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192 Cards in this Set
- Front
- Back
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What is magnification? |
How much bigger an image looks compared with the original object. |
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What is resolution? |
The ability of an optical instrument to see or produce an image that shows detail clearly. |
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Light microscope |
Max mag 2000x Resolution 200nm |
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Light microscope pros and con |
Cheap Easy to use Potable Able to study live specimens Limited resolution |
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Laser scanning microscopes |
Max mag approx 2000x High resolution Displayed on a computer Best for looking at living cells Can focus on structures at different depths |
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Laser scanning microscopes cons |
Low resolution compared to electron microscope Not portable Expensive |
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Transmission election microscopes TEM |
Max mag approx 5,000,000x Very high resolution Best for looking at internal structure of objects |
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Transmission election microscopes TEM cons |
Can’t be used to look at living things Expensive Specimen has to be chemically fixed i.e. dehydrated |
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Scanning electron microscopes SEM |
Max mag approx 500 000x Best for looking at surfaces of objects Able to see objects in 3D |
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Scanning electron microscopes SEM cons |
Resolution often not as high as the transmission electron microscope Electrons do not pass through the specimen Expensive Great skill/training to use |
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Staining samples for use in light microscopy |
A lot of biological material inside a cell isn't coloured, so staining helps distinguish different features. Chemicals bind to other chemicals on, or in the specimen or specific structures. |
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Colouring in electron microscopy |
Starts off black ands white, colour is added by specialised computer programs afterwards |
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Equation for image size |
Image size= Actual size x Magnification |
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Structures of eukaryotic cells (14) |
Nucleus, Nucleolus , nuclear envelope, rough and smooth endoplasmic reticulum, Golgi apparatus, ribosomes, mitochondria, lysosomes, chloroplasts, plasma membrane, centrioles, undulipodia and cilia. |
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Function of Nucleus |
Stores all of the cells genetic material in the form of DNA, which contains the instructions for protein synthesis |
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Function of Nucleolus |
Makes ribosomes and RNA which passes into the cytoplasm and are used in protein synthesis. |
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Function of Nuclear envelope |
A double membrane with nuclear pores |
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Function of rough endoplasmic reticulum (RER) |
Transports proteins made by the attached ribosomes |
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Function of smooth endoplasmic reticulum (SER) |
Involved in making lipids |
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Function of Golgi apparatus |
Modifies proteins received from the RER and then packages them into vesicles so they can be transported
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Function of ribosomes |
Site of protein synthesis |
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Function of mitochondria |
Where ATP is made
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Function of Lysosomes
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Contain digestive enzymes that are used to break down material
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Function of Chloroplasts
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Site of photosynthesis in plant cells
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Function of Plasma membrane
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Controls the entry and exit of substances into and out of the cell. |
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Function of Centrioles |
Form the spindle which moves chromosomes during cell division |
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Function of undulipodia and cilia |
Move by ATP, e.g wave mucus along or make sperm swim |
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Making and secreting a protein |
1. A gene with instructions encoded is copied onto a piece of mRNA. 2. mRNA leaves nucleus through nuclear pore 3. mRNA attaches to a ribosome, reads instructions to assemble the protein 5. Molecules pinched off in vesicles and travel to to Golgi apparatus 6. Vesicle fuses with G.A, that processes and packages the molecules ready for release 7. Pinched off in vesicles from the G.A travel to the plasma membrane 8. Vesicle fuses with it P.M opens and releases molecule outside |
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Cytoskeleton providing- 1. mechanical strength 2. aiding transport with cells 3. enabling cell movement |
Due to protein fibres that keep the cells shape by giving an internal framework- microfilaments and microtubes |
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Functions of microfilaments and microtubes |
supporting organelles strengthening the cell and maintaining cell shape transporting materials within the cell (e.g. spindle during mitosis) cell movement (cilia and flagella) |
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Cells prokaryotic and eukaryotic both have |
plasma memebrane cytoplasm ribosomes for assembling amino acids into proteins DNA and RNA |
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Prokaryotic differences from eukaryotic |
