CLASS-10 CHAPTER-7 approach 10-12 years of age.

[CBSE
2008]
CONTROLS AND COORDINATION
Ans: Testosterone released from testes in
IMPORTANT QUESTIONS males, estrogen released from ovaries in
females.
1.Define ‘reflex action’. [CBSE 2009]
Ans:It is an automatic, spontaneous and an 8. Name the hormone that helps in
immediate involuntary response to a stimulus regulating level of sugar in our blood.
controlled usually by the spinal cord. e.g. Name the glands that secretes it. [CBSE
knee jerk movement. 2010]
Ans: Insulin hormone secreted by pancreas.
2. Name the largest cell in the human
body. [CBSE 2003] 9. Name a plant hormone that inhibits
Ans: Nerve cell (Neuron). growth. Write its one more function.
[CBSE 2014]
3.Give an example of plant hormone that
Ans: Abscisic acid inhibits growth in plants.
promotes growth. [CBSE 2008]
It also causes closure of stomata during water
Ans: Auxin
stress.
4. What are plant hormones? [CBSE
10.A potted plant is made to lie
2008]
horizontally on the ground. Which part of
Ans: The chemical substances produced in
the plant will show: [CBSE 2010]
plants which help in the growth and
(i) Positive geotropism
development of plant, its tissues and other
(ii) Negative geotropism
plants.
Ans:(i) Roots will shows positive
5. Name the part of neuron [CBSE 2008] geotropism.
(а) where information is acquired. (ii) Shoots will show negative geotropism.
(b) through which information travels an
11.Name a plant hormone which promotes
electrical impulse.
growth in plants. [CBSE 2008]
Ans: (a) Dendrite (b) Axon
Ans: Auxin is a plant hormone that promotes
6.Name two tissues that provide control growth and cell elongation in plants.
and coordination in multicellular animals.
12.State one function each of pons and
[CBSE 2009]
cerebellum.
Ans: Muscular tissues and nervous tissue.
Ans: Pons: Regulates rate of respiration
7.Name the hormone, the secretion of Cerebellum: Maintains equilibrium of the
which is responsible for dramatic changes body during walking, jumping, etc.
in appearance in girls and boys when they
13. Name a gaseous plant hormone. Give Ans: (i) Thyroxin (ii) Parathyroid hormone
its role. (iii) Adrenaline (iv) Vasopressin
Ans: Ethylene is a gaseous hormone. It
regulates fruit ripening. 19. What is an association neuron?
Ans: Association neurons are present in
14. How many spinal and cranial nerves
cortex part of spinal cord between the
are present in human body?
sensory neuron and motor neuron. It helps to
Ans: Spinal nerves = 31 pairs
interconnect the signals between the sensory
Cranial nerves = 12 pairs
neuron and motor neuron by forming synapse
15.What are meninges? with axon of sensory neuron and dendrite of
Ans: The three membranes which cover the motor neuron.
brain to protect it are called meninges.
20. How are the brain and spinal cord
16. How do we detect smell of hot spicy
protected from mechanical shock?
food from a distance?
Ans: Brain is present in a bony box called
Ans: We have olfactory receptors in our nose
cranium (skull), spinal cord is protected by
which detect the smell of hot spicy food.
vertebral column. The cerebrospinal fluid
This information is transmitted by nerve
present around the brain and spinal cord
impulse to olfactory lobes of forebrain which
protect it from mechanical shock.
interpret the information.
17. Why do tendrils coil around hard 21. Which functions are regulated by the
objects or support? forebrain?
Ans: The tendrils coil around hard objects or Ans: The thinking part of the brain is
forebrain which controls
support due to a stimulus of touch
 Movement of voluntary muscles.
(thigmotropism) which causes less growth on  Hearing, smell, sight, hunger, thirst, pain,
the side in contact with support than the side etc. by its association areas.
which is away from it. This unequal growth  It also stores information and controls
of two sides of tendril makes it coil around intelligence.
the support.
22. Explain how a squirrel responds a
18. Name the hormones reponsible for dangerous situation with help of its
regulation. . [CBSE 2007] hormonal system.
(i) Metabolism of carbohydrates, fats and Ans: When a squirrel perceives a dangerous
proteins situation, adrenaline hormone is released in
(ii) Balance of calcium and phosphate its blood which increases its heart beat and
(iii) Blood pressure blood supply to tissues. This provides energy
(iv) Water and electrolyte balance to its cells and tissues at a faster rate and
enables it to run away from emergency
situation.

