B3 Revision Posters

B3a – Molecules of LifeControls 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 MovingPlasma – yellow-ish fluid, carries glucose and CO2

Red Blood Cells – carry the oxygen

White Blood Cells – fight off infection

Platelets – clot the blood

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 cellsFor 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

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

A gestation period is the time spend developing in the womb in most animals.

B3f – Controlling plant growthPlant hormones (also known as PLANT GROWTH REGULATORS or AUXINS) are chemicals that control

growth of ROOTS and SHOOTS

Roots are negatively phototropic, away from light

Roots are positively geototropic, towards gravity

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

B3g – New genes for old

The order of triplets in a gene determines the sequence of amino acids.

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.

1 – select the characteristic you want to improve – larger eggs2 – cross breed the best hen with the best cockerel3 –select the offspring which produce the largest eggs and mate that with your best cockerel 4. and repeat this over several generations

Is when scientists transfer one gene from one living organism to another.

GENETIC ENGINEERING

B3h – More of the sameADVANTAGES OF CLONINGWhy clone animals? Animals or plants with special qualities could be mass produced to help in the manufacture of important drugs.

DISADVANTAGES OF CLONING• 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