Do not have a nucleus No membrane bound organelles Cell wall made of peptidoglycan not cellulose Smaller ribosomes Naked DNA as a loop floating free in cytoplasm Small loops of DNA called Plasmids |
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Prokaryotic cell division |
Binary fission- before they divide their DNA is copied so that each new cell receives the large loop of DNA and any smaller plasmids |
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Structure and ultrastructure of plant cells |
Cell wall thats outside the cell surface membrane and made of cellulose, its strong and is kept rigid by the pressure of the fluid inside the cell. The vacuole makes the cell stable and turgid which supports the whole cell. |
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Cell cycle- M phase |
Checkpoint chemical triggers condensation of chromatin Halfway through metaphase ensures the cell is ready to complete mitosis Cell growth stops Pro, meta, ana, tele and cytokineses occurs |
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Cell cycle- G0 phase |
Testing phase triggered early during G1 Cells may undergo apoptosis (programmed cell death) differentiation (changes type of cell) or senescence (makes cells divide) Some cells (neurons) remain in this phase for a very long time or indefinitely
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Cell cycle- G1 phase |
Checkpoint- ensures that the cell can enter S phase and begin DNA synthesis Transcription of genes to make RNA occurs Organelles duplicate |
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Cell cycle- S phase |
All DNA molecules are replicated Housekeeping genes duplicated Once cells enter its committed to finishing the cycle DNA replicated The phase is rapid as DNA pairs susceptible to mutagenic agents reducing mutations
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Cell cycle- Cytokine |
Any number of substances which are secreted by certain cells of the immune system and have an effect on the other cells |
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Pre Mitosis, interphase |
DNA prepares to divide, and replicates |
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Mitosis, prophase |
Chromosomes supercoil & become visible under a Light microscope The nuclear envelope breaks down Centriole divide in two and move to opposite ends of the cell to form a spindle |
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Mitosis, metaphase |
Chromosomes line up along the middle of the cell They attach to the spindle thread by their centromere |
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Mitosis, anaphase |
Replicated sister chromotids are separated yen the centromere splits Spindle fibres shorten, pulling the chromotids apart |
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Mitosis, telophase |
Separated sister chromotids reach the poles of the cells A new nuclear envelope forms around each set Spindle breaks down Chromosomes uncoil so they are no longer visible under a light microscope |
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Cytokinesis, post mitosis |
The whole cell splits down to two new cells, each one identical to each other and to the parent cell |
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Meiosis (first division) prophase |
Chromosomes condense then arrange themselves Ito homologous pairs and crossing over occurs Like mitosis- centrioles move opposite end of cell spindle fibres forms Nuclear envelope breaks down |
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Meiosis (first division) Metaphase
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Homologous pairs line up at centre of cell Attach to the spindle fibres by their centromeres |
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Meiosis (first division) Anaphase
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Spindle contracts, separating homologous pairs One chromosome goes to each end of the cell |
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Meiosis (first division) Telophase
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A nuclear envelope forms around each group of chromosomes |
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Meiosis cytokinesis |
Division of cytoplasm, occurs and two haploid daughter cells are produced |
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Meiosis (second division) |
At the end of meiosis 1= two haploid daughter cells The two daughter cells undergo that stages again, PMATC again |
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Meiosis (second division) anaphase |
Sister chromatids are separated, each new daughter cell inherits one chromatid from each chromosome. 4 genetically different- haploid daughter calls are made (the gamete) |
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Chromatids cross over in prophase 1 |
Homologous pairs of chromosomes pair up, bits of chromatids swap over. Chromatids still contain the same gene but have a different combination of alleles |
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How meiosis produces genetic variation |
Crossing over during P1shuffles alleles Independent assortment of chromosomes in A1leads to chromosomes line up randomly Haploid gametes are produced that undergo random fusion with gametes |
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erythrocytes (red blood cells) |
biconclave disc shape to maximise surface area no nucleus = more room for haemoglobin |
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Neutrophils |
Flexible shape to engulf foregoing particles or pathogens Many lysosomes contain digestive enzymes to break down the engulfed particles |
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Epithelial cells |
Some have cilia to move particles They are flattened in shape |
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Sperm cells (spermatozoa) |
Many mitochondria, sperm head contain enzymes Undulipodium to move, small, long and thin Nucleus contains half chromosomes |
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palisade cells |
