Biology Flashcards
Aerobic Respiration
Oxygen + Glucose -> Carbon Dioxide + Water
6O² + C⁶H¹²O⁶ -> 6CO² + 6H²O
Longer form exercise usually over a larger event e.g marathons
Water cycle
Purpose: Recycle water naturally
Stages
- 1: Evaporation
River/Sea/Surface water Evaporates into the atmosphere - 2: Condensation
Water vapour condense under the temperature of the atmosphere creating clouds - 3: precipitation
Once clouds become too heavy they rain letting water droplets out - 4: drainage
The water runs down providing vital nutrients for photosynthesis, Some water evaporates from the plants back into clouds. - 5: transpiration
Alternatively the water runs down into lakes/rivers or oceans and starts the process again
Anaerobic Respiration
Glucose -> Lactic Acid + Energy
Short form, Usually for sprinters or High intensity short form exercises
Photosynthesis
6CO² + 6H²O -> C⁶H¹²O⁶ + 6O²
Respiration found in plants for energy
Reasons why people have more severe water shortages
Climate change has increased the area of desert’s
More water is used to grow crops
How do microorganisms recycle Carbon from leaves in the soil so that it can be used on new plant growth?
The leaves decay plants use respiration by the decomposers
Respiration releases **carbon dioxide **
Carbon dioxide is used in photosynthesis
Benefit of fallen leaves from living plants
Nitrates are released into the soil
Human activities leading to pollution of rivers/seas/oceans
- Sewage released into the rivers, caused by algae growth, Algae blocks light , plants die without the light. Sewage leads to pathogens
- fertiliser leaks into causing algae growth leading to lack of oxygen in water
- pesticides runs into rivers/seas build up in the food chain
- toxic chemicals from factories or power stations, Builds up the food chain, may lead to mutations or chemicals may act as hormones
Radiation leaks from nuclear power stations and acid rain forms, acidification of the rivers
-
Build of waste products
Litter affects leaving organisms like fish or sea life
Biotic factors which lead to plant growth
- Competition
- herbivores
- trampolining
- pollinators
- pathogens
Methods to an effective investigation
Scenario question: If the amount of water in the soil affects the number of buttercup’s in a field
1- Mark out an effective area related to the question, E.g A Wet and dry area.
2- Use quadrats to measure area effectively
3- count the number of samples in the quadrant (Buttercups)
4- use at least 5 different quadrats
5- take measurements of the desired characteristics (moisture of the soil) by using the correct/accurate equipment
6- find the mean of each area
7- use the mean of the area to check the correlation between the two variables
Abiotic Vs biotic factors
Abiotic factors are non-living parts of an ecosystem that affect the distribution of living organisms.
Biotic factors are living parts of an ecosystem that affects the distortion or growth of living organism
Types of variables
independent Variable
- The thing that changes e.g amount of water
Dependant
- The thing affected by the change e.g amount of plants grown
** Control **
- External factor that will have an impact on the study e.g amount of sunlight on each plant
Hormones in the pancreas
Glycogen and insulin
Interaction of the menstrual hormones
Days 1 to 12 - oestrogen gradually increases and peaks approximately on the 12th day. Progesterone, LH and FSH stay approximately at the same levels and begin to increase slightly from around day 12.
FSH and LH patterns are very similar and peak during ovulation at approximately 14 days during this cycle. They drop sharply on day 15 and stay constant until day 28.
Oestrogen drops during days 13 and 14, and progesterone continues to gradually increase until about day 21, when it slowly beings to decrease again. Oestrogen mirrors this shape and also has a second lower peak at about day 21.
Menstrual Cycle Hormones( FSH)
- Causes an egg to mature in an ovary; stimulates the ovaries to release oestrogen
- Located in Pituitary gland
Menstrual Cycle Hormones (Oestrogen)
- Stops FSH being produced (so that only one egg matures in a cycle); repairs, thickens and maintains the uterus lining; stimulates the pituitary gland to release LH
- Located in the Ovaries
Menstrual Cycle Hormones (LH)
- Triggers ovulation (the release of a mature egg)
- Located in the Pituitary gland
Menstrual Cycle Hormones ( Progesterone)
- Maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy
- Located in Ovaries
Stages of Genetic Engineering
- selection of the desired characteristic
- the gene responsible for the characteristic is ‘cut out’ of the
chromosome with enzymes - the gene is transferred and inserted into another organism
- replication of the modified organism.
