biology gcse paper ocr a

Created by

Nidhi Modi

Cards (98)

what is the function of a nucleus?
stores genetic information and controls the function of the cell
what is the function of a cytoplasm?
a gel like substance where most chemical reactions occur
what is the function of the cell membrane ?
controls what enters and exits the cell
what is the function of the mitochondria?
where aerobic respiration occurs to release energy
what are the function of ribosomes?
where protein synthesis occurs (where proteins are made)
what is the function of the cell wall 
a structure surrounding the cell that gives it strength and support
what is the function of the permanent vacuole?
contains cell sap
what is the function of chloroplasts?
contains chlorophyll for photosynthesis to occur
what are the function of plasmids? 
a small ring of DNA found in bacterial cells
order these from smallest to largest : nucleus, gene, chromosome, cell 
gene, chromosome, nucleus, cell
characteristics of electron microscopes
- they use electrons to form an image
- very expensive
-very high resolution
- very high magnification
characteristics of a light microscope
-they use light to form an image
- relatively cheap
- low resolution
- low magnification
how do you calculate magnification
magnification = image size / actual size
what does magnification mean
how much bigger an image is compared to the actual size of the object
what does resolution mean
the ability to distinguish between two points that are close together
what is differentiation
the process by which a cell becomes specialised to carry out its function
what are the 8 life processes 
movement
respiration
sensitivity
growth
reproduction
excretion
homeostasis
nutrition
how do you convert centimetres to millimetres
multiply by 10
how do you convert millimetres into micrometers
multiply by 1000
how do you convert micrometers into nanometers
multiply by 1000
how do you convert nanometers into micrometers
divide by 1000
how do you convert micrometers into millimeters 
divide by 1000
how do you convert millimeters into centimetres 
divide by 10
what does highly specialised mean
when a cell has a specific shape and size
what is a stem cell
completely undifferentiated cell
what does undifferentiated mean
when a cell is unspecialised
what cells can differentiate in humans
skin and blood
what are the 5 kingdoms of life
animals, plants, fungi, bacteria, protoctists
how are sperm cells specialised
- have a flagellum to swim
- contain acrosome (enzymes to digest egg)
- lots of mitochondria
how are nerve cells specialised?
- long axon to transmit over distances
- synapses to connect to over nerves
- fatty sheath to speed up impulses
how are muscle cells specialised
-contract and relax for movement
-contains filaments of protein that slide over each other
- lots of mitochondria
- lots of ribosomes
-elongated
How are xylem cells specialised?
- the ends are broken to allow water to move through
- narrow
- hollow
- elongated
how are phloem cells specialised?
- contain small hands le's to allow food products to move up and down
- they have sieve tubes for transport
- no nuclei
how are root hair cells specialised
- a large surface area for absorbing mineral ions from the soil
- a lot of mitochondria that release energy in order to provide the energy needed for active transport
what is a cell
the smallest structural and functional unit of an organism
what is a tissue
a group of similar cells that work together to carry out a function
what is an organ
a group of different tissues that work together to perform a specific function
what is an organ system?
a group of organs that work together to perform a specific function
what is diffusion ?
diffusion is the net movement of molecules from a high to low concentration (down a concentration gradient)
what are the factors that affect diffusion
temperature
concentration gradient
diffusion distance
surface area