topic 2 Flashcards
chromosome
a linear DNA molecule tightly coiled around proteins
outline prophase
DNA condenses, chromosomes become visible, nuclear membrane disappears
cell division in body cells
occurs in all body cells, occurs at a slower rate when older than younger bc growth stops and it’s only needed for replacement and repair
cell division in plants
only occurs in meristematic tissue, rate is constant throughout it’s life
what is the spinal cord
a long and thin structure of neurones that extends from the medulla oblongata to the spine
what is the spinal cord’s function?
it connects the peripheral nervous system to the brain
nervous system function
allows an organism to rapidly react to environmental and internal changes
neurones
nerve cells adapted to quickly transit nerve impulses, they are the functional units of the nervous system
axon function
it carries impulses away from the cell body and enables the transmission of nerve impulses over long distances
dendrites and dendron functions
carry impulses towards the cell body, dendrites provide a large surface area to receive impulses
structure and function of the cornea
transparent outer covering of the eye
refracts light entering the eye
structure and function of iris
pigmented ring of circular and radial muscles
controls pupil size and how much light enters the eye
structure and function of lens
transparent, bi-convex structure
suspensory ligaments attach the lens to a ring of ciliary muscle
refracts light, focusing it onto the retina
structure and function of the retina
light sensitive layer made of rod and cone cells
converts light energy into neural signals that are sent to the brain via the optic nerve
what are rod cells
cells in the retina that are sensitive to light intensity