contains chloroplasts to absorb light thin walls so that CO2 can diffuse in |
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Root hair cells |
Hair like projections to increase surface area to absorb water and minerals from the soil |
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Guard cells |
thin outer wall, thick inner wall in light they absorb water to become turgid and allow gaseous exchange
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tissue |
group of similar cells that perform a particular function |
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Organ |
a collection of tissue that work together to form a specific overall function |
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organ system |
a number of organs working together to form a life function |
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Ciliated epithelial tissue |
Column shaped, exposed surface covered with cilia Move in synchronised waves, e.g. waft mucus/eggs Found on saurface of tubes |
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Cooperation between cells example |
Movement: due to muscular and skeletal system, only if the nervous system 'instructs'. It uses energy so requires supply of nutrients and oxygen from the circulatory system Receiving chemicals from digestive and ventilation systems |
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Cartilage |
Hyaline cartilage- forms the embyonic skeletion Fibrous cartilage- occurs in discs between vertebrae Elastic cartilage makes up the outer ear and the epiglottis |
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Muscle tissue |
Vascularised (many blood vessels) Elongated & contain myofilaments made of protein |
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Types of muscle |
Skeletal- connective tissue sheets Cardiac- walls of the heart Smooth- walls of intestine, blood vessels, propels along these tracts (passages) |
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Epidermial Tissue |
Flatterned cells, form protective covering over leaves, stem and rools Some have walls impregnated with a waxy substances, forming a cuticle |
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Vascular Tissue |
Tissue concerned with transport Xylem & Phloem both present in vascular bundles |
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How Xylem derives from meristem (cambuim cells differentiate into xylem vessels) |
Lignin (woody substances) deposited in their cell walls- reinforce, waterproof them but also kills the cell Ends of cells break down, Xylem forms continuous columns with wide lumens to carry water and dissolved minerals |
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How phloem derives from meristem (cambium cells differentiate into phloem sieve tubes or companion cells) |
Sieve tubes loose most of their organelles and sieveplates develop betweeen them Companion cells retain their organelles and continue metabolic function to provide ATP for active loading of sugar into sieve tubes |
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Stem cells |
Undifferenated cells able to express all of its genes and divide by mitosis |
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Sources of stem cells |
Early embryo- when zygote begins to divide Umbilical cord blood Adult stem cells- bone marrow |
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Bone marrow transplants |
Treats dieases of blood (sickle cell anamia & leukaemia) and immune system |
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Stem cells, development in biology |
Enables a better understanding of how multicellular organism develop cell functions & what goes wrong when diseased |
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Why plants need a transport system |
All living things need to take substances and return waste to their environment |
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Examples parts of the plant can that can do one thing but not another |
Roots can obtain water but not sugars Leaves can produce sugars but cannot obtain water from the air |
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Xylem and phloem tissue in Roots |
Xylem is arranged in an X shape, phloem found between the arm of the xylem |
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Xylem and phloem tissue in Stem |
Vascular bundles found around the outside of the stem in a ring shape Xylem on the inside, phloem on the outside separated by a layer of cambium- meristem cells |
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Xylem and phloem tissue in Leaves |
Xylem on top, phloem in the 'veins' of a leaf |
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Xylem function and structure |
Transports water and mineral ions from the roots up to the leaves- vessels do this Fibers help support the plant Living parenchyma cells which act as packing tissues to separate and support the vessels |
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Xylem Vessels |
Long thick walls impregnated by waterproof lignin- prevents collapsing, creates patterns making the stem or branch flexble Vessels always stay open Lignification is not complete= pits or bordered pits- allow water to leave & pass into living parts of the plant |
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Sieve tube elements |
Little cytoplasm No nucleus Form a tube - sugars are transported Sieve plates- cross walls that are perforated Thin walls
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Companion cells |
Found between sieve tubes Cytoplasm, nucleus, mitochondria ATP loads sucrose into the phloem Plasmodesmata between companion cells allows flow of minerals between the cells |
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Plasmodesmata |
Gaps in the cell wall containing cytoplasm that connect two cells |
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Apoplast pathway |
Water passes through spaces in cell walls By mass flow Dissolved mineral ion & salts carried with water |
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Symplast pathway |
Water passes through plasma membrane Can pass through plasmodesmatas |
