BIOLOGY REVISION
magnification of microscope
eyepiece x magnification of objective
magnification of image
size of image / resl size of object
chromosomes
carry genetic info called dna
why do cells divide
when an organism grows or an organism becomes damaged and needs to profuce new cells
stem cells
cells that have not undergone differentation (not specialised)
embryonic stem cells
a type of stem cell found in the embryo, capable of dividing into almost any cell type
adult stem cells
a type of stem cell found in specific locations in adults. adult stem cells csn only differentiate into s limited number of related cell types
mitosis
1- interphase- the cell doubled its subcellular structures
2-metaphase- the chromosomes form a single line down the centre of the cell
3. cytokenesis- the cell membrane and cytoplasm divife to form 2 seperste cells
solute
the dissolved substance in a solution
solvent
the liquid which the solute dissolved to form a solution
concentration gradient
the difference in the concentration of a chemicsl across a membrane
osmosis
the diffusion of wster molecules in a partially permeable membrane
sctive transport
movement of substances against a concentration gradient
cancerous cells
divide uncontrollably
tumour
a group of cancerous cells
benign
slow growing and non invasive
malignant
grows quickly and invasive of other parts of the body and form secondary tumours
cancer risks
-diet
-smoking
-viruses
-radiation snd ultraviolet exposure
eutrophication
the run off of fertilisers into streams snd rivers that leads to the overgrowth of algae thst orevents sunlight from passing through. this kills the plsntd snd then the fish
peat bogs
areas msde of partially decomposed organic matter due to water logging - store alot of carbon- and are being dig up to be used in soil
how do we maintsin biodiversity
-breeding programs
-habitat protection
-hedgegrows
-recycling
biodiversity
variety of all the living things and their interactions
quadrat
a square frame used for sampling the abundance and distribution of non moving organisms
systematic sampling
used if there is a trend or pattern across the habitst
meiosis
reduction division in a cell where the chromosome number is halved from diploid to haploid
meiosis
1- copies the genetic info
2- the cell divided to form 4 gametes, esch with a single set of chromosomes (haploid)
3- all the gametes are different
genome
the complete set of dna found in an organism
chromosomes
the structure of dna that codes for all the characteristics of sn organism
allele
different versions of the same gene
genotype
the collection of alleles that determine characteristics and can be expressed as a phenotype
phenotype
the visible characteristics of an organism which occur as a result of its genes
cystic fibrosis
an inherited disease that affects the lungs snd digestive stystem by clogging them with thick dticky mucus
trachea
windpipe - leads from mouth to lungs
bronchi
2 msjor air tubes in the lungs
alveoli
tiny air sacs in the lungs where gas is exchanged during breathibg
intercostal muscles
raise and lower the diaphrsm
stomach
begins the digestion of protein
small intestine
helps to futher digest the food from the stomach