Life processes are the series of actions, such as movement, respiration, sensitivity, growth, reproduction, excretion and nutrition that are essential for a living being to sustain.  The processes, which collectively perform the maintenance of our body system, are known as life processes. The maintenance processes protect us from damage and break-down; however, to keep these maintenance processes working properly, we need to provide energy to them. Healthy food is the best source of such energy.The processes, which collectively perform the maintenance of our body system, are known as life processes. The maintenance processes protect us from damage and break-down; however, to keep these maintenance processes working properly, we need to provide energy to them. Healthy food is the best source of such energy.The processes, which collectively perform the maintenance of our body system, are known as life processes. The maintenance processes protect us from damage and break-down; however, to keep these maintenance processes working properly, we need to provide energy to them. Healthy food is the best source of such energy.

1. Life Process
Class 10
Priya Jha
TGT Science
E@learning

2. Life processes are the series of
actions, such as movement,
respiration, sensitivity, growth,
reproduction, excretion and
nutrition that are essential for a
living being to sustain.

3. • The processes, which collectively perform the
maintenance of our body system, are known
as life processes.
• The maintenance processes protect us from
damage and break-down; however, to keep
these maintenance processes working
properly, we need to provide energy to them.
Healthy food is the best source of such energy.

4. • Question 1: Why is diffusion insufficient to meet the oxygen requirements of
multi-cellular organisms like humans?
• Answer: Multicellular organisms such as humans possess complex body designs.
They have specialised cells and tissues for performing various necessary
functions of the body such as intake of food and oxygen. Unlike unicellular
organisms, multicellular cells are not in direct contact with the outside
environment. Therefore, diffusion cannot meet their oxygen requirements.
• Question 2: What criteria do we use to decide whether something is alive?
• Answer: Any visible movement such as walking, breathing, or growing is
generally used to decide whether something is alive or not. However, a living
organism can also have movements, which are not visible to the naked eye.
Therefore, the presence of life processes is a fundamental criterion that can be
used to decide whether something is alive or not.
• Question 3: What are outside raw materials used for by an organism?
• Answer: An organism uses outside raw materials mostly in the form of food and
oxygen. The raw materials required by an organism can be quite varied
depending on the complexity of the organism and its environment.
• Question 4: What processes would you consider essential for maintaining life?
• Answer: Life processes such as nutrition, respiration, transportation, excretion,
etc. are essential for maintaining life.

5. Nutrition in Plants and Animals
• Nutrition: The process by which an organism takes food and
utilizes it, is called nutrition.
• Need for Nutrition: Organisms need the energy to perform
various activities. The energy is supplied by the nutrients.
Organisms need various raw materials for growth and repair.
These raw materials are provided by nutrients.
• Nutrients: Materials which provide nutrition to organisms are
called nutrients. Carbohydrates, proteins and fats are the
main nutrients and are called macronutrients. Minerals and
vitamins are required in small amounts and hence are called
micronutrients.

6. Modes of Nutrition
1. Autotrophic Nutrition.
2. Heterotrophic Nutrition

7. Autotrophic Nutrition
• The mode of nutrition in which an organism
prepares its own food is called autotrophic
nutrition. Green plants and blue-green algae
follow the autotrophic mode of nutrition.
• The organisms which carry out autotrophic
nutrition are called autotrophs (green plants).
• Autotrophic nutrition is fulfilled by the process,
by which autotrophs intake CO2 and H2O, and
convert these into carbohydrates in the presence
of chlorophyll, sunlight is called photosynthesis.

8. Equation

9. Nutrition in Plants:
• Green plants prepare their own food. They
make food in the presence of sunlight.
Sunlight provides energy’, carbon dioxide and
water are the raw materials and chloroplast is
the site where food is made.

10. What is Photosynthesis
• Photosynthesis: The process by which green plants
prepare food is called photosynthesis.
• During this process, the solar energy is converted into
chemical energy and carbohydrates are formed.
• Green leaves are the main site of photosynthesis.
• The green portion of the plant contains a pigment
chloroplast, chlorophyll (green pigment).
• The whole process of photosynthesis can be shown by
the following equation:
•

11. Raw Materials for Photosynthesis
• Sunlight
• Chlorophyll: Sunlight absorbed by chloroplast
• CO2: Enters through stomata, and oxygen (O2)
is released as a byproduct through stomata on
the leaf.
• Water: Water + dissolved minerals like
nitrogen, phosphorous etc., are taken up by
the roots from the soil.

12. How do raw materials for photosynthesis
become available to the plant?
• Water comes from the soil, through the xylem
tissue in roots and stems.
• Carbon dioxide comes in the leaves through
stomata

13. Site of Photosynthesis
• Chloroplast in the leaf. Chloroplast contains
chlorophyll (green pigment)
• https://www.youtube.com/watch?v=NVRtYPn
Z9MA
• Chlorophyll is necessary for Photosynthesis
• https://www.youtube.com/watch?v=-
Z7Daq7JuK4

14. Carbondioxide is necessary for
Photosynthesis
https://www.youtube.com/watch?
v=km_pMPuBcFc

15. Main Events of Photosynthesis:
• Absorption of light energy by chlorophyll.
• Conversion of light energy into chemical energy + splitting
(breaking) of water into hydrogen and oxygen.
• Reduction of CO2 to carbohydrates.
• Sunlight activates chlorophyll, which leads to splitting of the water
molecule.
• The hydrogen, released by the splitting of a water molecule is
utilized for the reduction of carbon dioxide to produce
carbohydrates.
• Oxygen is the by-product of photosynthesis.
• Carbohydrate is subsequently converted into starch and is stored
in leaves and other storage parts.
• The splitting of water molecules is a part of the light reaction.