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Vacuolar pathway |
Water passes through plasma membrane and vacuoles |
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Water potential |
The tendency of water molecules to move from one place to another |
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Transpiration |
The loss of water vapour from the aerial parts of a plant due to evaporation |
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Transpiration a consequence of gaseous exchange- how plants reduce water loss |
Stomata opens- water can be lost to reduce this: Waxy cuticle- prevents water through epidermis Stomata closes at night Deciduous plants loose leaves in winter- conserve the water that they have got |
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Factors that affect transpiration rate |
Number of leaves Number-size-position of stomata Presence of cuticle Light Temperature Relative humidity Air movement Water available |
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How a potometer is used to estimate transpiration Pt 1 |
Cut healthy shoot underwater to stop air entering xylem Cutting shoot at a slant to increase surface area Ensure apparatus is full of water and that there is only the desired air bubble Insert shoot into apparatus underwater |
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How a potometer is used to estimate transpiration Pt 2 |
Remove potometer form water and ensure it is airtight around the shoot Dry leaves and Keep conditions constant to allow shoot to acclimatize (adjust) Shut screw fixed and record position of air bubble Start timing and measure distance moved per unit of time |
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The movement of water between plant cells |
Water passes from cell with higher water potential (less negative) To the cell, with the lower water potential (more negative) |
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The movement of water between plant cells and their environment |
Water moves down the water gradient If water potential inside the cell is greater than the water potential outside the cell Water moves out of the cell by osmosis Vice versa |
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The pathway water is transported from the root cortex to the air surrounding the leaves Pt 1 |
Water enters the root hair cells by osmosis At the same time, minerals are actively pumped from the root cortex into the xylem Consequentially water moves from root hair cell along symplast pathway to follow the xylem |
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The pathway water is transported from the root cortex to the air surrounding the leaves Pt 2 |
Casparian strip blocks the apoplast pathway between the cortex and the xylem Water must join the symplast pathway to reach the xylem When water reaches the top of the xylem it enters the leaves Leaves the leaves through the stomata |
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How Adhesion transports water from the root cortex to the air surrounding the leaves |
Water molecules form hydrogen bonds with the walls of the xylem As the xylem vessels are narrow H bonds can pull water up the sides of the vessel |
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How cohesion and the transpiration stream transports water from the root cortex to the air surrounding the leaves |
Water molecules attract to each other due to forces of cohesion The forces are strong enough t hold the molecules together in a long chain As molecules are lost from the top the whole column is pulled up ad one chain This is called the transpiration stream |
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How the if some xerophytes are adapted to reduce water loss by transpiration |
Smaller leaves less surafce area Densely packed spongy mesophyll Thicker waxy cuticle Closing stomata, stomata in pits Hairs on surface of leave trap layer of air reduce diffusion of water out of stomata
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Hyrophytes |
Plants that live in water Large air spaces in the leaf Stomata are on the upper epidermis Large air spaces in the stem helps with buoyancy and diffuse quickly |
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Translocation |
The transport of assimilates (substances that have become a part of the plant)throughout a plant |
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Translocation between sources (where the sugars come from eg leaves) and sinks (where they go eg roots) |
Sugars made in leaves and transported to roots in early spring leaves need energy to grow so sugars are transported from the roots (now the source) to the leaves (now the sink) |
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Transport in the phloem involving active loading at the source and removal at the sink Pt 1 |
ATP used by companion cells to actively transport proteins out of their cytoplasm and into the surrounding tissue This sets up a diffusion gradient and the hydrogen inn diffuse back into the cells Done through cotransport proteins which enable H ions to bring sucrose back into the cell with them |
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Transport in the phloem involving active loading at the source and removal at the sink Pt 2 |
Concentration of sucrose molecules builds up, they diffuse into the sieve tube elements through the plasmodesmata The entrance of sucrose into the sieve tube elements reduces the water potential water follows by osmosis and increases the hydrostatic pressure at the source to lower hydrostatic pressure at the sink |
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Transport in the phloem involving active loading at the source and removal at the sink Pt 3 |
Sucrose moves via either diffusion or active transport from sieve tube to the surrounding cells This increases the water potential in the sieve tube elements so water moves into surrounding cells by osmosis this reduces the hydrostatic pressure at the sink |
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Role of membrane within cells and at the surface of cells |
