Edexcell ppt Biology 2.17-2.32 Used in lessons to scaffold class teaching and as a revision resource for students

1. NUTRITION
(Yum Yum Yum)

2. PLANT NUTRTITION
2.17 describe the process of photosynthesis and understand its importance in the
conversion of light energy to chemical energy
Nutrition in Plants:
Plants are photoautotrophic (i.e. they generate
their own “food” using energy from the Sun.) They
do this through photosynthesis.

3. Photosynthesis Equation
2.18 write the word equation and the balanced chemical symbol equation for photosynthesis
Nutrition in Flowering Plants:
The equation for photosynthesis can be written as:
-Word equation
-Chemical equation
In both cases reaction uses a catalyst (chlorophyll)

4. Light ….. Glucose….. ?
2.18 write the word equation and the balanced chemical symbol equation for photosynthesis
Through photosynthesis light energy is converted
into chemical energy in the bonds in glucose. Plants
use glucose for the following;
1) Respiration
2) Stored as Starch
3) Turned into Cellulose (cellulose is a
polymer of glucose)
4) Used to make fats and oils

5. Photosynthesis Rate
2.19 understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis
At any point the rate of photosynthesis can be
increased by adding:
1) More CO2
2) More light
WAIT!!!!
3) Heating towards optimum temperature
This (photosynthesis is not is catalyzed the by whole
enzymes).
story

6. Limiting Factors
2.19 understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis
a)At a certain point the addition of MORE
(light & CO2) will not increase the rate of
photosynthesis any further.
b)This is because a second factor is limiting
the rate of photosynthesis.
c)Adding more of the rate-limiting factor
will increase the rate further until another
factor becomes limiting.

7. Drawing the Graph
2.19 understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis
The addition of MORE (light & CO2) will
not increase the rate of photosynthesis
after reaching a rate limiting factor.
What about Temperature?

8. ?Temperature?
2.19 understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis

9. ?Temperature?
2.19 understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis
Without enough light, a plant cannot
photosynthesize very quickly, even if there is
plenty of water and carbon dioxide.
1) Increasing the temperature will boost the
speed (rate) of photosynthesis.
2) Increasing the intensity will boost the
speed (rate) of photosynthesis.

10. Changing the Limiting Factor
2.19 understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis
Adding more of the rate-limiting factor increases the rate
further…….............until another factor becomes limiting.

11. What about Water?
2.19 understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis
Water is not seen as a limiting factor.
Plants have enough water in their tissues for
photosynthesis.
If they do not have enough water the plant will wilt
and die anyway.
Very sad, but very true.

12. Leaf Structure
2.20 describe the structure of the leaf and explain how it is adapted for photosynthesis
You need to know the parts of the leaf and their
adaptations.
DO NOT
DRAW
THIS
DIAGRAM

13. SIMPLE CROSS SECTIONAL LEAF DIAGRAM
2.20 describe the structure of the leaf and explain how it is adapted for photosynthesis

14. More Complicated Cross Section
2.20 describe the structure of the leaf and explain how it is adapted for photosynthesis

15. In Real Life
2.20 describe the structure of the leaf and explain how it is adapted for photosynthesis

16. LABEL
2.20 describe the structure of the leaf and explain how it is adapted for photosynthesis

17. Adaptation
2.20 describe the structure of the leaf and explain how it is adapted for photosynthesis

18. Which Tissues Are Missing?
2.20 describe the structure of the leaf and explain how it is adapted for photosynthesis
Please add into your notes any tissue missing
and write in their functions:
1) Xylem
2) Phloem
3) Vascular Bundle
4) Spongy Mesophyll

19. Minerals for Nutrition
2.21 understand that plants require mineral ions for growth and that magnesium ions are needed for chlorophyll and nitrate ions are needed for
amino acids
In addition to water and CO2 plants also need specific
minerals;
• Nitrate – used to make amino acids for use in plant
proteins Magnesium – forms part of the chlorophyll
molecule
• Potassium - essential for cell membranes
• Phosphate - essential part of DNA and cell
membranes

20. Experiment we CAN NOT do!

21. EXPERIMENTS WE CAN DO
2.22 describe experiments to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and
chlorophyll

22. Using Pond Weed
2.22 describe experiments to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the
requirements of light, carbon dioxide and chlorophyll
You must know an experiment that shows how the rate of
photosynthesis is affected by rate-limiting factors.
Example: Use pond weed (Elodea) which produces bubbles of O2 as it
photosynthesizes.
1) The rate of bubble production is proportional to the rate of
photosynthesis.
2) When you add light or give it more CO2, the rate of bubble
production increases.
Watch out:
 Cut Elodea underwater or air bubbles will form in xylem
 Make sure the O2 is a result of light and not temperature
 The examiner may ask for a better way to measure O2 production

