B4 Revision stuff

1. 12/27/14
OCR Additional ScienceOCR Additional Science
B4 The Processes of LifeB4 The Processes of Life
W Richards
The Weald School

2. 12/27/14
B4.1 How do Chemical ReactionsB4.1 How do Chemical Reactions
take place in living things?take place in living things?

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Photosynthesis IntroductionPhotosynthesis Introduction
Basically, photosynthesis is the process through which a plant
makes large food molecules using carbon dioxide and water and
it happens in plants as well as some micro organisms:
That’s a nice plant. I’m
going to put it in the sun
and give it lots of water
and air…
CO2
H2O

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Respiration IntroductionRespiration Introduction
I enjoy taking samples using quadrats. In
order to do this, I need energy. Where
does this energy come from?
All living things, including plants, get their
energy from respiration. Respiration is
basically the process of breaking down the
large food molecules that were probably
originally made in plants.

5. 12/27/14
Enzyme use in natureEnzyme use in nature
Cells use glucose to generate
energy – this process is called
“respiration”. Respiration
happens in mitochodria and is
catalysed by enzymes.
Photosynthesis is
catalysed by enzymes
in the cells.
Enzymes are proteins that speed up chemical uses. Here are
two important natural uses for them:

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EnzymesEnzymes
Enzymes are biological catalysts. They help the reactions
that occur in our bodies by controlling the rate of reaction.
An enzyme is basically a protein molecule made
up of long chains of amino acids. Cells make
enzymes according to the instructions carried in
their genes.
The enzyme’s shape helps another
molecule “fit” into it:
This shape can be destroyed by
high temperatures or the wrong
pH:
Enzyme Substrate

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The “Active Site”The “Active Site”
Enzyme Substrate
Active site

8. 12/27/14
Enzymes are
denatured
beyond 40O
C
EnzymesEnzymes
Enzymes work best in certain conditions:
Enzyme activity
Temp pH pH400
C
Could be
protease (found
in the stomach)
Could be amylase
(found in the
intestine)
Enzymes are used in industry to bring about reactions at
normal temperatures and pressures that would otherwise be
expensive. However, most enzymes are denatured at high
temperatures and can be costly to produce.

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B4.2 How do Plants make food?B4.2 How do Plants make food?

10. 12/27/14
Travels up
from the roots
WATER
CARBON DIOXIDE
Enters the leaf through small
holes on the underneath
SUNLIGHT
Gives the plant energy
CHLOROPHYLL
The green
stuff
where the
chemical
reactions
happen
Photosynthesis – the 4 things you needPhotosynthesis – the 4 things you need

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Carbon dioxide + _____ glucose + _____
6CO2 + 6H20 C6H12O6 + 6O2
Sunlight
Chlorophyll
Sunlight
Chlorophyll
The GLUCOSE produced by photosynthesis is used by the
plant for _______ (through ____________). It is stored
in the plant as ___________.
Words – respiration, starch, water, oxygen, energy
Photosynthesis equationsPhotosynthesis equations

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What is the glucose used for?What is the glucose used for?
1) Glucose (sugar) can be used to make long chains of insoluble starch…
Glucose
molecules
Starch
molecule
2) Glucose can be used to make cellulose for cell walls…
3) Glucose can be combined with nitrates to make proteins (for growth)…
Glucose
molecules
Glucose
molecules
Cellulose
Proteins
Glucose can also be used for respiration,
either by the plant or by what eats it!

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A Typical Plant Cell:A Typical Plant Cell:
Cell wall – made
of cellulose which
strengthens the cell
Cell membrane
– controls what
comes in and out
Nucleus – controls
what the cell does and
stores genetic info for
making proteins
Large vacuole –
contains sap and
helps support the
cell
Cytoplasm –
Chemical reactions
happen here
Chloroplasts – contains
chlorophyll and enzymes for
photosynthesis reactions

14. 12/27/14
2 common nutrients…2 common nutrients…
Nitrates:
 Used to make proteins
 Lack of it leads to stunted growth
Magnesium:
 Used to make chlorophyll
 Lack of it leads to yellow leaves

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DiffusionDiffusion
Diffusion is when something travels from an area of high
concentration to an area of low concentration. For example,
consider the scent from a hamburger…
The “scent particles” from
this hamburger are in high
concentration here:
Eventually they will
“diffuse” out into this area
of low concentration:
Carbon dioxide and oxygen pass in and out
of leaves by diffusion.

16. 12/27/14
Diffusion SummaryDiffusion Summary
Diffusion is when particles spread from an area of high
concentration to an area of ___ concentration. The particles
move along a “concentration _____” and this process takes no
_____ (it’s a “passive” process”). Diffusion can be accelerated
by increasing the _______ of the particles, which makes them
move _______.
Words – faster, low, gradient, temperature, energy

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OsmosisOsmosis
Osmosis is a “special kind of ___________”. It’s when water
diffuses from a __________ area to a less concentrated area
through a partially permeable _________ (i.e. one that allows
water to move through but not anything else):
Water Sugar solution
In this example the water
molecules will move from
left to right (along the
concentration ______) and
gradually _____ the sugar
solution. Plants use osmosis
to take in water through
their roots.
Words – membrane, concentrated, dilute, diffusion, gradient

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Strong
sugar
solution
Medium
sugar
solution
Weak
sugar
solution
Potatocells

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Active TransportActive Transport
In diffusion substances moved along a concentration gradient.
In active transport, substances move against this gradient:
Outside cell Inside cell
This process takes ______ and
this comes from ___________.
It enables cells to take in
substances even though there
are in very small __________.
Root hair cells take in ______
using active transport.
Cell membrane Words – concentration, energy,
respiration, nutrients

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Carbon dioxide diffuses
into the leaf through
holes in the bottom
surface.
Diffusion and Active Transport in plantsDiffusion and Active Transport in plants
More
concentrated
Less
concentrated
Mineral
…while plant nutrients are taken
in by root hair cells using active
transport.

