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[powlmao]

BIOLOGY STUDY NOTES
PATTERNS IN NATURE

• Organisms are made of cell that have similar structural characteristics

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Cell theory

1. Cells are the basic units of life, making up all living things
2. All cells come from pre-existing cells
3. All living things are made up of one or more cells

• Cells are the basic structural and functional unit of organisms
• All energy flows of life occurs within cells

• Outline the historical development of cell theory, in particular the contribution of Robert Hooke and Robert Brown

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1590	Han & Jansen	Made first compound microscope (placed two convex lenses in a tube)
1663	Robert Hooke	Introduced the term ‘cell’ while observing cork under a light microscope, worked at improving the microscope, telescope and barometer.
1674-1682	Anton Van Leeuwenhoek	Made lenses of higher quality. Discovered unicellular organisms. Also bacteria.
17th	Henri Dutrochet	Suggested that cells are the basic units of life
1801	Robert Brown	First described the cell nucleus while observing plant cells in an orchid. Noticed the random movement of pollen grains (Brownian motion).
1838	Matthias Schleiden	Stated that parts of plants are made of cells (not visible to the unaided eye).
1839	Theodor Schwann	Stated that animals are made of cells (agreed with Schleiden). They
	Schleiden & Schwann	Published the cell theory in a book, stating that: 1. The cell is the unit of structure of all living things. 2. The cell exists as distinct entity & building block in construction of organisms.
1855	Rudolph Virchow	Introduced idea that cells reproduce by dividing, stating all living cells can only arise from other living cells
1933	Ernst Ruska	Built the fi rst electron microscope
1938	Fritz Zernike	Invented the phase contrast microscope-used to observe living, unstained cells
1955	Marvin Minsky	Invented the scanning electron microscope

The work of Hooke (recorded the compartmentalised nature of cork and named them ‘cells’ more then 150 year before) and Brown (discovered the nucleus 6 years before). Without them Schlieden and Schwann could not have built their cell theory which is the valid theory today

• Describe evidence to support cell theory

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Spontaneous generation theory – organisms originated from inanimate (non-living) materials.

• Theory was disapproved by:

Francesco Redi - showed that maggots developed from flies that laid their eggs on meat
Louis Pasteur – micro-organisms arose from pre-existing organisms

• Rudolf Virchow- proposed theory: all cells come from pre-existing cells. This disapproves spontaneous generation
• The improvements in the microscopes
• The electron microscope could view more detail in the cells
• Discovery of cell division
• Spontaneous generation: belief that creatures could originate from inanimate (non-living) material.
  • Discuss the significance of technological advances to cell theory development

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Light microscope	Electron microscope
Uses light to view	Uses electron beams to view
Low resolution	High resolution
Low magnification	High magnification
Can view living active organisms	Organism must be dead
Less expensive, small and easily maintained	Very large, expensive, and kept at constant temperature & pressure
Cannot see internal structures (only at cellular level)	Can see internal structures (sub-cellular level) as it shows huge detail

The construction and improvement of lens has enable a view of the cell’s internal structure and led to the development of the cell theory. The creation of the electron microscope enables even more detailed observations of cells, because it has a higher resolution and magnification unlike the light microscope.
Resolution- ability to deliver clear details of image
Magnification- how much the microscope enlarges the object being viewed

• Identify cell organelles seen with light & electron microscope

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Organelles you can see through a:

Light microscope	Electron microscope
Vacuole	Mitochondria
Nucleus	Golgi body
Cytoplasm	Endoplasmic reticulum
Chloroplasts	Ribosomes
Cell wall	Lysosomes
Cell membrane	(The smaller objects)

• Describe relationship between structure of organelles and function

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Organelle	Structure	Function	Plant / Animal cell
Mitochondria		Site of aerobic respiration	Plant & Animal
Nucleus		Controls cell activities. Contains cell’s DNA	Plant & Animal
Nucleolus		Manufacture of proteins-ribosomes	Plant & Animal
Endoplasmic reticulum		Connects cell membrane with nuclear membrane, transports materials	Plant & Animal
Ribosomes		Produces protein from amino acids	Plant & Animal
Golgi body		Packages and stores proteins in its vesicles, before secretion	Plant & Animal
Cell membranes		Semi-permeable membrane, protects & supports organelles and made of double layer of phospholipids	Plant & Animal
Chloroplast		Site of photosynthesis, contains the green colour	Plant
Lysosomes		Dissolves large food molecules to small molecules, breaking down proteins, carbs, lipids	Animal
Cell wall		Protects & supports the cell, maintains cell structure	Plant
Vacuole		Stores food, water, dissolved solutes and waste. More in plants	Plant & Animal

