Bio Y9

  • Created by: Ella
  • Created on: 31-05-13 16:25

Structure of a plant

  • Leaf

-light, surface area, photosynthesis

  • Stem

-Support, leaf position = photosynthesis, xylem + pholem

  • Roots

-water, nutrients, support, anchorage, root hairs, surface area

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Parts of the leaf

  • Waxy cuticle reduces water loss. It is thicker on the upper surface since this surface is usually more exposed to the warmer rays of sunlight 
  • Upper epidermis - a complete covering which is usually one cell thick. -transparent to allow the free passage of light. -prevents the entry of disease causing organisms
  • Stomata - these mini pores are mainly present in the lower epidermis. This surface is less exposed to the sun's radiaition so that evaporation of water is kept to a minimum
  • Paliside mesophyll - tall think cells arranged in columns and separated by very narrow air spaces. They contain chloroplasts for photosynthesis
  • Vein - the transport system in and out of the leaf
  • Spongy mesophyll - These cells are rather loosly packed and are covered with a thin layer of water. The air spaces between them aid the diffusion of gases through the leaf. 
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Photosynthesis and plant nutrition

  • Photosynthesis is the process in which light energy, trapped by chlorophyll, is used to turn carbon dioxide and water into glucose and oxygen 

                                         light energy

  • Carbon dioxide + water  -------------  glucose + oxygen


  • Plants manufacture everything out of simple ions and compounds that can be found in the environment. 
  • The building up of more complex molecules from simpler substances (synthesis) requires energy and enzymes. The enzymes are in the plants and the energy comes from sunlight. The process is called photosynthesis
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Aerobic Respiration

  • Mitochondria specialised structures found in the cell cytoplasm are the main sites of aerobic respiration
  • Aerobic respiration uses oxygen to oxidize glucose
  • Chemical energy is released along with the waste products; carbon dioxide and water 

SUGAR    +    OXYGEN     -------     CO2    +    WATER     +     CHEMICAL ENERGY

  • Sugar is found in food/photosynthesis , oxygen is found in the atmosphere/photosynthesis , carbon dioxide is found in the atmosphere/gas exchange and water is found in most things
  • What is the energy released used for? 

- To build larger molecules using smaller ones (biosynthesis eg. proteins from amino acids) , to enable muscles to contract (movements eg. peristalis in the gut) , to maintain a steady body temperature in colder sorroundings (thermoregulation eg. mammals and birds) , the active transport of materials across boundaries (eg. absorbtion of nitrates from the soil in plant roots)

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  • The breathing system (= gas exchange system) takes air in and out of the body ( = ventilation) so htat oxygen from the air can pass into the bloodstream and carbon dioxide can pass out of the bloodstream into the air ( = gas exchange)
  • The lungs are located in t he upper part of the abdomen ( = thorax). They are protected by the rib cage and separated from the lower abdomen by a thin sheet of muscle called the diaphragm 
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Lungs - Breathing in, breathing out


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Structure of the lungs


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  • The alveoli function to efficiently exchange gases (O2, CO2) between the air and blood. They are very well designed and maximize the rate of diffusion. 

How are alveoli adapted? 

1. Very large surface area

2. Very dense/rich capillary blood supply 

3. 1 cell thick alveoli wall

4. Thin layer of moisture on the inside of the alveoli increase diffusion

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Lung ventilation and breathing movements


  • Muscles between the ribs contract and so the ribcage move up and out 
  • Diaphragm muscles flatten
  • Increase in volume and drop in pressure in the thorax
  • Air enters to equalize the pressure


  • Muscles between ribs relax and the ribcage drops under its own weight
  • Diaphragm muscles relax and push upwards into the thorax
  • The volume in the thorax is reduced and there is an increase in pressure 
  • Air leaves the thorax to equalize the pressure
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Heart structure


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Effect of exercise on the body

Why is it important?

