Lesson: Control and Coordination
Which of the following statements is correct about receptors?
(a) Gustatory receptors detect taste while olfactory receptors detect smell
(b) Both gustatory and olfactory receptors detect smell
(c) Auditory receptors detect smell and olfactory receptors detect taste
(d) Olfactory receptors detect taste and gustatory receptors smell
Electrical impulse travels in a neuron from:
(a) Dendrite → axon → axonal end → cell body
(b) Cell body →dendrite →axon → axonal end
(c) Dendrite → cell body →axon → axonal end
(d) Axonal end →axon → cell body → dendrite
In a synapse, chemical signal is transmitted from:
(a) Dendritic end of one neuron to axonal end of another neuron
(b) Axon to cell body of the same neuron
(c) Cell body to axonal end of the same neuron
(d) Axonal end of one neuron to dendritic end of another neuron
In a neuron, conversion of electrical signal to a chemical signal occurs at/in:
(a) Cell body
(b) Axonal end
(c) Dendritic end
Which is the correct sequence of the components of a reflex arc?
(a) Receptors → Muscles → Sensory neuron → Motor neuron → Spinal cord
(b) Receptors → Motor neuron → Spinal cord → Sensory neuron → Muscle
(c) Receptors → Spinal cord → Sensory neuron → Motor neuron → Muscle
(d) Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle
Which of the following statements are true?
(i) Sudden action in response to something in the environment is called reflex action.
(ii) Sensory neurons carry signals from spinal cord to muscles.
(iii) Motor neurons carry signals from receptors to spinal cord.
(iv) The path through which signals are transmitted from a receptor to a muscle or a gland is called reflex arc.
(a) (i) and (ii)
(b) (i) and (iii)
(c) (i) and (iv)
(d) (i), (ii) and (iii)
Which of the following statements are true about the brain?
(i) The main thinking part of brain is hind brain.
(ii) Centres of hearing, smell, memory, sight etc. are located in fore brain.
(iii) Involuntary actions like salivation, vomiting, blood pressure are controlled by the medulla in the hind brain.
(iv) Cerebellum does not control posture and balance of the body.
(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)
Posture and balance of the body is controlled by:
Spinal cord originates from:
The movement of shoot towards light is:
The main function of abscisic acid in plants is to:
(a) Increase the length of cells
(b) Promote cell division
(c) Inhibit growth
(d) Promote growth of stem
Which of the following is not associated with growth of plant?
(d) Abscisic acid
Iodine is necessary for the synthesis of which hormone?
Choose the incorrect statement about insulin.
(a) It is produced from pancreas
(b) It regulates growth and development of the body
(c) It regulates blood sugar level
(d) Insufficient secretion of insulin will cause diabetes
Select the miss-matched pair:
(a) Adrenaline: Pituitary gland
(b) Testosterone: Testes
(c) Estrogen: Ovary
(d) Thyroxin: Thyroid gland
The shape of guard cells changes due to change in the _________.
(a) protein composition of cells
(b) temperature of cells
(c) amount of water in cells
(d) position of nucleus in the cells
The growth of tendril in pea plants is due to_____________.
(a) Effect of light
(b) Effect of gravity
(c) Rapid cell divisions in tendrillar cells that are away from the support
(d) Rapid cell divisions in tendrillar cells in contact with the support
The growth of pollen tubes towards ovules is due to ___________.
The movement of sunflower in accordance with the path of sun is due to ___________.
What triggers the fall of mature leaves and fruits from plants?
(c) Abscisic acid
Which of the following statements about transmission of nerve impulse is incorrect?
(a) Nerve impulse travels from dendritic end towards axonal end.
(b) At the dendritic end electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron.
(c) The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in a dendrite of another neuron.
(d) A neuron transmits electrical impulses not only to another neuron but also to muscle and gland cells.
Involuntary actions in the body are controlled by ____________.
(a) Medulla in fore brain
(b) Medulla in mid brain
(c) Medulla in hind brain
(d) Medulla in spinal cord
Which of the following is not an involuntary action?
(c) Heart beat
When a person is suffering from severe cold, he or she cannot ___________.
(a) Differentiate the taste of an apple from that of an ice cream
(b) Differentiate the smell of a perfume from that of an agarbatti
(c) Differentiate red light from green light
(d) Differentiate a hot object from a cold object
What is the correct direction of flow of electrical impulses?
Which statement is not true about thyroxin?
(a) Iron is essential for the synthesis of thyroxin.
