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Biology revision - see Year 10 term 2 doc - Coggle Diagram
Biology revision - see Year 10 term 2 doc
Excretion
In plants
Plants release waste products of respiration + photosynthesis through excretion
Aerobic respiration
Waste product - carbon dioxide
Photosynthesis
Waste product - oxygen
All excretion in plants takes place in the
stomata
, as there are no specialised organs for excretion.
Stomata have guard cells which control the opening and closing of them, depending on if the guard cells are turgid (full of water) or flaccid (empty of water)
In humans
Have specialised organs for excretion
Lungs
Excrete carbon dioxide
When the body exhales, carbon dioxide is excreted as a waste product of aerobic respiration.
Kidneys
Excretes excess water, salts and urea
Excrete the above substances by filtering the blood and producing urine.
Skin
Excretes water, salts and urea
Excretes water and salts through sweat glands.
Water is not actually excreted as it is produced in excess to lower body temperature.
The removal of the waste substances of metabolic reactions, toxic materials and substances in excess of requirements
Responses to environment
organisms respond to internal and external changes in their environment (stimuli) to ensure survival
chemical response
navigated via the endocrine system
coordinated by glands
nervous response
navigated via the nervous system
coordinated by the brain and/or the spinal cord
Plant growth responses
Known as tropisms
Geotropism
Grows away from the centre of gravity (negative)
Grows towards the centre of gravity (positive)
Phototropism
Grows towards the direction of light (positive)
Grows away from the direction of light (negative)
occurs as a result of auxin being produced in the tip of the plant shoot
auxin diffuses onto the shaded side pf the plant, elongating the cells in order for the plant to grow towards the direction of light
Central nervous system
The CNS
The brain and spinal cord
The peripheral nervous system
Everything in the nervous system that isn’t the brain or the spinal cord
sensory neuron
navigates electrical signals inside the CNS itself
motor neuron
sends electrical messages to effectors to bring about a response
relay neuron
the neuron which sends impulses from the CNS to motor neurons located near effectors
effector
muscls or glands that can bring about a response to the stimulus
receptor
cells which detect stimuli
response
the action which responds to the stimulus
stimulus
a change in the environment which affects homeostasis
Structure of neurones
Motor neuron
Sensory neuron
Relay neuron
Connect the sensory and motor neuron together in the CNS
Are very small to reduce the amount of time it takes for the impulse to travel
Synapses
The gap between two neurones
The space in which neurotransmitters are diffused.
Neurotransmitters
Diffuses across the synapse
Is a chemical which causes an impulse tio begin again at the next axon terminal of the nearest neuron.
Reflex arc
is an unconscious response
does not involve the conscious part of the brain
is extremely quick
reflexes are hard wired into the human body
they are extremely quick as to ensure our survival or less chance of injury
refers to the route the automatic electrical impulse takes
Structure of the eye
How to focus
The eye adjusting itself to be able to view an object more clearly is called
accommodation
The lens is elastic, and changes shape when the suspensory ligaments are pulled tight or become loose.
This change is brought about by the contract or relaxation of the ciliary muscles.
Sclera
tough, white outer layer of the eye which protects it from damage
Fovea
Area of retina that provides the clearest vision
Iris
Regulates the amount of light entering the pupil
Pupil
hole that allows light to enter the eye
Ciliary muscles
relax and contract to change the shape of the lens
Retina
contains the highest concentration of light receptors - 'rods'(which detect the
intensity
of light)and 'cones' (which detect coloured light)
Cornea
refracts light which enters the eye
Optic nerve
sensory neuron
which sends signals to the brain
Lens
focuses light rays onto the retina
Suspensory ligament
connect the
lens
to the Ciliary muscles
viewing an item far away
ciliary muscles relax
suspensory ligaments tighten
lens shape becomes thinner
less light is refracted
viewing an item close by
suspensory ligaments become loose
ciliary muscles contract
lens shape becomes wider
more light is refracted
labelled diagram
Temperature regulation
When body gets too hot
When body gets too cold
Sensory neurones in the
Hypothalamus
respond to temperature changes in the body
Endocrine system
Releases hormones
Hormones travel through the bloodstream
Does not target a specific area of the body, but releases hormones everywhere and target organs detect and respond to them.
Target organs - organs which have receptors on their surfaces to detect specific hormones.
Blood glucose levels
blood glucose levels increase
this is detected by the pancreas which then releases the hormone insulin
insulin allows glucose to be absorbed into body cells
blood glucose levels decrease
blood glucose levels decrease
This is detected by the pancreas
Pancreas releases glucagon
Pancreas stops releasing insulin
Blood glucose levels increase by breaking down glucagon
