(a) Pancreas - Insulin and Glucagon
(b) Pituitary - Growth hormone
(c) Testis - Testosterone
(d) Ovary - Progresterone and Oestrogen.

(a) Dwarfism if less hormone; Gigantism if secreted more.
(b) Diabetes
(c) Goitre
(d) Masculine characters will not develop properly in male.

Thyroxine is the hormone secreted by the thyroid gland. This hormone regulates the metabolism of carbohydrates, fats and proteins. By regulating the metabolism it helps in optimum growth and development of the body.

The part of the hindbrain that takes part in the regulation of respiration is medulla oblongata.

Pancreas. It secretes hormones and digestive enzymes.

Adrenaline hormone.

Dendrite, cell body, axon and nerve ending.

Adrenaline hormone is secreted from adrenal gland into the blood and carried to different parts of the body. At the time of emergency, danger or stress, it is released in large quantities. As a result, it causes fast beating of heart, resulting in more supply of oxygen to muscles.
The blood supply to the digestive system and skin is reduced due to contraction of muscles around small arteries in these organs. The breathing rate also increases because of the contraction of diaphragm and rib muscles. All these responses together help the animal to deal with the emergency situation.

Auxins promote cell elongation and are present at the shoot tip. When tendril comes in contact with a support, auxin stimulates faster growth of the cells on the opposite sides. Thus, the tendril coils around the support.

Brain has limited role to play in reflex action. It is an extremely quick action, which does not involve any thinking by the brain. In this type of action, the stimulus is received by the spinal cord that sends a response,e.g. coughing, The action is registered in cercbral brain just for memory.

Information passes through neuron in the form of electro-chemical signals. These signals are called impulse.
When an impulse reaches the end of the axon it sets off the release of some chemicals. These chemicals cross the gap or the synapse and start a similar electrical impulse in a dendrite of the next neuron. A similar synapse allows the delivery of impulses from the neurons to other cells, like muscle cells or glands.

Differences between movement of leaves and movement of shoot towards light are as follows:

Reflex action is a special case of involuntary movement involuntary organs. When a voluntary organ is in the vicinity of a sudden danger, it is immediately pulled away from the danger to save itself. For example; when your hand touches a very hot electric iron, you move away your hand in a jerk. All of this happens in flash and your hand is saved from the imminent injury. This is an example of reflex action.
Reflex Arc: The path through which nerves signals; involved in a reflex action; travel is called the reflex arc. The following flow chart shows the flow of signal in a reflex arc. Receptor \(\rightarrow\) Sensory Neuron\(\rightarrow\) Relayneuron \(\rightarrow\) Motor neuron \(\rightarrow\) Effector (muscle) The receptor is the organ which comes in the danger zone. The sensory neurons pick signals from the receptor and send them to the relay neuron. The relay neuron is present in the spinal cord. The spinal cord sends signals to the effector via the motor neuron. The effector comes in action moves the receptor away from the danger.

Various plant hormones and their effects are as follows:
(i) Auxin : Promotes cell elongation and thus promotes growth of a plant part.
(ii) Gibberellins : Promotes growth.
(iii) Cytokinin :  Promotes cell division and thus promotes growth.
(iv) Abscissic acid : Inhibits growth and is responsible for shedding or older parts.