Separate cell contents and components from the outside environment Cell recognition and signalling Holding the components of some metabolic pathways in place Regulating the transport of materials into or out cells |
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Phospholipids membranes |
Have a hydrophobic head and fatty acid tail Form a bi-layer Fluid so components can move around freely Permeable, small, non polar but impermeable to large molecules and ions |
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Cholesterol membranes |
Mechanical Stability Sit between fatty acid tails making the barrier more complete |
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Glycolipids membranes |
Phospholipid molecules that have a carbohydrate part attached Used for cell signalling, cell surface antigens and cell adhesion |
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Proteins Membranes |
Channel proteins allow the movement of large molecules into and out of the cell as they can't travel directly through the membrane Carrier proteins actively move substances across the membrane |
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Glycoproteins membranes |
Phospholipid molecules with a protein attached with a chain of carbohydrate molecules |
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Temperatures effect on phospholipids |
Increasing temp = more kinetic energy membrane becomes more permeable so increases the fluidity |
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Temperature effect on cholesterol |
Increased temperature = cholesterol pulls phospholipids together as they are attached to the cholesterol The molecules in the membrane are closer = the fluidity of the membrane decreases |
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Unsaturated tails affect of membranes |
Tails are bent = more distance Double carbon bonds More distance = increased fluidity |
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Saturated tails affect of membranes |
Tails are straight = narrower distance Single bond Less distance = decreased fluidity |
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Passive transport |
Transport of molecules without using energy Diffusion net movement from high conc to low conc down a conc gradient Larger molecules travel through carrier proteins shape only allow one molecule through often gated Carrier proteins shaped to fit a specific molecule, then change shape to allow it to the other side |
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Active transport |
Movement of molecules or ions across membranes, using ATP to drive 'protein pumps' within the membrane |
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Endocytosis |
When large quantities of a material are brought into the cell using ATP |
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Exocytosis |
When large quantities of a material are moved out the cell using ATP |
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Osmosis in terms of water poteintal |
The movement of eater molecules from a region of higher water potential to a region of lower water potential across a partially permeable membrane |
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Hyper-tonic |
The concentration of solutes is greater inside the cell than outside of it |
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Hypo-tonic |
The concentration of solutes is greater outside the cell than inside it |
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Hyper-tonic in Plants |
Water moves out of cells by osmosis down a water potential gradient Plant membrane pulls away from cell wall as water leaves the cell is plasmolysed |
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Hyper-tonic In animals |
Water moves out of cells by osmosis down a water potential gradient Animal cell shrinks and appears wrinkled it is crenated |
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Hypo-tonic in plants |
Water moves in by osmosis down a water potential gradient plant cell wall prevents bursting membrane pushes against wall the cell is turgid |
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Hypo-tonic in animals |
Water moves in by osmosis down a water potential gradient animal cell bursts open it is cytolysed |
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Water as a liquid |
Water molecules constantly move around and continually make and break hydrogen bonds |
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Density of water |
Ideal habitat for living thing Ice is less dense than water |
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Water as a solvent |
Metabolic processes in all organisms rely on chemicals being able to react together in a solution |
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Cohesion in water |
Water molecules stick to each other creating surface tension at the water surface |
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Synthesis of dipeptides and polypeptides |
The -OH from one amino acid and then the -H from the -COOH from the other are removed to make water and the C and the N join together via a peptide bond |
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Hydrolysis of dipeptides and polypeptides |
A water molecule is used to break the peptide bond The -H joins back to the N, and the -OH back to the C |
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Primary structure |
Sequence of amino acids found in a protein molecule |
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Secondary structure |
The coiling or folding due to the formation of hydrogen bonds synthesised Main forms are the alpha-helix and the beta-pleated sheet |
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Tertiary structure |
3-D structure, result of interactions between parts of the protein molecule such as hydrogen bonding disulfide bridges ionic bonding hydrophobic and hydrophilic interactions |
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Quaternary structure |
Proteins made up of more than one polypeptide chain e.g. Haemoglobin made up of 4 polypeptide chains |
