Life Processes

LIFE PROCESS

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

Ans. Multicellular organisms have millions of cells and thus their energy requirement is also too high. Since, the every cell o0f the Multicellular organism cannot be brought into the direct contact with atmospheric oxygen. Therefore, diffusion insufficient to meet the oxygen requirements of multi-cellular.

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

Ans. To decide whether an organism is living or not, we consider the following factors:-

a). It must be capable of reproduction.

b). It must be able to show the locomotion and other type of movements.

c). It must carry the various life process such as digestion, respiration, excretion etc.

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

Ans. For any organism to remain alive it needs food, air and oxygen. For example in plants sunlight, co_2, and water are compulsory to carry out the process of photosynthesis.

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

Ans. In order to maintain the life an organism must carry out the basic life processes such as digestion, respiration, transportation and excretion.

Page No. 192

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

Autotrophic	Heterotrophic
1.    In this mode of nutrition organisms can prepare their own food.	1.    In this mode, of nutrition organisms cannot prepare their own food.
2.    The organisms which have autotrophic nutrition are called as autotrophs.	2.    The organisms which have heterotrophic mode of nutrition are called as heterotrophs.
3.    Autotrophic organisms cannot move from one place to another.	3.    Heterotrophic organisms can move from one place to another.
4.    Autotrophic organisms take in simpler substances and convert them into complex substances.	4.    Heterotrophic organisms take in complex substances and convert them into simpler substances.
5.    They need co2, sunlight and chlorophyll to produce their food.	5.    They do not need any such thing.
6.    Autotrophic organisms take in co2, and release o2.	6.    Heterotrophic organisms take in o2 and release co2.
7.    For Example, Green plants, blue green algae etc.	7.    For example Human beings, animals.

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

Ans. The photosynthesis is a process by which all the green plants can prepare their own food. The outside raw materials required for the photosynthesis is co₂, water and sunlight.

      1.    Carbon dioxide (Co₂): Plants obtain the co₂ from the atmosphere where it has been released by various heterotrophic organisms.

     2.    Water (H₂o): Plant obtains the water from the soil with the help of roots. The xylem tissue presents in the roots lift the water upwards.

    3.    Sunlight:  Plant obtains the sunlight from the sun.

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

Ans. The acid present in our stomach is hydrochloric acid (HCL). This acid plays an important role in our stomach.

i)                   It makes the acidic medium.

ii)                It kills the foreign harmful micro-organism that enters into our body.

Q4. What is the function of digestive enzymes?

Ans. Digestive enzymes are biological catalysts which break down the complex food molecules like carbohydrates, proteins and fats into small particles which can be easily absorbed by the walls of small intestine.

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

The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area absorption. The villi are richly supplied with  blood vessels which take the absorbed food to each and every cell of the body where it is utilized for obtaining energy, building up new tissues and the repair  of old tissues.

Page-196

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

Ans. The terrestrial organisms obtain the oxygen directly from the atmosphere. On the other hand, aquatic organisms obtain the oxygen from the water in dissolved form. Since, the quantity of oxygen present in the water, Therefore, Aquatic organisms has lesser amount of oxygen available for the respiration.

Q2. What are the different ways in which glucose is oxidised to provide energy to various- organisms?

Ans. Respiration is a process in which there is breakdown of glucose with release of energy. In other terms, when oxidation of glucose takes place with the release of energy, it is called as respiration.

There are two methods of respiration.

     1.    Aerobic Respiration: It is a type of respiration which takes place in presence of oxygen. Large amount of energy is released during aerobic respiration. E.g., Human beings, animals etc.

     2.     Anaerobic Respiration: It is a type of respiration which takes place in absence of oxygen. Usually, small amount of energy is released during anaerobic respiration. E.g., Muscle cells, yeast etc.

Q3. How is oxygen and co₂ transported in human beings?

Ans. Oxygen is transported from respiratory organs to0 the cell with the help of haemoglobin present in the RBCs of blood. The oxygen combines with haemoglobin to form oxyhaemoglobin.

Hb         +o₂                                               Hbo₂

HG       oxygen              oxyhaemoglobin

The blood rich in oxygen reaches to the tissue which contains deoxygenated blood. In this tissue oxyhaemoglobin breaks down with the release of oxygen. This oxygen is utilized by the cell and co₂ present in it is send back. However, some amount of oxygen is also transported through plasma.

Transportation of co₂

Co₂ is more soluble in plasma than oxygen. Therefore, maximum amount of co₂ is transported through plasma in dissolved form. The co₂ from the blood reaches to lungs from where it is expelled out through nostrils. Some amount of co₂is also transported in the form of bi-carbonate ions.

