Blood
vascular system may be
open or closed. In open circulatory system, blood flows partly through vessels and partly through haemocoelomic spaces. In
a closed circulatory
system, the blood vessels form
a complete circuit in the body, carrying blood to and away from the organs. Closed circulatory system occurs in annelids (earthworm),
some molluscs (cephalopods), echinoderms and all vertebrates. 😍
The blood in open circulatory system is
called haemolymph. Open circulatory system is found in some
molluscs and in some arthropods. In a closed circulatory
system, the blood vessels form a complete
circuit in the body, carrying blood to and away from the organs.😀
Blood is a fluid connective tissues that circulates through the heart, arteries, capillaries and veins, carrying nutrients and oxygen to the body cells. Major elements of blood consists of cellular (RBC, WBC,
platelets)
and fluid (plasma) elements.😀
Plasma contains three major
classes of plasma proteins viz. serum albumin, serum globulins and fibrinogen. They serve as a source of proteins for tissue cells. 😀
Albumin and globulins
retain water in blood plasma
by their osmotic effects. Plasma functions in (a) transport (b) body immunity (c)
prevention of blood loss (d) retention of fluid in blood (e) maintenance of blood pH (f) uniform distribution of heat all over the
body, and (g) conduction of heat to skin for dissipation.😀
Haemoglobin is the gas transporting
protein molecule that makes up 95% of a red
blood cell. Each red blood cell has about
270,000,000 iron rich
haemoglobin molecules.😀
Optimum amount of haemoglobin in male is
about 16
gm/100 ml blood and
13-14 gm/100 ml blood in female.😀
Process
of RBC formation is known
as erythropoiesis (completed in 72 hours). The ageing cells (RBC) swell up to a
spherelike shape and are engulfed by phagocytes,
destroyed and their materials are released into the blood. The main sites of destruction are the liver and the
spleen. The heme constituent of haemoglobin is eventually excreted as bilirubin.😀
Leucocytes are larger than red blood cells and have a
definite nucleus. Leucocytes can be divided into two
components-
granulocytes (polymorphonuclear leucocytes)
and agranulocytes (mononuclear
leucocytes).😀
Neutrophil,
eosinophil and
basophil are categorised as granulocytes. 😀
Neutrophils (constitute 60 - 70%) can
be recognized by their segmented nuclei and the presence of abundant, small, pale staining granules in their cytoplasm.😀
Neutrophils are the most abundant and are produced
in red bone marrow.😀
Neutrophils are active in
phagocytosis, play a role in the
healing of wounds and repairing worn out
and damaged tissue; and prevent infections from
spreading to other tissues of the body.😀
Nongranular
leucocytes (or mononuclear leucocytes) can be grouped into two
classes - lymphocytes and monocytes.😀
Lymphocytes are produced in the
spleen, tonsils and lymph nodes and
are the smallest of the white blood
cells. Lymphocytes
are of two
types - B and T
lymphocyte.😀
Lymphocytes are involved in the
synthesis and distribution
of antibodies in the blood. The B cells are responsible for humoral or antibody
immunity and T cells are responsible for cellular immunity.😀
Serum is a pale yellow fluid that separates from the blood upon coagulation,when all cellular elements are removed.😀
Anticoagulants like heparin, sodium or potassium oxalate are chemical substances which prevent blood clotting. The cation necessary for
coagulation of blood is calcium.😀
Platelet aggregation and fibrin formation
both require the proteolytic enzyme thrombin. Platelets are the source of
thromboplastin. Lymph, chiefly made of plasma and leucocytes is an interstitial fluid, present between the cells
of a tissue.😀
If the formation rate of lymph exceeds the
rate of its return to blood then
oedema occurs. Blood groups are the special characteristic of blood in human and related primates due to the presence of genetically controlled
antigens and antibodies.😀
Antigens are relatively large proteins molecules that provide the biological signative of an individuals blood type.😀
Within blood there are substances called
antibodies which distinguish particular antigen from others and causing bursting or agglutination of the
red blood cells when alien antigen are found.😀
More than 20 different blood
group systems are recognized in medicine. Of these, the best
known are the ABO system and the Rh system.😀
The antigens of ABO systems are A, B and H. The H antigen is the precursor to the A and
B antigens.😀
What is the Positive and Negative sign attached to blood Group like A+ or A-?