23. How are sensory neurons different

from motor neurons?
Ans: Sensory neurons take information from
receptors and transmit the impulses towards
Answer:
central nervous system. Motor neurons carry
(a) Sensory neuron
message from control nervous system to the
(b) Spinal cord (part of CNS)
muscle, gland or an organ to enable it to
(c) Motor neuron
respond.
(d) Effector (Muscle)
24. How are receptors different from
27. Name the plant hormones responsible
effectors?
for the following:
Ans: Receptors are cells, tissues or organs
(a) elongation of cells
which receive the information in form of
(b) growth of stem
stimulus. For example, photoreception,
(c) promotion of cell division
gustatory receptors, etc. Effectors are
(d) falling of senescent leaves
muscles, glands tissues or cells which
Ans: (a) Auxin (b) Gibberellin (c)
respond according to the information
Cytokinin (d) Abscisic acid
received through motor neuron from the
central nervous system.
28. Label the endocrine glands in figure
given below.
25. Define peripheral nervous system.
What are its components?
Ans: The nerves that directly arise from the
central nervous system and contact different
parts of our body to help their involuntary
controls. Spinal nerves and cranial nerves are
components of peripheral nervous system.
Ans: Answer:
26. (a), (b), (c) and (d) and show the
(a) Pineal Gland (b) Pituitary Gland (c)
direction of flow of electrical signals in the
Thyroid
given figure.
29.Label the parts of a neuron in figure
given below:
 hormone can regulate its further formation
with the help of a regulatory mechanism
called feedback mechanism.

Example: Hypothalamus regulates thyroxin

levels in blood by secreting thyroid
stimulating hormone (TSH). If the thyroxine
levels increases then hypothalamus stop
secreting TSH in order to reduce the
Ans: production of thyroxine from thyroid gland.
(a) Dendrite
(b) Cell Body Low levels of thyroxin in blood again
(c) Axon switches on the release of TSH from
(d) Nerve ending hypothalamus to increase levels of thyroxin
30: Match the terms of Column (A) with in blood.
those of Column (B)
33. What are the different types of
neurons and their functions in the human
body?
Ans:
There are mainly three types of neurons:
1. Sensory neuron: They transmit
Ans: (a) (iii) (b) (iv) (c) (i) (d) (ii) information from receptors towards the
central nervous system.
2. Motor neuron: They transmit
31: What are nastic and curvature information from the central nervous
movements? Give one example of each. system to effectors like muscles or glands.
3. Relay neuron: It serves as a link between
[CBSE 2010]
the sensory and the motor neurons in the
Ans: The non-directional responses to brain or spinal cord.
stimuli are called nastic movements e.g.,
drooping of leaves of touch-me-not plant. 34. What are the limitations to the use of
Curvature movement are the movement of electrical impulse?
Ans: The limitations to electrical impulse are
plant parts towards or away from stimulus
1. Only those cells used that are connected by
e.g., bending of shoot towards light. nervous tissue, while other tissues do not
receive the information directly.
32: How does feedback mechanism 2. It takes some times to reset the mechanism
regulate the hormone action? Explain with of generation of new electrical impulse
the help of an example. once an electrical impulse had been
Ans: The presence or absence of a particular generated.
35. Depict the mechanism of Nervous (c) Blood sugar level rises due to
tissue action. deficiency of which hormone?
Ans: The mechanism of nervous tissue (d) Iodine is necessary for the synthesis of
action is: which hormone? [NCERT Exemplar]
Ans: (a) Oestrogen (b) Growth hormone
(c) Insulin (d) Thyroxin