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

Ans. Human lungs are designed in a perfect way to ensure that maximum surface area is available for the exchange of gases within the lungs; the passage divides into smaller and smaller tubes which finally terminate in balloon-like structures which are called alveoli. The alveoli provide a surface where the exchange of gases can take place. The walls of the alveoli contain an extensive network of blood-vessels. When we breathe in, we lift our ribs and flatten our diaphragm and the chest cavity becomes larger as a result. Because of this air is sucked into the lungs and fills the expanded alveoli. The lungs always contain a residual volume of air. So that there is sufficient time for oxygen to be absorbed and for the co₂ to be released.

Page no. 201

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

Ans. Transport system in human beings consists of blood circulatory system. Circulatory system in human beings consists of  following elements:

1.    Heart:- The heart is a muscular organ which is as big as our fist. Because both oxygen and carbon dioxide have to be transported by the blood, the heart has different chambers to prevent the oxygen –rich blood from mixing with the blood containing co₂.

Functions of Heart:

i)                   Its muscles contract to generate pressure to pump blood into arteries.

ii)                The left auricle- receives purified blood from the lungs and pushes it into left ventricle.

iii)              It sends deoxygenated blood to lungs for oxygenation.

2.    

Blood Vessels:- These are long tubes with muscular walls. These are of three types i.e., arteries, veins and capillaries.

Functions of Blood vessels:

i)                   Arteries: Arteries carry oxygenated blood from heart to body organs.

ii)                Veins: Veins carry deoxygenated blood from body organs to heart.

iii)              Capillaries: Capillaries have thin walls and helps in exchange of materials between blood and cells.

3.    Blood: It is a reddish viscous fluid connective tissue. An adult human being has about 5-6 ltrs of blood. Blood consists of two parts- plasma and formed elements. (RBC, WBC and Blood platelets).

 Functions of Blood

i)                   Plasma transports food, co₂ and nitrogenous waste in dissolved form.

ii)                RBCs transport oxygen

iii)              Blood platelets help in blood clotting to prevent loss of blood from injured part.

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

Ans. Birds and mammals are warm blooded organisms. Moreover, being multicellular organisms, they required large amount of energy to maintain their body temperature and other basic life functions. This high demand of e3nergy can only be met by the separation of oxygenated and deoxygenated blood.

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

Ans. Highly organized plants have the specific tissues of the transportation of food and water.

Q5. Explain the process of Transportation of food in plants.

Ans. In highly organized plants, transportation of food takes place with the help of phloem tissue. The phloem tissue consists of phloem fibre, phloem parenchyma, seed roots and companion cells. The phloem tissue can conduct the food materials (provide to by the green leaves) in any direction.

The Transport of food in plants is called translocation. Food molecules enter the phloem cells from mesophyll cells of the leaf.

Q4. Explain the process of Transportation of water and minerals.

Ans. In highly organized plants, xylem tissue conducts water and minerals from the roots to the other parts of the plant. The xylem tissue consists of xylem fibre, xylem parenchyma, xylem vessels and xylem tracheids. The root hairs absorb the water from the soil by the process of diffusion and pass it in upward direction.

In xylem tissue, vessels and tracheids of the roots stem and leaves are inert-connected to form a continuous system of water-conducting reaching all parts of the plant.

What is Nutrition?

Ans. The process of obtaining nutrients which are to utilized by the body to get energy for various life carrying activities is called as Nutrition.

Q. Explain in detail Respiratory system in human beings.

Ans.  The Respiratory system in human beings consists of following parts:-

1.    Nostril and Nasal cavity: Nostrils are the two nasal opening through which the air enters in our body. The nasal cavity secrets mucus which helps to remove the dust particle in air.

2.    Pharynx: It is a junction between nasal cavity and larynx. It is regarded by epiglottis.

   3.    Larynx: It is also known as Adams apple. It serves as voice box.

4.    Trachea: It is about 4 inches long. It prevents the collapse of air in larynx even when there is very less air in it.  This is done with the help of cartilaginous rings.

5.    Bronchi: The bronchi are formed by the bilateral bifurcation of trachea. It is further divides into bronchioles, which ends into alveoli inside lungs.

6.    Lungs: These are two spongy elastic. Right lung has three lobes and left lung has two lobes. The actual purification of blood in coordination with-heart is done by lungs.

7.    Alveoli: The Bronchioles have tiny air sacs at their ends called alveoli. It is the alveoli where the actual exchange of the gases takes place.

Q Explain the process of Execratory system in human beings.

Ans.  Execratory system in human beings consists of the following parts:

1.     Kidneys: There are two kidneys in human beings. Each kidney is like bean shaped where left kidney is placed slightly higher than the right kidney. The left artery brings impure blood to kidney where it is filtered with the help of neuron.

