limiting factor’ giving
examples
How is water and glucose
moved around the plant?
Where would you find an
increased number of
phloem and xylem
vessels?
What is the symbol
equation for
photosynthesis? Try to
balance the symbol
equation (glucose:
C6H12O6)
C grade
B grade
A grade
Leaves contain chloroplasts and therefore
Sunlight,
Carbon dioxide + water  chlorophyll to absorb light energy. Expect a
water and
oxygen and glucose
large surface area, thin cell walls and high
carbon dioxide
concentrations of chloroplasts lining the
leaves.
Competition,
animals eating
it, poor
nitrates in the
soil, damage
by humans
and weed
killers.
Xylem vessels
carry water
and phloem
vessels carry
sugar
(glucose)
Chloroplasts contain
chlorophyll which convert
sunlight energy into
chemical energy, which is
stored in glucose.
A limiting factor is a factor
that could influence the
growth of a plant.
Common limiting factor
include light, water and
carbon dioxide.
Vessels called the xylem and the phloem
carry water and glucose around the plant.
Phloem vessels carry glucose and xylem
vessels carry water. There would be many
phloem vessels located in the leaves
where photosynthesis takes place, where
as xylem vessels would be found in the
roots and stem.
6CO2 + 6H2O  C6H12O6 + 6O2
More keywords…
• Cellulose – material used to make cell walls
• Chlorophyll – green pigment in plants used in
photosynthesis
• Starch – an insoluble sugar
• Glucose – a soluble sugar
• Sunlight – light energy carries out photosynthesis
• Oxygen – produced by plants, breathed in by humans
• Carbon dioxide – breathed out by humans, plants absorb it
light energy
carbon
dioxide
Photosynthesis
water
glucose
oxygen
chlorophyll
What is the equation of photosynthesis?
• In this reaction water is split into oxygen gas and
hydrogen ions
• The second stage to photosynthesis is when carbon
dioxide gas combines with hydrogen and forms
glucose (eventually)
• It is obviously much more complex than this…
Rate of photosynthesis
• Photosynthesis increases during summer so crops
grow faster – as well as sunlight what else might
affect the rate of photosynthesis?
Increased temperature = increases enzyme activity
• Sunny warm days are the best days for
photosynthesis to occur
• If farmers can control conditions, they can increase
photosynthesis
Factors affecting
photosynthesis
• The rate of photosynthesis is proportional to light
intensity
• Gas exchange
occurs in the
leaves – we will
look at how this
occurs tomorrow
and next week
Osmosis
• Similar to diffusion but the movement of water only
• Used in plants
• Lots of water and not very much solute = high
water potential
• Not very much water and lots of solute = low water
potential
• Can you draw a picture on your whiteboard to
represent a high water potential? What about a low
water potential? (you might need a key…)
Osmosis in plants
Osmosis is the movement of water from a high water
potential to a low water potential through a
partially permeable membrane.
• Osmosis depends on a difference in the water
potential
• No difference – no movement and therefore no
osmosis
https://www.youtube.com/watch?v=IaZ8MtF3C6M
https://www.youtube.com/watch?v=nH4WkUo_m-4
Osmosis in plant cells and animal
cells
• Use osmosis to describe what you think has happened in
each of the diagrams – write your answers under the
pictures
• Why do you think we see the effect we see on an animal
cell?
• Do you think the same would happen if a plant cell
absorbed too much water? Why? (HINT: Think of the cell
structure)
The Leaf
• Leaves are adapted so that
photosynthesis can take place.
• Plants need carbon dioxide,
water, sunlight and chlorophyll
to carry out this important
process.
TASK – Observing a Leaf under a Microscope
Take a leaf and observe it under the microscope. What can you
see? Comment on any observations you make.
How are leaves adapted?