23. Set up for Photosynthesis Rate Vs Light intensity
2.22 describe experiments to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements
of light, carbon dioxide and chlorophyll
Change:
Light
intensity
(distance of
lamp from
Elodea)
Measure:
Number of
bubbles per
minute

24. Setup for Photosynthsis Rate Vs CO2
Concentration
2.22 describe experiments to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements
of light, carbon dioxide and chlorophyll
Change: Concentration
of Sodium Hydrogen
Carbonate Solution (CO2)
Measure: Number of
bubbles per minute

25. Testing Photosynthesis by Starch
2.22 describe experiments to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements
of light, carbon dioxide and chlorophyll
You need to know an experiment that proves that
light and CO2 are essential for the production of
starch.
A good example is the Geranium plant. It’s leaves
normally turn blue-black in the presence of iodine
solution showing starch is present
(you have to boil it in ethanol first to remove the
chlorophyll to show the colour).

26. Testing Photosynthesis by Starch
2.22 describe experiments to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements
of light, carbon dioxide and chlorophyll
Negative Test:
Reddish / Brown
Positive Test:
Blue / Black
Safety: Why is it dangerous to
boil ethanol directly with a
Bunsen Burner instead of using
a water bath?

27. Destarching
2.22 describe experiments to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon
dioxide and chlorophyll
You will want to destarch a leaf for this experiment.
To remove the starch (destarch)
1) put the poor plant in a dark room for 24 hours.
2) No light means no photosynthesis, no
photosynthesis means no glucose produced, no
glucose produced means no starch stored in the leaf.
Sadly the leaf still needs to respire so it will break all
the previously stored starch back into glucose to use
in respiration. No more starch, poor leaf…

28. Destarching
2.22 describe experiments to investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon
dioxide and chlorophyll
However, if one leaf is
put in aluminium foil
and another is kept
with lime water both
do not turn blue-black.
Both CO2 and light are essential for starch production
and, therefore, essential for photosynthesis.

29. Nutrition in Humans
Syllabus points 2.23 – 2.32

30. Balanced Diet
2.23 understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre(TA)
A diet that contains
adequate amounts of all the
necessary nutrients required
for healthy growth and
activity.
A balanced diet is one that
contains all the ingredients
needed for our body to
healthily continue its day to
day functions in the most
efficient way.

31. Balanced Diet
2.23 understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre(TA)

32. Balanced Diet
2.23 understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre(TA)
72% of our body is WATER.
We contain so much water because water:
-Distributes essential nutrients to cells,
such as minerals, vitamins and glucose as
part of the plasma in our blood
-Is an integral part of urine and faeces,
which removes waste from our body
-Is needed for sweat (sweat is essential in
controlling our internal body
temperature)

33. What do you have to eat
2.24 identify sources and describe functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, and the mineral ions calcium and iron, water and dietary fibre as components of
the diet
Component Function Example of sources
Carbohydrate Short-term chemical energy Bread, potatoes
Lipids (fats and oils) Long-term chemical energy Bacon, beef
Protein Growth & Repair Fish, egg
Vitamin A Eyesight Carrots, fish liver oil
Vitamin C Healthy skin + gums Oranges
Vitamin D Absorb Ca (calcium) Sunlight
Mineral ions – Fe (iron) Making haemoglobin in RBC Spinach, animal liver
Mineral ions – Ca (calcium) Strong bones and teeth milk
Dietary fiber Peristalsis Vegetables, cereal
Water Transport system
To sweat
All chemical reactions occur in
solution inside cells
Fruits like watermelon

34. Not all bodies are Energy (J) Equal
2.25 understand that energy requirements vary with activity levels, age and pregnancy (TA)
Person Energy needed per day (kJ)
Newborn baby 2000
Age 2 5000
Age 6 7500
Gril age 12-14 9000
Boy age 12-14 11000
Girl age 15-17 9000
Boy age 15-17 12000
Female office worker 9500
Male office worker 10500
Heavy manual worker 15000
Pregnant woman 10000
Breast-feeding woman 11300

35. Not all bodies are Energy (J) Equal
2.25 understand that energy requirements vary with activity levels, age and pregnancy (TA)
The two groups that provide energy (through respiration) are lipids and
carbohydrates.
Per mass lipids have about 10x more energy in them than
carbohydrates.
The energy in food is measured in Calories (equivalent to 4.2 kJ).
If Males need to consume 2500 Calories a day and Females need to consume 2000
Calories a day how many kJ do they need to consume in a day?
If:
Fat: 1 gram = 9 calories
Carbohydrates: 1 gram = 4 calories
How many grams of each do you need to supply your energy for the day?

