Lesson: Control and Coordination

Question 1

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

(d) Olfactory receptors detect taste and gustatory receptors smell

Solution:

Question 2

Electrical impulse travels in a neuron from:

(a) Dendrite → axon → axonal end → cell body

(b) Cell body →dendrite →axon → axonal end

(d) Axonal end →axon → cell body → dendrite

Solution:

Question 3

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

(d) Axonal end of one neuron to dendritic end of another neuron

Solution:

Question 4

In a neuron, conversion of electrical signal to a chemical signal occurs at/in:

(a) Cell body

(b) Axonal end

(d) Axon

Solution:

Question 5

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

(d) Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle

Solution:

Question 6

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)

(d) (i), (ii) and (iii)

Solution:

Question 7

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)

(d) (iii) and (iv)

Solution:

Question 8

Posture and balance of the body is controlled by:

(a) Cerebrum

(b) Cerebellum

(d) Pons

Solution:

Question 9

Spinal cord originates from:

(a) Cerebrum

(b) Medulla

(d) Cerebellum

Solution:

Question 10

The movement of shoot towards light is:

(a) Geotropism

(b) Hydrotropism

(d) Phototropism

Solution:

Question 11

The main function of abscisic acid in plants is to:

(a) Increase the length of cells

(b) Promote cell division

(d) Promote growth of stem

Solution:

Question 12

Which of the following is not associated with growth of plant?

(a) Auxin

(b) Gibberellins

(d) Abscisic acid

Solution:

Question 13

Iodine is necessary for the synthesis of which hormone?

(a) Adrenaline

(b) Thyroxin

(d) Insulin

Solution:

Question 14

Choose the incorrect statement about insulin.

(a) It is produced from pancreas

(b) It regulates growth and development of the body

(d) Insufficient secretion of insulin will cause diabetes

Solution:

Question 15

Select the miss-matched pair:

(a) Adrenaline: Pituitary gland

(b) Testosterone: Testes

(d) Thyroxin: Thyroid gland

Solution:

Question 16

The shape of guard cells changes due to change in the _________.

(a) protein composition of cells

(b) temperature of cells

(d) position of nucleus in the cells

Solution:

Question 17

The growth of tendril in pea plants is due to_____________.

(a) Effect of light

(b) Effect of gravity

(d) Rapid cell divisions in tendrillar cells in contact with the support

Solution:

Question 18

The growth of pollen tubes towards ovules is due to ___________.

(a) Hydrotropism

(b) Chemotropism

(d) Phototropism

Solution:

Question 19

The movement of sunflower in accordance with the path of sun is due to ___________.

(a) Phototropism

(b) Geotropism

(d) Hydrotropism

Solution:

Question 20

What triggers the fall of mature leaves and fruits from plants?

(a) Auxin

(b) Gibberellin

(d) Cytokinin

Solution:

Question 21

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.

Solution:

Question 22

Involuntary actions in the body are controlled by ____________.

(a) Medulla in fore brain

(b) Medulla in mid brain

(d) Medulla in spinal cord

Solution:

Question 23

Which of the following is not an involuntary action?

(a) Vomiting

(b) Salivation

(d) Chewing

Solution:

Question 24

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

(d) Differentiate a hot object from a cold object

Solution:

Question 25

What is the correct direction of flow of electrical impulses?

Solution:

Question 26

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.

(d) Thyroxin is also called thyroid hormone.

Solution:

(a)

Question 27

Dwarfism results due to _______________________.

(a) Excess secretion of thyroxin

(b) Less secretion of growth hormone

(d) Excess secretion of growth hormone

Solution:

(b)

Question 28

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.

(d) Testosterone from thyroid gland and estrogen from pituitary gland.

Solution:

(c)

Question 29

A doctor advised a person to take an injection of insulin, because _____________.

(a) His blood pressure was low

(b) His heart was beating slowly

(d) His sugar level in blood was high

Solution:

(d)

Question 30

What is the name of the hormone which increases fertility in males?

(a) Oestrogen

(b) Testosterone

(d) Growth hormone

Solution:

(b)

Question 31

Which of the following endocrine glands is unpaired?

(a) Adrenal

(b) Testes

(d) Ovary

Solution:

(c)

Question 32

Junction between two neurons is called

(a) Cell junction

(b) Neuro muscular junction

(d) Synapse

Solution:

(d)

Question 33

In humans, the life processes are controlled and regulated by:

(a) Reproductive and endocrine systems

(b) Respiratory and nervous systems

(d) Nervous and endocrine systems

Solution:

(d)

Question 34

Label the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in the figure given below:

Solution:

(a) Sensory neuron

(b) Spinal cord (CNS)

(d) Effector = Muscle in arm

Question 35

Name the plant hormones responsible for the following:

(a) Elongation of cells

(b) Growth of stem

(d) Falling of senescent leaves

Solution:

(a) Auxin

(b) Gibberellin

(d) Abscisic acid

Question 36

Label the endocrine glands in the given figure.