• Membranes around cells provide separation & links with external environment

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• Identify the major groups of substances found in living cells and their uses in cell activities

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Chemicals found in cells are grouped in to 2 different groups:



Inorganic – contain elements other than carbon combined with hydrogen, make up the non-living structures

• Gases including: CO₂ (carbon dioxide) even though it contains carbon it does not have hydrogen with it, O₂ (oxygen)
• Mineral salts such as calcium salts, sodium chloride and phosphates
• H₂0 (water)

Organic – contain carbon and hydrogen, are made of (or) by living things

• Carbohydrates- sugars and starch
• Proteins
• Lipids- fats and oils

Organic compounds	Composition	Function	Forms of organic compound
Carbohydrates	Carbon Hydrogen Oxygen	Used for respiration, when energy is needed the glucose is broken down	Monosaccharides- the basic building blocks of more complex carbohydrates Disaccharides, i.e. sucrose, lactose, maltose Polysaccharides i.e. starch is the main food store for plants.
Proteins	Carbon Hydrogen Oxygen Nitrogen	Used in the structure, storage, movement and transport of cells	Amino acids is the basic unit for protein, it joins together by peptide bonds to form polypeptides
Lipids	Carbon Hydrogen Oxygen	Stores energy but is more difficult to release than carbohydrates. It breaks down into fatty acids and glycerol	Fats, oils, waxes and steroids
Nucleic acids	Sugar, Nitrogen Phosphate	A vital role for heredity. Nucleic acids are long – chain of nucleotides	DNA, RNA, these are the most complex and largest organic compounds

Living organisms use organic and inorganic compounds to functions. Inorganic compounds contained in cells are water, oxygen and salts. Organic compound found in living organisms are carbohydrates, proteins, lipids, and nucleic acids.

• Identify that there is movement of molecules into and out of cells

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For any cell to function substances need to enter and exit the cell through its cell membrane. Substances for functioning need to move in to cells (gases, nutrients and water). Waste substances (urea, uric acid, excess carbon dioxide), products secreted that are needed to coat outside of cell (mucus) and substances that need to be passed to other cells (hormones) need to move out of cells.
The movement of these cells occurs across cell boundary- cell membrane which controls entry of water, and other molecules.
Cell membrane is selectively permeable allowing only certain molecules to pass though.

• Describe current model of membrane structure and explain how it accounts for movement of some substances into & out of cells

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Fluid mosaic model- current model of membrane structure

In 1972 Singer and Nicholson proposed selectively permeable membrane as a fluid-mosaic, a ‘lipid sea’ with ‘many various proteins floating in it’
Membranes are composed of 40% lipids and 60% proteins.

Lipid component:
Made of 2 layers of phospholipids:

1. Hydrophobic tails facing in
2. Hydrophilic heads facing out

These phospholipids are arranged in a bilayer

Protein Component:
Protein molecules are scattered throughout bilayer. They either:

• Cholesterol molecules- embedded within membrane
• Carbohydrates- attached to external surfaces
• Integral protein- span the length of bilayer forming channels
• Peripheral proteins- attached to integral proteins
• Glycoproteins- have attached carbohydrates for cell recognition

Movement of molecules across cell membranes
The permeability of a membrane to a molecule depends on the molecules:

• Size:

Small molecules move across fast and easily.

