Define reflex action with suitable examples.
When we suddenly withdraw our hands on pricking a pin, it is a reflex action. This type of sudden response to a stimulus is involuntary. A reflex action is defined as an unconscious and involuntary response of effectors to a stimulus. In reflex actions, a message from the receptors is relayed by sensory nerves to the spinal cord, which sends information for response via motor nerves to effectors. The pathway is called reflex arc. The simplest type of reflex action is knee-jerk reflex. In this case, while sitting with freely hanging legs, a strike below the knee cap kicks the leg forward. Other reflex actions are coughing, sneezing, yawning and blinking of eyes.
What is the function of insulin hormone ? What type of patients are given insulin injections ?
(a) Name the hormones secreted by the following endocrine glands :
(i) Thyroid gland (ii) Parathyroid glands (iii) Pancreas (iv) Adrenal glands
(b) Write the functions of testosterone and oestrogen hormones.
(a) What does a stem (or shoot) do in response to gravity ? What is this phenomenon known as ?
(b) What does a root do in response to light ? What is this phenomenon known as ?
(a) Which plant hormone is present in greater concentration in the areas of rapid cell division?
(b) Give one example of a plant growth promoter and a plant growth inhibitor.
Give the scientific terms used to represent the following :
(a) Bending of a shoot towards light.
(b) Growing of roots towards the earth.
(c) Growth of a pollen tube towards ovule.
(d) Bending of roots towards water.
(e) Winding of tendril around a support
(a) What does a plant root do in response to water ? What is this phenomenon known as ?
(b) What happens to the moonflower (i) during daytime, and (ii) at night ? What is this phenomenon known as ?
Which halogen element is necessary for the making of thyroxine hormone by the thyroid gland ?
What is the general name of chemical substances which bring about control and coordination in plants ?
a) What are the short fibres of a neuron known as ?
What is the long fibre of a neuron known as ?
Which one term in each of the following includes the other three ?
(a) thyroid, ductless gland, thymus, pituitary, ovary
(b) adrenalin, insulin, hormone, thyroxine, estrogen
State the functions of the following hormones :
(a) Thyroxine (b) Adrenaline (c) Growth hormone
(a) What is a reflex action ? Explain with the help of an example.
(b) Define reflex arc. Give the flow chart of a spinal reflex arc.
(c) How are involuntary actions and reflex actions different from each other ?
Name various plant hormones. Also give their physiological effects on plant growth and development.
What causes a tendril to encircle or coil around the object in contact with it is? Explain the process involved.
State the functions of any three of the structural and functional unit of nervous system.
Name, the two main organs of our central nervous system. Which one of them plays a major role in sending command to muscles to act without involving thinking process? Name the phenomenon involved.
Name and explain the function of the hormone secreted by the pituitary gland in humans.
Name the plant hormones which help/promote (i) cell division (ii) growth of
the stem and roots?
Give one example of the movement of a plant part which is caused by the loss of water (or migration of water).
(a) What does a Mimosa pudica plant do in response to touch ? What is this phenomenon known as ?
(b) What happens to the dandelion flower (z) during daytime, and (ii) at night ? What is this phenomenon known as ?
Explain the difference between each of the following pairs of terms :
(a) receptor and effector (b) cerebrum and cerebellum
Mention one function for each of these hormones:
(a) Thyroxin (b) Insulin (c) Adrenaline (d) Growth hormone (e) Testosterone.
Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron but not the reverse?
(i) Name the hormones that are released in human males and females when they reach puberty.
(ii) Name a gland associated with brain. Which problem is caused due to the deficiency of the hormone released by this gland ?
Write one example each of the following tropic movements :
(i) Positive phototropism (ii) Negative phototropism
(iii) Positive geotropism (iv) Negative geotropism
(v) Hydrotropism (vi) Chemotropism
(a) How is brain protected from injury and shock?
(b) Name two main parts of hind brain and state the functions of each.
What are 'hormones'? State one function of each of the following hormones:
(i) Thyroxine (ii) Insulin