That shows the presence or absence of Rhesus (Rh) factor. Rh factor is an antigen (a type of protein that is inherited) on the surface of red blood cells. For example if your blood group is A+, it means your blood group is A with the presence of Rh factor. Majority of people are Rh positive. It is an issue when a Rh negative pregnant mother having a Rh positive baby. The body might not recognise the Rh factor presented in the baby and treat that as a foreign particle in the body. Hence, the antibodies in the mother would attack the baby’s blood cells. Therefore, pregnant ladies are always given a blood group test.
NCERT Questions With Answers
Chapter :- Life Process
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.
Question
1:
What are the differences between autotrophic nutrition and
heterotrophic nutrition? Answer
|
Autotrophic
nutrition
|
|
Heterotrophic
nutrition
|
(i)
|
Food
is synthesised from simple inorganic raw materials such as CO2 and
water.
|
(i)
|
Food is obtained directly or indirectly from
autotrophs. This food is broken down with the help of enzymes.
|
(ii)
|
Presence of green pigment (chlorophyll) is
necessary.
|
(ii)
|
No pigment is required in
this type of nutrition.
|
(iii)
|
Food
is generally prepared during day time.
|
(iii)
|
Food can be prepared at all
times.
|
(iv)
|
All
green plants and some bacteria have this type of nutrition.
|
(iv)
|
All
animals and fungi have this type of nutrition.
|
Question 2:
Where do plants get each of the raw materials required for
photosynthesis? Answer
The following raw materials are required for photosynthesis:
• The raw material
CO2 enters from the atmosphere through stomata.
• Water is absorbed
from the soil by the plant roots.
• Sunlight,
an important component to manufacture food, is absorbed by the chlorophyll and
other green parts of the plants.
Question 3:
What is the role of the acid in our stomach? Answer
The hydrochloric acid present in our stomach dissolves bits of food
and creates an acidic medium. In this acidic medium, enzyme pepsinogen is
converted to pepsin, which is a protein-digesting enzyme.
Question 4:
What is the function of digestive enzymes? Answer
Digestive enzymes such as amylase, lipase, pepsin,
trypsin, etc. help in the breaking down of complex food particles into simple
ones. These simple particles can be easily absorbed by the blood and thus
transported to all the cells of the body.
Question
5:
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.
Enlarged view of a villus
Question
1:
What advantage over an aquatic organism does a terrestrial organism
have with regard to obtaining oxygen for respiration?
Answer
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.
Question 2:
What are the different ways in which glucose is oxidized to provide
energy in various organisms? Answer
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.
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.
Question 3:
How is oxygen and carbon dioxide transported in human beings? Answer
Haemoglobin transports oxygen molecule to all the body cells for
cellular respiration. The haemoglobin pigment present in the blood gets
attached to four O2 molecules that are obtained from breathing. It
thus forms oxyhaemoglobin and the blood becomes oxygenated. This oxygenated
blood is then distributed to all the body cells by the heart. After giving away
O2 to the body cells, blood takes away CO2 which is the
end product of cellular respiration. Now the blood becomes de-oxygenated.
Since haemoglobin pigment has less affinity for CO2,
CO2 is mainly transported in the dissolved form. This de-oxygenated
blood gives CO2 to lung alveoli and takes O2 in return.
Transportation of O2
and CO2 in blood
Question
4:
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.
Question 1:
What are the components of the transport system in human beings?
What are the functions of these components?
Answer
The main components of the transport system in human beings are the
heart, blood, and blood vessels.
· Heart pumps oxygenated blood throughout the body. It
receives deoxygenated blood from
the various
body parts and sends this impure blood to the lungs for oxygenation.
·
Being a fluid connective tissue, blood helps in the transport of oxygen,
nutrients, CO2, and nitrogenous wastes.
·
The blood vessels (arteries, veins, and capillaries) carry blood either
away from the heart to various organs or from various organs back to the heart.
Question 2:
Why is it necessary to separate oxygenated and deoxygenated blood in
mammals and birds? Answer
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.
Question 3:
What are the components of the transport system in highly organised
plants? Answer
In highly organised plants, there are two different types of
conducting tissues − xylem and phloem. Xylem conducts water and minerals
obtained from the soil (via roots) to the rest of the plant. Phloem transports
food materials from the leaves to different parts of the plant body.