• Electrical charge:

High charge molecules are not very soluble, have low membrane permeability. Neutral molecules have high permeability (e.g. gases- CO₂, O₂)

• Lipid solubility:

Lipid-soluble have high permeability, are easily penetrated. Water-soluble has difficulty.
Water-soluble molecules are highly charged therefore do not penetrate easily. But they are highly permeable because of osmosis.
Molecules that have low permeability rely on carrier proteins to transport them across membranes in cells

• Compare the process of diffusion and osmosis

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OSMOSIS	Substance that moved	Water molecules
Concentration gradient	Low to high
Energy requirement	None
Only across selectively permeable membranes	Yes
Examples	Plant cells exposed to air lose water to surroundings by osmosis
DIFFUSION	Substance that moved	Any molecules
Concentration gradient	High to low
Energy requirement	None
Only across selectively permeable membranes	No
Examples	Human- oxygen from cells of lungs moving into blood capillaries
ACTIVE TRANSPORT	Substance that moved	Molecules
Concentration gradient	Low to high
Energy requirement	Input of energy
Only across selectively permeable membranes	Yes
Examples	White blood cell in human body engulfs & digests bacteria fighting infection

Osmosis
Substance that moved- water
Concentration gradient- low to high
Energy requirement-none
Osmosis is the movement of water molecules across a semi-permeable membrane, from a low solute concentration to a high solute concentration (high water to low water). Requires no energy input.
The water moves through special tiny protein channels (pores) called aquaporins.
Diffusion
Substance that moved- any molecules
Concentration gradient- high to low
Energy requirement-none
Diffusion is the movement of any molecules from a high concentration to a low concentration until the concentration is the same.

There is a higher concentration of salt outside the cell, therefore the water moves out

In living cells, diffusion is a way at which the cells take in materials from the environment and also the way of ridding any unwanted material

	There is a lower concentration of solute outside the cell, therefore the water moves in

Active transport
Substance that moved- molecules
Concentration gradient- low to high
Energy requirement-input of energy
Active transport is the movement of molecules from an area of low concentration to an area of high concentration, requiring the input of energy.

• Explain how surface area to volume ratio affects the rate of movement of substances into and out of cells

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Surface area- is the outside area of the cell. Controls the rate of removal and absorption of wastes and nutrients.
Volume- is the capacity inside the cell. Determines the metabolic needs and waste products.

Surface Area / Volume = SA: V
As a cell grows larger its rate of exchanging and removing of materials and wastes decreases, so if the cell grows too big it divides into two cells so it can maintain an efficient surface area to volume ratio as smaller cells are more efficient.

• OBTAINING NURTIENTS

Plants & animals have specialised structures to obtain nutrients from their environment

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Unicellular- single celled, simple diffusion and some osmosis
Multicellular- many cells, diffusion and osmosis

• Identify some examples that demonstrate the structural and functional relationships between cells, tissues, organs and organ systems in multicellular organisms.

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Different types of cells have different structures and activities, but they work together so that the organism functions as a coordinated whole.

Sperm	Head section that contains nucleus enabling it to penetrate the egg at fertilisation. Mitochondria in the middle section provides energy, and a tail to propel itself
Red blood cell	Disc – shaped and lack of nucleus, contains red pigment haemoglobin which is responsible for oxygen transport
White blood cell	Colourless cell, contains a nucleus and helps fight infections
Plant epidermal cells	Layer that protects the cells (outermost layer) in a plant which allow gaseous exchange.
Tissues	Groups of cells that are similar in structure and function. For example, muscle cells make up tissues of a stomach.
Organs	Groups of similar tissues make up organs. For example, the tissues of a stomach make up a stomach, which is an organ.
Systems	Groups of similar organs make up a system within the body. For example, the organs like stomach make up the digestive system in humans.

• Distinguish between autotrophs and heterotrophs in terms of nutrient requirements.

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Autotrophs
Self-feeding organisms. Can make organic materials to feed themselves through photosynthesis. E.g. carbon dioxide, water, inorganic material.

• Plant cells
• Have chloroplasts

Heterotrophs
Feed on something different. Obtain the substances they need from their external environment, from autotrophs.

• Animal cells
• Do not have chloroplasts.

Organic nutrients: release energy that as ATP, (which is essential for cell functioning).

