GCSE Biology condensed notes for all topics. Targetted at AQA but can be used for other exam boards. Concise and precise notes for effective revision. Includes mindmaps, diagrams and summaries.
Topics include:
1) Cell biology
2) Cell division
3) Enzymes
4) Organising animals
5) Organising p...
Alveoli- specialised to Osmosis- practical Microscopy-practical
Fish minimise the diffusion of 1) Cut up potato into identical cylinders and get 1) Add a drop of water to a clean slide.
-Gills are the exchange surface oxygen and carbon some beakers with different sugar solutions. One
2) Cut up onion and separate into layers. Use tweezers to
in fish. dioxide. should be pure water, another should be
concentrated (1mol/dm³). Then a few others with peel of epidermal tissue.
-Each gill is made up of thin - Large surface
plates called gill filaments, concentrations in-between (0.2/0.4/0.6 mol/dm³). 3) Using tweezers place tissue into the water on the slide.
area 2) Measure mass of cylinders, then put one in each 4) Add a drop of iodine solution. (Stains are used to
which give a big surface area
for exchange of gases.
- Thin walls beaker for 24 hours.
highlight objects in a cell by adding colour to them).
- Good blood 3) Take them out and dry with paper towels and
-The gill filaments are covered measure masses again. 5) Place cover slip on top.
in lots of tiny structures called supply 4) If cylinders increase in mass then water has been
lamellae, which increase the drawn in by osmosis. If water has been drawn out
surface area even more. Villi- (small intestine) then they will have decreased in mass.
-The lamellae have lots of - Increase surface area so Independent variable: concentration of sugar solutions.
blood capillaries to speed up that digested food is Dependent variable: chip mass
diffusion.
absorbed much more
- They also have thin surface
layer of cells to minimise the quickly into the blood.
distance that the gases have - Very good blood supply Use Light Microscope to look at the slide:
to diffuse. to assist quick 1) Clip the slide onto stage.
absorption. 2 )Select lowest-powered objective lens.
Osmosis 3) Use coarse adjustment knob to move stage up to
Movement of water Active transport Examples of active transport: Required just below the objective lens.
molecules across a partially Moves substances - Root hair cells absorb mineral ions
Practicals 4) Look down the eyepiece.
permeable membrane from from a dilute to a from dilute solutions in the soil by
Diffusion, 5) Adjust focus with fine adjustment knob, until a clear
a area of high water concentrated active transport.
- Glucose an be absorbed out of the Osmosis, image is formed.
concentration to an area of solution (against a Active
gut and kidney tubules against a 6) To see the slide with greater magnification, swap to
low water concentration. concentration Transport
concentration gradient by active a higher-powered objective lens and refocus.
gradient).
Turgor Pressure- no more water can enter a cell -
transport.
Cystic fibrosis(have thick, sticky
Biology-T1 Cells Eukaryotic- animals/plants.
due to pressure inside. mucus because active transport Cell Biology Prokaryotic- single- celled organisms (bacteria).
1) Water moves into the cell by osmosis system in their mucus cells do not
2) The vacuole swells work properly.
3) The cytoplasm is pressed against the cell
wall. Specialised cells Nucleus-contains genetic material(controls activities in a cell.
Diffusion
4) The cell becomes rigid Movement of particles from an area Sperm cells Cytoplasm- chemical reactions occur ( contains enzymes that controls these reactions .
5) The leaves and stem becomes rigid. of high concentration to an area of - Long Nerve cells
Cell membrane-controls what goes in and out of the cell.
Isotonic-solution with the same low concentration tail/streamlined - Carries electrical signals
Mitochondria-reactions of aerobic respiration take place.
concentration. Rate of diffusion is affected by: head to swim. from one part of the
Hypertonic-solution is more - Concentration - Many body to another. Ribosomes-where protein synthesis takes place.
concentrated. - Temperature mitochondria for - Long cells and branched
Hypotonic-solution is more energy connections to connect
- Surface area
dilute.
Animal cell - Digestive enzyme nerve cells throughout
- Hypotonic solution (cell will swell and to break down the the body.
possibly burst. Examples of diffusion: egg.
- Hypertonic solution (water moves out of - Diffusion of oxygen and glucose Chloroplasts-contain chlorophyll, absorbing light for photosynthesis.
into cells of the body from the Root hair cells Muscle cells
the cell and shrinks. Permanent vacuole-contains cell sap.
bloodstream for respiration. - Long hair to provide - Cells are long so
Plant cells they have space to Cell wall- supports the cell.
- Diffusion of oxygen and carbon a large surface area
- Hypotonic solution ( keeps the cell rigid and dioxide in opposite directions in to absorb mineral contract.
supports the plant. the lungs (gas exchange). ions and water from - Contains lots of
- Hypertonic solution ( loses water and becomes - Diffusion of simple sugars and the soil. mitochondria –
flaccid, so the plant wilts. If kept in a hypertonic amino acids from the gut - Many mitochondria energy for
solution in a laboratory a lot of water leaves the cell. through cell membranes. to transfer energy contraction.
The vacuole and cytoplasm shrink and the - Diffusion of carbon dioxide into needed for active
membrane pulls away from the cell wall. This is actively photosynthesising plant transport of mineral
referred to plasmolysis. cells. ions into the cell.
