B1 Flashcards
What is the equation for magnification ?
Image size / real size
How many of each are in a metre?
Centimetre, millimetre, micrometre, nanometre
100cm in a 1m
1000mm in 1m
1000000ųm in 1m
1000000000nm in 1m
How does a light microscope work?
Use light and lenses to form an image of a specimen and magnify it
How do electron microscopes work?
Uses electrons instead of light to form an image
Which microscope is better? And why?
Electron microscopes because they have a higher magnification and resolution so can see smaller internal structures
What is a prokaryotic cell?
A bacteria cell
What is a eukaryotic cell?
A plant or animal cell
How are prokaryotic and eukaryotic cells structurally different?
Eukaryotic contain a nucleus which holds genetic information whereas prokaryotic have no nucleus, they contain a single loop of dna and plasmids to hold genetic information
What three things does a plant cell have that animal cells don’t?
Cell wall, vacuole and chloroplasts
What is the function of all sub-cellular structures?
Nucleus: controls the cell
Cell membrane: controls what goes in and out of the cell
Cytoplasm: where most chemical reactions happen
Mitochondria: where aerobic respiration takes place
Ribosomes: where protein synthesis takes place
Cell wall: supports and strengthens cell
Chloroplasts: contain chlorophyll which absorbs sunlight for photosynthesis
Vacuole: contains cell sap
What is the cell wall made of?
Cellulose
What is the function of the sperm cell?
Reproduction
What is the function of a nerve cell
Rapid signalling
What is the function of a muscle cell?
Contraction
What is the function of red blood cell?
Transporting oxygen
What is the function of root hair cell?
Absorbing water and minerals
What is the function of palisade cell?
Absorb sunlight for photosynthesis
What is the function of phloem and xylem cells?
Transporting substances
How is the sperm cell specialised?
Lots of mitochondria: gives energy
Long flagellum: able to swim
Enzymes: eat away egg in order to fertilise it
How is the nerve cell specialised?
Branches: connect to skin cells
Long: form network to send signals
How is the muscle cell specialised?
Long: allows space to contact
Lots of mitochondria: more energy to contact
How is the red blood cell specialised?
No nucleus: more space to carry oxygen
Large surface area: able to absorb oxygen
What are stem cells?
Cells that can differentiate into other cells
Where are stem cells found?
Animal: embryos or bone marrow
Plant: meristem tissue (roots and shoots)
What cells can each stem cell turn into?
Embryotic cells can turn into any type of cell
Bone marrow stem cells can turn into white blood cells, red blood cells and platelets
Meristem can turn into any sort of plant cells
What is meant by therapeutic use of stem cells?
The use of stem cells to treat diabetes or paralysis
How does therapeutic use of stem cells work?
1.skin cell from patient and egg cell from donor
2. Nucleus removed from skin cell then implanted into egg cell
3. Egg cell develops into embryo by mitosis
4. Stem cells removed from embryo and placed in Petri dish
5. Stem cells differentiate into needed cell, e.g. pancreatic cells
Advantages of stem cell use
Cure serious disease
Improve mental health
Disadvantages of stem cell use
Embryo discarded (ethical issues)
not thoroughly tested
Expensive
What is chromosome?
Coiled up length of dna, contain genetic information
How many chromosomes does an adult cell have?
23 pairs (46)
What is the stage where the cell divides called?
Mitosis
Why does mitosis occur?
Growth and repair, replacement of damaged cells
What are the steps of the cell cycle?
- DNA replication
- chromosomes line up in centre and pulled apart to opposite poles by cell fibres
- Nucleus, cytoplasm, cell membrane divide (mitosis)
- Two identical daughter cells are formed
What is binary fission?
Single cell division that happens within bacteria (prokaryotic cells) and occurs rapidly
How long does binary fission take?
20 minutes
What is meant by diffusion?
the spreading out/movement of particles from an area of high concentration to an area of low concentration
What is meant by osmosis?
the movement of water molecules from an area of high water concentration to low water concentration, across a partially permeable membrane.
What is meant by active transport?
The movement of particles from an area of low concentration to an area of higher concentration using energy.
Factors that effect the rate of diffusion
Concentration gradient
Temperature
Surface area
How are organ systems for exchanges substances?
Having a large surface area
A thin membrane - short diffusion distance
Having a good blood supply
Being ventilated (gas exchange)
What is magnification?
The number of times bigger the image appears compared to the size of the real object
What is resolution?
The smallest distance between two objects that can be distinguished
What to wear can bacteria be grown?
Nutrient broth solution
colonies on agar gel plate
What nutrients are required for bacteria to grow?
All nutrients including nitrogen carbohydrates and other minerals
What are uncontaminated cultures of microorganisms needed for?
Investigating disinfectant and antibiotic action
What is done during the preparation of uncontaminated culture?
Use pre-sterilised plastic pet dishes and agar gel
Palister tile agar gel into the petri dish and allow the time to set
Sterilise the Covid tin loop bypass three constant burner filling
Dip the inculpating leap into the solution in micro organisms
Puts the lid on the patch and security with tip label accordingly then turn and start upside down
Thank you be at the culture at 25°
What happens during the preparation of uncontaminated culture?
Use pre-sterilised plastic petri dishes
Poor the sterile agar into the petri dish and let it set
Sterilise the inoculating loop by passing it through a Bunsen burner
Dip the inoculating loop into the solution of microorganisms and add to surface of agar
Put the lid on the Petri dish and security with tape and store upside down
Incubate the culture at 25°
Why most petrol dishes be sterilised before use?
To kill Amy bacteria present
Why must inoculating loops be sterilised?
To kill any bacteria present
Why must petri dishes be secured with tape?
Stop bacteria in the air contaminating the culture
The lid is not fully sealed to prevent the growth of anaerobic bacteria in lack of oxygen
Why must petrol dishes be stored upside down?
To prevent condensation from forming and dripping down onto the bacteria colonies
Why are cultures incubated at 25°?
Harmful pathogens are less likely to grow at this temperature
What does active transport require that diffusion and osmosis does not?
Energy from respiration