2.    Ureters: These are two long tubes. They collect urine from kidneys and pass it into the bladder drop by drop.

3.    Urinary bladder: It is a bag like structure which contains urine for some time. The urinary bladder open to outside through urethra when it is filled with urine it contracts and urine is expelled out through it.

4.    Urethra: It is a small muscular tube opening outside the body. The waste fluid store in urinary bladder is thrown out through urethra.

Page no. 203

Q1.  Describe the structure and functioning of Nephrons.

Ans. Nephrons are the main functioning units of our kidney. Each kidney has large number of filtration units called Nephrons. It consists of tubule, which is connected with a collecting duct at the one end and tiny cup shaped structure at the other end, called as Bowman’s capsule. Each Bowman’s capsule contains the cluster of capillaries called as Glomerulus within cup shaped structure. The blood enters in the glomerulus through the renal artery and leaves it to through arteriole.

The main functions of the Nephrons are:

     1.    Filtration of blood takes place in Bowman’s capsule in the capillaries of glomerulus.

    2.    Various filtrates such as glucose, amino-acids, urea etc. are reabsorbed into the blood.

    3.    The waste harmful filtrate which is collected from Nephrons is passed to urethra.

     4.    Purified blood is also sent back towards the heart.

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

Ans. Plants use following methods to get rid of excretory/waste products.

     1.    The excess of waste present in plants is removed through transpiration.

     2.    Co₂ and water products during respiration are used in photosynthesis.

    3.    O₂ produced during photosynthesis is either released or used up in respiration.

    4.    Some waste products get collected in leaves and are removed by shedding.

     5.    Plants also excrete some waste substances in the soil.   

       6 .    Some waste products are stored as resins and gums especially in old xylem.

Q3. How is the amount of urine regulated?

Ans. The amount of urine produced is regulated by the body’s requirement of salt and water.

During hot days we sweat and lose lot of water and salt. Thus, the volume of urine produced will be less.

During winter, we do not sweat a lot. Hence, little water and salts will be reabsorbed and the volume of urine produced will be more.

Page no. 204

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

Ans. The small intestine is the site of complete digestion of carbohydrates, proteins and fats. It receives the secretions of the liver and pancreas for this purpose. The food coming from the stomach is acidic and has to be made alkaline for the pancreatic enzymes to act. Bile juice from the liver accomplishes this in addition to acting on fats. Fats are present in the intestines in the form of large globules which makes it difficult for the enzymes to act in them. Bile salts break them down into smaller globules increasing the efficiency of enzyme action.

Finally, the fats emulsified by the bile are converted into the fatty acids and glycerol by the pancreatic juices.

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

The saliva contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give sugar. The food is missed thoroughly with saliva and moved around the mouth while chewing by the muscular tongue.

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

Ans. Autotrophic mode of nutrition is a mode of nutrition in which an organism can prepare its own food with the help of chlorophyll in presence of co₂ and sunlight.

Therefore, the basic conditions for the autotrophic mode of nutrition are:-

i)                   Sunlight

ii)                Co₂

iii)              Water

iv)              A green pigment called as chlorophyll

Chlorophyll

6CO₂ + 6H₂O                      C₆H₁₂O₆ +6O₂

                                                        Sunlight

The byproducts of the autotrophic mode of nutrition are starch, water, glucose and oxygen.

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

Ans.

Aerobic	Anaerobic
1.    It is a type of respiration which takes place in presence of oxygen.	1.    It is a type of respiration which takes place in the absence of oxygen.
2.    Large amount of energy is released.	2.    Small amount of energy is released.
3.    Its byproducts are energy and co2.	3.    Its end products are lactic acid/ ethanol, co2 and energy.
4.    Aerobic respiration gets completed in mitochondria.	4.It gets completed in        cytoplasm
5.    It is harmless process	5.It is toxic in plants
6.    It takes place in higher organisms.	6. It takes place in lower organism.
7.      eg.,Human beings, animals etc.	7.  eg., Yeast, muscle cells etc.

The various organisms that use anaerobic mode of nutrition are some bacteria, yeasts, and intestinal worms like ascaris, tapeworm. This type of respiration is also called fermentation.

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

Ans. The average hemoglobin context of a blood irrespective of sex is 14.5g per hundred ml. If hemoglobin reduces in the blood, its oxygen carrying capacity will also decrease. It is because hemoglobin plays an important role in the transportation of oxygen. Thus, the deficiency of hemoglobin in the blood can cause anemia. The early symptoms of anemia are tiredness, breathlessness etc.

Q 11. Describe double circulation in human beings? Why is it necessary.

