Topic 2- Cells and control Flashcards
What do chromosomes contain ?
genetic material
Explain the process of mitosis:
Card 15
What is cell differentiation?
Is when a cell changes to become specialised for its function and allows multicellular organisms to work more efficiently .
What is cell elongation?
Is where the cells of the plant expand making it grow.
What is mutation?
A random change in a gene
Explain how cancer is formed through cell division\\
If there is a change in a gene that controls cell division then the cell may start dividing uncontrollably which may lead to tumour and lead to cancer.
What cell can differentiate into any other type of cell?
Stem cells
Where does cell division happen?
In meristems - tips of the root and top of the shoots
What are undifferentiated cells called?
stem cells
Where are stem cells found?
In early human embryo , adults also have them and they are found in bone marrow.
What do meristems produce?
Unspecialised cells
What do unspecialised cells turn into ?
Xylem and phloem
Explain the risks of stem cells in medicine:
1, Tumour development - they divide quickly and scientists may not be able to control them
2, Disease transition
3, Rejection - your body may identify them as foreign and have an immune response
What does the cerebellum in the brain control?
Muscle coordination and balance
What does medulla oblongata contol?
unconscious activities such as heart rate and breathing
Which scanners can be used to investigate brain function?
CT scanning-uses x-rays , shows main structure of the brain but does not show its main functions
PET scanners- very details uses radioactive chemicals can can show both structures and functions
Name in order the central nervous system responses:
Stimulus Receptor Sensory neuron Relay neuron Motor neuron Effector Response
Explain what a myelin sheeth used for
it acts as an electrical insulator speeding up the electrical impulse
Sensory neuron contains…
Long dendrites and short axons
Motor neuron contains…
Many short dendrites
One long axon
Relay neuron contains…
Many short dendrites
An axon
What is the connection between two neurons called?
synapse
What chemical transfers the nerve signal?
neurotransmitters
What slows down the impulse ?
the synapse , causes a gap and diffusion takes time
What slows down the impulse ?
the synapse , causes a gap and diffusion takes time
Explain how reflex helps to protect your eye?
Light receptors in the eye help detect bright light and send the message to the brain along the sensory neuron.
Explain how a structural problem with the eye may cause a person to be long-sighted?
The lens may be the wrong shape or the eyeball might be too short , meaning light from near objects is brought into focus behind the retina.
Explain why short-sighted people can’t see far
Because the lens is the wrong shape and bends light too much or the eyeball is too long. So light is bought in front of the retina
Function of cornea
refracts (bends) light into they eye
Function of an iris
Controls how much light enters the pupil
Function of an lens
Also refracts light focusing it onto retina