(b) It regulates carbohydrates, protein and fat metabolism in the body.
(c) Thyroid gland requires iodine to synthesis thyroxin.
(d) Thyroxin is also called thyroid hormone.
Dwarfism results due to _______________________.
(a) Excess secretion of thyroxin
(b) Less secretion of growth hormone
(c) Less secretion of adrenaline
(d) Excess secretion of growth hormone
Dramatic changes of body features associated with puberty are mainly because of secretion of ________________________.
(a) Oestrogen from testes and testosterone from ovary.
(b) Estrogen from adrenal gland and testosterone from pituitary gland.
(c) Testosterone from testes and estrogen from ovary.
(d) Testosterone from thyroid gland and estrogen from pituitary gland.
A doctor advised a person to take an injection of insulin, because _____________.
(a) His blood pressure was low
(b) His heart was beating slowly
(c) He was suffering from goitre
(d) His sugar level in blood was high
What is the name of the hormone which increases fertility in males?
(d) Growth hormone
Which of the following endocrine glands is unpaired?
Junction between two neurons is called
(a) Cell junction
(b) Neuro muscular junction
(c) Neural joint
In humans, the life processes are controlled and regulated by:
(a) Reproductive and endocrine systems
(b) Respiratory and nervous systems
(c) Endocrine and digestive systems
(d) Nervous and endocrine systems
Label the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in the figure given below:
(a) Sensory neuron
(b) Spinal cord (CNS)
(c) Motor neuron
(d) Effector = Muscle in arm
Name the plant hormones responsible for the following:
(a) Elongation of cells
(b) Growth of stem
(c) Promotion of cell division
(d) Falling of senescent leaves
(d) Abscisic acid
Label the endocrine glands in the given figure.
(a) Pineal gland
(b) Pituitary gland
In the given figure, (a), (b) and (c), which appears more accurate and why?
Figure (a) is more appropriate.
In a plant, shoots are negatively geotropic. Hence, they grow upwards opposite to the direction of gravity. On the other hand, roots grow in the direction of gravity and thus, they are positively geotropic.
Label the parts of a neuron in the given figure.
(b) Cell body
(d) Nerve ending
Match the terms of Column (A) with those of Column (B).
(a) Olfactory receptors
(b) Thermo receptors (temperature receptors)
(c) Gustatory receptors
What is a tropic movement? Explain with an example.
The movement of a plant in the direction of external stimuli is called tropic movement. Such movements can be either towards the stimulus, or away from it. The movement of a plant is said to be positive if it is directed towards the stimulus and negative if is directed away from the stimulus.
Example: Bending of shoots towards light and bending of roots away from light are examples of positive and negative phototropism, respectively.
What will happen if intake of iodine in our diet is low?
Following things might occur if iodine intake in our diet is low:
(a) The release of thyroxin from thyroid gland will be less.
(b) Iodine deficiency will affect the carbohydrate, protein and fat metabolism and thus slow down the growth of the body.
(c) Deficiency of iodine will lead to goitre.
What happens at the synapse between two neurons?
Electrical signal on reaching the axonal end of one neuron causes the axon bulb to release a chemical substance. This diffuses across the synapse and stimulates the dendritic end of the next neuron. These dendrites then generate another electrical signal to their cell body to be carried along the axon.
Answer the following:
(a) Which hormone is responsible for changes noticed in females at puberty?
(b) Dwarfism results due to deficiency of which hormone?
(c) Blood sugar level rises due to deficiency of which hormone?
(d) Iodine is necessary for the synthesis of which hormone?
(b) Growth hormone
Answer the following:
(a) Name the endocrine gland associated with brain?
(b) Which gland secretes digestive enzymes as well as hormones?
(c) Name the endocrine gland associated with kidneys?
(d) Which endocrine gland is present in males but not in females?
Draw the structure of a neuron and explain its function.
Neurons are also known as nerve cells. They are basic building blocks of our nervous system. They are responsible for transmitting and receiving signals from different parts of our body.
The structure of a neuron is shown below:
The components of a neuron are:
· Dendrites: Dendrites are tree-like extensions which receive information from a body part or other neurons and transmit electric signals to the cell body.
· Cell body: Cell body (also known as soma) is the place where all dendrites are joined. It produces all necessary proteins for other parts of a neuron.
· Nucleus: Nucleus is the most important organelle which contains genes that consist of DNA.
