Transcript B4 The Processes of Life - Blackpool Aspire Academy

B4 The Processes of Life
Year 11 Revision
Cells
• All living things made
up of cells
• MRS GREN
• Movement,
Reproduction, Sense,
Growth, Respiration,
Excretion, Nutrition
• All reactions in
organisms catalysed by
enzymes
Making Enzymes
• Fermenters used to grow
bacteria so their enzymes
can be harvested.
• Contain a nutrient
solution
• Conditions such as pH,
temperature and oxygen
levels carefully controlled
for optimum values.
• Food, textiles industries
and biological washing
powders
Enzymes
• Chemical reactions in
cells rely on catalysts
• Proteins, made up of
long chains of amino
acids which fold into
different shapes
• Sequence of amino
acids determined by
instructions in a gene
Lock and Key Model
• Some enzymes break
down larger molecules
into smaller ones,
others join molecules
together
• Molecules must fit into
enzyme’s active site
Why do we need them?
• At 37oC, chemical
reactions would happen
too slowly to keep you
alive
• If you increased the
temperature, you would
damage cells, would
need more food to fuel
respiration
• 80% energy keeps body
warm
Temperature
• At low temps, enzyme
reactions increase if the
temp is increased
• Above certain
temperatures, enzyme
becomes denatured
• Active site shape
changed, no longer works
• All enzymes have an
optimum temperature
pH
• Proteins can also be damaged by acids and
alkalis.
• Shape will change is bonds are affected
• Substrate no longer able to fit – denatured
• Every enzyme has an optimum pH
Graphs
Examples of Enzymes
Enzyme
What it does
Optimum pH
Salivary amylase
Breaks down starch
to sugar (maltose)
Breaks down
proteins into short
chains of amino
acids
4.8
Breaks down
hydrogen peroxide
into water and
oxygen
7.6
Pepsin
Catalase
2.0
Photosynthesis
• Capturing energy from
sunlight, used to make
molecules for growth –
sugars, starch, enzymes
and chlorophyll.
• These molecules feed
others in the food chain
Equation
•
light
• 6CO2 + 6H2O
C6H12O6 + 6O2
•
chlorophyll
• Glucose is made up of CHO so is a carbohydrate
• Photosynthesis takes place in chloroplasts. Contain
chlorophyll which absorbs light and uses the energy to
start photosynthesis
• Energy from light splits water molecules into H and O
atoms. The H is combined with CO2 from the air to
make glucose. O is released as a waste product
•
Glucose and Starch
• Glucose can be converted
into starch for storage or
cellulose to make new cell
walls. Both are polymers
of glucose
• Glucose can also be built
up into fats, proteins and
chlorophyll
• Glucose molecules are
broken down by
respiration, releasing
energy to power chemical
reactions in cells
Diffusion
• Molecules of liquids and
gases move around
randomly, collide with
each other and spread
out.
• The y move from areas
of high to low
concentration
• Passive process
Stomata
• Underside of leaf
contains thousands of
tiny holes
• Allow carbon dioxide in
and oxygen out
Osmosis
• Special type of diffusion
• Move water molecules in
and out of cells across a
partially permeable
membrane
• Water moves from area of
high concentration to area
of low concentration of
water molecules
• Drives uptake of water
• Lack of water - wilting
Storage
• Glucose made by
photosynthesis
• Glucose transported
from leaves together
cells where is stored
until it is needed for
respiration. Water
would move to this area
unless stored as starch
• Insoluble starch grains
Need Nitrogen!
• Proteins are long chains
of amino acids
• Nitrogen needs to be
combined with carbon,
hydrogen and oxygen
from glucose made in
photosynthesis
• Absorbed from soil as
nitrate ions
• Absorbed by root hair
cells
What else do plants need?
• Magnesium to make
chlorophyll
• Phosphates to make DNA
• Proteins are needed to build
cells and make enzymes, so
nitrates are needed in the
highest quantities
• Fertilisers contain minerals
such as phosphates and
nitrates
Active Transport
• Nitrate ions are at a higher
concentration inside the
root cells, compared to the
surrounding soil
• Diffusion should move ions
out into soil.
• Plants use active transport
to overcome this
• Cells use energy from
respiration to transport
molecules across the
membrane
Yields
• The amount of product a
farmer has to sell
• Limiting factors of
photosynthesis –
temperature, light intensity,
carbon dioxide, water and
chlorophyll
• Stomata may close to
conserve water, but stops
carbon dioxide entering the
leaf
Habitats
• Plants need different amounts of light, water
and minerals.
• Factors such as soil pH, temperature, light
intensity and the availability of water can be
measured.
• Samples are taken to get a picture of what the
habitat is like
Measurements
• Quadrats (identification
keys; percentage
growth)
• Random (removes bias)
• Transect (how species
change across
landscapes)
• Light meters
Aerobic Respiration
• Cells need constant supply of energy for
chemical reactions
• Glucose from food reacts with oxygen
• Reactions release energy from the glucose
• C6H12O6 + 6O2
6CO2 + 6H20 (energy)
Where does it occur?
• Mitochondria –
contains the enzymes
for aerobic respiration
• Energy made used to
make polymers – starch,
cellulose, proteins, fats
and oils
Anaerobic Respiration
• Short bursts of intense
energy
• Doesn’t use oxygen
•
•
•
•
•
Glucose
lactic acid
(+ energy)
Releases less energy
Lactic acid is toxic
Parts of plants; seeds;
micro-organisms
Useful anaerobic respiration
• Glucose
Ethanol + Carbon Dioxide (energy)
• Bacteria and yeast can be used in bread,
cheese, yoghurts, alcoholic drinks and vinegar.
Yeast and Bacteria
Products
• Bioethanol – vehicle
engines (made from
sugars in plant material
such as beet, maize and
wheat)
• Fermentation – yeast
convert sugars
Biofuels
• Land may be used for
growing fuel instead of
food
• Forests may be cut
down
• New research using
algae hopefully will end
the need to use food
crops
Biogas
• From animal waste or
manure
• Bacteria break down
the manure and
produce methane gas
• Made in biodigester