Studied by 10 peopleWhat does resolution mean
Can be used to see very small objects in fine details when the light microscope cannot
How do you make an onion skin cell slide
1. Peel a small piece of onion epidermis from the onion
Using forceps place onion onto slide
Add a drop of iodine
Use forceps to lever the coverslip down over the skin
Why do you add a drop of iodine to the onion skin cell To stain the cells and make parts of the cells more easily seen
Why do you lever the coverslip on top of the skin To avoid trapping air bubbles
What are the parts of an animal cell Cell membrane, cytoplasm, nucleus, nuclear membrane, chromosomes, mitochondria
What is the cell membrane Controls what enters and leaves the cell, selectively permeable
What is the cytoplasm Where chemical reactions take place
What is the nucleus Control centre of the cell. Contains the genetic information
What is the nucleus membrane Membrane surrounding the nucleus
What is the chromosome Generic information is contained on thread like structures found within the nucleus
What is the mitochondria Where aerobic respiration takes place and energy release. Found in the cytoplasm
What is the cellulose cell wall Immediately outside the cell membrane and provides support. Calcium Pectate helps cement cell walls together.
What is essential in making cell walls Calcium
What is the large permanent vacuole Contains cell sap. When full Pushes cell membrane against cell wall making the cell rigid and providing support
What is the chloroplast Found in the cytoplasm. Contains chlorophyll which is used in photosynthesis. Only found in the greeen parts of the plant
Wha us essential in chlorophyll production Magnesium
What is in a plant cell Cell membrane cytoplasm chloroplast nuclear membrane nucleus permanent vacuole cell wall
What do bacterial cells contain Loop of DNA, Plasmids ( circular rings of DNA), and non-cellulose cell wall
What do a plant and bacterial cell have in common Both contain DNA
both contain a cytoplasm
What are two differences between plant snd bacterial cells Plant cells have a mitochondria and chloroplasts, bacterial cells have neither
Bacterial cells do not gave a nucleus, plant cells do
Define stem cells Unspecialised cell which divides by mitosis and later becomes specialised
In animals what is one source if adult stem cells Bone marrow
What are differences between adult stem cells and embryonic stem cells Embryonic stem cells can differentiate into any cell in the body
Adult stem cells can only differentiate into red and white blood cells
In plants where can stem cells be found Apices or meristems
What can plant stem cells be used for Cloning such as Tissue culture and grafts producing lots of genetically identical plants very quickly
What are differences between plant stem cells and animals stem cells Plants retain the ability to re differentiate, human stem cells cannot re differentiate
How can embryonic stem cells be used in medicine Embryonic stem cells could be used to treat spinal injuries or grow new organs for transplants
How can adult stem cells be used in medicine Treating blood cancers like leukaemia
What are the risks of using adult stem cells in medicine In pre-treatment using radiotherapy which destroys the immune system
Viruses or diseases could be transferred
Formation of Tumors
How can these risks with adult stem cells in medicine be avoided Stem cells can be removed form the patients bone marrow, then it is a perfect match and they don't have to find a donor
What are side effects of radiotherapy Pre treatments kill cancer cells but also kill healthy cells meaning patients have a reduced immunity, side effects such as tumours, nausea, tiredness and hair loss
What is diffusion The move tan of a substance from where it is in high concentration to where the concentration is lower
What are the three factors tha affect the rate of diffusion 1. The concentration gradient
Temperature
Large surface area
How does the concentration gradient affect the rate of diffusion As the concentration increases the rate of of diffusion increases
How does temperature affect the rate of diffusion High temperature increases the kinetic energy of the molecules making them move faster and so increasing the rate of diffusion
Does diffusion use energy No
Explain an example of diffusion in humans Oxygen dissolves into the lining of the alveoli and into the red blood cells. Carbon dioxide leaves the blood plasma and moves into the alveoli
Define tissue Similar cells grouped together
What is an organ Made up of several types of tissue
Wha are the main organs in plants Root, stem and leaf
What is an organ system Organs that operate together to carry out a particular function
What is an organism A group of organ systems goruped together ina complex animal like a human
Why do large animals need need specialised organs They have a small surface area to volume ratio, cells are too far away from the surface so diffusion isn't fast enough so transport systems are needed
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