Solution:

(a) Pineal gland

(b) Pituitary gland

(d) Thymus

Question 37

In the given figure, (a), (b) and (c), which appears more accurate and why?

Solution:

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.

Question 38

Label the parts of a neuron in the given figure.

Solution:

(a) Dendrite

(b) Cell body

(d) Nerve ending

Question 39

Match the terms of Column (A) with those of Column (B).

Column (A)	Column (B)
(a) Olfactory receptors	(i) Tongue
(b) Thermo receptors (temperature receptors)	(ii) Eye
(c) Gustatory receptors	(iii) Nose
(d) Photoreceptors	(iv) Skin

Solution:

(a) $—$ (iii)

(b) $—$ (iv)

(d) $—$ (ii)

Question 40

What is a tropic movement? Explain with an example.

Solution:

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.

Question 41

What will happen if intake of iodine in our diet is low?

Solution:

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.

Question 42

What happens at the synapse between two neurons?

Solution:

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.

Question 43

Answer the following:

(a) Which hormone is responsible for changes noticed in females at puberty?

(b) Dwarfism results due to deficiency of which hormone?

(d) Iodine is necessary for the synthesis of which hormone?

Solution:

(a) Oestrogen

(b) Growth hormone

(d) Thyroxin

Question 44

Answer the following:

(a) Name the endocrine gland associated with brain?

(b) Which gland secretes digestive enzymes as well as hormones?

(d) Which endocrine gland is present in males but not in females?

Solution:

(a) Pituitary

(b) Pancreas

(d) Testes

Question 45

Draw the structure of a neuron and explain its function.

Solution:

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.

Question 46

What are the major parts of a brain? Mention the functions of different parts.

Solution:

Brain has three major parts namely:

· Fore-brain

· Mid-brain

· Hind-brain

Major Parts	Parts	Functions
Fore-brain	Cerebrum	· Controls voluntary actions and is the site for sensory perceptions.
	Cerebral hemispheres	· Controls intelligence and voluntary actions
	Olfactory lobes	· Centre of smell
	Diencephalon	· Has centres of hunger, thirst, etc.
	Motor areas	· Instruct muscles to do various types of jobs
Mid brain	Tectum	· Controls reflex movements of neck, head and trunk in response to visual and auditory stimuli
Mid brain	Cerebral peduncle	· Controls reflex movement of eye muscles, changes in pupil size and shape of the eye lens
Hind-brain	Pons	· Regulates respiration · Relays information between the cerebellum and the cerebrum maintaining posture and balance of the body.
	Cerebellum	· Coordinates motor functions and maintains posture and balance.
	Medulla	· Controls involuntary functions such as heart rate, breathing, etc. · Acts as a controlling centre for reflexes such as swallowing, coughing vomiting, etc.

Question 47

What constitutes the central and peripheral nervous systems? How are the components of central nervous system protected?

Solution:

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.

Question 48

Mention one function for each of these hormones:

(a) Thyroxin

(b) Insulin

(d) Growth hormone

(e) Testosterone.

Solution:

(a) Thyroxin regulates carbohydrate, fat and protein metabolism.

(b) Insulin regulates blood sugar level.

(d) Growth hormone regulates growth and development.

(e) Testosterone controls changes of body features associated with puberty in males.

Question 49

Name various plant hormones. Also give their physiological effects on plant growth and development.

Solution:

Plant Hormone	Physiological Effects
Auxin	· Promotes cell elongation and thus promotes growth of a plant · Plays an important role in formation of root and seedless fruit
Gibberellins	· Helps in growth of stem and flower · Helps in seed germination
Cytokinin	· Promotes cell division and thus promotes growth · Stimulates leaf expansion
Abscissic acid	· Inhibits growth and is responsible for shedding of older parts.

Question 50

What are reflex actions? Give two examples. Explain a reflex arc.

Solution:

Reflex Action:

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.

Example:

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.

Reflex Arc:

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.

Question 51

“Nervous and hormonal systems together perform the function of control and coordination in human beings.” Justify the statement.

Solution:

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.

Question 52

How does chemical coordination take place in animals?

Solution:

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.

Question 53

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?

Solution:

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.