16. Steps are part of the dark reaction
during photosynthesis.

17. Stomata
• Stomata: These are
tiny pores present in
the epidermis of leaf
or stem through
which gaseous
exchange and
transpiration occur.
• Functions of
stomata
• Exchange of gases,
O2 and CO2.
• Loses a large amount
of water (water
vapour) during
transpiration.

19. Opening and closing of stomatal pores:
• The opening and closing of
stomatal pores are controlled
by the turgidity of guard cells.
• When guard cells uptake water
from surrounding cells, they
swell to become a turgid body,
which enlarges the pore in
between (Stomatal Opening).
• While, when water is released,
they become flaccid shrinking
to close the pore (Stomatal
Closing).

20. Significance of Photosynthesis:
• Photosynthesis is the main way through which
solar energy is made available for different
living beings.
• Green plants are the main producers of food
in the ecosystem. All other organisms directly
or indirectly depend on green plants for food.
• The process of photosynthesis also helps in
maintaining the balance of carbon dioxide and
oxygen in the air.

21. Q)Where do plants get each of the raw
materials required for photosynthesis?
Ans)In the presence of sunlight, green plants use
photosynthesis to synthesize nutrients from carbon dioxide
and water. It includes chlorophyll, a green pigment that
produces oxygen as a by-product.
Required raw materials for photosynthesis:The
following raw materials are required for photosynthesis:
• Carbon Dioxide – Plants get CO2 from atmosphere through
stomata.
• Water – Plants absorb water from soil through roots and
transport to leaves.
• Sunlight – Sunlight, which is absorbed by the chlorophyll
and other green parts of the plant.

22. Heterotrophic Nutrition :The mode of
nutrition in which an organism takes
food from another organism is called
heterotrophic nutrition. Organisms,
other than green plants and blue-green
algae follow the heterotrophic mode of
nutrition. Heterotrophic nutrition can be
further divided into three types, viz.
saprophytic nutrition, holozoic nutrition,
and parasitic.

23. Saprophytic Nutrition:
• In saprophytic nutrition, the organism
secretes the digestive juices on the food. The
food is digested while it is still to be ingested.
The digested food is then ingested by the
organism. All the decomposers follow
saprophytic nutrition. Some insects, like
houseflies, also follow this mode of nutrition.

24. Holozoic Nutrition:
• In holozoic nutrition, the digestion happens
inside the body of the organism. i.e., after the
food is ingested. Most of the animals follow
this mode of nutrition.

25. Parasitic Nutrition:
• The organism which lives inside or outside
another organism (host) and derives nutrition
from it is known as parasites and this type of
mode of nutrition is called parasitic nutrition.
For example Cuscuta, tick etc.

26. Q)What are the differences between autotrophic
nutrition and heterotrophic nutrition?

27. Nutrition in Amoeba
• Amoeba is a unicellular animal which follows the
holozoic mode of nutrition.
• In holozoic nutrition, the digestion of food follows
after the ingestion of food. Thus, digestion takes
place inside the body of the organism.
• Holozoic nutrition happens in five steps, viz.
ingestion, digestion, absorption, assimilation and
egestion.

29. Steps of Holozoic Nutrition:
• Ingestion: The process of taking in the food is called
ingestion.
• Digestion: The process of breaking complex food
substances into simple molecules is called digestion. Simple
molecules, thus obtained, can be absorbed by the body.
• Absorption: The process of absorption of digested food is
called absorption.
• Assimilation: The process of utilization of digested food, for
energy and for growth and repair is called assimilation.
• Egestion: The process of removing undigested food from
the body is called egestion.

30. Nutrition in Amoeba
• Amoeba is a unicellular animal which follows the
holozoic mode of nutrition. The cell membrane of
amoeba keeps on protruding into pseudopodia.
Amoeba surrounds a food particle with
pseudopodia and makes a food vacuole. The food
vacuole contains food particle and water.
Digestive enzymes are secreted in the food
vacuole and digestion takes place. After that,
digested food is absorbed from the food vacuole.
Finally, the food vacuole moves near the cell
membrane and undigested food is expelled out.

31. Nutrition in Human Beings
• Human beings are complex animals, which
have a complex digestive system. The human
digestive system is composed of an alimentary
canal and some accessory glands. The
alimentary canal is divided into several parts,
like oesophagus, stomach, small intestine,
large intestine, rectum and anus. Salivary
gland, liver and pancreas are the accessory
glands which lie outside the alimentary canal

32. Structure of the Human Digestive
System:
• The human digestive system comprises of the
alimentary canal and associated digestive glands.
• Alimentary Canal: It comprises of mouth,
oesophagus, stomach, small intestine and large
intestine.
• Associated Glands: Main associated glands are
– Salivary gland
– Gastric Glands
– Liver
– Pancreas

33. Mouth or Buccal Cavity:
• The mouth has teeth and tongue. Salivary glands are also present in
the mouth.
• The tongue has gustatory receptors which perceive the sense of
taste.
• The tongue helps in turning over the food so that saliva can be
properly mixed in it.
• Teeth help in breaking down the food into smaller particles so that,
swallowing of food becomes easier.
• There are four types of teeth in human beings. The incisor teeth are
used for cutting the food.
• The canine teeth are used for tearing the food and for cracking hard
substances.
• The premolars are used for the coarse grinding of food. The molars
are used for fine grinding of food.

