Control and Coordination

•  Which plant hormone promotes dormancy in seeds and buds?(a) Auxin(b) Gibberellin(c) Cytokinin(d) Abscisic acid

  
  

  d
•  Roots of plants are:(a) positively geotropic(b) negatively geotropic(c) positively phototropic(d) None of these

  a
•  Response of plant roots towards water is called:(a) Chemotropismb) Phototropism(c) Hydrotropism(d) Geotropism

  c
• Movement of sunflower in accordance with the path of Sun is due to(a) Chemotropism(b) Geotropism(c) Phototropism(d) Hydrotropism

  c
• Which plant hormone promotes cell division?(a) Auxin(b) Gibberellin(c) Cytokinin(d) Abscisic acid

  c
• Any change in the environment to which an organism responds is called(a) stimulus(b) coordination(c) response(d) hormone

  a
• A part of the body which responds to the in-structions sent from nervous system is called(a) receptor(b) effector(c) nerves(d) muscles

  b
• What is Synapse?

  The small empty space between two nerve cells is called synapse
• What is the role of the brain in reflex action ?

  The brain has no role in reflex action
• Which is responsible for reflex action? the brain or the spinal cord?

  The involuntary actions are controlled by the spinal cord. These reflex actions take place immediately without thinking about how to respond to the stimuli
• What are plant hormones ?

  Plant hormones are also called phytohormones. Plant hormones are the chemical substances which help in controlling growth, flowering, height, development of plants and their response to the environment.
• Which plant hormone controls growth?

  Auxin
• Control and coordination in animals is done by the nervous system and the endocrine glands
• Hormones are also known as chemical messenger or mediators
• Nervous system can be further classified into central nervous system and peripheral nervous system
• The central nervous system includes the brain and the spinal cord
• The peripheral nervous system includes the cranial nerves and spinal nerves
• endocrine glands produce hormones
• What are receptors?

  Receptors are structures present on the surface of the cell which receive signals from the external environment
• What are the 5 types of receptors?

  gustatory receptors, photoreceptors, phono receptors, olfactory receptors, thermo receptors
• Gustatory receptors are present in the tongue and can sense taste
• Olfactory receptors are present in the nose and can sense smell
• Photo receptors are present in the eyes and can sense sight
• Phono receptors are present in the ear and can sense audio, sound and maintain balance in the body
• Thermo receptors are present in the skin and can detect the sense of touch
• The neuron is the longest cell in the human body. It is about 12-15cm in length
• Label the parts : A, B, C, D, E, where A is the centre of the head, B contains A, C collects information, D extends from one side to the other side of the neuron and E is where the neuron ends.

  Answer:

  A - Nucleus

  B - Cell body

  C - Dendrites

  D - Axon

  E - Synaptic knob

  
• Dendrites receive signals from the external environment
• The neurons that carry external signals to the brain are called sensory neurons
• The responsive signal from the brain is transmitted through motor neurons.
• Relay neurons coordinate sensory and motor neurons
• Reflex action:

  The spontaneous, automatic and immediate mechanical response by the spinal cord to the stimuli