2e) Nutrition

Flowering Plants 

Plants use the sun's energy to make food through the process of photosynthesis 

Word and symbols equations:

Carbon Dioxide and Water ----------> Glucose and Oxygen 

       6CO2                 6H2O                   C6H12O6        6O2 

The rate of photosynthesis
If the light intensity is increased the rate of photosynthesis will increase steadily, but only to a certain point



Even if there is plenty of light, a plant can't photosynthesise if there is insufficient CO2



Temperature:
too cold = decrease
too hot = enzymes denature



Leaf structure




Adaptations:

• Broad ~ large surface area and exposed to light
• most chloroplasts found in palisade layer ~ near the top to absorb the sunlight 
• upper epidermis ~ transparent: light can pass through 
• vascular bundles (xylem and phloem) ~ deliever water and minerals, and other nutrients and take away the glucose (also support the leaf structure) 
• waxy cuticle ~ reduces water loss 
• stoma(ta) ~ CO2 diffuses directly into the leaf 

Minerals for healthy plant growth:

Nitrates ~ nitrogen makes amino acids and proteins cell growth 

Potassium ~ help the enzymes needed for photosynthesis and respiration 

Phospates ~ make DNA and cell membranes and respiration + growth 

Magnesium ~ makes chlorophyll which makes the leaf green

Testing for starch in leaves:

1. boil the leaf for 2 mins 
2. put ethanol ~ makes it colourless 
3. put on white tile and add iodine solution

Oxygen Production:

• Shows rate of photosynthesis 

1. white light placed at a specific distance from the pondweed 
2. leave to photosynthesise for a set amount of time collect oxygen in capillary tube 
3. syringe used to draw the gas bubbles in tube 
• measure length of gas bubbles 
• proportional to volume of O2 produced 
4. experiment repeated with light source placed at different distances from pondweed 

Humans 

+-------------------------+--------------------------------+---------------------------------------------+
| Nutrient                | Found in                       | Function(s)                                 |
+-------------------------+--------------------------------+---------------------------------------------+
| Carbohydrates           | pasta, rice, sugar, jam        | starch ~ provide energy for brain and body  |
+-------------------------+--------------------------------+---------------------------------------------+
|                         |                                | sugar ~ convert glucose easily              |
+-------------------------+--------------------------------+---------------------------------------------+
| Protein                 | meat, fish, beans              | needed for growth and repair of tissue      |
+-------------------------+--------------------------------+---------------------------------------------+
|                         |                                | energy in emergencies                       |
+-------------------------+--------------------------------+---------------------------------------------+
| Lipids/ Fats            | butter, cream, oily fish, nuts | provide energy                              |
+-------------------------+--------------------------------+---------------------------------------------+
|                         |                                | energy store and insulation                 |
+-------------------------+--------------------------------+---------------------------------------------+
|                         |                                | prevents deficiency of certain fats         |
+-------------------------+--------------------------------+---------------------------------------------+
| Vitamin      A          | liver                          | improve vision and makes skin/hair healthy  |
+-------------------------+--------------------------------+---------------------------------------------+
|              C          | oranges                        | prevents scurvy                             |
+-------------------------+--------------------------------+---------------------------------------------+
|              D          | eggs and fish                  | calcium absorption ~ bones and teeth        |
+-------------------------+--------------------------------+---------------------------------------------+
| Mineral   Iron          | red meat                       | haemoglobin ~ healthy blood                 |
+-------------------------+--------------------------------+---------------------------------------------+
| Mineral   Calcium       | milk, cheese                   | makes bones and teeth                       |
+-------------------------+--------------------------------+---------------------------------------------+
| Water                   | food and drink                 | flushes away toxins and carries nutrients   |
+-------------------------+--------------------------------+---------------------------------------------+
| Dietary fibre           | wholemeal foods, fruit & veg   | aids the movement of foods through the gut  |
+-------------------------+--------------------------------+---------------------------------------------+
|                         |                                | prevents diabetes, cancer and heart disease |
+-------------------------+--------------------------------+---------------------------------------------+

Energy requirements:

Activity level ~ active people need more energy 

Age ~ children and teenagers more energy than older people 

Pregnancy ~ energy: pregnant women > other women, this is because they need energy for the baby to develop

The Alimentary Canal 

Mouth and Salivary Glands ~ produces amalase to dissolve food and teeth break down food 

Oesophagus ~ muscular tube passes food to stomach 

Liver ~ stores glucose as glycogen and produces bile 

Gall Bladder ~ stores bile: breaks down fats 

Stomach ~ muscular organ where digestion continues. Contains HCl which kills bacteria 

Pancreas ~ produces protease, amylase and lipase enzyme and releases to small intestine 

Small intestine ~ absorption of nutrients

Large intestine ~ absorption of water 

Rectum and anus ~ egestion 

Peristalsis:

The Digestive Process:

1. Ingestion: putting food into your mouth 
2. Digestion: break down of large, insoluble molecules into small molecules 

• mechanical: teeth and stomach muscles and chemical; enzymes and bile

      3. Absorption: moving molecules through the walls of intestines. Small ------> nutrients 

          Large -----> H2O 

•   Villi helps with the absorption:
• big surface area 
• microvilli
• single permeable layer 
• good blood supply 

      4. Assimilation: digested molecules are moved into body cells and become part of cells 

      5. Egestion: getting rid of faeces 

Enzymes and digestion:

enzyme	reaction catalysed
amylase	starch    →    sugars
protease	proteins    →    amino acids
lipase	lipids    →    fatty acids + glycerol

enzyme	where produced
amylase	salivary glands, pancreas, small intestine
protease	stomach, pancreas, small intestine
lipase	pancreas, small intestine

Bile:

HCl is too acidic, bile neutralises it and makes conditions alkaline 

enzymes work best in alkaline 

also emulsifies fats ------> bigger surface 

Energy in joules:

= Mass of Water x Temp. change of water x 4.2 

Energy in joules per gram:

= Energy of food (j)/ Mass of food (g) 

Notes in bold italics are for paper two only