Lesson: Life Processes
Question 1
Why is diffusion insufficient to meet oxygen requirements of multi-cellular
organisms like humans?
When compared to unicellular organisms, multi-cellular organisms have complex
body structures with specialized cells and tissues to perform various functions of
the body. Diffusion is a passive mode of transport and can transfer gases up to a
very small distance only. So, diffusion cannot meet oxygen requirement of multi-
cellular organisms.
Question 2
What criteria do we use to decide whether something is alive?
Breathing and respiration are two main criteria to check if something is alive.
Question 3
What are outside raw materials used for by an organism?
Water, gases, and minerals are the outside raw materials used by an organism.
Question 4
What processes would you consider essential for maintaining life?
Life processes such as nutrition, respiration, transportation, excretion and
reproduction are essential for maintaining life.
Question 5
What are the differences between autotrophic nutrition and heterotrophic
Autotrophic nutrition
Heterotroph nutrition
Organism prepares its own food.
Organism depends on other organisms for
Chlorophyll is required
Chlorophyll is not required
Food is synthesised from simple
inorganic raw materials such as
and water.
Food is obtained directly or indirectly from
autotrophs. Later, this food is broken down
with help of enzymes.
Question 6
Where do plants get raw materials required for photosynthesis?
Plants get carbon dioxide from atmosphere, and water and minerals from soil.
Question 7
What is the role of acid in our stomach?
Hydrochloric acid is found in our stomach. It dissolves bits of food and creates an
acidic medium. It also helps in killing harmful microorganisms that may have
come along with the food.
Question 8
What is the function of digestive enzymes?
Digestive enzymes such as amylase, lipase, pepsin, and trypsin fasten the process
of breaking-up complex food particles into simpler and absorbable particles.
These simple particles can be easily absorbed by the blood and transported to all
the cells of a body.
Question 9
How is the small intestine designed to absorb digested food?
Small intestine has millions of tiny finger-like projections called villi. These villi
increase the absorbing surface of small intestine. The blood capillaries in villi
absorb digested food and carry it to the blood stream.
Question 10
What advantage over an aquatic organism does a terrestrial organism have with
regard to obtaining oxygen for respiration?
Terrestrial organisms take up oxygen from atmosphere whereas aquatic animals
obtain oxygen from water. Air contains more O
as compared to water. Therefore,
terrestrial animals do not have to breathe quicker to get more oxygen. Therefore,
terrestrial organisms can facilitate better utilization of food by way of respiration.
Question 11
What are the different ways in which glucose is oxidised to provide energy in
various organisms?
There are two types of respiration for oxidization of glucose.
Anaerobic Respiration: This process takes place in absence of oxygen. For
example, during yeast fermentation, pyruvate is converted into ethanol and
carbon dioxide.
Aerobic Respiration: In aerobic respiration, breakdown of pyruvate takes
place in presence of oxygen. Hence, optimum output of energy is achieved.
Question 12
How is oxygen and carbon dioxide transported in human beings?
Transport of Oxygen: The respiratory pigment (haemoglobin) present in red
blood cell carry oxygen in blood. It carries oxygen to tissues which are deficient
in oxygen.
Transport of carbon dioxide: Carbon Dioxide is more soluble in water. Hence,
it is mostly transported from body tissues in dissolved form. It is transported from
blood plasma to lungs. In the lungs, it diffuses from blood to air and then is
expelled out through nostrils.
Question 13
How are lungs designed in human beings to maximise area for exchange of gases?
Lungs contain millions of air sacs called alveoli. The structure of the air sac
increases surface area inside lungs. This helps in making a larger area for
exchange of gases.
Question 14
What are the components of the transport system in human beings? What are the
functions of these components?
The main components of transport system in human beings are heart, blood, and
blood vessels, and lungs.
Heart pumps oxygenated blood throughout the body. It receives deoxygenated
blood from the various body parts and sends this impure blood to lungs for
Blood helps in transportation of oxygen, nutrients, CO
, and other nitrogenous
Blood vessels such as arteries, veins, and capillaries carry blood either from
the heart to various organs or from various organs to the heart.
Lungs facilitate transportation of oxygen and carbon dioxide to and from the
body respectively.
Question 15
Why is it necessary to separate oxygenated and deoxygenated blood in mammals
and birds?
Mammals and birds are warm blooded animals. They have higher energy need to
maintain their body temperature. So they require more oxygen to produce energy.
If deoxygenated blood gets mixed with oxygenated blood, it leads to less oxygen
supply to the cells. Under such oxygen deficient condition, cells will not function
normally and may not perform various activities normally. Therefore, it is
necessary to separate oxygenated and deoxygenated blood to maintain efficient
supply of oxygen to all cells warm-blooded animals.
Question 16
What are the components of the transport system in highly organized plants?
Plant transport system in highly organized plants contains xylem and phloem.
Xylem conducts water and minerals obtained from soil (via roots) to the rest of
the plant, whereas phloem transports food materials from leaves to different parts
of a plant body.
Question 17
How are water and minerals transported in plants?
In plants, water and minerals are transported from roots. Xylem cells extend from
roots through the stem and continue up to leaves. In leaves, it is clearly seen as a
pattern of veins. Water and minerals are transported from roots through xylem
tubes to all parts of a plant. In this process, water is absorbed by osmosis, while
minerals are absorbed as ions by active transportation.
Question 18
How is food transported in plants?
Food is transported in plants through phloem. Transportation of food in phloem is
achieved by utilizing energy from ATP which helps in creating osmotic pressure
that transport food from areas of high concentration to low concentration.
Question 19
Describe the structure and functioning of nephrons.
Nephrons are the functioning units of kidneys. Each kidney possesses large
number of nephrons, approximately 1-1.5 million. The main components of
nephrons are glomerulus, Bowman's capsule, and a long renal tubule.
Functioning of a nephron:
Blood enters kidneys through the renal artery that branches into many capillaries
associated with glomerulus. Filtration of blood takes place in Bowman's capsule
under very high pressure. Then the filtrate goes to a network of collecting tubules
which finally meet in a common collecting duct. The 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
Question 20
What are the methods used by plants to get rid of excretory products?
Plants can get rid of:
Excess of water by transpiration.
Carbon dioxide and oxygen through diffusion
Old branches and leaves through shedding
Some waste products are deposited near bark as resin or gums.
Question 21
How is the amount of urine produced, regulated?
The amount of urine produced depends on the amount of excess water and
dissolved wastes present in the body. The comparative concentration of water
gives a signal to the brain. Then the brain takes the required action of either
reabsorbing water or releasing more water. Thus, the amount of urine formation is
regulated by kidneys.