Topic 1: key concept in biology Flashcards
describe eukaryotic cells
Eukaryotic cells are found in plants, animals, fungi and -protists (single-celled organisms that don’t fit other categories).
They are 10 - 100 micrometres in size.
A eukaryote is an organism made up of eukaryotic cell.
have cell walls and ribosomes like prokaryotic
describe prokaryotic cells
Prokaryotic cells are 0.1 - 5.0 micrometres in size.
A prokaryote is an organism made up of prokaryotic cells.
Bacteria are prokaryotes.
have cell walls and ribosomes like eukaryotic
explain how the egg cell is adapted to its function
it contains nutrients in the cytoplasm to feed the embryo
it has a haploid nucleus ( has half the number of chromosomes as a normal human body cell)
straight after fertilisation its membranes changes structure to stop any more sperm getting in this makes the offspring end up with the right amount of DNA
explain how the sperm cell is adapted to its function
it has a long tail so it can swim to the egg
it has lots of mitochondria in the middle section to provide energy (from respiration) needed to swim.
it also has an acrosome at the front of the head where it stores enzymes needed to digest its way through the membrane of the egg cell
it also contains a haploid nucleus
explain how a microscope works
microscopes use lenses to magnify images. they also increase the resolution of an image.
higher resolution means the image can be seen clearly and more detail.
show the difference between a light microscope and an electron microscope
a light microscope works by passing light the specimen.
they let us see things like nuclei chloroplasts and living cells
electron microscopes use electrons not light and have higher magnifications
they can see the internal structure of chloroplasts and mitochondria in detail.
a disadvantage is that they cant be used to view living cells
what is the equation for total magnification
total magnifications=eyepiece lens magnification X objective lens magnification
milimeter - micrometer
micrometer - nanometer
nanometer - picometer
milimeter - micrometer x 1000
micrometer - nanometer x 1000
nanometer - picometer x1000
explain how and enzyme works
enzymes are catalysts produced by living this
the substrate is the thing that is changed in the reaction
enzymes have special shapes so they can catalyse reactions.
every enzyme has and active site- the part where it joins on to its substrate to catalyse the reaction
enzymes usually only work for one substrate.
this is because for the enzyme to work the substrate has to fit into the active site. if it doesn’t fit then the reaction will not be catalysed.
explain the effect of temperature on and enzyme-catalysed reaction.
changing the temperature will have an effect on the rate of reaction
if it is too cold the reaction will be very slow
if it is too hot the enzyme will get denatured so it will no longer fit so the reaction van no longer take place
explain the effect of ph on the enzyme
the ph interferes with the bonds holding enzymes together meaning that it can also denature the enzyme which mean it wont fit the substrate and the reaction wont happen
describe the movement in diffusion compared to active transport and osmosis
osmosis moves for a region of high concentration to a low concentration of water and diffusion is the movement of particles for an area of high concentration to low concentration but active transport is the movement of particles from an are of low concentration to high concentration
what can lipids be broken down into by lipase
gycerol and fatty acids
what big molecule is formed from simple sugars
carbohydrates can be synthesised from joining together simple sugars
