4.Life Processes

Q1. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?


In unicellular organisms, cells are in direct contact with the outside environment. Whereas in multicellular organisms, cells are not in direct contact with the outside environment. Multicellular organisms like humans possess complex body structure and designs. To various necessary functions are performed with the help of specialised cells and tissues inside the body. Therefore, diffusion cannot meet their oxygen requirements.


Q2. What criteria do we use to decide whether something is alive?


The visible movements like walking, breathing, or growing is considered to decide whether something is alive or not. On the other hand, a living organism can also have movements, which are not visible to the naked eye.

So the presence of life processes is a fundamental criterion that may be used to decide whether something is alive or not.


Q3. What are outside raw materials used for by an organism? 


The raw material that is required by an organism varies depending on the complexity of the organism and its environment. They use outside raw materials commonly in the form of food and oxygen for their survival.


Q4. What processes would you consider essential for maintaining life?


Life processes such as nutrition, respiration, transportation, excretion, etc. are essential for maintaining life.


Q1. What are the differences between autotrophic nutrition and heterotrophic nutrition?


             Autotrophic nutrition

            Heterotrophic nutrition

Food : It is synthesised from simple

inorganic raw materials such as CO2and water.

Food:It  is obtained directly or indirectly from autotrophs and food is broken down with the help of enzymes.

Green pigment(chlorophyll)= Presence  is necessary.

 Pigment Not Required.

Food is generally prepared during day


Food can be prepared at all times.

All green plants and some bacteria are of

this type of nutrition.

All animals and fungi are of this type of nutrition.


Q2. Where do plants get each of the raw materials required for photosynthesis?


Following are the required raw materials used for photosynthesis:

i)CO2(raw material) enters from the atmosphere through stomata.

ii)Water is absorbed from the soil by the plant`s root.

iii)Sunlight is absorbed by the chlorophyll and other green parts of the plants.


Q3. What is the role of the acid in our stomach?


HCl (hydrochloric acid) is present in our stomach which dissolves parts of food we take and creates an acidic medium. Here, enzyme pepsinogen gets converted to pepsin in acidic medium, which is a protein digesting enzyme.


Q4. What is the function of digestive enzymes?


Types of digestive enzymes present in our body are amylase, lipase, pepsin, trypsin, etc.

The presences of these enzymes helps in the breaking down of complex food particles into simple one so that they can be easily absorbed by the blood and thus transport it to all the cells of the body.


Q5. How is the small intestine designed to absorb digested food?


Small intestine contains 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.


Q1. What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?


               Terrestrial organisms

             Aquatic organism

Oxygen intake : from the atmosphere

Oxygen intake : present in water

Air contains more oxygen

Water contain less oxygen than air

Need not breathe faster for oxygen

Breathe faster for oxygen requirement

Do not have to show various adaptations for better gaseous exchange.

Show various adaptations for better gaseous exchange.


Q3. How is oxygen and carbon dioxide transported in human beings?


The function of haemoglobin is to transport oxygen molecule to all the body cells for cellular respiration. The haemoglobin pigment present in the blood gets attached to four O2 molecules which are obtained from breathing and forms oxyhaemoglobin and the blood becomes oxygenated. Then the heart distributes this oxygenated blood to all the body cells. 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.


Q4. How are the lungs designed in human beings to maximise the area for exchange of gases?


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.


Q1. What are the components of the transport system in human beings?What are the functions of these components?


The main components of the transport system in human beings are

i) Heart,ii) Blood and iii) Blood vessels


i)Heart: It 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.

ii)Blood:Being a fluid connective tissue, blood helps in the transport of oxygen, nutrients, CO2, and nitrogenous wastes.

iii)Blood vessels: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.


Q2. Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?


To maintain a constant body temperature, warm-blooded animals such as birds and mammals require more oxygen (O2) for cellular respiration.

They do so by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment.

Thus, to make their circulatory system more efficient and maintain their constant body temperature it is necessary for them to separate oxygenated and de-oxygenated blood.


Q3. What are the components of the transport system in highly organised plants?


There are two different types of conducting tissues –xylem and phloem which act as transport system in highly organised plants.


It conducts water and minerals obtained from the soil (via roots) to the rest of the plant.