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Structure and function of haemoglobin |
Globular protein Soluble in water Wide range of amino acids constituents in primary structure Contains a prosthetic group- haem Wound into alpha-helix structures
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Structure and function of collagen |
Fibrous protein Insoluble in water 35% of the molecule's primary structure is gycine Does not have a prosthetic group Much of the molecule consists of left handed helix structures |
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Structure of an alpha-glucose |
pic |
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Structural difference between alpha and beta glucose |
In alpha the -OH on carbon 1 is below the plane of the ring In beta it is above the chain of the ring |
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Formation of disaccharide |
water is eliminated as the -OH from one glucose and the -H from an -OH from the other leaves The remaining O joins to the C on the other glucose making a disaccharide |
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Breaking of a disaccharide |
Water is used to break the glycosidic bond between the subunits The -H returns to the O and the -OH returns to C4 In polysaccharides there are many glucose subunits joined together by 1,4 gycosidic bonds |
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Amylose |
Made up of alpha glucose straight chain tends to coil up plant storage polysaccaride |
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Cellulose |
Made up the beta glucose in a chain, alternate glucose subunits are inverted forms straight chains The beta glycosidic bond can only be broken down by an enzyme which herbivores have Form plant cell walls |
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Structure and function of glycogen |
Mostly like amylase, as it has many 1,4 glycosidic bonds, but there are 9% 1-6 branches As it is highly branched it can be brake down the glucose very quickly |
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The function in living organisms of glucose |
Simplists sugar, used in respiration |
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The function in living organisms of amylose |
Insoluble in water so does not affect the water potential of the cell |
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Triglyceride |
Glycerol plus three fatty acids The function in living organisms compact energy store insoluble in water doesn't affect cell water potential |
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Test for presence for protein (biuret test) |
If present, turns from bale blue to lilac |
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Test for presence for reducing sugars (Benedict's test) |
Add Benedict's, heat to 80 degrees from blue to orange-red |
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Test for presence for non-reducing sugars (Benedict's test) |
If reducing sugar test is negative, boil with hydrochloric aid, cool and neutralise with sodium hydrocarbonate, repeat benedict's test |
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Test for presence for starch (iodine solution) |
Turns from yellow to blue-black if starch prent |
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Test for presence for lipids (emulsion test) |
Mix the ethanol pour into water if an emulsion forms a lipid is present |
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Nucleic acids DNA |
DNA is a polynucleotide, usually double stranded Nucleotides containing bases A adenine T thymine C cytosine G guanine |
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RNA |
Is a polynucleotide, usually single stranded made up of nucleotides containing bases A adenine U uracil C cytosine G guanine |
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Formation of DNA |
AT pair up = (purines), CG pair up = (pyrimidines) Hydrogen bonds between complementary base Strands are anti parallel chains and twist like a rope ladder to form a double helix |
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How DNA replicates |
Double helix is untwisted H bonds brake between bases, DNA 'unzips' by the eznyme helicase Free DNA nucleotides are H bonded onto their exposed complementary bases DNA polymerase catalyses the formation of covalent bonds between the phosphate of one molecule and the sugar of the next one, continues all the way down till there are two identical strands, these are proof read by DNA polymerase to prevent mistakes |
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Protein synthesis |
Gene exposed by splitting the hydrogen bonds that hold the double helix together (mRNA) is complementary strand which is a copy of the DNA coding strand mRNA peels away from the DNA and leaves nucleus from pores attaches to ribosome tRNA bring amino acids to ribosome in correct order according to base sequence on mRNA Amino acids joined by peptide bonds to give a protein with a specific tertiary structure |
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An enzyme |
Are globular proteins Specific tertiary structure Catalyse metabolic reactions in living organisms |
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Extracellular Intracellular |
EX= outside the cell IN= inside the cell |
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Active site |
The area on an enzyme to which the substrate binds |
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lock and key hypothesis |
The theory of enzyme action in which the enzyme active site is complementary to thesubstrate molecule, like a lock and key |
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induced-fit hypothesis |
induced-fit hypothesis,The theory of enzyme action in which the enzyme molecule changes shape to fit thesubstrate molecule more closely as it binds to it |
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enzyme-substrate complex |
The intermediary formed when a substrate molecule binds to an enzyme molecule |
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enzyme-product complex |