36. Not all bodies are Energy (J) Equal
2.25 understand that energy requirements vary with activity levels, age and pregnancy (TA)
Energy requirements vary according to several factors:
• Age: growing people require more energy than others.
• Gender: on average, males require more energy than
females.
• Pregnancy: pregnant women require more energy to
nourish themselves and the baby.
• Activity levels: more active people require more energy
as they use up more energy throughout the day.

37. Name that structure
2.26 describe the structures of the human alimentary canal and describe the functions of the mouth, oesophagus, stomach, small intestine, large intestine and pancreas
game

38. Describe the function
2.26 describe the structures of the human alimentary canal and describe the functions of the mouth, oesophagus, stomach, small intestine, large intestine and pancreas
• Functions
Mouth • Physical digestion by teeth
• Salivary glands produce saliva 
moistens food  making it easier to be
swallowed
• Chemical digestion by amylase breaks
down starch into maltose
Oesophagus • Food is moved by peristalsis
Stomach • Produces HCl & protease (pepsin)
enzymes
Small intestine • Produces carbohydrase (maltase),
protease (trypsin) & lipase enzymes
• Absorbs digested food
Large intestine • Absorbs water
Pancreas • Produces carbohydrase (maltase),
protease (trypsin) & lipase enzymes

39. Flow Chart the Process
2.27 understand the processes of ingestion, digestion, absorption, assimilation and egestion
Ingestion
• Taking food into
the body
Digestion
• The breakdown of large
insoluble molecules into
small soluble molecules
so they can be absorbed
into the blood
Absorption
• The process of
absorbing nutrients
into the body after
digestion
Assimilation
• Using food
molecules to build
new molecules
Egestion
• Getting rid of
undigested/unwan
ted food

40. Flow Chart the Process
2.27 understand the processes of ingestion, digestion, absorption, assimilation and egestion
Digestion can be mechanical or chemical
Mechanical Digestion: digestion by physically breaking food into smaller pieces (i.e. not using
enzymes). Carried out by;
• mouth and teeth chewing food
• stomach churning food
Chemical Digestion: digestion using enzymes

41. Peristalsis
2.28 explain how and why food is moved through the gut by peristalsis
Food is moved the digestive
system by a process known as
peristalsis.
This is the contractions of two
sets of muscles in the walls of
the gut.
1) One set runs along the gut
2) The other set circles it.
Their wave-like contractions
create a squeezing action,
moving down the gut. ani

42. Digestive Enzymes
2.29 understand the role of digestive enzymes, to include the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and
glycerol by lipases
Enzymes and digestion
The enzymes involved in respiration, photosynthesis and protein synthesis work inside
cells.
Other enzymes are produced by specialised cells and released from them these are
digestive enzymes.
They pass out into the gut, where they catalyse the breakdown of food molecules.
Different enzymes
(Different enzymes catalyse different digestion reactions)
Amylase Starch → sugars
Amylase catalyses the breakdown of starch into sugars in the mouth and small intestine
Protease Proteins → amino acids
Proteases catalyse the breakdown of proteins into amino acids in the stomach and small intestine
Lipase Lipids → fatty acids + glycerol
Lipases catalyse the breakdown of fats and oils into fatty acids and glycerol in the small intestine

43. Bile is not so Vile
2.30 understand that bile is produced by the liver and stored in the gall bladder, and understand the role of bile in neutralising stomach acid and emulsifying lipids
After the stomach, food travels to the small intestine. The enzymes in
the small intestine work best in alkaline conditions, but the food is
acidic after being in the stomach.
• Bile is alkaline substance
• Bile is produced by the
liver
• Bile is stored in the gall
bladder.
• Bile is secreted into the
small intestine, where it
emulsifies fats
This is important, because it
provides a larger surface
area in which the lipases can
work.

44. Silli Villi
2.31 describe the structure of a villus and explain how this helps absorption of the products of digestion in the small intestine
The Villus is the location of Absorption of small soluble
nutrients into to blood.

46. How much energy is in that crisp?
2.32 describe an experiment to investigate the energy content in a food sample.(TA)
You need to know an experiment that can show how much energy there is in food.
Burn a sample of food and use it to heat a fixed volume of water. Record the change in
temperature of the water and use the equation below to find out the energy the food gave to the
water;
Energy = change in temp. x volume of water x 4.2J/g/°C
Problem is that not all the food will burn.
To control this, you measure the start and end mass of the food and calculate the mass that
actually burned.
To standardize this, you can divide your calculated energy value by the change in mass to give
you the change in mass per gram of food
(which will allow you to compare values fairly between different food samples)

47. How much energy is in that peanut?
2.32 describe an experiment to investigate the energy content in a food sample.(TA)
There are problems with using this system:
Heat from food item does not heat water
Not all the food burns
Water looses heat to environment
So what is the solution?