34. Salivary glands secrete saliva
• Saliva makes the food slippery which makes it
easy to swallow the food. Saliva also contains
the enzyme salivary amylase or ptyalin.
Salivary amylase digests starch and converts it
into sucrose, (maltose).

37. Oesophagus:
• Taking food from mouth to stomach by
Peristaltic movement.
Peristaltic movement: Rhythmic
contraction of muscles of the lining of the
alimentary canal to push the food forward.

38. Stomach
• Stomach is a bag-like organ. Highly muscular walls of
the stomach help in churning the food.
• The walls of the stomach secrete hydrochloric acid.
Hydrochloric acid kills the germs which may be present
in food.
• Moreover, it makes the medium inside the stomach as
acidic. The acidic medium is necessary for gastric
enzymes to work.
• The enzyme pepsin, secreted in the stomach, does
partial digestion of protein.
• The mucus, secreted by the walls of the stomach saves
the inner lining of the stomach from getting damaged
from hydrochloric acid.

40. Q)What causes movement of food
inside the alimentary canal?
Ans)Peristalsis mainly causes movement of food
inside the alimentary canal. The wall
of alimentary canal contains muscle layers.
Rhythmic contraction and relaxation or these
muscles pushes the food forward.

41. Q)What is the role of the acid in our
stomach?
Ans)The primary role of acid in our stomach is to
prevent infections in our stomach and to aid in
the digestion of food. Also known as gastric juice,
it is primarily composed of hydrochloric acid,
sodium chloride and potassium chloride.
• The acid also performs another crucial function –
denaturing proteins. The digestive enzymes such
as pepsin break down proteins so that it can be
absorbed by the body. An average human
produces around 1-5 litres of gastric acid every
day.

42. Small Intestine:
• It is a highly coiled tube-like structure. The small
intestine is longer than the large intestine but its
lumen is smaller than that of the large intestine.
The small intestine is divided into three parts, like
duodenum, jejunum and ileum.
• The beginning portion of the small intestine (the
duodenum) begins at the exit of the stomach
(pylorus) and curves around the pancreas to end
in the region of the left upper part of the
abdominal cavity where it joins the jejunum.

44. Liver:
• Liver is the largest organ in the human body.
The liver manufactures bile, which gets stored
in the gall bladder. From the gall bladder, bile
is released as and when required.

45. Pancreas:
Pancreas is situated below the stomach. It
secretes pancreatic juice which contains many
digestive enzymes.

46. Digestion in Small Intestine

48. • Bile and pancreatic juice go to the duodenum
through a hepatopancreatic duct. Bile breaks
down fat into smaller particles. This process is
called emulsification of fat. After that, the
enzyme lipase digests fat into fatty acids and
glycerol. Trypsin and chymotrypsin are
enzymes which digest protein into amino
acids. Complex carbohydrates are digested
into glucose. The major part of digestion takes
place in the duodenum.

49. Q)What is the function of digestive
enzymes?
Ans)Digestive enzymes break down polymeric macromolecules into smaller
building blocks to facilitate their absorption by the body. Thus, digestive
enzymes convert the food into smaller molecules that your tissues, cells,
and organs utilize for many metabolic functions.
• Amylase is defined as a digestive enzyme that breaks starch into small
carbohydrate molecules.
• Protease enzyme breaks down protein into amino acids, which are its
building blocks. The three main protease enzymes are trypsin, pepsin,
and chymotrypsin.
• Lipase enzyme breaks down dietary fats into smaller molecules known as
glycerol and fatty acids. In addition, a small quantity of lipase, known as
gastric lipase, is produced by the cells of the stomach.
• Proteases are produced in the stomach and pancreas. The main ones are:
pepsin, trypsin, chymotrypsin, carboxypeptidase A and carboxypeptidase
B

50. No digestion takes place in the
jejunum:
• The inner wall in the ileum is projected into
numerous finger-like structures, called villi.
Villi increase the surface area inside the ileum
so that optimum absorption can take place.
Moreover, villi also reduce the lumen of the
ileum so that food can stay for a longer
duration in it, for optimum absorption.
Digested food is absorbed by villi.

51. Q)How is the small intestine designed
to absorb digested food?
Answer) The small intestine has millions of tiny
finger-like projections called villi. These villi
increase the surface area for more efficient
food absorption. Within these villi, many
blood vessels are present that absorb the
digested food and carry it to the blood stream.
From the blood stream, the absorbed food is
delivered to each and every cell of the body.

53. Q)How are fats digested in our bodies?
Where does this process take place?
Ans)Fats are digested in the small intestine. The
secretion of liver, called bile, breaks down the
large globules of fat into smaller globules. This
is called emulsification of fats. The bile also
makes the medium alkaline so that the
pancreatic enzyme containing lipase further
digest fats to form fatty acids.

54. Q)What is the significance of
emulsification of fats?
Ans)Bile salts help in the breakdown of oil
droplets into small globules forming a
milky emulsion. This process is
called emulsification. This process facilitates
further digestion of fats. Steapsin is a
pancreatic lipase which acts on the
already emulsified fats and converts them to
fatty acids and glycerol.

