Paper 1 Major Topic Flashcards
Practical using a light microscope (Practical)
For plant cell (onion) and for animal cell (cheek cell)
- Use tweezers to peel off a layer of onion skin/use a cotton bud and swab inside your cheek.
- Lay onion cell on a clean microscope slide/rub cotton bud onto the centre of a clean microscope slide.
- For onion cells add a drop of iodine/for cheek cells add methylene blue. (Use as a stain)
- Use a mounting needle slowly lower the coverslip, and avoid air bubbles
- View under a light microscope first with low power and increase magnification.
Animal cells vs Plant cells
Animals cells: Cell membrane, mitochondria, cytoplasm, ribosomes, nucleus.
Plant cells: (All the parts in animal cells) +chloroplast, cell wall and a permanent vacuole.
Eukaryotic cells vs Prokaryotic cells
Eukaryotic cell - Plant + animal cells,
Prokaryotic cell - Bacteria –> single celled organisms
plasmid - rings of DNA (antibiotic resistance)
Genetic information isn’t enclosed in a nucleus
Flagellum - tail made out of protein strands
Specialised cells - Animal cells
Sperm cells, nerve cells, muscle cells
Animal cells :
Sperm cells (fertilise egg with male genetic information)
- tail - move faster
- mitochondria - more energy
- nucleus - genetic information
- acrosomes - break into egg
Nerve cells (Carry electrical impulses around the body)
- Dendrites - connect to other nerve cells
- Axon - carries nerve impulse
- Synapses - pass impulses to another cell
Muscle cells (Contract and relax to move)
- Special proteins - slide over each others
- Mitochondria - more energy
- Store glycogen - broken down to use for respiration
Specialised cells - Plant cells
Root hair cells, Photosynthetic cells, Xylem, Phloem
Plants cells :
Root hair cells (take up water from the soil)
- Large SA - increase availability for water to move into the cell
- Large permanent vacuole - speeds up the movement of water by osmosis
- Mitochondria - transfers energy for active transport.
Photosynthetic cells (carry out photosynthesis)
- Chloroplast - contain chlorophyll to absorb light
- Continuous layers in leaves and outer layers, absorb as much light as possible
- Large permanent vacuole, cell rigid
Xylem (carries water and minerals ions from the roots)
- Formed lignin and builds up spirals, they die and form long hollow tubes.
- Spirals and rings of lignin make them stronger and help withstand high pressure.
Phloem (Transports food made by photosynthesis)
- Special sieve plates allow water carrying dissolved food to move freely
Different types of transport
Diffusion - Movement of particle from high to low concentration.
Increase diffusion rate - Increase temperature, increase surface area, increase concentration gradient.
Osmosis - Movement of water particles from a high to low concentration.
Active transport - Movement of particles against the concentration gradient, low to high.
Hypertonic, Isotonic and Hypotonic
Isotonic - Concentration of solutes outside the cell is same as internal concentration.
Hypertonic - Concentration of solutes outside the cell is higher than the internal concentration
Hypotonic - Concentration of solutes outside the cell is lower than the internal concentration.
Osmosis potato investigation (Practical)
- Cut potatoes into cylinders (all same size)
- Get beakers with different sugar solution. One with pure water, another with very concentrated sugar solution
- Measure starting mass.
- Leave potatoes in the solution for a certain amount of time.
- Take them out and dry them
- Weigh the potatoes again
- Potatoes in low sugar concentration should gain mass
Food Test for Carbohydrates, Protein, Lipids
Carbohydrates - Starch - Yellow red iodine - Blue Black
- Sugars - Blue Benedict solution - Brick red on heating
Protein - Biuret - Blue to purple
Lipids - Ethanol - cloudy white layer formed
Different blood vessels
Arteries - Carries blood away from heart (high pressure)
- Walls are strong and elastic
- Thick layers of muscle to be strong.
- Elastic fibres to allow them to stretch
Capillaries - exchange materials at tissues
- Arteries branch into capillaries
- permeable membrane for diffusion
- One cell thick for diffusion
- Supply food and O2 and take waste away
Veins - Carry blood to the heart (low pressure)
- Capillaries join to form vein
- Bigger lumen to help with low pressure
- Valves to prevent backflow
Coronary heart disease (What is it and how to cure it)
Coronary artery that supply the blood to the muscle of the heart get blocked by layers of fatty deposits.
Cured by :
Stents - tubes inserted inside the arteries and keep them open. It lowers the risk of heart attack, effective for a long time.
However, complication during the operation and increase risk of blood clot,
Statins - Reduces the amount of ‘bad’ cholesterol in the blood stream. It reduces the risk of strokes, coronary heart disease and heart attacks. Increase beneficial cholesterol.
However, long term drug (need to be taken regularly), cause negative side effects (headaches etc) , effect is not instant.
Making monoclonal antibodies
- Mouse is injected with an antigen
- Obtain a fast dividing tumour/cancer cell
- Take out the B - Lymphocyte from the mouse
- Fuse the B - Lymphocyte with the tumour/cancer cell
- Divides quickly to produce lots of clones that produce the monoclonal antibodies
Plant leaf (Epidermal tissues, upper epidermis, palisade layer, xylem and phloem, lower epidermis, stomata and guard cells, spongy mesophyll)
Epidermis tissues - Covered with waxy cuticle, reduce water loss.
Upper epidermis - Transparent, so light can pass to palisade layer.
Palisade layer - Lots of chloroplast
Xylem and Phloem - Deliver water and nutrients to leaf and take away glucose.
Lower epidermis - Contains stomata
Stomata - Let CO2 diffuse into the leaf
Guard cells - Control stomata to open and close.
Spongy mesophyll - Air spaces increases the rate of diffusion
Transpiration (What is it and factors affecting it)
Loss of water from a plant. Caused by evaporation and diffusion.
Factors :
Light intensity - Brighter the light the greater transpiration rate. Stomata closes at night, no light for photosynthesis, no need to let CO2 in.
Temperature - warmer, faster rate of transpiration. Water particles gain more energy and evaporate and diffuse out the stomata.
Air flow - Better air flow, greater transpiration rate. Poor air flow, water around the leaves doesn’t move away, so less transpiration.
Humidity - Drier the air around the leaf, faster transpiration. Humid air, lots of water in it, so not much concentration difference.
Types of pathogens
Bacteria, Virus, Protists, Fungi
Bacteria - very small cells, reproduce rapidly inside your body
Make you feel ill by producing toxins which damage cells and tissues
Virus - very tiny, reproduce rapidly inside your body. Replicate themselves inside cells, and burst cells. Cell damage causes illness
Protists - Single celled eukaryotes. Protist are parasites and parasites live on or inside other organisms. Often transferred by a vector.
Fungi - Singled celled, some are made up of hyphae. Hyphae can grow and penetrate human skin and surface of plants. They produce spores which can spread.