• Identify the materials required for photosynthesis and its role in ecosystems

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Photosynthesis requires:

• Light (energy)
• chlorophyll
• carbon dioxide
• water
  • to make: sugars and oxygen

Role in ecosystems:

• photosynthesis is the initial path of energy for all ecosystems
• organisms that photosynthesise are producers: which form the basis of all food webs providing glucose.
• Glucose can be converted & stored as : lipids, proteins, carbohydrates
• Organic compounds which rely on photosynthesis for their production
  • Provide the structural basis for all living cells
  • Source of energy for all cellular processes

• Identify the general word equation for photosynthesis and outline this as a summary of a chain of biochemical reactions

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Photosynthesis occurs in two stages:

1. Light phase (photolysis)

Radiant energy is absorbed by the chlorophyll pigments and is converted into chemical energy. Some of the energy is used to split water molecules into hydrogen and oxygen. This reaction occurs on the internal membranes of the chloroplast, the thylakoids.

1. Light-independent phase (carbon-fixation stage)

The hydrogen released from the first reaction combines with carbon dioxide to form sugar, the energy used to form sugar is used from the absorption of light. This reaction occurs in the stroma of chloroplasts.

During the day the sugar is stored as starch in the leaf and at night, they are converted back to sugars.

• Explain the relationship between the organisation of the structures used to obtain water and minerals in a range of plants and the need to increase the surface area available for absorption

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Water uptake- by osmosis
Mineral uptake- by diffusion

ROOT FUNCTIONS

1. To absorb water and mineral from the soil
2. To anchor the plants
3. To act as a store of food in some plants

TYPES OF ROOT SYSTEMS

Tap roots	Main root & small side branches Reaches water deep underground Anchors plant effectivley May act as storage organs May store food reserves E.g. carrots
Fibrous roots	Many main branches Form a network of roots close to the surface area Spread out widely to anchor plant Bind the soil to prevent erosion
Mycorrhiza	Association between fungi and roots of plant The fungi provide the plant with mineral nutrients The plant provides the fungi with carbon products. Fungal threads; increase its surface area for more effective absorption of nutrients
Aerial roots	Grow above the ground May help to support the plant Help in gas exchange.

ROOT HAIR LAYERS

• Located behind root cap
• Increase surface area for water uptake
• Approx. 4mm long
• Have a slender and flexible slippery structure which allows them to penetrate between soil particles.

MOVEMENT OF WATER & MINERALS ACROSS ROOTS
Water and minerals:

1. Enter through epidermal
2. Move across root to xylem (water-conducting tissue in centre of root)
3. Water moves by osmosis through the cells
4. Water and minerals move across cortex into central vascular tissue
5. Xylem transports water and dissolved mineral salts from the roots up to rest of plant

• Explain the relationship between the shape of leaves, the distribution of tissues in them and their role

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The role of leaves

1. Absorb sunlight
2. Make food
3. Transpiration- to release water to cool plant down and create a suction pull to lift water from roots to the top of plant.

Plants need to photosynthesize (with their leaves):

• To absorb sunlight and carbon dioxide
• To release oxygen
• To provide chlorophyll
• Make glucose and transport to other parts of plants

Structure of leaves in relation to their function

Leaves are very important as all life depends on their photosynthesis as a source of food, their energy.
The structural features needed by a leaf:

• Large surface area: to absorb light and carbon dioxide
• Pores in the leaf surface: exchange of gases with environment
• Cells inside that contain chloroplasts: trap energy of sunlight
• Water transport system: form roots to leaves
• Food transport system: from leaves to other parts of plant

Leaves are broad, flat, thin ® large SA ® capture of sunlight, exchange of gases ® for photosynthesis

TISSUE	CELL TYPE	POSITION IN LEAF	FUNCTION	STRUCTURAL SUITABILITY
Epidermis	Epidermal cells	Top and lower surface just below the cuticle	Protect delicate inner tissues and prevent evaporation by secreting a waterproof cuticle	Simple, flattened cells
Guard cells	In the epidermis and surrounding the stomata pore	Control the exchange of gasses and loss of water	Bean-shaped cells occurring in pairs: protecting from both sides (two of them) for efficiency
Mesophyll	Palisade cells	DORSIVENTRAL LEAF Right below upper epidermis	Main photosynthetic cells in leaves	Elongate cells containing numerous chloroplasts for its function of photosynthesis
ISOBILATERAL LEAF Above the lower and below the upper epidermis
Spongy cells	Beneath the palisade tissue and above the lower epidermis	Main role is Gaseous exchange and second most important for photosynthesis	Irregular in shape and have fewer chloroplasts. They have large air spaces for gaseous exchange