Stages of Selective Breeding
- Decide which characteristics are important enough to select.
- Choose parents that show these characteristics from a mixed population. They are bred together.
- Choose the best offspring with the desired characteristics to produce the next generation.
-Repeat the process continuously over many generations, until all offspring show the desired characteristics.
Reasons for Selective Breading (Animals)
Desired characteristics in animals:
-animals that produce lots of milk or meat
-chickens that lay large eggs
-domestic dogs that have a gentle nature
Mainly for Economical Reasons
Reasons for selective breeding (Plants)
Desired characteristics in plants:
-disease resistance in food crops
-wheat plants that produce lots of grain
-large or unusual flowers
Usually for economical reasons
What is a mutation?
A mutation is a change in a
gene or chromosome. Mutations arise spontaneously and happen continually. A mutation rarely creates a new phenotype, but if the phenotype is suited to a particular environment, it can lead to rapid change in a species.
Natural selection
Commonly known as survival of the fittest, Refers to species who are most suited for their role being the ones who live on longer
For example, Polar Bears with whitest fur allow them to camouflage to attack prey.
RPA : Microscope
Equipment List
* a small piece of onion
* a knife
* a white tile
* forceps
* a microscope slide
* a coverslip
* a microscope (Some microscopes have a built-in light instead of a mirror)
* iodine solution in a dropping bottle
* prepared animal and plant cells
* Perspex ruler.
Method
1. Use a dropping pipette to put one drop of water onto a microscope slide.
2. Separate one of the thin layers of the onion.
3. Peel off a thin layer of epidermal tissue from the inner surface.
4. Use forceps to put this thin layer on to the drop of water that you have placed on the microscope slide.
5. Make sure that the layer of onion cells is flat on the slide.
6. Put two drops of iodine solution onto the onion tissue.
7. Carefully lower a coverslip onto the slide. Do this by placing one edge of the coverslip on the slide and
using the forceps to lower the other edge onto the slide
8. There may be some liquid around the edge of the coverslip. Use a piece of paper to soak this liquid
up.
9. Put the slide on the microscope stage.
10. Use the lowest power objective lens. Turn the nosepiece to do this.
11. The end of the objective lens needs to almost touch the
slide. Do this by turning the coarse adjustment knob. Look
from the side (not through the eyepiece) when doing this.
12. Now looking through the eyepiece, turn the coarse
adjustment knob in the direction to increase the distance
between the objective lens and the slide. Do this until the
cells come into focus.
13. Now rotate the nosepiece to use a higher power objective
lens.
14. Slightly rotate the fine adjustment knob to bring the cells
into a clear focus and use the low-power objective (totalling
40 magnification) to look at the cells.
15. When you have found some onion epidermal cells, switch
to a higher power (100 or 400 magnification).
16. Make a clear, labelled drawing of some of these cells. Make sure that you draw and label any
component parts of the cell.
17. Write the magnification underneath your drawing.
18. Use this technique to draw a range of animal and plant cells on prepared slides.
Variables
Independent - Magnification
Dependent - Size of the cell
Control - Cell type
RPA : Microbiology
Equipment List
* a nutrient agar plate
* a Bunsen burner
* a heatproof mat
* a disposable plastic pipette
* a culture of bacteria (E. coli)
* a glass spreader
* filter paper discs
* disinfectant bench spray
* a ‘discard beaker’ of disinfectant
* 1% VirKon disinfectant
* forceps
* clear tape
* hand wash
* a wax pencil
* access to an incubator (set to 30oC)
* three antiseptics (such as mouthwash, TCP,
and antiseptic cream)
Method
1. Spraying the bench where you are working with disinfectant spray.
Then wipe with paper towels.
2. Put the Bunsen burner on the heatproof mat in the middle of
where you are working. Light the Bunsen on a yellow flame.
3. Mark the underneath of a nutrient agar plate (not the lid) with
the wax pencil as follows (make sure that the lid stays in
place to avoid contamination):
* divide the plate into three equal sections and number them 1,
2 and 3 around the edge
* place a dot into the middle of each section
* around the edge write your initials, the date and the name of
the bacteria (E. coli)
4. Wash your hands with the antibacterial hand wash.
5. Turn the Bunsen flame to blue.
6. Remove the lid of the bottle containing the culture of bacteria (keep the lid in your hand). Then flame
the neck of the bottle through the Bunsen flame. Do this by quickly twisting the bottle from side to side.
