Cells and Control Flashcards
What are the ways of measuring growth?
- Size ( height, length, circumference)
- West mass = includes all the mass in an organism, including water and fluid in the body ( highly variable )
- Dry mass = mass of an organism which has no water present ( scientifically accurate but is a destructive method )
What things happen for growth in plants and animals ?
Plants :
- cell division- the cell divides
- cell elongation-cells fill up with water in the elongation zone and stretch and grow in size
- cell differentiation- when a cell becomes specialised to a certain role, it means multicellular organisms work more efficiently.
What is a stem cell?
Stem cells are cells that can differentiate into nearly any type of cell (They are undifferentiated)
What is an embryonic stem cell?
Embryonic stem cells are found in early human embryos. Embryonic cells are pluripotent and can become almost any cell in the body.
What are adult stem cells?
Adult stem cells are multi potent. This means they can become a limited amount of cells. They are found within certain differentiated tissues such as bone marrow. They are used to grow of replace damaged tissue.
What are the benefits, drawbacks and risk of embryonic stem cells?
Benefits :
-They are pluripotent, so can become a wide range of cells
-Due to techniques such as IVF, it is easy to get them.
-Can be cloned from patient’s own cells to avoid rejection.
Drawbacks :
-ethnical issues ( such as catholic contraception beliefs and murder)
-ethnical concerns ( it is illegal in some countries or restricted by law )
-seen as illegal cloning of humans
Risks :
- Differentiated cells may be rejected in treatment as come from another patient
- cancer and uncontrolled growth
What are the benefits, drawbacks and risks of adult stem cells?
Benefits :
-no ethnical issues
-carry lower rejection rates
Drawbacks :
-difficult to identify and remove from the body ( mixed with differentiated cells)
- less useful as they are multi potent so can only become a limited amount of cells so can only cure a limited amount of diseases.
Risks :
-Risk of rejection if not from patient
- cancer and uncontrolled growth
-disease transmission as the donor may pass on a virus/ get infected.
What is the nervous system made up of ?
CNS ( central nervous system) made up of the brain and spinal cord.
PNS ( peripheral nervous system) made of every nerve in your body other than the brain and spinal cord.
What are the stages of the reflex arc?
SRSSRSMER Stimulus Receptor Sensory neurone Synapse Relay neurone Synapse Motor neurone Effector Receptor
What is meristem?
- Meristem is where cell growth and mitosis occurs in plants.
- Meristem is found in the areas of a plant that are growing ( the tips of roots and shoots)
- Meristem produces unspecialised cells that can divide and form into any cell in the plant (similarly to embryonic stem cells)but they can do this throughout the plants life.
- unspecialised cells go on to form specialised tissues like xylem and phloem.
What structure and function to sensory neurones have?
- One long dendron that carries nerve impulses from receptor cells to the cell body ( located in the middle of the neurone )
- One short axon carries nerve impulses from the cell body to the CNS.
- what impulses are sent along to reach the CNS
What is the structure and function of a motor neurone?
- Many short dendrites carry nerve impulses to the cell body
- One long axon carries nerve impulses from the cell body to the effector cells
( you can get myelinated motor neurones which have a myelin sheath of unmyelinated ones.)
-sends information from the CNS to the effector cells
What is the structure and function of a relay neurone ?
- many short dendrites carry nerve impulses from the sensory neurone to the cell body
- an axon carries nerve impulses from the cell body to motor neurones.
- impulses travel through the CNS along relay neurones
What is a synapse?
A synapse is the gap / connection between two neurones.
What happens at a synapse ?
- At a synapse the nerve signal is transferred by chemicals called neurotransmitters, which diffuse ( move ) across the gap.
- Synapses are there to help filter information. It also ensures that the impulses only travel in one direction.
- electrical impulses travel along a neurone, at a synapse it is transferred to chemical energy and then when transferred into the next neurone it is transferred to electrical energy again.
What is a reflex ?
Reflexes are automatic, rapid responses to stimuli that can reduce chances of being injured. The impulses pass through either the spinal cord or an unconscious part of the brain to create a quicker response. They also travel in the pattern of the reflex arc ( SRSSRSMER)
How does the eye focus on near and distant objects ?
To looks at a distant object the ciliary muscles relaxes which allows the suspensory ligaments to pull tight. This then pulls the lens into a less rounded shape so light is refracted less.
To look at a near object the ciliary muscle contracts which slackens the suspensory ligaments. The lens then becomes a more rounded shape and more light is refracted.
What happens to long sighted people?
Long sighted people are unable to focus on near objects.
- this occurs when the lens is the wrong shape and doesn’t bend the light enough or the eyeball is too short.
- light from near objects is bought into focus behind the retina
- you can use glasses on contact lenses with a convex lenses to correct it.
What happens to short sighted people?
Short sighted people are unable to focus on distant objects
- This occurs when the lens is the wrong shape so bends the light too much or the eyeball is too long
- Light from distant objects is bought into focus in front of the retina
- use a lens with a concave lens to correct it.
What is colour blindness and can it be treated ?
Colour blindness is when cones on the retina aren’t working causing certain colours to not be seen ( most commonly red-green)
There is no cure for colourblindness as at the moment cones cannot be replaced.
