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Past GCSE Paper- Biology Higher Tier 2018 Combined revision - Coggle…
Past GCSE Paper- Biology Higher Tier 2018 Combined revision
Cell Structure
eukaryotic cells
eukaryotic cells all have cell membrane, cytoplasm and genetic material enclosed in a nucleus
include animal and plant cells
prokaryotes
small and simple
single cell organism
plant cells
cell wall made of cellulose
permanent vacuole contains sap , weak solutions of sugar and salt
animal cells
nucleus contains genetic mat. that controls activity of cell
mitochondria aerobic respo takes place. respo trans energy that the cell needs to work
cytoplasm- gel like sub, chem reac happens. contains enzymes that control these chem reac
cell membrane- holds cell together =, controls what goes in and out
ribosomes , proteins are made in the cell
non communciable diseases
CHD
coronary arteries supply blood the the heart muscle. these may become blocked by build up of fatty plaques containing cholesterol, resulting in CHD
if coronary arteries are blocked, the blood supply to part of heart is blocked off
cause of heart attack
person develops chest pain
blood clot can block coronary arteries
blood clot can form on a fatty deposit
causes
poor diet- eating saturated fat increases cholesterol levels
stress and smoking
lack of exercise
overweight
high levels of salts
treatment
statins
daily meds to control blood chol. levels
adv; drugs reduce blood chol. levels
dsv: may cause side effects
angioplasty
surgery insert small balloon into blood vessel , then inflated to remove blockage
adv; improve blood flow in coronary vessels preventing heart attack
dsv; sometimes only temp
lifestyle changes
diet and exercise, stop smoking
adv; reduces risk of heart disease and reduces bp
dsv; high level of willpower is req, to maintain the change
Photosynthesis
light intensity on the rate of photosynthesis
limiting factors;
at night
in winter; mainly temp
if it it's warm and bright enough, CO2 is usually limiting
chlorophyll can also be a limiting factor of photosynthesis
the amount of chlorophyll in a plant can be affected by disease, environmental stress- lack of nutrients,
light provides energy for photosynthesis
as light level is raised, the rate of photo increases steadily but only up to certain point
beyond that it wont make difference,as light intensity increases, the rate will no longer increase.
because it will be either the temperature or co2 level which is now the limiting factor
the temp has to be just right
oxygen production shows the rate of photosynthesis
pondweed is used to measure the effect of light intensity on the rate of photosynthesis
the rate at which the pondweed produces oxygen corresponds to the rate of which it is photosynthesising-
the faster the rate of oxygen production, the faster the rate of photosynthesis
1) a source of white light is placed at specific distance from pondweed
2) the pondweed is left to photosynthesise for set amount of time as it photosynthesises the oxygen released will collect in capillary tube
3) at the end of the experiment the syringe is used to draw the gas bubble in the tube up alongside the ruler and length of the gas bubble is measured .
this is proportional to the volume of oxygen produced
4) any variable that could affect the results should be controlled- temperature, time
the experiment is repeated twice with the light source at the same distance and the mean volume of oxygen produced and calculated
the inverse square law
when the lamp is moved away from the pondweed the amount of light that reaches the pondweed decreses
as distance increases the light intensity decreases- they are inversely proportional to each other
it turns out that light intensity decreases in proportion to the square of the distance- inverse square law
means if you halve the distance the light intensity will be four times greater and if you divide by three the night intensity will be nine times greater
if double distance, light intensity will be four times smaller and if you treble distance light intensity will be 9 times smaller
6CO2 + 6H2O ------LIGHT------- C6H12O6 + 6O2
carbon dioxide + water ----light---- glucose + oxygen
photosynthesis is endothermic, meaning energy is transferred from the environment in the process
glucose use
for respiration- transfers energy from glucose
making cellulose- glucose converted to cellulose makes strong plant cell walls
making amino acids- glucose combined with nitrate ions
stored as oils or fats- glucose turned into lipids for storing into seeds
stored as starch and stored in roots. starch is insoluble makes it better for storing glucose
concentration of sugar solution
????
measles
spread by droplets from infected persons sneeze or cough
develop red skin rash and show signs of fever
can be serious fatal + complications
can lead to pneumonia or brain infection- encephalitis
most people are vaccinated when younger
explain the differences between antibody production after the vaccine injection and after exposure to measles virus
stem cells
mitosis
differentiation is the process by which a cell changes to become specialised for its job
undifferentiated cells- stem cells can divide to produce lots more undifferentiated cells
adult stem cells cant turn into any cell type at all, only certain ones
found in early human embryos
found incertain places in adults, bone marrow
stem cells can produce identical plants
chroosomes contain our genetic info.
most cells in bod have nucleus.
chromosomes are coiled up lengths of DNA molecules
each chromosome carries a large number of genes. differebt genes control development of different characteristics- hair colour and eye colour
body cells in multicellulr organisms divide to produce new cells as part of series of stages celled cell cycle
the stage of cell cycle whenthe cell divides is called
mitosis
cell cycle
in cell thats not divideing, dna is spread out in long strings
before divdes cell has grow and increase amount of subcellular strucutres ; mirtochondria and ribosomes
then duplicates its DNA
1 more item...
once completed
DNA has been copied the cell is ready fro mitosis
chromosome line up in centre of cell- cell fibres pull thwm apart. the two arms of each chrome go opp ends of cell
1 more item...
Microscopy
magnification formula
magnification= image size divide by real size
50 µm wide. Calculate the width of the image of the specimen under a magnification of x 100. Give your answer in mm.
1) rearrange the formula- image size = magnification x real size
2) fill in the values you know- image size-= 100 x 50
3) 5000 µm
4) convert the units = 5mm