55. Q)Match the terms in Column (A) with
those in Column (B)
Column(A) Column(B)
a)Trypsin (i)Pancreas
b) Amylase (ii) Liver
c) Bile (iii) Gastric glands
d) Pepsin (iv) Saliva

56. Large Intestine:
• Large intestine is smaller than the small intestine.
• Undigested food goes into the large intestine.
• Some water and salt are absorbed by the walls of
the large intestine. After that, the undigested
food goes to the rectum, from where it is
expelled out through the anus.
• Large Intestine bbsorb excess of water. The rest of
the material is removed from the body via the
anus. (Egestion).

57. Respiration

58. Respiration
• The process by which a living being utilises the
food to get energy, is called respiration.
Respiration is an oxidation reaction in which
carbohydrate is oxidized to produce energy.
Mitochondria is the site of respiration and the
energy released is stored in the form of ATP
(adenosine triphosphate). ATP is stored in
mitochondria and is released as per need.

59. Steps of respiration:
• Breaking down of glucose into pyruvate: This step happens
in the cytoplasm. Glucose molecule is broken down into
pyruvic acid. Glucose molecule is composed of 6 carbon
atoms, while pyruvic acid is composed of 3 carbon atoms.
• Fate of Pyruvic Acid: Further breaking down of pyruvic acid
takes place in mitochondria and the molecules formed
depend on the type of respiration in a particular organism.
Respiration is of two types, viz. aerobic respiration and
anaerobic respiration.
• Respiration involves
– Gaseous exchange: Intake of oxygen from the atmosphere and
release of CO2 → Breathing.
– Breakdown of simple food in order to release energy inside the
cell → Cellular respiration

60. Types of Respiration
• Aerobic respiration: This type of respiration happens in
the presence of oxygen. Pyruvic acid is converted into
carbon dioxide. Energy is released and water molecule
is also formed at the end of this process.
• Anaerobic respiration: This type of respiration
happens in the absence of oxygen. Pyruvic acid is
either converted into ethyl alcohol or lactic acid. Ethyl
alcohol is usually formed in case of anaerobic
respiration in microbes, like yeast or bacteria. Lactic
acid is formed in some microbes as well as in the
muscle cells.

61. Q) What are the differences between aerobic and anaerobic
respiration? Name some organisms that use the anaerobic
mode of respiration.
• Ans) Anaerobic respiration occurs in the roots of some waterlogged plants,
some parasitic worms, animal muscles, and some micro-organisms such as yeasts.
Aerobic respiration Anaerobic respiration
1. It occurs in the presence of
O2.
1. It occurs in the absence of
O2.
2. It involves the exchange of
gases between the organism
and the outside environment.
2. Exchange of gases is absent.
3. It occurs in cytoplasm and
mitochondria
3. It occurs only in cytoplasm.
4. It always releases CO2 and
H2O.
4. End products vary.
5. It yields 36 ATPs. 5. It yields only 2 ATPs.

62. The equations for the above reactions
can be written as follows:

63. Pain in leg muscles while running:
• When someone runs too fast, he may experience
throbbing pain in the leg muscles. This happens
because of anaerobic respiration taking place in
the muscles.
• During running, the energy demand from the
muscle cells increases. This is compensated by
anaerobic respiration and lactic acid is formed in
the process.
• The deposition of lactic acid causes pain in the leg
muscles. The pain subsides after taking rest for
some time.

64. Q)What advantage over an aquatic organism does a
terrestrial organism have with regard to obtaining
oxygen for respiration?
• Ans) Terrestrial organisms take up oxygen from
the atmosphere whereas aquatic animals need to
utilize oxygen present in the water. Air contains
more O2 as compared to water. Since the content
of O2 in air is high, the terrestrial animals do not
have to breathe faster to get more oxygen.
Therefore, unlike aquatic animals, terrestrial
animals do not have to show various adaptations
for better gaseous exchange.

65. Q)What are the different ways in which glucose is
oxidized to provide energy in various organisms?
Ans) Glucose is first broken down in the cell
cytoplasm into a three carbon molecule called
pyruvate. Pyruvate is further broken down by
different ways to provide energy.
The breakdown of glucose by different
pathways can be illustrated as follows.

67. In yeast and human muscle
cells, the breakdown of pyruvate occurs in the
absence of oxygen whereas in mitochondria,
the breakdown of pyruvate occurs in the
presence of oxygen.

68. Human respiratory system
• The human respiratory system is composed of
a pair of lungs. These are attached to a system
of tubes which open on the outside through
the nostrils.
Following are the main structures in the
human respiratory system:

69. • Nostrils: There are two nostrils which converge to form a nasal
passage. The inner lining of the nostrils is lined by hair and remains
wet due to mucus secretion. The mucus and the hair help in filtering
the dust particles out from inhaled air. Further, air is warmed up
when it enters the nasal passage.
• Pharynx: It is a tube-like structure which continues after the nasal
passage.
• Larynx: This part comes after the pharynx. This is also called voice
box.
• Trachea: This is composed of rings of cartilage. Cartilaginous rings
prevent the collapse of trachea in the absence of air.
• Bronchi: A pair of bronchi comes out from the trachea, with one
bronchus going to each lung.
• Bronchioles: A bronchus divides into branches and sub-branches
inside the lung.
• Alveoli: These are air sacs at the end of bronchioles. The alveolus is
composed of a very thin membrane and is the place where blood
capillaries open. This is alveolus, where the oxygen mixes with the
blood and carbon dioxide exits from the blood. The exchange of
gases, in alveoli, takes place due to the pressure differential.

