cells and control Flashcards
What are cells which possess both pairs of chromosomes called
Diploid
What are cells that only contain one pair of chromosomes called?
Haploid cells (eg. sex cells, gametes)
How do chromosomes divide?
-start as a parent chromosome
-split into 2 identical copies (sister chromatoids) but are still attached together at the centre
-sister chromatoids spilt apart and are now called daughter chromosomes
how is cancer caused
some cells lose control of their cell cycle and keep rapidly dividing, producing masses of undifferentiated cells (tumours).
Tumours may spread and destroy organs
how to treat cancer
-cut out the tumour if possible
-chemotherapy (take drugs which are toxic to rapidly dividing cells)
-radiotherapy
what is a zygote
fertilised egg cell
how does an egg develop into an adult
-egg cell is fertilised
-egg cell goes through mitosis, producing undifferentiated cells (embryo)
-cells in embryo switch in genes to differentiate into specialised cells
what is a plant meristem
-groups of undifferentiated cells at the tips of roots/shoots
-allow the plant to grow until death
where are the xylem and phloem in
vascular bundle (shoot)
what does xylem do
carry water from roots to stem and leaves.
comprised of dead cells
what does phloem do
transport dissolved sugars from leaves to where the plant needs it for growth or other processes
what is a stem cell
an unspecialised cell that produces a different type of specialised cell
What is the CNS
-brain and spinal chord
-allows us to respond to stimuli and to move
What is the PNS
peripheral nervous system
-contains sensory and motor neurones
what are synapses
junctions where neurones communicate with eachother
