as biology unit 2 notes

Topics: DNA, Protein, Gene Pages: 13 (2249 words) Published: October 10, 2013
Unit 2 Bullet Point Handouts
Tests for closely-related species
(Compare) DNA;
Sequence of bases/nucleotides;
DNA hybridisation;
Separate DNA strands / break hydrogen bonds;
Mix DNA/strands (of different species);
Temperature/heat required to separate (hybrid) strands indicates relationship; Compare same/named protein;
Sequence of amino acids /primary structure;
Immunological evidence – not a mark
Inject (seahorse) protein/serum into animal;
(Obtain) antibodies/serum;
Add protein/serum/plasma from other (seahorse) species;
Amount of precipitate indicates relationship;
Treatment of Control group
Given the placebo/dummy drug; (in context)
Otherwise treated the (exact) same
Usage of logarithmic scale
Large range of results so logarithmic scale needed to plot them. Cellulose structure: function relationship
Long straight chains of glucose molecules (with a 1-4 linkage) Held together by hydrogen bonds
Can form microfibrils
Importance of courtship behaviour
Recognition of same species;
Stimulates release of gametes;
Recognition of mate/opposite gender;
Indication of sexual maturity/fertility;

Prediction of something using a graph
Use line of best bit
Extrapolate line and read off

Groups within (larger) groups;
with no overlap
Smaller taxa are grouped into one larger taxon
where there’s no overlap between taxa

Classification rankings

Comparison of species
Fossil records
Homologous features
Evolutionary history
DNA Base sequence
Ecological Niches

Oxygen dissociation curve of haemoglobin with increase of respiration

Increase in/more carbon dioxide;
Curve moves to the right/depressed;

Reduction of genetic diversity
Reduced variety/number of different alleles/DNA / reduced gene pool (in new population); Founder effect;
A few individuals from a population become isolated/form colonies (Genetic) bottlenecks;
(Significant) fall in size of population
Selective breeding / artificial selection;
Using organisms with particular alleles/traits/phenotypes/characteristics;

Pathways by which water moves in plants

Symplastic pathway — water moves through the membrane and cytoplasm of cells Apoplastic pathway — water moves only through cell walls and intercellular spaces

Features of gas exchange system
Plant leaf
Respiratory Medium

Exchange Surface

Plasma Membrane
Gill lamellae
Plasma membranes of spongy mesophyll cells

Movements of mouth and gill create one-way flow
Abdomen dilates/contracts, pressure decreases/
Large surface area to volume ratio due to:

Small volume of cells
Large area of lamellae
Large area of tracheoles
Large surface area of cell surfaces and loose packing of cells

Oxygen concentration maintained by:

Use of oxygen in cell
Ventilation/counter-current system in lamellae
Ventilation/use of oxygen in body cells
Use of oxygen by mesophyll cells
Exchange surface thin due to:

Thin plasma membrane
Thin layer of cells in walls of lamellae
Thin walls of tracheoles
Only cell wall and plasma membrane at exchange surface

Roles of three main types of blood vessel
Arteries — carry blood under high pressure away from heart to the organs – where they branch into the arterioles Veins — carry blood under low pressure away from the organs towards the heart Capillaries — carry blood close to every cell within an organ.

Formation of tissue fluid
At (arteriole) end of capillary;
Hydrostatic / blood pressure;
Forces out soluble / small molecules;
And water;
Protein remains in blood / plasma;
Molecules too large;
More negative / lower water potential at (venule) end;
Water drawn in by osmosis / diffuses in;
Some fluid returned (to blood) by lymphatic system;

Difference between viral DNA and other organisms...
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