AS Biology OCR Spec notes excluding biodiversity module

Hi, I made these notes tailor to the Spec, comments are appreciated :)

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  • Created on: 10-03-13 20:46
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Water is an excellent solvent
Ionic substances such as sodium chloride dissolve easily in water because the positively
and negatively charged ions are separated
Molecules like glucose and amino acids also have charged groups and therefore dissolve
Water is liquid at room temperature(good medium)
Water has low viscosity thus will flow through small capillaries
High latent heat of fusion so it takes a lot of energy to change state
High Latent heat of evaporation causing cooling as water uses energy to evaporate
Primary Structure Secondary Structure Tertiary structure Quaternary structure
Linear sequence of amino Hydrogen bonding that 3-D coiled secondary Numerous tertiary
acids in a peptide R-group repeats the primary structure e.g. globular structures e.g. enzym
determines how the structure e.g. pleated proteins, held by sulphur and haemoglobin
polypeptide is folded fibrous proteins with bridges, hydrogen and
cross-linkages ionic bonding
High specific heat capacity thus can stay at the same temp for a while in extreme
Ice floats insulating as ice less dense because molecules form crystal lattice. water (below
ice kept at higher temperature, so organisms do not freeze which allows, currents /
nutrients, to circulate solubility ions interact with, water; plants / animals, uptake nutrients
,high (specific) heat capacity;
Amino acid structure:
All amino acids have a carbon atom attached
to an amino group (-NH2) and a carboxyl
group (-COOH); R-groups are concerned with
how amino acids join into chains and depends
on whether the R-group is polar or not; but
when there is attraction a condensation
reaction occurs and a strong peptide link
bond is made, which results in a structure of
a dipeptide, then into a polypeptide, then a
protein.NH2 amine group & R group
determines the shape of the active site,
properties of proteins depend on the R group,
some are charged

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Amino acid peptide bond is between the amine and carboxyl group of each
Cofactors could be halogen ions
Synthesis and breaking of a polypeptide
Structure of haemoglobin- describe accumulatively
primary structure: chain of amino acids joined by peptide bonds.
secondary structure alpha / helix & small regions of beta pleated sheet held by hydrogen /
H, bonds then fold into tertiary structure. Further disulfide / ionic / hydrogen bonds for
quaternary structure.…read more

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And is branched, starch is stored as glucose in plants
Cellulose: made up of a long chain of glucose molecules bonded by a beta 1,4 bond. And is
unbranched, cellulose is used as the cell wall of plants
There are two forms of starch, amylose and amylopectin. Glycogen is very similar to
amylopectin except that glycogen has more extensive branching and appears as large
granules.…read more

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Beta-glucose make chains called cellulose abundant in plants, they are stronger than
Amylose as every other monomer is flipped over as shown in figure 3.
Cellulose=> Hydrogen bonding=> Microfibrils=> Hydrogen bonding=> Macrofibrils
Macrofibrils are important for Turgor Pressure and the arrangement of Microfibrils
determine how guard cells work .…read more

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If test is positive, but does not follow the colour pattern for reducing sugars.…read more

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Statins- compete with cholesterol for active site of HMG-CoA reductase, a liver enzyme
which helps make cholesterol (reversible)
Penicillin (an antibiotic) can kill or inhibit the growth of microorganisms. Penicillin is an
inhibitor of a bacterial enzyme that forms cross-links in the bacterial cell wall of some
o Penicillin is structurally similar to the polysaccharide sub-units substrates used in
wall building.…read more

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Pesticides: chemicals that kill pests, most are specialised, or may harm non-pests
Fungicide: reduces fungal growth in leaves and roots
Antibiotics: infected animals are treated when intensively farmed which may slow
growth and impair reproductions
Herbicides: kill plants by disrupting hormones, similar to pesticides
Food spoilage:
Visible growth of microorganisms on food (fungi)
Microorganisms use an external digestion process, releasing enzymes into food and
absorb nutrients released by breakdown
Produces toxins, that seriously harm
Treatment of food spoilage:
Cooking denatures enzymes killing microorganisms
Pasteurising, servere…read more

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Conditions are very specific and small changes kill microorganisms
Health: a state of mental, physical and social wellbeing, not just absence of disease
Disease: a departure from good health caused by a malfunction of the mind or body
Parasite: an organism that lives in or on a host organism that causes harm to it
Pathogen: an organism that causes disease
Immune response: the specific response to a pathogen, which involves lymphocytes and
antibody production
Antigens: molecules that stimulate an immune response
Antibodies: protein molecules that…read more

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Global distribution: widely distributed across the tropics and subtropics
More than 1 million people die of malaria each year, mostly infants in Africa
Mosquitoes are resistant to insecticides
Plasmodium is drug resistant
Acquired immune deficiency syndrome is caused by human immodeficiency virus, which
infects T-cells by:
The virus injects viral RNA reverse transcriptase into host cell
Becomes host cell DNA
HIV DNA activates Protein synthesis or mitosis
Protein enter t-cells membrane
Virus infects all cells in immune response
Higher production of WBC is triggered, and…read more

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Natural Natural immunity by infection Advantage: Immediate
Advantage: long-term immunity protection
Disadvantage: disease may be Disadvantages: short-term, no
fatal memory cells
Example: antibodies passed from
mother to child across placenta,
foetal blood or breast milk
(exposed to lots of antigen
Artificial Example: vaccination-actual antibodies and injected
antigens injected Advantages: immediate
Advantages: long-term immunity, protection, in blood stream
Memory cells Disadvantages: Short-term, no
memory cells
Primary Response- when a foreign Ag is first detected, there is antibody production, this
takes a few days before the…read more


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