38. 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? [NCERT
Exemplar]
36. What is a tropic movement? Explain Ans: (a) Pituitary (b) Pancreas (c) Adrenal
with an example. [NCERT Exemplar] gland (d) Testes
Ans: The directional movements caused in
plants due to an external stimuli are called
tropic movements.
39. Differentiate between tropic and nastic
Example: During phototropism, the shoot
movements in plants. [CBSE 2006]
bends towards light and show positive
Ans: Tropic Movements:
phototropism while the roots bend away from
light to show negative phototropism. 1. There is directional growth of a plant or
part of a plant in response to an external
36. What will happen if intake of iodine in
stimulus i.e., direction of stimulus
our diet is low? [NCERT Exemplar]
controls direction of growth.
Ans: Iodine helps in the synthesis of
2. The effect is more or less permanent.
thyroxin hormone from thyroid gland.
3. It is easily observed in stems and roots
Thyroxin hormone is necessary for
of plants.
carbohydrate, proteins and fat metabolism.
4. It occurs due to unequal growth on the
Deficiency caused due to low level of iodine
two sides of a stem or root.
in diet might result is a disease called goitre
5. For example, bending of root towards
in the person.
gravity and bending of shoot towards
37. Answer the following: light.
(a) Which hormone is responsible for the
Nastic Movements:
changes noticed in females at puberty?
1. The growth or movement is independent
(b) Dwarfism results due to deficiency of
of the direction of stimulus.
which hormone?
 2. The effect is temporary and reversible. Ans: The information received by the
3. It occurs in specialised parts and organs dendrites of neurons present at receptors is
of plants like leaves and petals of transferred in form of electrical impulse to
flowers. the cell body, axon and the nerve endings at
4. It usually involves alterations in cell the ends of axon. At the axonal ends,
volumes. chemicals are released between junction of
5. For example, folding on leaflets of two neurons called synapse. The chemical
touch-me-not plant on touching them. diffuses towards the dendrite of the next
neuron where it generates an electrical
40. Mention one function for each of these impulse again. So, the electrical signals
hormones: change to chemical signals and again to
(a) Thyroxin electrical signals for the next neuron.
(b) Insulin Since the chemicals Eire released at the
(c) Adrenaline axonal ends and absent at dendrite end, the
(d) Growth hormone signal travels from axonal end to dendrites
(e) Testosterone end of another neuron but not the reverse i.e.,
Ans: the flow of electrical impulse is
(a) Thyroxin: It regulates carbohydrates, fat unidirectional only.
and protein metabolism.
(b) Insulin: It regulates blood sugar level. 43. While most of our actions are
(c) Adrenaline: It increases heart beat rate coordinated by the brain, still some of our
and supply of blood to various organs. actions need to be coordinated by the
(d) Growth hormones: It regulates growth spinal cord. Why?
and development of an organism. Ans: Brain is the thinking part which
(e) Testosterone: It controls the bodily coordinates the various activities and
features, secondary sexual characters in processes in human beings. But, some
males during puberty. actions which need to be quick, automatic
and involuntary, do not involve any thinking
41. How does chemical coordination take
processes. So, such immediate responses are
place in animals?
coordinated by the spinal cord and are called
Ans: Hormones secreted by the endocrine
reflex actions.
glands are directly poured into the blood
stream as they are ductless glands. Blood
carries these hormones to specific target 44. The movements shown by the leaves of
tissue or organ where they act and trigger a ‘touch me not’ plant on touching are
particular biochemical or physiological different from the movement shown by
activity in response to the stimulus received. seedling. Elaborate.
Ans: The opening and closing of the leaves
42.Why is the flow of signals in a synapse of the ‘touch me not plant’ is a result of
from axonal end of one neuron to water change in amount of water in the plant
dendritic end of another neuron but not cells, which is not dependent on growth. But,
the reverse? [NCERT Exemplar] the movement of the seedling is a growth-
dependent movement because it will not point to another, whereas, hormones are first
show any movement if it is prevented from released in the blood and they have to travel
growth. to the target site to bring about the response,
which takes more time than reflex actions.
45. The level of hormones should be well
balanced in human beings in order to 48. Villagers living in a hilly area were
maintain the normal functioning of the facing a problem that a lot of children in