Use the disposable pipette to collect approximately 1 ml of the bacterial culture.
7. Quickly flame the neck of the bottle again and replace the lid.
8. Carefully lift the lid of the agar plate at an angle. Do not open it fully. The lid should only be fully open
on the Bunsen burner side.
9. Pipette the bacteria onto the agar plate and replace the lid.
10. Place the pipette into the ‘discard beaker’. Turn the Bunsen burner flame back to yellow.
11. Dip the glass spreader into the VirKon disinfectant. Remove the glass spreader and tap off the excess.
Then pass the glass spreader through the flame. Hold the glass spreader horizontally to ensure nothing
drips down onto your hand.
12. Allow the spreader to cool for a count of 20 seconds.
13. Lift the lid of the agar plate. Again, the lid should be at an angle so only the side next to the Bunsen
burner is fully open. Spread the bacteria around the plate using the glass spreader.
14. Remove the glass spreader and put into the discard beaker. Lower the lid of the agar plate.
15. Put different antiseptics onto the three filter paper discs. This can be done by either soaking them in
the liquid or spreading the cream or paste onto them.
16. Lift the lid of the agar plate as in step 8. Use forceps to carefully put each disc onto one of the dots
drawn on with the wax pencil.
17. Make a note of which antiseptic is in each of the three numbered sections of the plate.
18. Secure the lid of the agar plate in place using two small pieces of clear tape. Do not seal the lid all the
way around as this creates anaerobic conditions. Anaerobic conditions will prevent the E. coli bacteria
from growing and can encourage some other very nasty bacteria to grow.
19. Incubate the plate at 30 °C for 48 hours.
20. Measure the diameter of the clear zone around each disc by placing the ruler across the centre of the
disc. Measure again at 90° to the first measurement so that the mean diameter can be calculated.
21. Record your results in a table.
Variables
Independent - Temperature incubated at
Dependent - Diameter of the zone
Control - Surrounding temps, Moisture of surface
RPA : Osmosis
Equipment List
* a potato
* a cork borer or potato chipper/ vegetable stick cutter
* a ruler
* a 10 cm3 measuring cylinder
* labels
* three boiling tubes
* a test tube rack
* paper towels
* a sharp knife
* a white tile
* a range of sugar solutions
* distilled water
* a top-pan balance.
Method
1. Use a cork borer to cut three potato cylinders of the same diameter.
2. Trim the cylinders so that they are all the same length (about 3 cm).
3. Accurately measure and record the length and mass of each potato cylinder.
4. Measure 10 cm3 of the 0.5 M sugar solution and put into the first boiling tube. Label boiling tube as:
0.5M sugar.
5. Measure 10 cm3 of 0.25 M sugar solution and put into
the second boiling tube. Label boiling tube as: 0.25M
sugar.
6. Measure 10 cm3 of the distilled water and put into the
third boiling tube. Label boiling tube as water.
7. Add one potato cylinder to each boiling tube. Make
sure you know the length and mass of each potato
cylinder in each boiling tube.
8. Record the lengths and masses of each potato cylinder in a table.
9. Leave the potato cylinders in the boiling tubes overnight in the test tube rack.
9. Remove the cylinders from the boiling tubes and carefully blot them dry with the paper towels.
10. Re-measure the length and mass of each cylinder (make sure you know which is which). Record your
measurements in the table. Then calculate the changes in length and mass of each potato cylinder.
12. Plot a graph with ‘Change in mass in g’ on the y-axis and ‘Concentration of sugar solution’ on the xaxis.
13. Plot another graph with ‘Change in length in mm’ on the y-axis and ‘Concentration of sugar solution’ on
the x-axis.
14. Compare the two graphs that you have drawn
Variables
Independent - Sugar Contents in liquid
Dependent - Rate of Osmosis
Control - Liquid amount, Mass of potato
RPA : Food Tests (Protien)
Equipment List
* food to be tested
* a pestle and mortar
* a stirring rod
* a filter funnel and filter paper
* 2 beaker, 250 ml
* a test tube
* Biuret solution
* safety goggles.
Method
1. Use a pestle and mortar to grind up a small sample of food.
2. Transfer the ground up food into a small beaker. Then add distilled water.
3. Stir the mixture so that some of the food dissolves in the water.
4. Filter using a funnel with filter paper to obtain as clear a solution as possible. The solution should be
collected in a conical flask.
