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?
How would you distinguish experimentally between an alcohol and a carboxylic acid?
Which of the following hydrocarbons undergo addition reactions: C2H6, C3H8, C3H6, C2H2 and CH4.
What would be the consequences of a deficiency of haemoglobin in our bodies?
Ethane, with the molecular formula C2H6 has
(a) 6 covalent bonds.
(b) 7 covalent bonds.
(c) 8 covalent bonds.
(d) 9 covalent bonds.
Why does dry HCl gas not change the colour of the dry litmus paper?
A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.
Name the sodium compound which is used for softening hard water.
What kind of mirror – concave, convex or plain – would be best suited for use in a solar cooker? Why?
Explain the following terms with one example each.
(a) Corrosion
(b) Rancidity
What criteria do we use to decide whether something is alive?