72. Q) How are the lungs designed in human beings to
maximize the area for exchange of gases?
• Answer: The exchange of gases takes place between
the blood of the capillaries that surround the alveoli
and the gases present in the alveoli. Thus, alveoli are
the site for exchange of gases. The lungs get filled up
with air during the process of inhalation as ribs are
lifted up and diaphragm is flattened. The air that is
rushed inside the lungs fills the numerous alveoli
present in the lungs.
Each lung contains 300-350 million alveoli. These
numerous alveoli increase the surface area for gaseous
exchange making the process of respiration more
efficient.

74. Breathing Mechanism
• The breathing mechanism of lungs is controlled
by the diaphragm and the intercostalis muscles.
• The diaphragm is a membrane which separates
the thoracic chamber from the abdominal cavity.
• When the diaphragm moves down, the lungs
expand and the air is inhaled.
• When the diaphragm moves up, the lungs
contract and air are exhaled.

77. Labelled diagram of Human
Respiratory System

78. How to draw respiratory system?
https://www.youtube.com/watch?
v=MTbjYgWR1eo

79. Q) What would be the consequences of a deficiency of
haemoglobin in our bodies?
Ans) Haemoglobin is the respiratory pigment
that transports oxygen to the body cells for
cellular respiration. Therefore, deficiency of
haemoglobin in blood can affect the oxygen
supplying capacity of blood. This can lead to
deficiency of oxygen in the body cells. It can
also lead to a disease called anaemia.

80. Q) Explain the transportation of oxygen and carbon
dioxide in human beings.
Ans)Exchange of gases takes place between the alveoli of lungs and
the surrounding blood capillaries. The two main gases exchanged
are oxygen and carbon-dioxide. Oxygen is absorbed by the blood
capillaries from the lungs alveoli by diffusion while carbon dioxide
is absorbed by the lungs alveoli from blood capillaries by
diffusion. Transport of oxygen and carbon dioxide occurs with the
help of respiratory pigment called hemoglobin.
Haemoglobin, the iron-containing respiratory pigment is a
red coloured pigment of blood, which has a very high affinity for
oxygen. Haemoglobin though is purple coloured but
oxyhemoglobin is of bright red colour. Oxygen is transported from
lungs to the body cells in the form of oxyhemoglobin. Carbon
dioxide is transported from the body cell to the lungs in the forms
of carboxyhemoglobin, carbonic acid, bicarbonates of sodium and
potassium.

81. Q)Why do fishes die when taken out of
water?
Ans) When the water reaches the fish via its
mouth, the dissolved oxygen is taken inside
and the carbon dioxide is released. -
When fishes are taken out of the water, the
supply of oxygen to the fish is reduced as they
cannot respire using the oxygen present in the
atmosphere. Thus, they will die when taken
out of water.

82. Q)Name the energy currency in the
living organisms. When and where is it
produced?
Ans) ATP (Adenosine Triphosphate) is the energy
currency in the living organisms.
It is produced at the end of respiration in
mitochondria

83. Which of the following statement(s) is
(are) correct?
(i) Pyruvate can be converted into ethanol and
carbon dioxide by yeast
(ii) Fermentation takes place in aerobic bacteria
(iii) Fermentation takes place in mitochondria
(iv) Fermentation is a form of anaerobic
respiration
• (a) (i) and (iii) (b) (ii) and (iv)
• (c) (i) and (iv). (d) (ii) and (iii)

84. Transportation
Circulatory system of human being,
transportation in plants. Human beings like
other multicellular organism need a regular
supply of foods, oxygen etc. This function is
performed by a circulatory system or
transport system.

85. Transportation in Human Beings:
• The circulatory system is responsible for
transport of various substances in human
beings. It is composed of the heart, arteries,
veins and blood capillaries. Blood plays the
role of the carrier of substances.

87. https://www.youtube.com/watch?
v=CWFyxn0qDEU&ab_channel=Ma
yoClinic

89. Q) What is the advantage of having
four chambered heart?
Ans) In four chambered heart left half is
completely separated from right half by septa.
This prevents oxygenated and deoxygenated
blood from mixing. This allows a highly
efficient supply of oxygenated blood to all
parts of the body. This is useful in animals that
have high energy needs such as birds and
mammals.

90. Q) Why is it necessary to separate oxygenated
and deoxygenated blood in mammals and
birds?
• Ans) Warm-blooded animals such as birds and
mammals maintain a constant body temperature
by cooling themselves when they are in a hotter
environment and by warming their bodies when
they are in a cooler environment. Hence, these
animals require more oxygen (O2) for more
cellular respiration so that they can produce
more energy to maintain their body temperature.
Thus, it is necessary for them to separate
oxygenated and de-oxygenated blood, so that
their circulatory system is more efficient and can
maintain their constant body temperature.

91. Heart
• Heart is a muscular organ, which is composed of
cardiac muscles.
• It is so small that, it can fit inside an adult’s wrist. The
heart is a pumping organ which pumps the blood.
• The human heart is composed of four chambers, viz.
right atrium, right ventricle, left ventricle and left
atrium.
• Systole: Contraction of cardiac muscles is called systole.
• Diastole: Relaxation of cardiac muscles is called
diastole.

92. Arteries
• These are thick-walled blood vessels which
carry oxygenated blood from the heart to
different organs.
• Pulmonary arteries are exceptions because
they carry deoxygenated blood from the heart
to lungs, where oxygenation of blood takes
place.