5. Put 2 cm3 of this solution into a test tube.
6. Add 2 cm3 of Biuret solution to the solution in the test tube. Shake gently to mix.
7. Note any colour change. Proteins will turn the solution pink or purple.
Colour
- Purple
Solution
Biuret Solution
RPA : Food Tests (Starch)
Equipment List
* food to be tested
* a pestle and mortar
* a stirring rod
* filter funnel and filter paper
* 2 beaker, 250 ml
* a conical flask
* 2 test tube
* Benedict’s solution
* iodine solution
* kettle for boiling water
* a thermometer
* safety goggles.
Method
1. Use a pestle and mortar to grind up a small sample of food.
2. Transfer the ground up food into a small beaker. Then add distilled water.
3. Stir the mixture so that some of the food dissolves in the water.
4. Filter using a funnel with filter paper to obtain as clear a solution as possible. The solution should be
collected in a conical flask.
5. Half fill a test tube with some of this solution.
6. Add 10 drops of Benedict’s solution to the solution in the test tube.
7. Put hot water from a kettle in a beaker. The water should not be boiling. Put the test tube in the beaker
for about five minutes.
8. Note any colour change. If a reducing sugar (such as glucose) is present, the solution will turn green,
yellow, or brick-red. The colour depends on the sugar concentration.
9. Take 5 ml of the solution from the conical flask and put it into a clean test tube.
10. Add a few drops of iodine solution and note any colour change. If starch is present, you should see a
black or blue-black colour appear.
11. Record your results in a table.
Colour
- Black/blue colour
Solution
- Iodine Solution
RPA : Food Tests (lipids/fats)
Equipment List
* food to be tested
* a pestle and mortar
* a stirring rod
* 2 beaker, 250 ml
* a test tube
* Sudan III stain solution.
* safety goggles
Method
1. Use a pestle and mortar to grind up a small sample of food.
2. Transfer the ground up food into a small beaker. Then add distilled water.
3. Stir the mixture so that some of the food dissolves in the water. Do not filter.
4. Half fill a test tube with some of this solution.
5. Add 3 drops of Sudan III stain to the solution in the test tube. Shake gently to mix.
6. If fat is present: a red-stained oil layer will separate out and float on the water surface.
Colour
- Red will appear if present
** Solution**
- Sudan 3
RPA : Food Tests (Sugar)
Equipment List
* food to be tested
* a pestle and mortar
* a stirring rod
* filter funnel and filter paper
* 2 beaker, 250 ml
* a conical flask
* 2 test tube
* Benedict’s solution
* iodine solution
* kettle for boiling water
* a thermometer
* safety goggles.
Method
1. Use a pestle and mortar to grind up a small sample of food.
2. Transfer the ground up food into a small beaker. Then add distilled water.
3. Stir the mixture so that some of the food dissolves in the water.
4. Filter using a funnel with filter paper to obtain as clear a solution as possible. The solution should be
collected in a conical flask.
5. Half fill a test tube with some of this solution.
6. Add 10 drops of Benedict’s solution to the solution in the test tube.
7. Put hot water from a kettle in a beaker. The water should not be boiling. Put the test tube in the beaker
for about five minutes.
8. Note any colour change. If a reducing sugar (such as glucose) is present, the solution will turn green,
yellow, or brick-red. The colour depends on the sugar concentration.
9. Take 5 ml of the solution from the conical flask and put it into a clean test tube.
10. Add a few drops of iodine solution and note any colour change. If starch is present, you should see a
black or blue-black colour appear.
11. Record your results in a table.
Colour
- Solution will turn brick red
Solution
- Benedicts Solution
RPA : Enzymes
Equipment List
* test tubes
* a test tube rack
* spotting tiles
* 5cm3 measuring cylinder
* syringes
* a stop clock
* starch solution
* amylase solution
* iodine solution
* syringes
* water bath (electrical or bunsen burner and beakers)
* buffered solutions covering a range of pH, each with a labelled syringe/ plastic pipette
Method
1. Place one drop of iodine solution into each depression on the spotting tile.
2. Place labelled test tubes containing the buffered pH solutions, amylase solution and starch solutions in
to the water bath
3. Allow the solutions to reach 30 °C
4. Add 2cm3 of one of the buffered solutions to a test tube.
5. Use the syringe to place 2 cm3 of amylase into the buffered pH solution.
6. Use another syringe to add 2 cm3 of starch to the amylase/buffer solution.
7. Immediately start the stop clock and leave it on throughout the test.
8. Mix using a glass rod.
9. After 10 seconds, remove one drop of the mixture with a glass rod.
10. Place this drop on the first depression of the spotting tile with the iodine solution. The iodine solution
should turn blue-black.