The features of leaf that make it suitable for photosynthesis are:
• A leaf is broad and flat to capture lots of sunlight
• Veins (xylem) carry water to the leaf and take food from the leaf
to the rest of the plant. Veins also help to support the leaf
• Certain plant cells contain chloroplasts with chlorophyll
• Small holes called stomata in the underside of a leaf allow
gases in and out
Inside a Leaf
The Structure of a Leaf
• The epidermis protects the
leaf and is transparent to
let light through.
• The palisade mesophyll
layer is where
photosynthesis mostly
takes place. The cells are
tall and closely packed to
absorb maximum light.
They contain many
chloroplasts.
The Structure of a Leaf
• The spongy mesophyll layer contains numerous air spaces where
gas exchange takes place. It also captures light and makes food
• The veins contain xylem (top part of vein) for water transport and
phloem (lower part of vein) to take away dissolved food
• The stomata has tiny holes in the epidermis of the leaf. They are
usually on the underside of the leaves. They control the water loss
and gas exchange by opening and closing. Since a lot of water
vapour can be lost through the stomata they only open for
photosynthesis in daylight; at night they close to reduce loss of
water vapour.
To start…
Draw a plant with roots, a stem and leaves
• Where would you expect the xylem vessels to
run?
• What happens once the water reaches the
necessary cells?
Transport in plants
• Water evaporates when it turns to a gas
• In plants this is called transpiration
• This is the movement of water up a plant, through
the stem and out of the leaves
https://www.youtube.com/watch?v=mc9gUm1mMzc
Transport in plants
• Xylem transports water through transpiration
• Water is used to dissolve sugars, for
photosynthesis, support and to cool it down
• Phloem carries dissolved solutes through
translocation
• Sugars are used to form cellulose which in turn
forms the cell wall of plants – a complex sugar
• Controlling the levels of water in plants is vital and
must be controlled – adaptations in the leaf prevent
this loss
Affecting the rate of transpiration
• You can measure the rate of transpiration using
a potometer
Explain to the
person next to
you how this
would work…
Stomata and Guard cells
Transpiration in detail
•
http://www.y
outube.com
/watch?v=At
1BJJDcXhk
•
http://www.k
science.co.
uk/animatio
ns/transpira
tion.swf
DIFFUSION
OSMOSIS
How oxygen
leaves a leaf
Involves water only
Is passive
High to low
concentration
Involves
transport of
solutes
How water
keeps plant
cells turgid
Movement
of particles
Occurs
in nature Needs a semi-
Requires energy
permeable
membrane
How minerals get
into root hair cells
Against a
concentration
gradient
ACTIVE TRANSPORT
Needed to make chlorophyll
Important for photosynthesis
Used for respiration and
photosynthesis
Magnesium
Used to make amino acids
Nitrates
Phosphates
Make proteins used for
enzymes
Used to make DNA
Potassium
Used for root growth
Used for respiration and
photosynthesis
Bell work…
What are these pictures of?
How do they work?
The process of decay by micro-organism
occurs faster in warm, moist, oxygen rich
conditions
Condition
Reason
Moisture
Spores cannot germinate in dry conditions. Moisture is
needed for the microbes to grow and multiply.
Warmth
Microbes reproduce and multiply best in a warm
environment. This means that decay occurs faster in
warmer temperatures.
Oxygen
The aerobic micro-organisms which are responsible for the
bringing about of decay, require oxygen to respire.
Decay in food chains
• Dead and decaying animals and plants are called
detritus
• Detritivores are maggots, earthworms and
woodlice – need detritus to survive
• Both of the species above are needed to maintain
Construct
food
chain for a forest – you must
food chainsaand
ecosystems
have 5 levels of your food chain
Compost production
• Microorganism action is dependant on enzymes
• More enzymes - more decay
• Optimum temperature is 37°C for bacteria and
25°C for fungi
• Respiration of bacteria, digestion and growth all
happen faster in warmer conditions
• More oxygen – more decay
Saprophyte
• Organisms such as fungi feed off dead and
decaying matter are called saprophytes
• Live in or on decaying matter
• Digestions takes place outside the body and is
called extracellular – juices are released onto the
dead/decaying matter