human body. Explain this statement with the village were developing swollen necks.
two examples. The priest of the village told that it was
Ans: The level of hormones should be due to the acts of the villagers who had
balanced in human beings because a annoyed their Goddess and they needed to
deficiency or excess secretion of some offer sacrifice for getting rid of this
hormones can have adverse effects on the problem. Dr. Kamal visited the village and
human body. For example, properly listened to the problem of the
villagers and advised them to use iodised
salt instead of normal salt in their food.
 A deficiency in the secretion of insulin
Villagers agreed to Dr. Kamal’s advice
from the pancreas increases the blood
and within a few months the problem was
sugar level and causes diabetes.
overcome to a large extent.
 A deficiency in the secretion of growth
(a) What was the cause of the swollen neck
hormone causes dwarfism whereas it
of children in the village?
excess secretion causes gigantism.
(b) What values are shown by Dr. Kamal?
46. Chemical coordination plays a vital (c) Why was use of iodised salt advised to
role in the activities of plants. Elaborate. villagers by Dr. Kamal?
Ans: Coordination in human beings is carried Ans:
out both by the nervous as well as the (a) The swollen neck is a disease called
hormonal system. But, coordination in plants goitre. Goitre occurs due to deficiency of
is dependent on the chemicals called as thyroxine hormone.
hormones. The hormone auxin and (b) Scientific aptitude, patience, problem
gibberellins help in the growth of the stem. solving ability and helpful nature.
Cytokinins help in cell division. Abscisic (c) The use of iodised salt was advised
acid inhibits growth. Auxin is also involved because Iodine helps in production of
in the bending of plants towards light. thyroxine hormone which helps to prevent
goiter.
47. The response of the body due to reflex
actions is faster than those carried out by 49 Akhilesh saw a plant in his school
secretion of adrenaline in emergency garden which closed its leaves on touching.
situations. Why? He observed the plant very closely for a
Ans: The reflex actions are the result of long time. In the recess, he saw that some
chemical-electrical impulses which are faster students were trying to pluck the plant
as they move through the nerve cell from one from the pot. He went to them and advised
them not to pluck the plant as it was their
school’s property. He also told them about glucose level. On the basis of the text,
the importance of the plants and the answer the following questions:
peculiar behavior of the said plant. In this (i) Name the disease he is suffering from
way, he was able to convince the students and name the hormone whose deficiency
to not harm the plant. causes it.
(a) Why did the leaves of the plant close on (ii) Identify the gland that secretes it and
touching? mention the function of this hormone.
(b) How is this response of plant different (iii) Explain how the time and amount of
from reflex action in animals? secretion of this hormone is regulated in
(c) What values are shown by Akhilesh? human system.
Answer: (iv) What values were shown by Smita and
(a) The leaves of the sensitive plants like her father? [CBSE 2012, 2015]
Touch-me-not close on touching as they lose Ans:
the liquor pressure in cells which causes (i) Disease-Diabetes, Hormone: Insulin
drooping of its leaves/leaflets. (deficiency of insulin hormone causes
(b)Movement in Sensitive Plant: diabetes)
1. The response is produced due to the (ii) Gland-Pancreas: The blood glucose level
change in amount of water in the plant is regulated by insulin hormone secreted by
cells. the pancreas.
2. No nerve or specialised tissue involved (iii) Cells of pancreas secrete insulin
in the conduction of information. hormone when level of blood glucose level
Reflex action: increases in the blood. Insulin regulates the
1. An automatic, immediate, involuntary blood glucose level and its secretion gets
response of an organism. reduced when blood glucose level falls down.
2. It is controlled by the spinal cord. (iv) Decision making, intelligence, scientific
(c) Environment friendly, responsible, aptitude and caring nature is shown by Smita.
leadership, analytical thinking. Her father had shown an attitude of
carelessness towards his health.

50.Smita’s father was complaining about

frequent urination, pain in legs and a
frequent weight loss to Smita’s mother
and she discussed the things with her
daughter when Smita returned from
school. Listening to this Smita told her
mother that her father should go and visit
a doctor immediately. The doctor
diagnosed that Smita’s father was having
an elevated level of blood glucose. He
should take care of his diet and should
exercise regularly to maintain his normal