11. Use the glass rod to remove one
drop of the mixture every 10
seconds. Put each drop onto
the iodine solution in the next
depression on the spotting tile.
Rinse the glass rod with water
after each drop. Continue until
the iodine solution and the
amylase/ buffer/ starch mixture
remain orange.
12. Repeat the procedure with
solutions of other pH values.
13. Record your results in a table
Variables
Independent - Concentration of Iodine solution
Dependent - pH values of solutions
Control - measurement of mixtures as well as equipment
RPA : Photosynthesis
Method
Equipment List
* a boiling tube
* freshly cut 10 cm piece of pondweed
* a light source
* a ruler
* a test tube rack
* a stop watch
* 0.2% solution of sodium hydrogen carbonate mix.
* a glass rod.
Method
1. Set up a test tube rack containing a boiling tube at a distance of 10 cm away from the light source
2. Fill the boiling tube with the sodium hydrogen carbonate solution.
3. Put the piece of pondweed into the boiling tube with the cut end at the top. Gently push the pondweed
down with the glass rod.
4. Leave the boiling tube for 5 minutes.
5. Start the stop watch and count the number of bubbles produced in one minute.
6. Record the results in a table.
7. Repeat the count twice more. Then use the data to calculate the mean number of bubbles per minute.
8. Repeat steps 1‒7 with the test
tube rack and boiling tube at
distances of 20 cm, 30 cm and
40 cm from the light source.
Variables
Independent - Distance of the LED light source away.
Dependent - Amount of bubbles in one minute
Control - Temperature, Water, Other light sources.
RPA : Reaction Time
Equipment List
* a metre ruler
* a chair
* a table
* a partne
Method
1. Use your weaker hand for this experiment. If you are right handed then your left hand is your weaker
hand.
2. Sit down on the chair with good upright posture and eyes looking across the room.
3. Place the forearm of your weaker arm across the table with your hand overhanging the edge of the
table.
4. Your partner will hold a ruler vertically with the bottom end (the end with the 0 cm) in between your
thumb and first finger. Practice holding the ruler with those two fingers.
5. Your partner will take hold of the ruler and ask you to remove your fingers.
6. Your partner will hold the ruler so the zero mark is level with the top of your thumb. They will tell you to
prepare to catch the ruler.
7. Your partner will then drop the ruler without telling you.
8. You must catch the ruler as quickly as you can when you sense that the ruler is dropping.
9. After catching the ruler, look at the number level with the top of your thumb. Record this in a table.
10. Have a short rest and then repeat the test. Record the number on the ruler as attempt 2.
11. Continue to repeat the test several times.
12. Swap places with your partner. Repeat the experiment to get their results.
13. Use a conversion table to convert your ruler measurements into reaction times.
Variables
Independent - Time when ruler is dropped
Dependent - Distance travelled before caught
Control - Tiredness, Point of beginning, which finger is being measured.
RPA : Germination
Equipment List
* white mustard seeds
* petri-dishes
* cotton wool
* a ruler
* water
* access to a light windowsill and a dark cupboard.
Method
1. Set up three petri dishes containing cotton wool soaked in equal amounts of water.
2. Put ten mustard seeds in each petri dish.
3. Put the petri dishes in a warm place. They must not be disturbed or moved.
4. Allow the mustard seeds to germinate. Add more water if the cotton wool gets dry (equal amounts of
water to each petri dish).
5. Each petri dish should have the same number of seedlings after the seeds have geminated. Remove
excess seedlings from any dish that has too many. For example, one dish has eight seedlings which
are the fewest compared to the other petri dishes. Therefore, remove seedlings from the other petri
dishes so that each dish has eight.
6. Move the petri dishes into position.
* One should be placed on a windowsill in full sunlight.
* One should be placed in partial light.
* The third should be placed in darkness.
7. Measure the height of each seedling. Do this every day, for at least a week.
8. Record the heights in a table, including full sunlight, partial light and darkness.
9. Calculate the mean height of the seedlings each day.
10. Plot a graph with ‘Mean height in mm’ on the y-axis and ‘Day’ on the x-axis.
11. The graph should include data for full
sunlight, partial light and darkness.
