Part 6 - Responses To Stimuli Flashcards
What is stimuli?
Something that elicits a response
Something that produces a reaction in a living organism
Something that a living organism reacts to
Can you distinguish between a heterotroph and an autotroph?
A heterotroph gets its food from other organic sources whereas an autotroph makes its own food
Define the term chemotaxis?
Chemo - chemical
Taxis- movement
Movement of organisms due to chemical stimulation
What are chemoattractants?
They result in an organism moving towards the chemical
What are chemorepellents ?
They result in the organism moving away
What is flagella (flagellum) and what is its role?
It is a whip like structure that protrudes from the membrane of bacteria
It’s primary role is to help the bacteria move but they can also function as sensory organelles being sensible to chemicals and temperatures outside of the cell
How do amoebae and bacterial know to move towards a chemoattractant?
They must first
Recognise it
Then respond to the stimuli
Where does recognition from a single celled organism of a chemical occur?
On the outside of the cell membrane and cell surface receptors
What are cell surface receptors?
They are biological complexes found in the cell membrane that allow recognition of a specific extracellular chemicals
What is the transference of the message from outside of a cell to the inside known as?
Signal transduction
What is a ligand?
It is a small compound that attaches to one type of cell surface receptor and induces a change in the shape of the receptor
This results in the message being transferred into the cell
What is tropism?
It is a plants response to stimuli
What external stimuli will green plants need to grow towards and why?
Plants will need to grow towards the sun to allow photosynthesis to occur. Plants may also grow towards water
What is the term given for when plants grow towards light?
Phototropism
What is gravity?
The force that attracts the body to the Earth
What is gravitropism?
It is a phenomenon where plants grow up and defy gravity
Are plants stems
Positively phototropic or negatively phototropic?
Positively phototropic
Are plant roots
Positively phototropic or negatively phototropic?
Negatively phototropic
Are any stems
Negatively gravitropic
Or positively gravitropic
Negatively gravitropic
Are plant roots
Negatively gravitropic
Positively gravitropic
Positively gravitropic
Why do you think it is that roots are gravitropic?
Roots growing down and away from light are more likely to find soil, water and minerals they need
Why do you think plant stems are phototropic?
They need to grow towards the light to be able to expose their leaves so that photosynthesis can occur
What are the hormone/chemical messengers in plants called?
Auxins (meaning to grow)
What observations can you make when seedlings grow?
They grow towards the light source (positive phototropism)
The seedlings change their direction of growth towards the light source
They do not grow at the same rate
What 5 senses do animals have?
5 Touch Taste Smell Sight Hearing
What do senses allow animals to receive?
Information about their external surroundings
What external change can be detected by animals ?
Animals can detect visual and audible stimuli, as well as temperature, day length, gravity and the earths magnetic field. They can also detect chemical changes.
How does an adder sense without the ability to hear?
The adder senses vibrations in the ground and uses its forked tongue to detect chemical change in the air
What is a nervous system?
It is the sensory and control apparatus of the body
It responds to external stimuli
What is the job of the nervous system?
To take information from the external environment
Compute the information
And respond appropriately
What is the a nerve cell called?
Neuron
What method of transmission does the nervous system use to transmit messages ?
Electrical and chemical
What is the gap between each neuron called where electrical impulses jump from one cell to another?
Synapses
What method of transmission does a synapses use in a nerve pathway?
A chemical transportation of the message
What method of signal transmission is used within the neuron and what system is used to transmit messages between neurons?
Impulses are transmitted as electrical messages within a neuron and as chemical messages between neurons
