2i) Excretion

Flowering plants 

Substance being excreted - Oxygen (O2) 

Origin of these excreted substances- leaf/ photosynthesis 

equations- Carbon Dioxide (6CO2) + Water (6H2O) -------> Glucose (C6H12O6) + Oxygen (6O2) 

Humans 

Organs of excretion in the human body are the lungs, kidneys and skin

Excreted substances- water, urea, potassium 

Why is it important to remove urine- urea is POISONOUS 

The kidney:

The Nephron (which is located in the cortex):

Kidney Machine:

Osmoregulation:

2g) Gas Exchange

Flowering Plants 

When plants photosynthesise they use up CO2 from the atmosphere and produce O2 which is a waste product

When plants respire -----> use up O2 and produce CO2 which is a waste product. Movement of gases happens through diffusion. 

Net exchange of gases:

• depends on light intensity 
• photosynthesis -----> during day, but plants respire all the time = energy = live 
• day -----> make oxygen and release use up > CO2 than take in 
• night -----> plants ONLY respire, NOT ENOUGH light so- take in O2 and release CO2 

Leaf Adaption:

1. leaves are broad -----> large surface area: diffusion
2. thin -----> gases travel short distance 
3. air spaces -----> large surface area: gas exchange 
4. stomata -----> let gases and water diffuse/osmosis in and out, closes in the dark, close when water from the roots start to dry up and open and close controlled by guard cells. 

Hydrogen carbonate indicator:effect of light 

Low CO2: Purple <----- Normal: Red -----> High CO2: Yellow 

Humans 

Trachea- takes air to the bronchus 
Bronchi- split air in two lungs (left and right)
Lungs- organ where gas exchange takes place  
Bronchiole- takes air to the alveoli
Alveoli- allows gas exchange to occur 

Intercostal muscles- contract and relax ribs 
Ribs- protect lungs and heart 
diaphragm- muscle holds lungs together

Inhalation:

requires energy: active 

• intercostal muscles and diaphragm contract 
• volume increases 
• ribs up and out 
• pressure goes down 
• air flows in 

Exhalation:

passive 

• Intercostal muscles and diaphragm relaxes 
• volume decreases 
• ribs down and in 
• pressure goes up 
• air flows out

Alveoli:

• large surface area- quick gas diffusion
• thin- gas exchange is quicker and doesn't have to go through loads of cells 
• moving blood-allows more red blood cells to be oxygenated
• air sack 

Smoking:

• damages alveoli- reduces surface area. emphysema- disease
• tar damages cilla- chest infections are more likely
• irritates bronchioles and bronchi[tar]- smokers cough
• carbon monoxide reduces the amount of O2 blood can carry- increase blood pressure
• chemicals can lead to cancer- carcinogens  

Investigation:

• sit still for 5 mins. 1 min count number of breaths you take. 4 mins exercise- stop count breaths (1 min) 
• exercise- increases breathing rate, more O2 and less CO2 
• control variable e.g. temperature of room/area and time spent exercising 

Paper Two in bold, italics 

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