1. OCR Additional Science
10/04/2017
B4 The Processes of Life
OCR Additional Science
M Barker
Shirebrook Academy

2. B4.1 How do Chemical Reactions take place in living things?
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B4.1 How do Chemical Reactions take place in living things?

3. Photosynthesis Introduction
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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

4. Respiration Introduction
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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 Respiration is basically the process of breaking down the large food molecules that were probably originally made in plants.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. Enzyme use in nature
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Enzymes are proteins that speed up chemical uses. Here are two important natural uses for them:
Photosynthesis is catalysed by enzymes in the cells.
Cells use glucose to generate energy – this process is called “respiration”. Respiration happens in mitochodria and is catalysed by enzymes.

6. Enzymes
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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.
Enzyme
The enzyme’s shape helps another molecule “fit” into it:
Substrate
This shape can be destroyed by high temperatures or the wrong pH:

7. The “Active Site”
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Active site
Enzyme
Substrate

8. Enzymes are denatured beyond 40OC
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Enzymes work best in certain conditions:
Enzymes are denatured beyond 40OC
Could be protease (found in the stomach)
Could be amylase (found in the intestine)
Enzyme activity
Temp pH
400C
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.

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

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

11. Photosynthesis equations
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Carbon dioxide + _____ glucose + _____
6CO H20 C6H12O O2
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

12. What is the glucose used for?
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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…
Glucose molecules
Cellulose
3) Glucose can be combined with nitrates to make proteins (for growth)…
Glucose molecules
Proteins
Glucose can also be used for respiration, either by the plant or by what eats it!

13. A Typical Plant Cell:
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Cell wall – made of cellulose which strengthens the cell
Cell membrane – controls what comes in and out
Chloroplasts – contains chlorophyll and enzymes for photosynthesis reactions
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

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

15. Carbon dioxide and oxygen pass in and out of leaves by diffusion.
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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. Words – faster, low, gradient, temperature, energy
Diffusion Summary
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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

17. Words – membrane, concentrated, dilute, diffusion, gradient
Osmosis
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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):
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.
Water
Sugar solution
Words – membrane, concentrated, dilute, diffusion, gradient

18. Strong sugar solution Medium sugar solution Potato cells
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Strong sugar solution
Medium sugar solution
Potato cells
Weak sugar solution

19. Words – concentration, energy, respiration, nutrients
Active Transport
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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.
Words – concentration, energy, respiration, nutrients
Cell membrane

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

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

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

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

24. Recording light levels
Fieldwork techniques
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Recording light levels
Using quadrats
Fieldwork techniques also involve using a key to identify plants.

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

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

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

28. Respiration Introduction
10/04/2017
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. (Aerobic) Respiration
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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.
Words – breathing, energy, grow, respiration, food, mitochondria

30. Muscles and exercise
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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. Anaerobic respiration
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Unlike aerobic respiration, anaerobic respiration is when energy is provided WITHOUT needing _________:
Glucose lactic acid + a bit of energy
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

32. Sugar ethanol + carbon dioxide + energy
Making Ethanol
Ford Escape E85 – runs on 85% ethanol
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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:
Sugar ethanol + carbon dioxide + energy

33. Bacteria Consider a bacteria cell in more detail:
The cell contains a number of features, including:
Chromosomal DNA, containing the genetic info of the cell
Plasmid DNA, containing extra information such as defence mechanisms
Flagella, which helps the cell move
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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.

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

36. Using Anaerobic Respiration
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Anaerobic respiration in micro organisms is used to make fuels through:
Manure or other waste that can be used to release methane (biogas)
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.