SB2 Flashcards
Cells and control
How do animals grow
- Cell division (the cell cycle)
- Cell differentiation
What is the cell cycle
- Interphase
- Mitosis
- Cytokinesis
What happens during interphase
- Cell grows in size
- DNA duplicates
- More organelles are made
- Increase in mitochondria and ribosomes
What are the stages of mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
What happens during prophase
- Spindle fibres form
- DNA condenses into chromosomes
- Nuclear membrane disappears
What happens during metaphase
- Chromosomes and chromosome copies line up in the middle of the cell
What happens during anaphase
- Spindle fibres pull away chromosomes and chromosome copies to opposite ends of the cell
What happens during telophase
- New nuclear membrane forms around the chromosomes on opposite ends
What happens during cytokinesis
- Cell membrane pinches, cells divide
- New cytoplasm forms within the two cells
Describe the importance of mitosis in growth, repair and asexual reproduction
- Growth - produces new cells
- Repair - replaces dead or damaged cells
- Asexual reproduction - produces offspring that are genetically identical to the parent
Describe the features of daughter cells produced by mitosis
- Genetically identical
- Diploid
- Identical sets of chromosomes from single parent cell
How do plants grow
- Cell division
- Elongation
- Cell differentiation
Where does elongation occur in plants
- Occurs throughout the plant
Describe what meristems are
- Regions in a plant where mitosis occurs
- Found in tips of shoots and roots
How does cancer occur
- Change occurs in the cell
- Uncontrollable and rapid cell division
Why is cell differentiation important
It allows cells to specialise and be dedicated to a specificfunction
How do percentile charts help determine growth
- Where an organism lies on it shows its growth in comparison to other organisms
- If a bay is on the 50th percentile for weight, its is heavier than 50% and lighter than 50%
What is the difference between embryonic and adult stem cells
- Embryonic stem cells can differentiate into any type of cell, but are only available at the embryonic stage
- Adult stem cells can differentiate into only blood, skin and bone cells, but are available at all times
Benefits of stem cells in medicine
+ Create new tissues/organs
+ Less likely to be rejected (if they are directly from patient)
+ Replace damaged cells
Risks of stem cells in medicine
- Can be rejected
- Can pass on disease
- Viruses can be passed on
- Can start rapidly and uncontrollably dividing
Location and function of the cerebrum
- Two cerebral hemispheres at the top of the brain
- Speech, vision, memory, movement
Location and function of the cerebellum
- Back of the brain
- Muscle coordination and balance
Location and function of the medulla oblongata
- At the bottom of the brain
- Unconscious activities e.g. breathing, heart rate
Limitations when treating diseases in the CNS
- Blood brain barrier does not allow drugs to reach brain
- Tumour could be buried deep inside
- Not enough understanding of the brain
- Surgery could risk permanent damage
Function and features of a sensory neurone
- Connected to a receptor
- Dendrites, Dendrons, Cell body, Axon w/ myelin sheath, Axon terminal
- To pass on information obtained from receptor cells
Function and features of a relay neurone
- Rapidly passes impulse from a sensory neurone to a motor neurone
- Dendrites, Cell body, Short axon w/ myelin sheath, Axon terminal
Function and features of a motor neurone
- Send electrical impulse to effectors
- Dendrites, Cell body, Axon w/ myelin sheath, Axon terminal
What are effectors
- Muscles
- Glands
What is the purpose of the myelin sheath
- Prevents electrical impulse from escaping
- Insulates and speeds up neurotransmission
How are electrical impulses passed on
- Reaches the end of neurone - synapse
- Stimulates axon terminal to release chemical substances called neurotransmitters
- This is diffused across the synapse
- They bind to receptors on dendrites, stimulating a new electrical impulse
Name the parts of eye
- Cornea
- Iris
- Pupil
- Lens
- Ciliary muscles
- Suspensory ligaments
- Retina
- Optic nerve
(Can I please look closely so (I can) read optically)
What is the function of the cornea
- Helps focus light
- Refracts light
What is the function of the iris
- Coloured part of eye
- Controls how much light enters the pupil
What is the function of the pupil
- Hole in the eye that allows light to pass through it
What is the function of the lens
-Lets light enter the eye
- Focuses light onto the retina
What is the function of the ciliary muscles
- Contract/ relax to change the shape of the lens
What is the function of the suspensory ligaments
- Tighten/ slacken to change the the shape of the lens
What is the function of the retina
- Contains the receptor cells of the eye
What is the function of the optic nerve
- Sends information from the eye to the brain
What are rod cells
- Receptor cells in the eye
- Detect light intensity
- Work best in dim light
What are cone cells
- Receptor cells in the eye
- Detect colour
- Work best in bright light
What changes occur so the eye can see distant objects
- Ciliary muscles relax
- Suspensory ligaments tighten
- Lens becomes less round
What changes occur so the eye can see closer objects
- Ciliary muscles contract
- Suspensory ligaments slacken
- Lens becomes more round
What causes cataracts, what are the effects and how is is it treated
- Protein build up in lens
- Vision is cloudy and obscured
- Artificial lens
What causes colour blindness, what are the effects and how is is it treated
- Faulty (red or green) cone cells
- Colours appear differently/ inability to see certain colours
- Untreatable
What causes short sightedness, what are the effects and how is is it treated
- Eyeball is too long or cornea is too round
- Light is focused before the retina
- Distant objects are blurry
- Diverging/ Concave lens
What causes long sightedness, what are the effects and how is is it treated
- Eyeball is too short or cornea is not round enough
- Light is focused after the retina
- Close objects are blurry
- Converging/ Convex lens
