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B1 Topic 1: Classification, Variation and
Inheritance
Classification
Binomial naming system e
...
homo sapiens, homo is the genus and sapiens is the
species
...

KING PRAWN CURRY OR FAT GREASY SAUSAGES
Kingdom, phylum, class, order, family, genus, species
Kingdoms:






Animalia: multicellular, no cell wall or chlorophyll, heterotrophic
Plantae: multicellular, cellulose cell wall, chlorophyll, autotrophic
Fungi: multicellular, chitin cell wall, no chlorophyll, saprophytic
Protoctista: unicellular with nucleus
Prokaryotes: unicellular no nucleus

Animalia is divided into vertebrates and invertebrates
...

Speciation is where new species get made
...
A species is
‘split’ by, for example, a river
...
This
provides evidence of natural selection
...
Categorising things into
species can often cause problems:


Some hybrids are fertile
...

There can be significant variation within species (an example of this is a ring
species: in the diagram, 1 could interbreed with 2 could interbreed with 3 and
so on, but 1 could not interbreed with 7)
...


Variation
Variation can be continuous or discrete and environmental or genetic
...
Environmental variation is acquired variation, whereas genetic variation is
caused by reproduction (the genes you inherit from your parents) or mutation
(genetic mutation or ‘crossing over’, which is the exchange of bits of chromosomes
to the wrong pair)
...
This is the
process:
1
...

2
...

3
...

4
...

5
...

When you come up with theories the scientific community has to validate the
evidence:




Conferences
Peer review
Scientific journals

Adaptations
Adaptations are traits an animal has that enable it to survive in its environment
...
They’ve got thick, white fur and they’re also massive so they
proportionally speaking lose less heat
...
They’ve got light fur and big ears to lose heat through
...


Monohybrid Inheritance
Tl;dr: Gregor Mendel cross-bred pure-breeding short
plants with pure-breeding tall plants
...

He discovered their offspring were always tall, hence
dominant and recessive characteristics
...
You can use
them to work out probabilities
...

This can cause infertility (because it blocks ducts), malnutrition, breathing issues etc
...
It can cause fatigue, shortness of breath and ‘sickle cell crisis’
...

Hairs lie flat
...
This means more heat from blood is lost
through the skin)
...

Hairs go erect (they trap a layer of warm air next to your skin)
...
This means less heat from the blood is
lost through the skin and also keeps warm blood near organs)
...
Hypothalamus detects excessive water in blood
...
Pituitary gland releases less ADH
...
Kidneys reabsorb less water
...
Urine becomes more diluted and more water is removed
...
Everything’s swell
...
Hypothalamus detects lack of water in blood
...
Pituitary gland releases more ADH
...
Kidneys reabsorb much water
...
Urine becomes more concentrated and less water is removed
...
Everything’s swell once more
...

2
...

4
...

6
...


Too much blood sugar detected
...

Insulin converts glucose into glycogen
...

Too little blood sugar detected
...

Glucagon converts glycogen to
glucose
...
Yep
...
There are two types of
diabetes:
Type 1 Diabetes
...

Common in young people
...
Controlled by shots of insulin into the subcutaneous fat
...
Strong correlation with obesity
...
Controlled by diet and
exercise
...
Bundles of neurones form
nerves and these form the nervous system: the brain and spinal cord are the CNS,
and peripheral nerves connect to the sense organs
...
There are different types of receptor; photo, thermo etc
...
If someone can feel both pins, that’s a sensitive area
...

Dendrons (or dendrites, they
are the same thing) carry
electrical impulses to the cell
body
...
Motor
neurons have long axons
whereas sensory neurons have short ones
...

Stimuli and response pathway
SOME REALLY SILLY CHINESE MEN EAT RICE
SRSCMER
Stimulus-receptor-sensory neuron-CNS-motor neuron-effector-response
Stimulus: a change in the surroundings e
...
temperature
Receptor: the cell that picks up on this change e
...
thermoreceptor, photoreceptor
etc
...

CNS: brain or spinal cord
...

Motor neuron: carries the impulse from the CNS
...
g
...

Response: the action taken
...
When the impulse reaches the end of one
neuron (the axon terminal) it triggers the release of a
chemical called a neurotransmitter
...

Reflex arc
Basically, it bypasses your brain and goes straight to your spinal cord
...


Plant hormones
Auxins are made in the tips of the shoots and roots of plants, and they control
growth; they SPEED UP growth in shoots and SLOW DOWN growth in roots
...

Positive phototropism = growth towards light
...

Positive gravitropism = growth towards
gravity
...

Auxins collect in the shady side of a shoot
...

In roots, auxins collect in the underside
...

There are also other uses of plant hormones:





Rooting powder
...

Selective weedkiller
...
It effects weeds
more than other plants because they’ve broader leaves and absorb more
...
This makes seeds germinate at any time of year
...
This ensures fruit doesn’t ripen in transport and
does ripen in shops
...


B1 Topic 3: Problems of, and solutions to, a
changing environment
Drugs
Drug: a substance from outside the body that affects the CNS and brings about
changes in the body that can lead to addiction
...
g
...
These block the release of neurotransmitters so the
impulse can’t travel and you don’t feel pain
...
g
...
These make you sense things that aren’t real
...
g
...
Decrease reaction time
...
g
...
Increase reaction time
...
Increases chances of lung and mouth cancer
...
Narrows arteries
...

Carbon monoxide: binds to red blood cells and reduces their oxygen-carrying
capacities
...


Ethics of transplants
Some issues:





Transplants from animals
...

Rejection of organs
...
Should an alcoholic

get a liver? Should an obese person get a heart? How do we decide who
deserves the organs?

Diseases
A pathogen is an organism that causes
infectious diseases
...

Food, like salmonella
...

Bodily fluids, like HIV
...

Animals:
Houseflies spread dysentery pathogens to food with their feet
...
They feed on someone, suck up the protozoan
for malaria, and then bite someone else and pass it on
...
However, we mustn’t misuse
or overuse them, as it can cause them to be resistant
...

Antifungals: unsurprisingly, kill fungi
Antibacterials: anything that interferes with the growth of bacteria, but most
commonly refers to cleaners
...
Used to swab wounds, clean skin, clean
surfaces etc
...

Bodily defences: physical




Skin is one, obviously
...
Some of them we can use also, like tea
tree, garlic and lemon balm
...
Each level is smaller because energy is wasted on respiration,
reproduction etc
...
Examples:




Oxpeckers and large mammals
...

Nitrogen-fixing bacteria and plants
...
Examples:





Mammals and tapeworms
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Humans and headlice
...


Pollution
Eutrophication is the pollution of water through the use of nitrate and phosphate
fertilisers:
1
...

3
...

5
...


Fertilisers are washed into rivers/lakes
They cause an ‘algal bloom’
Algae blocks light from plants on the bed of the lake; can’t photosynthesize
Plants die
Decomposers increase in number, use up oxygen
Animals die

Indicator Species
The presence of an indicator species demonstrates the level of pollution of an
environment

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