It function is to transports food materials from the leaves to different parts of the plant body. 


Q4. How are water and minerals transported in plants?


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.


Q5. How is food transported in plants?


Phloem transports food materials from the leaves to different parts of the plant body with the help of  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. 


Q1. Describe the structure and functioning of nephrons.


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:

i) The blood enters the kidney through the renal artery, which branches into many capillaries associated with glomerulus.

ii)The water and solute are transferred to the nephron at Bowman’s capsule.

iii)The filtrate then moves down into the loop of Henle, where more water is absorbed.

iv)In the proximal tubule, some substances such as amino acids, glucose, and salts are selectively reabsorbed and unwanted molecules are added in the urine.

v)From here, the filtrate moves upwards into the distal tubule and finally to the collecting duct.

vi)Collecting duct collects urine from many nephrons.

vii)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.


Q2. What are the methods used by plants to get rid of excretory products?


The excess of water problem may be overcome by transpiration in plants.

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.


Q3. How is the amount of urine produced regulated?


It depends on the amount of excess water and dissolved wastes present in the body.Factors such as habitat of an organism and hormone such as Anti-diuretic hormone (ADH) also resposible and regulates the amount of urine produced in the body.


Q1. The kidneys in human beings are a part of the system for
(a) nutrition.
(b) respiration.
(c) excretion.
(d) transportation.


(c) excretion.


Q2. The xylem in plants are responsible for
(a) transport of water.
(b) transport of food.
(c) transport of amino acids.
(d) transport of oxygen.


(a) transport of water.


Q3. The autotrophic mode of nutrition requires
(a) carbon dioxide and water.
(b) chlorophyll.
(c) sunlight.
(d) all of the above.


(d) all of the above.


Q4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm.
(b) mitochondria.
(c) chloroplast.
(d) nucleus.


(b) mitochondria.


Q5. How are fats digested in our bodies? Where does this process take place?


i)Fats are present in the form of large globules in the small intestine so enzymes can not act on them.

ii)It gets the secretions in the form of bile juice and pancreatic juice respectively from the liver and the pancreas.

iii)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.

iv)Lipase digests emulsified fats.

v)The wall of the intestine contains glands which secrates intestinal juice.

vi)Enzymes present in it then converts fat into fatty acid and glycerol.


Q6. What is the role of saliva in the digestion of food?


i)It wets the food in the mouth which make it easy to swallow the food further.

ii)Sativary amylase enzyme found in it breaks down complex starch into sugar.


Q7. What are the necessary conditions for autotrophic nutrition and what are its byproducts?


The necessary conditions for autotrophic nutrition are 




iv)carbon dioxide

By-Products are

Oxygen and Glucose.


Q8. What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.


Aerobic Respiration

Anaerobic Respiration

Occurance:In the presence of oxygen

Occurance:In the absence of oxygen

Food:Break down completely

Food:Break down partially

Enery Released: Large

Enery Released: Less than that of aerobic respiration

Output:CO2 and H2O

Output:CO2,Ethanol and lactic acid


Example:Some Bacteria,Yeast etc.


Q9. How are the alveoli designed to maximise the exchange of gases?


Alveoli are small baloon like structure present in large numers in lungs.The walls are very thin and consists of extensive network of blood vessels.The alveolar surface when extends out covers about 80 m2area.This large surface area makes the gaseous exchange more efficient.


Q10. What would be the consequences of a deficiency of haemoglobin in our bodies?


As the haemoglobin shows very high affinity for oxygen in blood. So deficiency ofhaemoglobin may cause some of the serious health problems as it reduces the oxygen carrying capacity of blood. The diseases may include due to this efficiencies are:

i) Breathing problem

ii) Tiredness

iii) Loss of weight

iv) Lack of energy etc.


Q12. What are the differences between the transport of materials in xylem and phloem?




Transportation of mineral and water to the entire parts of the plants take place in xylem

Transportation of food from leaves to the entire parts of the plants takes place in xylem

Movement of minerals and water are always in upward direction in Xylem

Movement of food may be in upward or backward direction in Xylem


Q13. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.




Numerous tiny balloon shaped structures present inside lungs

Tubular structures present in the Kidneys

By-produts:CO2 and H2O

By-produts:Water,uric acids and urea during excretion



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