  • Regular exercise decreases pulse rate
  • Reduces blood pressure
  • Increases lung capacity
  • Reduces recovery time to a resting state following exertion
  • These factors can be used as indicators of fitness
  • Being fit reduces the stresses and strains on your heart
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- Notes in pink book

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1. A cell is taken from the organism to be cloned

2. The nucleus is removed and the rest of the cell is thrown away 

3. An egg cell is taken and the nucleus is replaced with the nucleus of the original organism

4. The egg now carries the genes of the original organism

Theraputic cloning - growing as part of an individual 

Reproductive cloning - growing a whole individual 

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  • Asexual reproduction is reproduction without sex. Asexual reproduction takes place by the organism splitting in two 
  • To 'clone' means to produce a genetically identical organism
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Selective breeding

  • Selective breeding is also called artificial selection, not natural selection!
  • This is because humans artificially select the plants or animals that are going to breed and flourish, according to what we want from them 

 Basic selective breeding prcess (in cows):

  • From your existing stock select the ones which have the best characteristics
  • Breed them with each other 
  • Select the best of the offspring, and combine them with the best that you already have and breed again 
  • Continue this process over several generations to develop the desired traits 

Slective breeding is very useful in farming:

  • Selectively breeding beef cattle to get the best beef (taste, texture, appearance etc.)
  • Selectively breeding milking cows to increase milk yield and resistance to disease
  • Selectively breeding chickens to improve egg size and number of eggs per hen 
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Selective breeding (plants)

Selective breeding produces better wheat, flowers, etc. 

  • Selectively breeding wheat to produce new varieties with better yields and better disease-resistance too 
  • Selectively bredding flowers to produce bigger and better and more colourful ones

Stages of selectively breeding wheat crops:

  • Cross wheat plants 
  • Plant the seeds from the 'crossed plants' 
  • Select the 'correct' offspring 
  • Interbreed offspring 
  • (Repeat the 4 stages until you grow the new variety of wheat) 
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Types of variation

  • Continuous variation - Caused by many genes working together. Can be affected by the environment. This is typically seen as a feauture that varies a great deal between individuals between extremes eg. height, finger length could be influenced by diet 
  • Discontinues variation - Caused by one or two working together. Not affected by the environment. Typically seen as a feature that is limited in variety eg. Blood group, ability to role tongue.
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Variation and inheritance

Where do you get variation from?

  • Living organisms vary in many ways eg. all humans have the same general shape and structure but may have different height, hair colour etc. This is called individual variation
  • Some features can be inherited from parents eg. eye colour. These are inherited characteristics and can not be changes, they are determined by your genes
  • Some are temporary eg. a suntan or scar and are not inherited.  These are called acquired characteristics and can be changed 
  • Your overall characteristics are a combination of both inherited and acquired feautures
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Inherited characteristics

  • Your inherited characteristics are a direct consequence of sexual reproduction and subsequent fertilization
  • Each egg and sperm showws genetic variation due to cll devision, so inherited characteristics are not always the same 
  • What is fertilization?The fusion of an egg and sperm cell 

How are twins produced?

  • 1 egg + 1 sperm fuse giving one embryo. The embryo splits to form genetically identical twind 
  • 2 or more eggs + 2 or more sperm fuse to give more than one embryo. Result is non-identical twins
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  • Plants and photosynthesis \square ( 

- Structure of plants \square (  Deforestation \square (  Parts of leaves \square (  

  • Respiration \square (

- Aerobic respiration \square ( 

  • Breathing \square (

- Structure of lungs \square (  Lung ventilation and breathing movements \square (   Lung diagram: breathing in and breathing out \square ( 

  • Diet \square (

- Carbohydrates, lipids and proteins \square (  Nutrition \square (   Vitamin C \square (   Defiecieny disorders \square (  Functions of nutrients (table) \square ( 'Molecules of life' sheet (equations) \square ( 

  • Drugs \square (
  • Circulation, exercise and health \square (
  • Variation and inheritance \square (
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Review part 2

  • Drugs \square (

- Alcohol \square (   Smoking \square (   

  • Circulation, exercise and health \square (

- Heart structure \square (   The heart and circulation (27th march) \square (   Blood flow around the body \square (    Capillaries \square (    Effect of exercise on the body \square (    

  • Variation and inheritance \square (

- Cloning \square (    Selective breeding \square (    Inheritance \square (    Variation \square (

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