, Food test:
Iodine Test: Benedict Test: Cell cycle: Stem Cells
1) Make a food 1) Prepare a food sample 1) The longest stage. The cells grow, increase
sample and (biscuits, cereal) and transfer in mass, and carry out normal cell Differentiation is the process by which a cell
transfer 5cm³ of 5cm³ to a test tube. activities. At the end of stage 1 the cells changes to become specialised.
your sample to a 2) Prepare a water bath so that replicate their DNA to make two copies of
test tube. its set to 75°C. every chromosome. They also make more Undifferentiated cells, are called stem cells, can
2) Add a few drops 3) Add some Benedict’s solution sub- cellular structures such as divide to produce lots more undifferentiated cells.
of iodine, (3/4 to the test tube (about 10 drops) mitochondria, ribosomes and chloroplasts. They can differentiate into different types of cells.
drops) If starch is using a pipette. 2) Mitosis: one set of chromosomes is pulled
present, solution 4) Place the test tube in the to each end of the dividing cell and the Stem cells are found in early human embryos and
will turn from water bath using a test tube nucleus divides. adult bone marrow.
yellow-red to holder and leave it in there for 3) The cytoplasm and cell membrane divide Risks: stem cells grown in a lab may become
blue-black. 5mins. to form two new identical cells. contaminated with a virus which could be passed
( Same test for Biuret 5) If the food sample contains Mitosis is important for grow or to replace cells that on to the patient, making them sicker.
and Sudan) sugar, the solution will turn from have been damaged. Advantage: replace faulty cells ( could make
blue to brick red. insulin- producing cells for diabetes, nerve cells for
• Iodine test for starch- yellow-red
will turn blue-black if iodine is
present.
T3 Biology-T2 paralysis.
Therapeutic cloning: embryo could be made to have
the same genetic information as the patient. This
• Benedict test for sugars- blue (Enzymes) Cell Division means that the stem cells produced from it would
will turn brick red if sugar such as also contain the same gene, therefore wouldn’t be
glucose is present. rejected by the patient’s body if used to replace
• Biuret test for protein- blue faulty cells.
turns purple if protein is present. Effect of PH on Enzyme Activity- Practical Against stem cell research:
• Sudan/ethanol test for lipids- 1) Put a drop of iodine solution into every well of spotting tile. Some people believe human embryos shouldn’t be
ethanol turns cloudy white. 2) Place a Bunsen burner on a heat-proof mat, and gauze over the used for experiments since each one is a potential
Sudan- top layer will be bright Bunsen burner. Put a beaker of water on top of the tripod and life. Others however think curing patients is more
red if lipid is present. heat the water until it is 35°C (use a thermometer to measure important.
the temperature).
Rate= amount that it is changed by/ time 3) Use a syringe to add 1cm³ of amylase solution and 1cm³ of a Stem cells can produce identical cells:
buffer solution with a PH of 5 to a boiling tube. 1) In plants stem cells are found in the
4) Use a different syringe to add 5cm³ of a starch solution to the meristems (part of the plant where
boiling tube. growth occurs).
5) Immediately mix the contents of the boiling tube and start the 2) These stem cells can be used to produce
timer. clones of whole plants quickly and
6) Use continuous sampling to record how long it takes for the cheaply.
amylase to break down all the starch. To do this use a dropping 3) They can be used to clone rare species.
pipette to take a fresh sample from the boiling tube every 30 4) Stem cells can also be used to grow
seconds and put a drop into a well. When the iodine solution crops of identical plats that have desired
remains browny-orange, starch is no longer present. features ( disease resistant).
7) Repeat experiment with different PH values.
, Enzymes can: A catalyst is a substance which increase the speed of a reaction, A tissue is a group of similar cells that work
• Build large molecules from many without being changes or used up in the reaction together to carry out a particular function.
smaller ones, such as building starch 1) Muscular tissue, which contracts to bring out
glucose molecules. Enzymes are biological catalyst: movement.
• Change one molecule into another Enzymes are large proteins. The shape of an enzyme is 2) Glandular tissue, produce substances such as
one, such as converting one type of vital for its function. The enzyme has an area called the hormones and enzymes.
sugar into another. active site where its substrate molecule can fit. 3) Epithelial tissue, covers some parts of the
• Break down larger molecules into The lock and key theory is a simple model of how body.
smaller one(digestive enzymes) enzymes work:
Metabolism: An organ is a group of different tissue that work
sum of all the together to perform a certain function:
Enzymes are 1) Muscular tissue, which moves the stomach wall to
affected by: reactions that
take place in a churn up to food
• PH 2) Glandular tissue, which makes the digestive juices to
• Temperature cell or in the
whole body. digest food.
( Pepsis works 3) Epithelial tissue, which covers the outside and inside of
best PH 2 etc…) the stomach.
Biology-T3 An organ system is a group of organ working together
to perform a particular function.
For example the digestive system is made up of these
organs:
Organisation and the digestive system 1) Glands (pancreas/salivary glands) which produce
digestive juices.
2) Stomach and small intestine, which digest food.
3) The liver, which produces bile
4) Small intestine, which absorbs soluble food
molecules.
5) Large intestine, which absorbs water from
undigested food, leaving faeces.
The villi are adapted to absorb
soluble food efficiently:
• A very large surface area
to absorb soluble food
molecules by diffusion
and active transport.
• A thin wall to provide a
short diffusion path.
• A good blood supply to
carry the food molecules
away to maintain a
concentration gradient.
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