HETEROTROPHS OBTAINING NUTRIENTS

• Describe the role of teeth in increasing the surface area of complex foods for exposure to digestive chemicals

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SOME DEFINITIONS
Ingestion:
The intake of food into a digestive tract (multicellular organisms) or into a cell (unicellular). Intake of complex organic food is eating
Digestion:
Breakdown of complex insoluble food into simpler, smaller, soluble molecules (such as amino acids- proteins, fatty acids and glycerol- lipids) that can be absorbed.
Absorption:
When basic units of food (glucose, amino acids, fatty acids, glycerol) are absorbed across digestive tract into bloodstream
Assimilation:
Conversion of absorbed simple substances into more complex useful molecules which become part of a structure of organism or used as energy
Egestion:
Elimination of undigested food as waste. E.g. fibre that cannot be digested.

The digestion of foods involves two stages:

1. Mechanical breakdown- food is chewed and large chunks are physically broken down into smaller bits
2. Chemical breakdown- digestive enzymes act on the food to chemically break down the large complex molecules into smaller, simpler molecules.

ENZYMES
Most digestive enzymes split food molecules by hydrolysis, in which a molecule is split at a particular point by adding a water molecule. There are 3 types of enzymes:

• Amylases - act on carbohydrates.
• Proteases - act on proteins
• Lipases - act on lipids.

Large food molecules are broken down several enzymes

• Teeth mechanically break the complex food into smaller pieces increasing the SA for exposure to digestive chemicals i.e. enzymes.
• Saliva then lubricates the food for easier swallowing
• The amylase digests starch to maltose

TEETH
There are four main types:

1.	INCISORS	Front teeth	Grasp hold and bite food
2.	CANINES	Eye teeth/fangs	Stabbing, gripping prey and tearing flesh
3.	PREMOLARS	Cheek teeth	Chewing, cutting flesh, cracking bones
4.	MOLARS	Back teeth	Grinding, crushing, chewing food

Carnivores: have large canines to tear and rip meat carcasses
Herbivores: have no canines, but have large flat double teeth to grind plant food
Omnivores: have some teeth for tearing and cutting meat and others for grinding plant food

• Proteins are absorbed after being broken down to amino acids.
• Carbohydrates are absorbed after being broken down to simple sugars (monosaccharides).
• Lipids are absorbed after being broken down to fatty acids and glycerol.
• Vitamins, minerals and water are absorbed directly.

• Explain the relationship between the length and overall complexity of digestive systems of a vertebrate herbivore and a vertebrate carnivore with respect to:
  • the chemical composition of their diet
  • the functions of the structures involved

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Type of animal	Chemical composition of diet	Functions of the structure involved
Herbivore	Herbivores have much longer intestines because cellulose is much harder to digest, their diet mainly composed of cellulose and food may remain there for a long time. No vertebrate can produce a fluid that can digest cellulose, so instead the micro – organisms convert cellulose to sugars.	Herbivores have 4 chambers, in the first chamber, rumen, where the food is acted upon by bacteria. It then moves to the honey comb bag where the food is chewed again. After chewing, the food goes to the third stomach where it is strained and is passed to the last chamber, the true chamber, where the gastric juices are secreted.
Carnivore	Carnivores have simple stomachs, they eat meat which requires less digestion	The acid in the stomach breaks down some muscle tissue and the protease digestive enzyme. The fats are broken down by the lipase enzymes. Protein and fat contain a higher amount of energy per gram than plant material, so they can eat less to gain the same amount of energy.