Compare the data
Variables
Independent - postions of the petri dish
Dependent - Height of the shoot
Control - Sunlight, light source, water amount.
RPA : Field Investigation
Equipment List
* white mustard seeds
* petri-dishes
* cotton wool
* a ruler
* water
* access to a light windowsill and a dark cupboard.
Method
1. Set up three petri dishes containing cotton wool soaked in equal amounts of water.
2. Put ten mustard seeds in each petri dish.
3. Put the petri dishes in a warm place. They must not be disturbed or moved.
4. Allow the mustard seeds to germinate. Add more water if the cotton wool gets dry (equal amounts of
water to each petri dish).
5. Each petri dish should have the same number of seedlings after the seeds have geminated. Remove
excess seedlings from any dish that has too many. For example, one dish has eight seedlings which
are the fewest compared to the other petri dishes. Therefore, remove seedlings from the other petri
dishes so that each dish has eight.
6. Move the petri dishes into position.
* One should be placed on a windowsill in full sunlight.
* One should be placed in partial light.
* The third should be placed in darkness.
7. Measure the height of each seedling. Do this every day, for at least a week.
8. Record the heights in a table, including full sunlight, partial light and darkness.
9. Calculate the mean height of the seedlings each day.
10. Plot a graph with ‘Mean height in mm’ on the y-axis and ‘Day’ on the x-axis.
11. The graph should include data for full
sunlight, partial light and darkness.
Compare the data
Variables
Independent - Location/conditions of the survey
Dependent - Items in different areas of investigation
Control - area covered, abiotic and biotic factors
RPA : Decay
Equipment List
* a small beaker containing full fat milk or single cream
* a small beaker containing sodium carbonate solution
* a small beaker containing lipase solution
* 250 cm3 beakers, to be used as water baths
* test tubes
* a test tube rack
* a marker pen
* 10 cm3 plastic syringes
* a stirring thermometer
* a stop clock
* Cresol red, in a dropper bottle
* an electric kettle, for heating water
* ice, for investigating temperatures below room temperature.
Method
1. Half fill one of the 250cm3 beakers with hot water from the kettle. This will be the water bath.
2. Label two test tubes as ‘lipase’ and ‘milk’.
3. In the ‘lipase’ test tube put 5cm3 of lipase solution.
4. In the ‘milk’ test tube put five drops of Cresol red solution.
5. Use a calibrated dropping pipette to add 5cm3 of milk to the ‘milk’ test tube.
6. Use another pipette to add 7cm3 of sodium carbonate solution to the ‘milk’ test tube. The solution
should be purple.
7. Put a thermometer into the ‘milk’ test tube.
8. Put both test tubes into the water bath. Wait until the contents reach the same temperature as the
water bath.
9. Use another dropping pipette to transfer 1cm3 of lipase into the ‘milk’ test tube. Immediately start
timing.
10. Stir the contents of the ‘milk’ test tube until the solution turns yellow.
11. Record the time taken for the colour to change to yellow, in seconds.
12. Repeat steps 1‒11 for different temperatures of water bath. You can obtain temperatures below room
temperature by using ice in the beaker instead of hot water.
13. Record your results in a table.
14. Plot a graph of your results.
Variables
Independent - Temperature of water bath
Dependent - Record time taken for the solution to become yellow
Control - Expiry date, Moisture.
RPA : Error and Solutions
Random errors are due to things you have no control over, such as a change in room temperature whilst you were collecting the results. Repeating your measurements and finding a mean will reduce the effect of random errors.
Systematic errors are due to problems with the equipment you used. For example, the balances you used may have been out by 0.1 g for every measurement.
Solution to Random
- Repeat the experiment
- Controlled Environment
- Keep conditions the same
Solutions to Systematic
- “Zero” your equipment
- Swap Equipment for more accurate equipment.
- Subtract the error from the final results.
Three domain system
Classification systems have continued to be developed by other scientists, such as Carl Woese who developed the three-domain system. This is based on evidence now available from chemical analysis.
The updated system divides organisms into:
- Archaea (primitive bacteria usually living in extreme environments)
- Bacteria (true bacteria)
- Eukaryotic (including protists, fungi, plants and animals)
Nervous System
Information is brought to the central nervous system and taken away by nerves which are bundles of neurons.