93. Veins
• These are thin-walled blood vessels which
carry deoxygenated blood from different
organs to the heart, pulmonary veins are
exceptions because they carry oxygenated
blood from lungs to the heart.
• Valves are present in veins to prevent back
flow of blood.

94. Q)Differentiate between an artery and
a vein.

96. Capillaries
• These are the blood vessels which have single-
celled walls.

97. Blood: Blood is a connective tissue which
plays the role of the carrier for various
substances in the body. Blood is composed of
1. Plasma 2. Blood cells 3. Platelets.

98. • Blood plasma: Blood plasma is a pale coloured
liquid which is mostly composed of water.
Blood plasma forms the matrix of blood.

99. • Platelets: Platelets are responsible for blood
coagulation. Blood coagulation is a defense
mechanism which prevents excess loss of
blood, in case of an injury.

100. Lymph:
• Lymph is similar to blood but RBCs are absent in lymph.
• Lymph is formed from the fluid which leaks from blood
capillaries and goes to the intercellular space in the
tissues. This fluid is collected through lymph vessels
and finally return to the blood capillaries.
• Lymph also plays an important role in the immune
system.
• Lymph a yellowish fluids escape from the blood
capillaries into the intercellular spaces contain less
proteins than blood.
• Lymph flows from the tissues to the heart assisting in
transportation and destroying germs.

101. • Lymph is the fluid that flows through the
lymphatic system, a system composed of
lymph vessels and intervening lymph nodes
whose function, like the venous system, is to
return fluid from the tissues to the central
circulation.

102. Differences between Blood and Lymph

103. Double circulation:
In the human heart, blood passes through the heart
twice in one cardiac cycle. This type of circulation is
called double circulation. One complete heartbeat in
which all the chambers of the heart contract and relax
once is called cardiac cycle. The heart beats about 72
times per minute in a normal adult. In one cardiac
cycle, the heart pumps out 70 mL blood and thus,
about 4900 mL blood in a minute. Double circulation
ensures complete segregation of oxygenated and
deoxygenated blood which is necessary for optimum
energy production in warm-blooded animals.

104. Q) Why is blood circulation in human
heart called double circulation
Ans) In human heart, blood passes through the
heart twice during one cardiac cycle. The
deoxygenated blood comes to the heart and
goes to the lungs for oxygenation.
Simultaneously, the oxygenated blood comes
to the heart from lungs and goes to different
organs. Due to this. blood circulation in
human heart is called double circulation.

107. Blood pressure
• The force that blood exerts against the wall of
a vessel is called blood pressure. This pressure
is much greater in arteries than in veins. The
pressure of blood inside the artery during
ventricular systole (contraction) is called
systolic pressure and pressure in artery during
ventricular diastole (relaxation) is called
diastolic pressure. The normal systolic
pressure is about 120 mm of Hg and diastolic
pressure is 80 mm of Hg.

108. Blood pressure is measured with an
instrument called sphygmomanometer

109. Q) What is hypertension?
Ans)High blood pressure (hypertension) is a condition in
which the force of the blood against the artery walls is too
high.
• Usually hypertension is defined as blood pressure above
140/90, and is considered severe if the pressure is above
180/120.
• High blood pressure often has no symptoms. Over time, if
untreated, it can cause health conditions, such as heart
disease and stroke.
• Eating a healthier diet with less salt, exercising regularly
and taking medication can help lower blood pressure.

110. Transportation in plants
• Like all living organism, plants also require an excretory
system to discharge excess water from their body. This
process of elimination of excess water from the plant
body is known as transpiration. It is generally the
evaporation of water from the surface of the leaves.
• During the process of transpiration, water molecules in
the plant tissues are removed from the aerial parts of
the plants. Only a small amount of water absorbed by
the plants is utilised in growth and development. The
rest is eliminated in the form of transpiration.

112. Types of Transpiration
A)Stomatal Transpiration
• It is the evaporation of water from the stomata of the plants. Most of the
water from the plants is transpired this way. The water near the surface
of the leaves changes into vapour and evaporates when the stomata are
open.
B)Lenticular Transpiration
• Lenticels are minute openings in the bark of branches and twigs.
Evaporation of water from the lenticels of the plants is known as
lenticular transpiration.
• Lenticels are not present in all the plants. A minimal amount of water is
lost through lenticels.
C)Cuticular Transpiration
• It is the evaporation of water from the cuticle of the plants. The cuticle is
a waxy covering on the surface of the leaves of the plants. About 5-10%
of the water from the leaves is lost through cuticular transpiration.
During dry conditions when the stomata are closed, more water is
transpired through the cuticles.

113. Guttation
• Guttation is a type of secretion which occurs
in low-temperature conditions only through
the margin of the leaves. Both these process
cause permanent loss of water from the
plants.

114. Xylem and phloem facilitate the
transportation of water, minerals and food
throughout the plant. Xylem carries water and
minerals from the roots to the leaves.
Whereas, phloem carries the food prepared
by the leaves to different parts of the plant.

115. Q) Why and how does water enter
continuously into the root xylem?
Ans)Root hair have thin walls. Due to this,
water enters the root hair because of
osmosis. Water from root hair continuously
moves into the root xylem. To maintain the
osmotic gradient, the cells of root hair
actively take up ions from the soil.

