Topic 1 Cell Level Systems Flashcards
Describe how you would use a light microscope
A specieman is put onto a slide and then stained. A cover slip is put on top of the slide and put onto the stage where the lamp light makes it visible.
Define magnification
the degree to which an object has enlarged
What is the formula for magnification of a mocrisocope
magnification of eyepiece x objective lens
What are some advantages of light microscopes
Cheap, can be used at most locations, no specialist needed, can observe living speciemen
What are disadvantages of light microcopes
Low resolution (200nm), low magnification strength (x1500), staining is required for some organelles to be visble
Describe how electron microscopes are used
They use beams of electrons as they have a smaller wavelength and can magnify smaller organelles
Advantages of electron microscopes
Can see small organelles and produce 3D images
Disadvantages of electron microscope
expensive, requires a specialist, can not magnify living organisms, not portable
Describe sub cellular structure of an eukaryotic
Nucleus (containing genetic material), Cytoplasm (where chemical reactions occur), Cell membrane (contain receptors which control what enters and exits the cell), Mitochondria (where aerobic respiration occurs), Ribosomes (where protein synthesis occurs)
What sub-cellular structures are only in plant cells
Chloroplasts, Permenant vaccuole (contains cell sap and makes plant rigid), Cell wall (cellulose and strengthens cell)
What sub cellular structures are there in prokaryotic organisms
Cytoplasm, Cell wall, Cell membrane, Plasmids (small rings of DNA), Single circular strand of DNA (which floats in cytoplasm)
Why is respiration essential
Provides our body with ATP / energy for cells to carry out their functions
What sort of reaction is respiration
Exothermic as heat energy is released
What is the word equation for respiration
glucose + oxygen → carbon dioxide + water
What are the 2 types of respiration
Aerobic, Anaerobic
Describe Anaerobic respiration
Only occurs when there is a lack of oxygen (eg: when running), it does not yield as much energy as aerobic respiration but fully oxidises glucose
What are the products of anaerobic resperation
Glucose → Lactic Acid, Glucose → ethanol + carbon dioxide (fermentation)
What is Photosynthesis
Process of making glucose from sunlight
What sort of reaction is photosynthesis
endothermic as it absorbs sunlight
What is the word equation for photosynthesis
Carbon dioxide + water (light)→ glucose + oxygen
Describe how light intensity can be investigated using pond weed
Pond weed is placed in a boiling tube containing sodium hydrogen carbonate, 10 cm away from an LED. After the pond weed has acclimatises vary distance and count the bubbles of oxygen being produced. You will find that the light intensity = (1/distance) squared
What are some errors in the pond weed experiment
Bubbles vary in size and you may not count all
Describe how to test for starch in a leaf
Boil the leaf in water and ethene, stain it with iodide and if the leaf turns from brown to blue/black starch is present
Describe how temperature affects photosynthesis
Temp is proportional to photosynthesis at a certain extent, then it decreases as enzymes star to denature
Describe how carbon dioxide concentration affects photosynthesis
They are proportional until another factor becomes limited
Describe how light intensity affects photosynthesis
They are proportional until another factor becomes limited
