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B3 Revision Posters
B3a – Molecules of Life
Controls movement in & out of cell
Chemical reactions take place here – e.g. enzymes
Site of
respiration
(provides
energy)
Site of Protein
Synthesis
DNA Fingerprinting
Comparing samples of DNA to help
identify samples
B3b - Diffusion
• The movement of a substance from a region of high
concentration to a region of low concentration
FOR EXAMPLE:
Leaves:
Lungs:
Placenta:
Intestines:
To INCREASE the rate of
diffusion – have a LARGE
surface area and GOOD
blood supply
B3c - Keep it Moving
Plasma – yellow-ish fluid,
carries glucose and CO2
Red Blood Cells – carry the
oxygen
Platelets – clot the blood
White Blood Cells – fight off
infection
The Heart
4 chambers – ventricles - atrium
Too much saturated fat and cholesterol – fatty
deposits in blood vessels – coronary heart disease
B3d – Divide & Rule
• MITOSIS
A diploid cell produces two diploid cells
For growth, repair and replacement
• MEIOSIS
A diploid cell produces four haploid cells
To make gametes (egg and sperm)
• FERTILISATION When sperm joins with egg
B3e – Growing up
A gestation period
is the time spend
developing in the
womb in most
animals.
Growth involves (a) Cell Division – by
MITOSIS (producing identical cells) and (b)
Cell Differentiation.
Cell differentiation involves producing
different types of cells from
undifferentiated cells called STEM CELLS
B3f – Controlling plant growth
Plant hormones (also known as PLANT
GROWTH REGULATORS or AUXINS) are
chemicals that control
growth of ROOTS and SHOOTS
Leaves are positively phototropic,
towards light
Leaves are negatively geotrophic, away
from gravity
AUXINS are
hormones
which collect
on the dark
side of a
shoot
causing the
cells to
lengthen
Roots are negatively phototropic, away
from light
Roots are positively geototropic,
towards gravity
B3g – New genes for old
1 – select the characteristic you want to
improve – larger eggs
2 – cross breed the best hen with the best
cockerel
3 –select the offspring which produce the
largest eggs and mate that with your best
cockerel
4. and repeat this over several generations
The order of
triplets in a gene
determines the
sequence
of amino acids.
GENETIC ENGINEERING
Is when scientists transfer one gene from
one living organism to another.
The
amino
acids join
together
to form a
protein
molecule
.
If genes produce incorrect proteins, cells may not function
properly. This is the cause of many inherited diseases.
B3h – More of the same
ADVANTAGES OF CLONING DISADVANTAGES OF
Why clone animals?
CLONING
Animals or plants with special qualities
could be mass produced to help in the
manufacture of important drugs.
•About 98% of cloning efforts fail.
•Usually a cloned embryo dies before birth
but sometimes afterwards too.
Stem cells have the
ability to differentiate
into different sorts of
cells – muscle, liver,
bone, etc
Cells lose this
ability as the
human gets older