· Axon hillock: The axon hillock is part of a cell body that receives signals from all dendrites and creates electric impulse which travels down the axon.
· Axon: Axon is a long tube which carries electric signals away from a cell body towards the terminal button and transmits them to other neurons.
· Myelin sheath: Myelin sheath is made up of proteins and fats and is responsible for protection and insulation of neurons.
· Synaptic terminals: Synaptic terminals are the terminal buttons that are located at the end of a neuron and are responsible for sending signals on to other neurons
· Synapse: Synapse is a small gap at the end of a neuron that allows information to pass from one neuron to the next muscle or gland.
What are the major parts of a brain? Mention the functions of different parts.
Brain has three major parts namely:
· Controls voluntary actions and is the site for sensory perceptions.
· Controls intelligence and voluntary actions
· Centre of smell
· Has centres of hunger, thirst, etc.
· Instruct muscles to do various types of jobs
· Controls reflex movements of neck, head and trunk in response to visual and auditory stimuli
· Controls reflex movement of eye muscles, changes in pupil size and shape of the eye lens
· Regulates respiration
· Relays information between the cerebellum and the cerebrum maintaining posture and balance of the body.
· Coordinates motor functions and maintains posture and balance.
· Controls involuntary functions such as heart rate, breathing, etc.
· Acts as a controlling centre for reflexes such as swallowing, coughing vomiting, etc.
What constitutes the central and peripheral nervous systems? How are the components of central nervous system protected?
The central nervous system is composed of brain and spinal cord.
The peripheral nervous system is composed of cranial nerves, spinal nerves and autonomous nervous system.
Brain is the main coordinating centre in a body. It is housed in the cranium. The spinal cord is a long cylindrical structure. It is enclosed in a bony cage called vertebral column. Additionally, the brain and the spinal cord are surrounded by a system of three layers called meninges. The space between these membranes is filled with a cerebrospinal fluid, which provides a cushion effect and protects the organs against mechanical shocks.
Mention one function for each of these hormones:
(d) Growth hormone
(a) Thyroxin regulates carbohydrate, fat and protein metabolism.
(b) Insulin regulates blood sugar level.
(c) Adrenaline increases heart rate and supply of blood to various organs.
(d) Growth hormone regulates growth and development.
(e) Testosterone controls changes of body features associated with puberty in males.
Name various plant hormones. Also give their physiological effects on plant growth and development.
· Promotes cell elongation and thus promotes growth of a plant
· Plays an important role in formation of root and seedless fruit
· Helps in growth of stem and flower
· Helps in seed germination
· Promotes cell division and thus promotes growth
· Stimulates leaf expansion
· Inhibits growth and is responsible for shedding of older parts.
What are reflex actions? Give two examples. Explain a reflex arc.
Reflex action is a special case of involuntary movement in voluntary organs. It is a rapid automatic response to a stimulus which is not under voluntary control of the brain.
1. When we touch a hot object, we immediately move our hand away from it.
2. When we step on something sharp, we immediately move our foot away from it.
All of this happens in a flash and our organ is saved from imminent injury.
The path through which nerve signals travel is called the reflex arc. The following flow chart and image shows the flow of signal in a reflex arc.
Receptor Sensory Neuron Relay neuron Motor neuron Effector (muscle)
The receptor is a 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 and moves the receptor away from danger.
“Nervous and hormonal systems together perform the function of control and coordination in human beings.” Justify the statement.
Nervous system controls and coordinates all functions in our body. However, nerves cannot reach every part of our body. So it carries out its functions in close coordination with the hormonal system to control all the parts of the body.
Nervous control is faster, whereas hormonal control is slower. Hormonal control is mainly based on feedback mechanism and based on a situation.
It tells the body to either pick up pace or slow down.
Nervous control is more of a direct control. So, both of them complement each other. Together, the nervous and hormonal systems perform the function of control and coordination in human beings.
How does chemical coordination take place in animals?
In animals, chemical coordination takes place through hormones. These hormones are chemical messengers. They are directly released in the bloodstream. The blood carries them to specific tissues or organs called target tissues/organs where they trigger a biochemical or physiological activity.
The hormones are of different types and perform different functions.
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?
The flow of signals through neurons takes place in the form of specialized chemicals. These chemicals, called neurotransmitters, can enter a neuron only through dedicated receptors located at the dendritic end but not at the axonal end. Hence, the flow of signals in a synapse happens from axonal end of one neuron to dendritic end of another neuron but not in reverse direction.