The intermediate structure in which product molecules are bound to an enzyme molecule |
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lowering of activation energy |
Enzymes reduce the activation enthalpy so the reaction can proceed at a much lowertemperature |
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Effect of pH on enzyme activity |
Low pH = lots of H+ ions H+ ion concentration can interfere with the hydrogen and ionic bondsholding the tertiary structure together. The pH affects the charge of the amino acids at the active site, so the properties of theactive site change and the substrate can no longer bind |
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Effect of temperature on enzyme activity |
Increasing temperature will increase the rate of reaction, as more collisions between enzymes and the substrate, Puts strain on the inter-molecular bonds,and some of the weaker bonds (H bonds and ionic bonds) may break, after enough break the- Tertiary structure will unravel and theenzyme will stop working, Becoming denatured |
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Effect of enzyme concentration on enzyme activity |
Enzyme concentration increases, the rate of reaction increases As more active sites are available Until the substrate concentration becomes a limiting factorand the rate stops increasing |
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Effect of substrate concentration on enzyme activity |
Increasing substrate concentration, the rate of reaction increases As moresubstrate molecules to react. At higher concentrations, all of the active sites become filled,so the rate of reaction remains the same |
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Competitive inhibitor molecules |
Similar shape to that of the substrate molecule. They occupy theactive site, forming enzyme-inhibitor complexes. Doesn't lead to theformation of products Most don't bind permanently to the active site and leaves the enzyme molecule unaffected. |
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Non-competitive inhibitors |
They attachto the enzyme at the allosteric site away from the active site and distorts the tertiary structure of the enzyme molecule changing the shape of the active site The substrate no longer fits into theactive site so the enzyme-substrate complexes cannot form and the reaction ratedecreases. Bind permanently to the enzyme molecule it's irreversible and are effectivelydenatured. |
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Cofactors |
Ions that increase the rate of enzyme-controlled reactions. Their presence allows enzyme substratecomplexes to form more easily. |
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Coenzymes |
Small, organic, non-protein molecules that bind for a short period of time to the active site.They may bind just before, or at the same time, as the substrate binds. The role is often to carry chemical groups between enzymes so they link togetherenzyme-controlled reactions that need to take place in sequence. Some coenzymes are permanent parts of the enzymes- prosthetic groups. |
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Metabolic poison that act as enzyme inhibitors |
Potassium Cyanide acts as a non-competitive inhibitor of the enzyme cytochrome oxidase, which isinvolved in the oxidation of ATP. When this is inhibited, aerobic respiration cannot occur, and sothe organism can only respire anaerobically, which leads to a build up of lactic acid, toxic to thecells.(i) state that some |
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Pathogen |
microorganism that causes disease |
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Bacteria |
Causes disease by damaging cells or releasing waste products or an toxins, toxic to the host e.g. E-coli, Salmonella, TB |
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Fungi |
Animals- when in the skin it's hyphae forms a mycelium under the skin surface hyphae that are specialised & reproduce are sent out grow and release spores on the surface e.g. athlete's foot Plants- vascular tissue is digested which causes decay from the hyphae releasing extracellular enzymes (cellulase) e.g. Black sigatoka (banana) |
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Viruses |
g |
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Transport in Animals: size of transport systems in multicellular animals |
Once an animal has several layers of cells any oxygen or nutrients diffusing in form the outside willbe used up by the other layers of cells The cells deeper in the body will not get any oxygen ornutrients. |
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level of activity in transport systems in multicellular animals |
If an animal is very active then it will need a good supply of nutrients and oxygen to supply theenergy for movement. |
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surface area:volume ratio of transport systems in multicellular animals |
It needs a range of tissues and structural support to givethe body strength. Their volume increases as the body gets thicker, but the surface area does notincrease as much. SA:V ratio of a large animal is relatively small. Largeranimals do not have a large enough surface area to supply all of the oxygen and nutrients that theyneed |
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single circulatory system |
A circulation in which the blood flows through the heart once during each circulation of the bodye.g. fish |
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double circulatory system |
A circulation in which the blood flows through the heart twice during each complete circulation ofthe body e.g. mammals |
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Open circulatory system |
The blood is not always in vesselse.g. insects |
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Closed circulatory system |
The blood is always in vesselse.g. fish |
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External structure of the mammalian heart |
Ventricles |
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Internal structure of the mammalian heart |
f |