116. Xylem
• Xylem is responsible for transportation of water
and minerals. It is composed of trachids, xylem
vessels, xylem parenchyma and xylem fibre.
Tracheids and xylem vessels are the conducting
elements. The xylem makes a continuous tube in
plants which runs from roots to stem and right up
to the veins of leaves.
• Carry water and minerals from the leaves to the
other part of the plant.

117. Phloem
• Phloem is responsible for transportation of
food. Phloem is composed of sieve tubes,
companion cells, phloem parenchyma and
bast fibers. Sieve tubes are the conducting
elements in phloem.
• Carries product of photosynthesis from roots
to other part of the plant.

119. Transport of food
• Transport of food in plants happens because
of utilization of energy. Thus, unlike the
transport through xylem, it is a form of active
transport. Moreover, the flow of substances
through phloem takes place in both directions,
i.e., it is a two-way traffic in phloem.
Transpiration is the process of loss of water as
vapour from aerial parts of the plant.
• Transport of food from leaves (food factory) to
different parts of the plant is called
Translocation.

120. Q)Are xylem cells dead?
Ans)Xylem cells are made up of a long chain of
dead cells known as vessel elements. The
vessel elements have no organelles. The
components of xylem tissues are highly
lignified and scalarified. Hence, xylem cells are
considered dead.

121. Q)Why are the phloem cells alive?
Ans)The cells that make up the phloem tissues
need to be alive to facilitate the active
transport of sucrose throughout the plant.

124. Factors affecting transpiration in plants
A)Cellular Factors B) Environmental Factors
A)Cellular Factors:
The cellular factors affecting the rate of
transpiration are:
• The orientation of leaf,
• The water status of the plant,
• Structural Peculiarities of the leaf,
• Total number and distribution of stomata in a
leaf.

125. B)Environmental Factors are :
• Light,
• Humidity,
• Temperature,
• Atmospheric pressure,
• Wind speed or velocity.

126. Ascent of Saps
When water evaporates through the leaves, a pull is
created through the xylem, and water moves back to
the leaves. This is known as the transpiration pull.
The ascent of sap that is driven by transpiration depends
on the following properties of water:
• Cohesion – This is the mutual attraction between
molecules of water.
• Adhesion – The attraction of water molecules towards
polar surfaces.
• Surface tension – The molecules of water are more
attracted to each other in the liquid phase than in the
gas phase.

127. Opening and Closing of Stomata

128. Q)Why is transpiration important for plants?
Ans) Significance of Transpiration in Plants are:
• The significance of transpiration is explained below:
• Transpiration helps in the conduction of water and minerals to
different parts of the plants.
• Due to the continuous elimination of water from the plant body,
there is a balance of water maintained within the plant.
• It maintains osmosis and keeps the cells rigid.
• A suction force is created by transpiration that helps in the
upward movement of water in the plants.
• Certain hydrophilic salts are accumulated on the surface of the
leaves, which keeps the leaves moist.
• It maintains the turgidity of the cells and helps in cell division.
• Optimum transpiration helps in the proper growth of the plants.
• The cooling effect of a tree is due to the evaporation of water
from its leaves.

129. Excretion
• The biological process of removal of harmful
nitrogenous metabolic waste from the body is
called excretion.
• Unicellular organisms excrete by diffusion and
multicellular organisms use specialized organ to
perform same function.
• For example- Aquatic animals excrete waste in
the form of ammonia, while birds and insects
excrete mainly uric acid. Humans produce urea as
the major excretory product.

130. • We all obtain our nutrients from different sources
which are later digested and metabolized in our
body. After metabolic reactions, the body starts
to sort out useful and toxic substances in
an individual. As we all know, the accumulation of
the toxins may be harmful and the body removes
all the metabolic wastes by the process called
excretion.
• Different organisms follow different modes of
excretion such as kidney, lungs, skin and eyes
depending on their habitat and food habit.

131. Excretory System Organs
The human excretory system organs include:
• A pair of kidneys
• A pair of ureters
• A urinary bladder
• A urethra

132. Kidneys
• Kidneys are bean-shaped structures located on either
side of the backbone and are protected by the ribs and
muscles of the back. Each human adult kidney has a
length of 10-12 cm, a width of 5-7 cm and weighs
around 120-170g.
• The kidneys have an inner concave structure. The
blood vessels, ureter and nerves enter the kidneys
through the hilum, which is a notch at the inner
concave surface of the kidney. The renal pelvis, a large
funnel-shaped space is present inner to the hilum, is
has many projections known as calyces

135. Structure of Kidney
• Capsule:The outer layer is called the capsule.
Inside the kidney, there are two zones- the
outer zone is the cortex and the inner zone is
the medulla. The cortex extends in between
the medullary pyramids as renal columns
called columns of Bertin.

136. • Nephrons:
• “Nephron is the basic functional unit of kidneys that
consists of a glomerulus and its associated tubules
through which the glomerular filtrate passes before it
emerges as urine”
• Nephrons are the functional units of the kidney. Each
nephron has two parts- glomerulus and renal tubule.
Glomerulus consists of a bunch of capillaries formed by
afferent arterioles. Blood from glomerulus is carried away
by efferent arterioles.
The renal tubule starts with a cup-like structure called
Bowman’s capsule and this encloses the glomerulus. The
malpighian body consists of glomerulus and Bowman’s
capsule. The highly coiled structure in the tubule next to
the Bowman’s capsule is the proximal convoluted tubule.