Ans. The type of circulation in which blood passes twice through the chambers of heart is called as double circulation system. Based on the type of tissue covered while circulation, double circulation system (DCS) is of two types.

     1)   Pulmonary Circulation: In this type of circulation, deoxygenated blood from the right ventricle enters to the left auricle through lungs. From the right ventricle, pulmonary arteries supply deoxygenated blood to the respective lungs for purification. In this way, oxygenated blood from the lungs is retained to the left auricle by pulmonary veins.

     2)   Systemic circulation:  It is a type of circulation in which blood from left ventricle enters to the right auricle through all the body parts except lungs. In this type of circulation, oxygenated blood is supplied to different parts of the body through veins. The deoxygenated blood collected by the large veins called superior and inferior venaecav is returned to right auricle.

Importance of DCS

          Double Circulation System is important because it separated

The oxygenated blood from deoxygenated blood and thus provide cell with oxygen-rich blood, which in turn fulfils the energy demand of the cell.

Extra Questions:

 

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.

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

3. Symbiotic Nutrition

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).

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.

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:

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.

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.

 

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.

·         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).

 

Heterotopic Mode of 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.

1. aprophytic Nutrition:  The mode of nutrition in which organisms feed on dead and decaying matter..In saprophytic nutrition, the organism secretes the digestive juices on the food. The food is digested while it is still to be ingested.

All the decomposers follow saprophytic nutrition. Some insects, like houseflies, also follow this mode of nutrition.

2. 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.

 

3. 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 exampleCuscuta, tick etc.

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.

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.

 

 

Digestive System in Human beings:

 

 

Human digestive system: Digestive system of man consists of alimentary canal and it's associated glands.

i ) Alimentary canal: It is nearly nine meters long extending from mouth to anus . It's various parts are :

a) Mouth and Buccal cavity: Mouth is a transverse slit like aperture which is bounded by two soft and movable lips. It is used for intake of food. The mouth leads to  Buccal cavity.

b) Pharynx: Buccal cavity leads into a funnel shaped Pharynx, which serves as a passage of food from Buccal cavity to oesophagus.

 

c) Oesophagus: It is a long, narrow , muscular tube, which opens into the stomach.

d) Stomach: It is a large muscular U-shaped sac located below the diaphragm. The food is stored and partly digested in stomach.

e) Small intestine: It is a coiled and narrow tube , which is divided into three regions - duodenum, jejunum and ileum. Small intestine serves two purposes i.e., digestion and absorption of food

(f) Large Intestine: It is much shorter and wider than small intestine and is divided into three regions-caecum,colon and rectum.

(g) Anus: Rectum leads into anus, which helps to remove the faecal matter from the body.

2. Digestive Glands: Various glands associated with alimentary canal are:

(a) Salivary Glands: There are three pairs of salivary glands namely parotid,sublingual and sub maxillary, which secrete saliva

(b) Gastric Glands: They are branched tubular glands,which lie in the wall of stomach and secrete gastric juice.

(c) Liver: It is largest gland of the body which secretes bile juice. Bile is, normally stored in gall bladder.

(d) Pancreas: It is the second largest gland of the body. It secretes pancreatic juice, both bile and pancreatic juice enter duodenum through common bile duct.

Differences between Parasitic Nutrition and saprophytic Nutrition

 

Parasitic Nutrition	Saprophytic Nutrition
In  this mode of Nutrition Organism derive its nutrition from  another living organism	In this mode of Nutrition organism feed on dead decaying matter
Here organism does harm the source of its Nutrition	Here Organism does not harm the source of its Nutrition s it is already dead
Eukaryotic Organisms follow parasitic mode of Nutrition.	Both Eukaryotic and prokaryotic  organism follow saprophytic Nutrition
They can sometime lead even to the death of an organism.	They can not lead to the death of an organism.
Parasitic organism do not clean the Environment	Saprophytic Organism clean the organism.
This mode of Nutrition usually involves intracellular digestion	This Mode of Nutrition is usually involves extracellular digestion
For example:  lice, stomach worms	For example: Bacteria, Fungi

  

 

Differences between Photosynthesis and Respiration

Photosynthesis	Respiration
It is the process in which green plants and few bacteria use sunlight and water to convert it into energy.	It refers to the process in which all living organisms except plants convert energy and offer to the different cells of the body
Its bi products are Glucose, oxygen, and water	Its bi products are Carbon dioxide, water, and energy (ATP)
It requires Carbon dioxide, water, and light energy	It requires Glucose and oxygen
It is Endothermic reaction because it needs energy	It is  Exothermic reaction because it releases energy
It absorbs carbon dioxide , water and  releases O2	It takes in Oxygen and releases carbon dioxide and water
It takes place in chloroplasts	It takes place in mitochondria