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Encouraging PhotosynthesisEncouraging Photosynthesis
Using knowledge of limiting factors, explain how plant growth
is encouraged in a greenhouse:

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Limiting PhotosynthesisLimiting Photosynthesis
1. Temperature – the best temperature is
about 300
C – anything above 400
C will
slow photosynthesis right down
2. CO2 – if there is more carbon dioxide
photosynthesis will happen quicker
3. Light – if there is more light
photosynthesis happens faster
What factors could limit the rate of photosynthesis?

23. 12/27/14
Drawing graphs of these factorsDrawing graphs of these factors
1. Temperature
Photosynthesis is controlled by
enzymes – these are destroyed
at temperatures above 400
C
2. Carbon dioxide
3. Light
Photosynthesis increases at
first but is then limited by a
lack of increase in temp or CO2
Photosynthesis increases at
first but is then limited by a
lack of increase in temp or light

24. 12/27/1412/27/14
Fieldwork techniquesFieldwork techniques
Recording light
levels
Using quadrats
Fieldwork techniques also involve using a key to identify plants.

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B4.3 How do living organisms obtainB4.3 How do living organisms obtain
energy?energy?

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Uses for energy from respirationUses for energy from respiration
Animals and plants have many uses for the energy they
generate from respiration:
1) To perform the life processes, such as moving, _____ etc
2) To build up body _______
3) To maintain a constant body ___________ (warm-blooded
mammals only)
4) To build up sugars, ________ and other nutrients in plants
5) Active __________
Words – nitrates, tissue, proteins, transport, growing

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SynthesisSynthesis
1) Glucose (sugar) can be used to make long chains of insoluble starch…
Glucose
molecules
Starch
molecule
“Synthesis” means “making large molecules out of small ones”.
Two examples:
2) Glucose can be combined with nitrates to make proteins (for growth)…
Glucose
molecules Proteins

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Respiration IntroductionRespiration Introduction
I enjoy taking samples using quadrats. In
order to do this, I need energy. Where
does this energy come from?
Our energy comes from a process called
respiration, which basically involves turning
food and oxygen into energy and this
reaction is controlled by enzymes.

29. 12/27/14
(Aerobic) Respiration(Aerobic) Respiration
Words – breathing, energy, grow, respiration, food,
mitochondria
All living organisms have to move, _____, reproduce etc. Each
of these life processes needs ENERGY. ___________ is the
process our bodies use to produce this energy:
Glucose + oxygen water + carbon dioxide + ENERGY
The glucose we need comes from ______ and the oxygen from
_________. Water and carbon dioxide are breathed out.
The MAIN product of this equation is _________.
Respiration happens in _________ in cells.

30. 12/27/14
Muscles and exerciseMuscles and exercise
When we exercise our muscles are supplied with more oxygen
and glucose, increasing the rate of respiration.
Muscles store glucose as glycogen
which can then be converted back
into glucose during exercise.

31. 12/27/14
Anaerobic respirationAnaerobic respiration
Unlike aerobic respiration, anaerobic respiration is when
energy is provided WITHOUT needing _________:
This happens when the body can’t provide oxygen quick enough
for __________ respiration to take place.
Anaerobic respiration produces energy much _______ than
aerobic respiration but only produces 1/20th
as much.
Anaerobic respiration can also take place in other low-oxygen
conditions, such as plant roots in _________ soil or
bacteria in ________ wounds.
Words – oxygen, aerobic, quicker, puncture, waterlogged
Glucose lactic acid + a bit of energy

32. 12/27/14
Making EthanolMaking Ethanol
Ethanol is an important chemical. Many
countries are increasing the amount of
ethanol put into their petrol supplies:
Ethanol is another product of anaerobic respiration in plant
cells and some micro organisms:
Ford Escape E85 –
runs on 85% ethanol
Sugar ethanol + carbon dioxide + energy

33. 12/27/14
BacteriaBacteria
Consider a bacteria cell in more detail:
Bacteria – containing
cytoplasm and a membrane
surrounded by a cell wall.
The genes are NOT in a
distinct nucleus.
The cell contains a number of features,
including:
1) Chromosomal DNA, containing the
genetic info of the cell
2) Plasmid DNA, containing extra
information such as defence
mechanisms
3) Flagella, which helps the cell move

34. 12/27/14
The Structure of BacteriaThe Structure of Bacteria
Bacteria also have plasmids
(circular strands of DNA) that
can be copied and move
between different bacteria.
This means that resistance to
antibiotics can be passed on
without the need for
reproduction.

35. 12/27/14
4)
2)
Respiration in CellsRespiration in Cells
Notice that plant and animal cells (and bacteria) have many
features that help respiration:
Mitochondria –
contain enzymes for
respiration reactions
Cell Membrane –
controls what comes in
and out
Cytoplasm -
where enzymes are
made
Nucleus – carries
genetic info for
making enzymes
1)
3)
In bacteria cells, this job
is done by circular DNA

36. 12/27/1427/12/14
Using Anaerobic RespirationUsing Anaerobic Respiration
Anaerobic respiration in micro organisms is used to make fuels
through:
1) Manure or other waste that can be
used to release methane (biogas)
2) Corn or sugar cane that can be broken
down in a fermenter to produce
alcohols like bio-ethanol.
Anaerobic respiration is also
used in fermentation to make
bread and alcohol.