Cells and control

• Adult stem cells can be differentiated into a limited range of cells, for example bone marrow stem cells
• Asexual reproduction includes a single parent that creates genetically identical offspring
• Axons are long fibres that conduct nerve impulses away from the body
• Cancer is a non-communicable disease caused by changes in the cell that lead to uncontrollable cell division
• Cell differentiation is when an undifferentiated cell becomes specialised for its function
• Cell elongation is when cells expand, enabling growth in the plant
• The central nervous system includes the brain and spinal cord
• Cerebellum is a part of the brain that controls muscle coordination and non-voluntary movements
• Cerebral hemisphere is one half of the cerebrum, the left hemisphere controls muscles on the right, vice versa
• Cerebrum is the largest region of brain consisting of 2 hemispheres, it controls movement, memory, intelligence, language and vision
• chromatids are one section of a replicated chromosome
• Chromosomes are long coiled molecules of DNA that carry genetic information in the form of genes
• cone cells found in the retina are sensitive to light intensity which helps detect different colours of light
• Corneas are the transparent outers coverings that reflect light entering the eye
• CT scans are medical imaging techniques used to create detailed images of internal organs
• dendrites are short branched extensions of dendrons that provide a large surface area to receive nerve impulses from other neurons
• An effector is an organ, tissue or cell that produce a response to stimuli
• Embryonic stem cells are found in very early embryos that are unspecialised and capable of differentiating into any type of cell
• The iris is a pigmented ring of muscle that controls the size of the pupil to alter how much light enters the eye
• The lens is a transparent structure that refracts light to focus it on the retina
• Long-sightedness-

  Near by objects appear unclear due to the convergence of light rays focusing behind the retina

  It is corrected using a convex lens
• Short-sightedness-

  Far away objects appear unclear due to the convergence of light rays focusing in front of the retina

  It is corrected using a diverging lens
• The Medulla oblongata is a region of the brain that regulates unconscious activities such as breathing or heart rate
• Meristem tissue is plant tissue containing undifferentiated stem cells
• Metaphase is the second stage of mitosis in which the chromosomes align at the centre of the cell
• Mitosis is a type of cell division that produces two genetically identical diploid daughter cells from one parent cell
• Motor neurones carry nerve impulses from the central nervous system to the effectors
• Mylin sheath is an electrically insulating layer that surrounds the axon and increases the speed of nerve impulses
• Neuron’s are nerve cells adapted to quickly transmit nerve impulses
• Neurotransmitters are chemicals used for communication between neuron's and their target cell
• Pupils are holes in the centre of the iris that allows light rays to enter the eye
• Reflexes are automatic responses to stimuli
• The reflex arc-

  Stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector, response
• Relay neurones carry nerve impulses from sensory neurons to motor neurons
• A retina is a light sensitive layer at the back of the eye composed at rod and cone cells, it converts light energy into neural signals which are sent to the brain
• Rod cells found in the retina and are sensitive to low light intensity
• Sensory neurones carry nerve impulses from the receptor to the central nervous system
• sensory receptors detect stimuli
• Synapses are small gaps between neurones where nerve impulses are transmitted via neurotransmitters
• Mitosis-

  prophase, metaphase, anaphase, telophase