• Gaseous exchange and transport systems transfer chemicals through the internal and between the external environments of plants and animals

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Gaseous exchange is the movement of gases by diffusion across cell membranes. Gases move into cells and others are expelled

• Compare the roles of respiratory, circulatory and excretory systems

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Systems	Roles
Respiratory	Allows gas exchange for an organism
Circulatory	System to circulate materials to supply cells with nutrients and remove wastes
Excretory	Allows the excretion of waste products

Respiratory system

• Take in oxygen
  • As it is needed for release of energy from food
• Remove carbon dioxide
  • Is a waste that must be moved because it is toxic in large quantities
• Allows gaseous exchange between organism and its external environment
• Respiratory system made of tissues and organs for gaseous exchange

Circulatory system

• Transport of gases, nutrients waste products, hormones, antibodies
• Maintains a constant internal environment (stabilizes pH levels)
• Removes toxins and pathogens
• Stabilizes body temperature

Excretory system

• Remove metabolic wastes from transport medium
• Expel these nitrogenous wastes

Excretory organs:

• Identify and compare the gaseous exchange surfaces in an insect, a fish, a frog and a mammal

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INSECT	Take in air through spiracles which have valves to make sure they don’t dry out Air that enters is drawn into tracheae Tracheae branches off to tracheoles (creating a large SA) Tracheoles carry air to and from the cells of the body Ends of tracheoles are filled with a watery fluid where gases are dissolved As they do not have blood to transport the gases
FISH	Respiratory organs are internal gills Water enters Flows over gills Lifts opecula to let water out Water movement is slowed down because of highly branched gill filaments and close stacking (relying on flow of water to keep tips of filaments apart) Each of these filaments has a capillary associated to carry the oxygen to the cells.
FROG	Gas exchange surfaces: Skin- main site for respiration when in water. Well supplied with blood vessels Floor of mouth- serves as buccal pump ventilating lungs. Well supplied with blood capillaries Lungs- pair of simple sacs used only when frog is active. Nostrils have valves that close to prevent the entry of water into the lungs All three surfaces are thin, moist and well supplied with blood
MAMMAL	Gaseous exchange takes place in millions of alveoli (air sacs) in the lungs Alveoli: forms boundary between air in external environment and blood capillaries. Increased SA: folding and branching Thin: alveoli have a thin lining to facilitate diffusion Moist: mucus and water vapour Well supplied with blood: numerous blood capillaries

Characteristics of gas exchange systems include:

• A large surface area
• Moist, thin surface
• Near to an efficient transport system

Organism	Gaseous exchange surfaces
Insects	Tracheae, a system of branching tubes. The tracheae opens through the spiracles along the abdomen, it branches throughout the tissues of the insects bringing air directly to the cells.
Fish	Gills over which water flows. Gills provide an external gas exchange surface. The gill filaments spread out to increase surface area, the rich supply of blood vessels enable gases to and from the gills.
Frogs	Lung and the skin, oxygen from the air diffuses into the moist skin which is transported by the blood to the body. The lungs are simpler structures with internal subdivisions.
Mammals	Lungs, the large surface area are increased by the highly folded microstructures called alveoli. There is a rich supply of blood to transport gases to and from the lungs.

• Outline the transport systems in plants, including:
  • Root hair cells
  • Xylem
  • Phloem
  • Stomates and lenticels

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Root hair cells	Water diffuses from the soil to the cytoplasm of cells by the process of osmosis
Xylem	Water enters the xylem from the roots and is transported upwards through the stem to the leaves
Phloem	Products of Photosynthesis are transported from the leaves to the rest of the plant
Stomates	Allow diffusion of gases, Stomates are usually located on the lower surface of the leaf.
Lenticels	Pores on woody stem of plants, gas exchange occurs here.

• Compare open and closed circulatory systems using one vertebrae and one invertebrae as examples

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Closed Circulatory System	Consists of a muscular pump that pumps fluid through a closed system of tubes which carry material throughout the body.	Humans have a heart the pumps blood through blood vessels which carry throughout the body.
Open Circulatory System	The heart pumps blood through blood vessels which open into interstitial spaces. The haemolymph that bathes the cells is reoxygenated in the heart.	Insects rely on their tracheal system, instead of blood carrying the oxygen. Thus insects do not have to have a fast blood flow.

 

[morts]

thank you lots an lots powlmoa did you tip this up yourself????

 

[mike12345678]

powlmao please do a hsc version of this

PM me when you do hahah

 

[powlmao]

powlmao please do a hsc version of this

PM me when you do hahah

Haha fuck off

I have a HSC version if you like