Question 4:
How are water and minerals transported in plants? Answer
The components of
xylem tissue (tracheids and vessels) of roots, stems, and leaves are
interconnected to form a continuous system of water-conducting channels that
reaches all parts of the plant. Transpiration creates a suction pressure, as a
result of which water is forced into the xylem cells of the roots. Then there
is a steady movement of water from the root xylem to all the plant parts
through the interconnected water-conducting channels.
Components of xylem tissue
Question 5:
How is food transported in plants? Answer
Phloem transports food
materials from the leaves to different parts of the plant body. The
transportation of food in phloem is achieved by utilizing energy from ATP. As a
result of this, the osmotic pressure in the tissue increases causing water to
move into it. This pressure moves the material in the phloem to the tissues
which have less pressure. This is helpful in moving materials according to the
needs of the plant. For example, the food material, such as sucrose, is
transported into the phloem tissue using ATP energy.
Components of phloem tissue
Question 1:
Describe the structure and functioning of nephrons. Answer
Nephrons are the
basic filtering units of kidneys. Each kidney possesses large number of
nephrons, approximately 1-1.5 million. The main components of the nephron are
glomerulus, Bowman’s capsule, and a long renal tubule.
Functioning of a nephron:
· The blood enters
the kidney through the renal artery, which branches into many capillaries
associated with
glomerulus.
· The water and
solute are transferred to the nephron at Bowman’s capsule.
·
In the proximal tubule, some
substances such as amino acids, glucose, and salts are selectively reabsorbed
and unwanted molecules are added in the urine.
· The filtrate then
moves down into the loop of Henle, where more water is absorbed.
·
From here, the filtrate moves
upwards into the distal tubule and finally to the collecting duct. Collecting
duct collects urine from many nephrons.
·
The urine formed in each kidney
enters a long tube called ureter. From ureter, it gets transported to the
urinary bladder and then into the urethra.
Question
2:
What are the methods used by plants to get rid of excretory
products? Answer
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.
Question 3:
How is the amount of urine produced regulated? Answer
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.
Question 1:
The kidneys in
human beings are a part of the system for
(a) nutrition.
(b) respiration.
(c) excretion.
(d) transportation.
Answer
(c) In human
beings, the kidneys are a part of the system for excretion.
Question 2:
The xylem in
plants are responsible for
(a) transport of water.
(b) transport of food.
(c) transport of amino acids.
(d) transport of oxygen.
Answer
(a) In a plant,
the xylem is responsible for transport of water.
Question 3:
The autotrophic
mode of nutrition requires
(a) carbon dioxide and water.
(b) chlorophyll.
(c) sunlight.
(d) all of the above.
Answer
(d) The
autotrophic mode of nutrition requires carbon dioxide, water, chlorophyll and
sunlight.
Question 4:
The breakdown
of pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm.
(b) mitochondria.
(c) chloroplast.
(d) nucleus.
Answer
(b)
The breakdown of pyruvate to give
carbon dioxide, water and energy takes place in mitochondria.
Question
5:
How are fats digested in our bodies? Where
does this process take place?
Answer
Fats
are present in the form of large globules in the small intestine. The small
intestine gets the secretions in the form of bile juice and pancreatic juice
respectively from the liver and the pancreas. The bile salts (from the liver)
break down the large fat globules into smaller globules so that the pancreatic
enzymes can easily act on them. This is referred to as emulsification of fats.
It takes place in the small intestine.
Question 6:
What is the role of saliva in the digestion of food? Answer
Saliva is secreted by the salivary glands, located under the tongue.
It moistens the food for easy swallowing. It contains a digestive enzyme called
salivary amylase, which breaks down starch into sugar.
Question 7:
What are the necessary conditions for autotrophic nutrition and what
are its by-products? Answer
Autotrophic nutrition
takes place through the process of photosynthesis. Carbon dioxide, water,
chlorophyll pigment, and sunlight are the necessary conditions required for
autotrophic nutrition. Carbohydrates (food) and O2 are the
by-products of photosynthesis.
Question 8:
What are the differences between aerobic and anaerobic respiration?
Name some organisms that use the anaerobic mode of respiration.
