Edexcel Biology paper 1 notes
- Created by: Kasia.kuczaj
- Created on: 29-11-19 20:54
Plant cell
- Cell membrane - what enters/leaves cell
- vacuole - keeps plant cell upright
- cell wall - strengthens cell
- mitochondria - energy
- ribosomes protein synthesis
- Cytoplasm - jelly like substance where reactions take place
- nucleus - dna
Animal cell
- Cell membrane - what enters/leaves cell
- mitochodondiria - energy
- ribosomes - protein synthesis
- cytoplasm - reactions
- Nucleus - dna
Bacterial cell
- Cell membrane - what enters/leaves cell
- cytoplasm - reactions
- chromosome/dna - not in nucleus
- flagella - movement
- ribosomes - protein synthesis
- cell wall
Differentiation
Stem cells = unspecialised cells
uses of stem cells
- treating parkinsons - growing new brain cells
- bone and spinal injury - growing new bone cells
- organ failure - growing new organs/parts of organs
Method for making stem cells
- nuclei removed from egg cell
- nuclei from patient cell removed and inserted into empty egg
- egg starts to develop embryo
- stem cells turns into new cells
- CONTREVERSY - Human embryos will be created and destroyed
Nervous system
- Brain, spinal chord (CNS)
- neurones and nerves
REFLEX goes to the spinal chord, not brain, needs to be a quick reaction
Synapse - slow chemical signal. Neurotransmitter has to diffuse between the neurones
Microscopy
Magnification = image hieght / object hieght
- Meter (m) = 100cm
- centimetre (cm) = 1 x 10^-2 metres
- Millimetre (mm) = 1 x 10^-3 metres
- Micrometer (mu m ) = 1 x 10^-6 metres
- Nanometer (nm) = 1 x 10^-9 metres
- Picometer (pm) = 1 x 10^-12 metres
Enzymes
Enzymes are biological catalysts
Lock and key method - Substratre fits into active site of the enzyme. When the substrate is in the active site this is called the enzyme-substrate complex. The substrate is then split into it's products
- Temperature affects enzyme activity: optimum temperature = highest rate of reaction. Not a high enough temp = not enough energy. Temp too high = denatured (active site destroyed)
- pH affects enzyme activity: optimum temp depends on the enzyme, same as temp
Types of enzymes
Lipase
- Breaks down fats into fatty acids and glycerol
- made in pancreas and small intestine
- works in small intestine
Protease
- Breaks down proteins into amino acids
- made in stomach, pancreas and small intestine
- works in stomach and small intestine
Amylase
- breaks down starch into sugars
- made in the salivary gland, pancreas and small intestine
- works in mouth and small intestine
Diffusion
net movement from high to low concentration (gases or liquid)
eg in lungs (alveoli) co2 diffuses from blood into lungs to be breathed out and oxygen diffuses into blood to be obsorbed
Osmosis
specifically water molecules moving from high to low concentration through semi-permeable membrane
Eg root hair cells absorbing water
Active transport
low to high concentration through a membrane using transport proteins, requires energy
Cancer
cells divide uncontrollably, leads to tumours.
- Benign tumours - slow growing and generally harmless
- Malignant tumours - fast growing, agressive and mobile. can spread to other parts of the body
Risk factors
- Smoking - can cause lung cancer
- sun - skin cancer
- sex - cervical cancer
Sexaul…
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