Section 3

Reproduction

2j) Co-ordination and Response

Flowering Plants 

Tropism- growth in response to a stimulus e.g. water and light 

+----------------+----------------+---------------------+----------------------------------+
| Response       | Part of plant  | Direction           | Advantage                        |
+----------------+----------------+---------------------+----------------------------------+
| + phototropism | stem tip       | towards light       | maximise the amount of light     |
+----------------+----------------+---------------------+----------------------------------+
| - phototropism | root tip       | away from the light | less chance of drying out        |
+----------------+----------------+---------------------+----------------------------------+
| + geotropism   | root tip       | towards gravity     | more chance of finding moisture  |
+----------------+----------------+---------------------+----------------------------------+
| - geotropism   | stem tip       | away from gravity   | more chance of finding light     |
+----------------+----------------+---------------------+----------------------------------+
| hydrotropism   | root tip       | towards water       |                                  |
+----------------+----------------+---------------------+----------------------------------+

Auxin- plant hormone produces in shoot tips which controls the direction of growth in response to light

Humans 

homeostatis ----> detection of a change in the body 

normal body temperature ----> 37C

Stimulus ----> Response ----> turn back to normal 

Receptors detect stimuli (sense organs) 

Effectors bring about a response to the stimuli 

Central Nervous System

• brain 
• spinal cord 
• send electrical impulses to effector along motor neurone after receptor detects a stimulus 
• coordinate the response

Reflex Arc

• control reactions in humans
• makes a fast automatic response possible 
• body releases the hormone adrenaline automatically 

+-----------+-----------+-----------------+---------------+----------------+-----------+----------+
| Stimulus  | Receptor  | Sensory neurone | Relay neurone | Motor neurone  | Effector  | Response |
+-----------+-----------+-----------------+---------------+----------------+-----------+----------+

Sensory and motor neurone:

The Eye: 

Different types of hormones;

Name of gland	Hormone	What does it do?
Pituitary	ADH	water regulation
Pancreas	insulin	low blood pressure
	glycogen	high blood pressure
Adrenal body	adrenaline	physical activity
Ovaries	oestrogen	development of female secondary
	progesterone	regulates the menstrual cycle
Testes	testosterone	development of male secondary characterists

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:

2h) Transport

Flowering Plants 

Phloem tubes transport food 

• living cells with perforated end plates to allow stuff through 
• transport food made in the leaves to all other parts of the plant in BOTH directions

Xylem tubes 

• not living cells 
• thick strong walls- lignin give support 
• carries water and mineral ions from the soil around the plant 
• hollow 

Root hair cell: 

• long hairs
• big surface area- absorbing water and minerals
• water taken almost entirely at the root hairs
• minerals also taken up- against a concentration gradient: 'active uptake' 

Transpiration:

loss of water from aerial parts of a plant leaves by evaporation and diffusion 

Rate of transpiration:

1. Light intensity: the brighter the light, the greater rate of transpiration
2. Temperature: the warmer, the faster transpiration happens due to more energy
3. Wind speed: higher the wind speed, the greater the transpiration rate 
4. Humidity: the drier air around the leaf, the faster transpiration happens

A Potometer can be used to estimate transpiration rates

• use stopwatch to record the distance moved by bubble per unit time
•  

Humans 

Blood has four main components:

1. plasma 
2. platelet
3. red blood cells 
4. white blood cells 

Plasma:

• Pale yellow liquid 
• Carries:
• other components in blood 
• CO2 
• Urea 
• Digested food products
• Hormones 
• Heat energy 

Platelets:

• help blood clot when a vessel is damaged 
• stop you from losing too much blood and other microorgansims from entering the wound 
• mesh of protein called fibrin  

Red blood cells: 

• transport oxygen from lungs to all respiring tissues 
• adaptations:
• biconcave shape- large surface area to release and absorb oxygen 
• haemoglobin- contains iron
• no nucleus- more space 

White blood cells:

Two types: 

1. Lymphocytes
• make antibodies to destroy microorgansims, some persists in blood after disease and give us immunity  
2. Phagocytes 
• Engulf bacteria (pathogens) and are non specific so attack anything that's not meant to be there 

http://www.bbc.co.uk/schools/gcsebitesize/science/21c_pre_2011/disease/diseaseresistancerev5.shtml

Vaccinations:

To avoid some diseases like polio, measles and rubella you can be vaccinated 

Involves-

Injecting dead or inactive pathogens 

Trigger immune response and lymphocytes produces antibodies to attack them 

Some lymphocytes remain in the blood as memory cells so if live pathogens of same types of disease appears the antibodies will kill them at a faster because they (antibodies) will be produced at a quicker rate 

The structure of the heart

The Heart rate;

• when you exercise, your muscles need more energy so you can respire more 
• blood has to flow faster, so the heart rate increases 
• exercise increases the amount of CO2 in your blood
• when receptors in the aorta and carotid artery detect high levels of Carbon dioxide, the brain sends signals to the heart -----> moves more frequently and with more force 
• Adrenaline is the specific receptor of the heart 

Blood vessels:

Artery carries the blood away from the heart 

• have thick walls with elastic fibres and smooth muscles 
• have a small lumen for the passageway of blood 
• contains blood under high pressure 

Vein carries blood to the heart 

• have thin walls with little muscle and elastic tissue 
• have a large lumen for a big passageway for blood 
• contain blood under low pressure
• has valves to prevent the back-flow of blood 
•  

Capillary exchange materials 

• one cell thick to allow quick gas exchange 
• have tiny holes to allow gas exchange 
• a tiny lumen 
• very low pressure 

The circulatory system:

Things for Paper Two are in bold, italics 

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 

2f) Respiration

Respiration is the process of Releasing Energy from Glucose which happens constantly In Every Living Cell

Animal Cell:

part	function
nucleus	contains genetic material, which controls the activities of the cell
cytoplasm	most chemical processes take place here, controlled by enzymes
cell membrane	controls the movement of substances into and out of the cell
mitochondria	most energy is released by respiration here
ribosomes	protein synthesis happens here

Aerobic Respiration Vs. Anaerobic Respiration:

Aerobic: with oxygen and most efficient way to release energy from glucose. use most of the time.

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

            C6H12O6      +  6O2     ----->         6CO2         +   6H2O 

Anaerobic: when there is not enough oxygen, usually during vigrous exercise less energy released from glucose and produces lactic acid 

In Humans) Glucose -----> Lactic Acid (and some energy)

                  C6H12O6 ------> 2C3H6O3 

In Plants) Glucose -----> Ethanol (alcohol) + Carbon Dioxide 

              C6H12O6-----> 2C2H5OH            + 2CO2

In Yeast) froth develops and its called fermentation

Aerobic respiration test in yeast- CO2 Purple <----- Normal red -----> Add CO2 Yellow 

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