139. • Henle’s loop:The next part of the tubule is Henle’s loop
which has an ascending and a descending limb. The
ascending loop continues as a distal convoluted tubule.
The distal convoluted tubules of many nephrons open
into the collecting duct.
The cortical region of the kidney comprises of
malpighian corpuscle, proximal convoluted tubule and
distal convoluted tubule and the medullary region
contains a loop of Henle.
There are two types of nephrons – cortical and
juxtamedullary. In the case of cortical, the loop of
Henle is very short and extends only a little into the
medulla. In juxtamedullary, the loop of Henle is very
long and runs deep into the medulla.

140. • Ureter:A pair of thin muscular tubes called the
ureter comes out of each kidney extending from
the renal pelvis. It carries urine from the kidney
to the urinary bladder.
• Urinary Bladder:It is a muscular sac-like
structure, which stores urine. The urinary bladder
is emptied by the process of micturition, i.e. the
act of urination.
• Urethra:This tube arises from the urinary bladder
and helps to expel urine out of the body. In
males, it acts as the common route for sperms
and urine. Its opening is guarded by sphincter
muscles.

142. Excretion in Humans:Mechanism of Excretion in Humans
The process of excretion in humans takes place in the following steps:
• Urine Formation:The urine is formed in the nephrons and involves the
following steps:
• Glomerular Filtration
• Tubular Reabsorption
• Secretion
• Glomerular Filtration:It is the primary step in urine formation. In this
process, the excess fluid and waste products from the kidney are filtered
out of the blood into the urine collection tubules of the kidney and
eliminated out of the body..The amount of filtrate produced by the
kidneys every minute is known as Glomerular Filtration Rate (GFR).
• Tubular Reabsorption:It is the absorption of ions and molecules such as
sodium ions, glucose, amino acids, water etc. Water involves passive
absorption, while glucose and sodium ions are absorbed by an active
process.
• Secretion:Potassium ions, hydrogen ions, and ammonia are secreted out
to maintain the equilibrium between the body fluids.

143. Micturition
• The urinary bladder is stretched and gets filled
with urine formed in the nephrons. The
receptors present on the walls of the urinary
bladder send signals to the Central Nervous
System thereby, allowing the relaxation of
sphincter muscles to release urine. This is
known as micturition.

144. Q) How is the amount of urine produced
regulated?
Ans) The amount of urine produced depends on
the amount of excess water and dissolved
wastes present in the body. Some other
factors such as habitat of an organism and
hormone such as Anti-diuretic hormone (ADH)
also regulates the amount of urine produced.

145. Dialysis
• Under certain circumstances such as poor
blood flow to the kidneys, infections, injuries,
etc. the kidneys fail to perform their functions.
In such situations, artificial kidneys are used
for blood filtration and this process is called
dialysis.
• Dialysis is the process of filtering and purifying
the blood with the help of a machine. This
balances our fluids and electrolytes when the
kidneys stop functioning. It is used to treat
people suffering from kidney disorders.

146. Q) What are the steps included in the elimination of
wastes?
Ans)The steps included in the elimination of
wastes are- glomerular filtration,
reabsorption, and secretion. These processes
remove only excess water and waste from the
body.

147. Q) What are the important functions of the
human excretory system?
Ans) The important functions performed by the
excretory system include- elimination of
wastes, eliminate waste byproducts excreted
by the cells, prevent the accumulation of
harmful chemicals in the body, and maintain a
balanced chemical concentration in the body.

148. Q) Why is excretion a vital process in the human
body?
Ans) The process of excretion helps to remove
the waste products from the body. If these are
allowed to accumulate, they cause poisoning
in the body that slows down the other
important processes in the body.

149. Q) What are the important human excretory
organs?
Ans) The important human excretory organs are-
kidneys, ureter, urethra, urinary bladder, skin,
liver, intestine and lungs.

150. Q) What are the different types of wastes
eliminated by living organisms?
Ans) The different types of wastes eliminated by
the living organisms include- ammonia, urea,
and uric acid and the organisms are classified
as ammonotelic, ureotelic and uricotelic
respectively based on the type of nitrogenous
waste eliminated by the body.

151. Excretion in plants
• Oxygen, a waste product of photosynthesis is
released.
• Excess water is removed by transpiration.
• Some waste products may get stored in the leaves
which fall off.
• Many waste products are stored in vacuoles.
• Some waste products are stored as resins and
gums in old xylem.
• Plants excrete some waste materials into the soil
around them.

152. • Other wastes may be stored in leaves, bark
etc. which fall off from the plant.
• Plants excrete some waste into the soil around
them.
• Gums, resin → In old xylem
• Some metabolic wastes in the form of crystals
of calcium oxalates in the leaves of colocasia
and stem of Zamikand.

153. Q) What are the methods used by plants to get
rid of excretory products?
Ans) : Plants can get rid of excess of water by
transpiration. Waste materials may be stored
in the cell vacuoles or as gum and resin,
especially in old xylem. It is also stored in the
leaves that later fall off.

154. Q) Compare the functioning of alveoli in the lungs and
nephrons in the kidneys with respect to their
structure and functioning.
Ans)

155. Q) Explain the importance of soil for plant growth.
Answer.
Ans) Materials required for plant growth are
obtained from soil, e.g. Nitrogen, Phosphorus,
other minerals and water. They have to be
transported to long distances depending upon
the size of the plants. Xylem moves water and
minerals from soil to aerial parts. Soil also
helps in anchoring plant, availability of oxygen
for respiration of root cells and symbiotic
association with microbes.

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