Answer
|
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.
|
Anaerobic respiration
occurs in the roots of some waterlogged plants, some parasitic worms, animal
muscles, and some micro-organisms such as yeasts.
Question 9:
How are the alveoli designed to maximise the exchange of gases?
Answer
The alveoli are the small balloon-like structures present in the
lungs. The walls of the alveoli consist of extensive network of blood vessels.
Each lung contains 300−350 million alveoli, making it a total of approximately
700 million in both the lungs. The alveolar surface when spread out covers
about 80 m2 area. This large surface area makes the gaseous exchange
more efficient.
Alveoli and capillaries
Question 10:
What would be the consequences of a deficiency of haemoglobin in our
bodies? Answer
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.
Question 11:
Describe double circulation in human beings. Why is it necessary?
Answer
The human heart is divided into four chambers − the right atrium,
the right ventricle, the left atrium, and the left ventricle.
Flow
of blood in the heart:
·
The heart has superior and inferior
vena cava, which carries de-oxygenated blood from the upper and lower regions
of the body respectively and supplies this de-oxygenated blood to the right
atrium of the heart.
Flow of blood in the human heart
·
The right atrium then contracts and
passes the de-oxygenated blood to the right ventricle, through an
auriculo-ventricular aperture.
·
Then the right ventricle contracts
and passes the de-oxygenated blood into the two pulmonary arteries, which pumps
it to the lungs where the blood becomes oxygenated. From the lungs, the
pulmonary veins transport the oxygenated blood to the left atrium of the heart.
· Then the left
atrium contracts and through the auriculo-ventricular aperture, the
oxygenated
blood enters the left ventricle.
·
The blood passes to aorta
from the left ventricle. The aorta gives rise to many arteries that distribute
the oxygenated blood to all the regions of the
body.
Schematic diagram of blood circulation in humans
Therefore, the
blood goes twice through the heart. This is known as double circulation.
Importance of double
circulation:
The separation of oxygenated and de-oxygenated blood allows a more
efficient supply of oxygen to the body cells. This efficient system of oxygen
supply is very useful in warm-blooded animals such as human beings.
As we know, warm-blooded animals have to 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, they require
more O2 for more respiration so that they can produce more energy to
maintain their body temperature. Thus, the circulatory system of humans is more
efficient because of the double circulatory heart.
Question 12:
|
Transport
of materials in xylem
|
|
Transport of materials in phloem
|
(i)
|
Xylem tissue helps in the transport of water and
minerals.
|
(i)
|
Phloem tissue helps in the
transport of food.
|
(ii)
|
Water is transported upwards
from roots to all other plant parts.
|
(ii)
|
Food is transported in both
upward and downward directions.
|
|
|
What are the differences between the
transport of materials in xylem and phloem? Answer
(iii)
|
Transport
in xylem occurs with the help of simple physical forces such as transpiration
pull.
|
(iii)
|
Transport
of food in phloem requires energy in the form of ATP.
|
Question
13:
Compare the functioning of alveoli in the lungs and nephrons in the
kidneys with respect to their structure and functioning.
Answer
Alveoli
|
Nephron
|
Structure
(i) Alveoli
are tiny balloon-like structures present inside the lungs.
(ii)
The walls of the alveoli are one
cell thick and it contains an extensive
network of blood capillaries.
Function
(i) The
exchange of O2 and CO2 takes place between the blood of
the capillaries that surround the alveoli and the gases present in the alveoli.
(ii)
Alveoli are the site of gaseous
exchange.
|
Structure
(i) Nephrons
are tubular structures present inside the
kidneys.
(ii)
Nephrons are made of glomerulus,
bowman’s capsule, and a long renal tube. It also contains a cluster of thin-
walled capillaries.
Function
(i) The blood
enters the kidneys through the renal artery which branches into many
capillaries in the glomerulus. The water and solute are transferred to the
nephron at Bowman’s capsule. Then the filtrate moves through the proximal
tubule and then down into the loop of henle. From henle’s loop, filtrate
passes into the distal tubule and
then to the collecting duct. The collecting duct collects the urine from many
nephrons and passes it to the ureter. During the flow of filtrate, some
substances such as glucose, amino acids, and water are selectively re-
absorbed.
(ii) Nephrons are the basic filtration unit.
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