Neurons are long cells which carry electrical signals along their length
Where two neurons meet there is a tiny gap called a synapse.
Signals pass chemically across the synapse where the impulse continues from the next neuron
** Process For Central Nervous System (CNS)**
-
Receptors
Sensory organs (Smell, sight, sound, touch and Taste) Start the chain sensing danger or something requiring response. - Sensory Neurons
-
Coordinator
For example the brain, Coordinates an effective response to the impulse. - Motor Neuron
-
effector
e.g Muscles or glands which respond to the problem based on the coordinators signal.
Process for detecting and responding
- **Stimulus **
e.g Feeling of Increased heat - **Receptor **
e.g touch on the skin - **Sensory Neuron **
- ** Relay Neuron **
- ** Motor neuron**
- ** Effector**
e.g Hand -
Response
e.g remove hand away from flame
Meiosis
Sexual reproduction uses the process of meiosis which creates gametes
Only happens in Sperm and egg cells in animals and pollen and ova in plants
Key Information
- Copies of Genetic information are made
- The cell divides twice to form four Gametes, Each with a single set of chromosomes.
- Gametes are haploid
- All gametes are genetically different from each other
Stages
- Parent cell
- Chromosomes make Identical Copies
- Similar chromosomes pair up
- Sections of DNA get swapped (Creates diversity)
- First cell division - chromosomes pairs separate
- Second cell division
Meiosis Vs Mitosis
Mitosis and Meiosis differ as Mitosis is a form of cell division which produces two diploid body cells
Meiosis Produces Four Non Identical ** Haploid sex cells** or Gametes
Cell Cycle
A growing and dividing cell goes through a series of stages called the Cell Cycle
The first stages of the cell cycle involve cell growth then synthesis of DNA. The single strand of DNA is an exact copy of itself
** Stages**
- Cell growth
- DNA synthesis - the chromosomes are now double stranded
- Further growth occurs and DNA checks for errors
- Mitosis
- Cytoplasm Separates creating two cells
- ** Temporary cell resting period or the cell stops dividing**
- (Repeat)
Cell Biology : Cell Structure
Cells
- Smallest Unit of life that can replicate independently
Some cells are whole organisms (Bacteria) so complete Asexual reproduction
Adults contain over 40 Trillion cells altogether
Known as Organelles or subcellular Structures
Animal Cells
- Eukaryotic
- Cell Membrane, Controls what gets in and out of a cell
- Nucleus, Contains genetic Material/DNA
- Cytoplasm, Where chemical reactions take place
- Mitochondria, Provide cells with the energy they need to function
- Ribosomes, site of Protien synthesis
Plant Cells
- Eukaryotic
- Cell Membrane, Controls what gets in and out of a cell
- Nucleus, Contains genetic Material/DNA
- Cytoplasm, Where chemical reactions take place
- Mitochondria, Provide cells with the energy they need to function
- Ribosomes, site of Protien synthesis
- Rigid Cell wall to provide support and structure to the cell
- Permanent Vacuole, Contains cell sap (Sugar, salts and waters)
- Chloroplast, used for photosynthesis contains chlorophyll
Bacteria Cell
- Prokaryotic/Unicellular
- Cell Membrane
- Cell wall
- Cytoplasm
- Ribosomes
- No Nucleus, No mitochondria
- Contains a circular strand of DNA, Contain need to survive and reproduce
- Plasmids - Extra Genes, antibiotic resistance
- Some may have flagella to allow movement
Cell Biology : Microscopes
Equation
Magnification = Image Size / object size (Real Size)
Microscopes
- Base
- Arm
- Light Source
- Stage
- Microscope slide
- Objective Lenses (Different Magnifications)
- Eyepiece lens (Fixed Magnification)
- Body tube
- Coarse focusing nobs
Object
- The real object or sample that you’re looking at
Image
- The image that we see when we look down the microscope
How it works
- Light from the room hits the mirror, pushing light through the sample through a lens, through the eye piece lens and into your eye to magnify the sample
Magnification
- How may times larger the image is than the object
Equation
Image Size / Object Size
Resolution
- The shortest distance between two points on an object that can still be distingued as two separate entities
Cell Biology : Light and Electron Microscopes
Light Microscopes
- Easy to use
- Relatively cheap
- Rely on light
- Limited to 0.2 Micrometers
- Any smaller will appear blurry
- Max resolution is 0.2 Micrometers
Electron Microscopes
- Large
- Expensive
