Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
Nervous system:- It is consist of neurons, bundles of nerve fibres, neuroglia cells and have neurosecretory cells. Human nervous system is consist of two main parts:- CNS (central nervous system)- lies along the main axis of the body, consists of upper large brain in head or narrow spinal cord in neck or trunk.
PNS (peripheral nervous system)- It is associated with the CNS defined by afferent nerve fibre that transmit impulses from receptors present in organs to CNS) and efferent nerve fibre which transmit regulatory impulses from CNS to peripheral organs.
It is divided into two parts:
1. Somatic nervous system relays voluntary impulses from CNS to skeletal muscles.
2. Autonomic nervous system relays impulses from CNS to involuntary parts of the body.
On the other hand, hormonal mechanism is slower than nervous mechanism. Hormones are the chemical messengers which brings control, secreted by endocrine glands and released into the blood stream from axon ending. Various hormonal secretion is done by hypothalamus and are under control of secretion of neurosecretory cells.
Draw the structure of a neuron and explain its function.
Which signals will get disrupted in case of a spinal cord injury?
How does chemical coordination take place in animals?
Why is the use of iodised salt advisable?
The brain is responsible for
(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the above.
How do we detect the smell of an agarbatti (incense stick)?
How do auxins promote the growth of a tendril around a support?
Which part of the brain maintains posture and equilibrium of the body?
How does our body respond when adrenaline is secreted into the blood?
What is the need for a system of control and coordination in an organism?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
What is a good source of energy?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
The essential difference between an AC generator and a DC generator is that
(a) AC generator has an electromagnet while a DC generator has permanent magnet.
(b) DC generator will generate a higher voltage.
(c) AC generator will generate a higher voltage.
(d) AC generator has slip rings while the DC generator has a commutator.
What is the principle of an electric motor?
Why does menstruation occur?
Which of the following terms does not represent electrical power in a circuit?
(a) I2R (b) IR2 (c) VI (d) V2/R
An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 h.
An object 5.0 cm in length is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position of the image, its nature and size.
Which of the following constitute a food-chain?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
What is the role of the split ring in an electric motor?
Which of the following correctly describes the magnetic field near a long straight wire?
(a) The field consists of straight lines perpendicular to the wire.
(b) The field consists of straight lines parallel to the wire.
(c) The field consists of radial lines originating from the wire.
(d) The field consists of concentric circles centred on the wire.