- Hard to use
- Use electrons instead of light
- Wavelength of 0.1 Nanometers
- Max resolution is 0.1 Nanometers
- 2000x better than light microscopes
Cell Biology : Microscope Units of Conversion
Scale
Nano Meter (Smallest)
Micrometers
Millimeters
Meters
Kilo Meters (Largest)
Gets 1000x larger further you go
e.g 6mm = 0.006m
Size Examples
Nanometer - Glucose
Micrometer - Bacteria
Millimeter - Insects
Meter - Planes
Kilometers - Planes
Cell Biology : Mitosis
Cell Cycle
Requires a continues supply of new cells for
-Growth
-development
-repair
3 Stages
- Growth
- DNA replication
Division
Growth
- Grows in size
- Increases the amount of sub cellular structures e.g mitochondria and ribosomes
- DNA then duplicates
When not dividing long strings
when dividing goes to chromosomes
Eukaryotic
- Pair of cells one from father and mother
- Humans have 23 Pairs of Chromosomes
Replication
Duplicates each chromosomes but stays attached to the original creating an X shape
When its ready to divide the chromosomes line up
Cell fibers pull the arms of the chromosomes to each pole of the cell , Separating them
Division/ cytokinesis
- Forms two daughter cells
- Each cell has the same DNA and are identical
- Used for growth, development and repair
- Will undergo the cell cycle eventually
Cell Biology : Stem Cells
Stem Cells
- Able to divide by Mitosis to from more cells
- Able to differentiate into specialized cells
When sperm and egg fertilize called a Zygote and uses mitosis
Forms a group of cells called an Embryo
Embryonic Stem Cell
Adult Stem Cells
- Can differentiate but only into blood cells
- Can do mitosis
- found in bone marrow
Two types of stem cells found in animals
- Adult Stem Cells
- Embryonic Stem Cells
Plant Stem Cells
- Meristems area of the plant that are continually growing
- Found in places that will continue to grow
- Last for the plants entire life
- Can differenarte
Cell Biology : Specialization and differentiation
Specialized cells example
Human
- Muscle Cells
- Sperm Cells
- Nerve cells
Plant
Root Hair cells
Phloem Cells
Xylem Cells
Cell Biology : Stem Cells in Medicine
Stem Cells
- They can divide by mitosis
- Can differentiate into specialized cells
- Embryonic (Any)
- Adult Stem cells (Different Blood cells)
A lot of conditions are due to faulty or damaged cells e.g type 1 diabetes or paralysis
Process
- Extract embryonic stem cells from embryos
- grow them in a laboratory
- stimulate them to differentiate into whichever type of specialized cell they want
- Then give them to the patient to replace the faulty cells
Cons
- Requires an embryo e.g limited supply and ethical issues
- Rejection; Patient genomes may reject the cells
- Side effects
Alternative
- Use adult stem cells
- Can be taken from the patient themselves
- Only used on blood cells
- Limited usage
Risks
1 - Virus transmission; If infected with a virus then following transition would pass the virus on
2 - Tumor Development ; Divide too quickly so could cause a tumor or a cancer
Ethical Issue
- Potential for human Life
- Religious ideas of who can affect and change life
Cell Biology : Diffusion
Diffusion
- Net movement of particles from an area of Higher concentration to an area of lower concentration
Can happen in both liquids and gases
Can only take place through patrially permeable membranes
- Only some molecules can diffuse through
Diffusion is a Passive Process
Rate of Diffusion
- Concentration gradient between two places (Bigger difference means a quicker Rate of Reaction)
- Temperature (Higher temp means greater rate of diffusion)
- Surface area ( Larger area means quicker rate of diffusion)
Cell Biology : Osmosis
Osmosis
- Net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentraion
- Special case of Diffusion
Water Concentration
- The amount of water, as compared to other molecules, like sugars or salts “solutes” that are dissolved in the water
Red blood cells would gain water and swell if placed in water
Cell Biology Active Transport
Active Transport
- Movement of molecules against their concentration gradient from a lower concentration to a higher concentration
- Requires Energy from the cell (Active Process)
- Always takes place across a membrane
**Energy for active transport **
- From cellular respiration stored in ATP molecules
Plants require Active transport to take in Minerals as there is a higher concentration inside than outside however still need them
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