Standard/ Class/ Grade - X SSC, CBSE; - VIII ICSE

Life Processes

Gurudatta K Wagh

Life Processes

Processes that are common to all living beings are called as life processes• nutrition • respiration • excretion • transportation • reproduction • sensitivity • growth

Overview of the Chapter

Nutrition• Digestive system in human beings• PhotosynthesisRespiration• Respiratory system in human beings• In plantsTransportation• Circulatory system in human beings• In plants (Root pressure, Transpiration,

Translocation)Excretion• Excretory system in human beings• In plants

Food contains several components called as nutrients

Nutrients and their functions

Based on their functions nutrients are divided into three types.

Types FunctionsEnergy giving Carbohydrates, fatsBody building ProteinsProtecting and regulating

Vitamins, minerals

Nutrition

Types Source FunctionsInorganic nutrients from inorganic

substances present in the soil and atmosphere through leaves and roots

for growth and to form various parts of the plant

Organic nutrients carbohydrates, proteins and fats of animal and plant origin

 build the body

Nutrients and their types

On the basis of chemical nature, the nutrients are of two types

Nutrition

Nutrition The process of intake of nutrients and its utilization by an organism

Nutrition provides the raw materials needed to sustain life

Mode of nutrition

Mode of nutrition The way by which an organism obtains its food

Nutrition

Mode of nutrition DependencyAutotrophic Plantsuse simple inorganic substances

Independent - organisms synthesize their own organic food

Heterotrophic animals and fungi

Dependent - depend on other organisms

Autotrophic Heterotrophic

Nutrition

Heterotrophic nutritionOrganism How do they obtain their

food?Fungi like yeast, mushrooms and some carnivorous plants

break down the food material into simple substances outside the body and then absorb it

Human being, cat, cow, etc. take in whole food and then break it down to simple substances inside their bodies and then absorb it

Cuscuta, ticks, lice, leeches, tapeworms, etc.

derive nutrition from other plants or animals without killing them but during the process they harm the host plant or animal

Nutrition

Basic steps of nutrition remain the sameName ProcessIngestion taking food insideDigestion The process of breaking down of complex organic

food into simpler soluble substances. Mechanically by teeth and chemically with the help of enzymes

Absorption After digestion is completed soluble digested food is absorbed into the blood

Assimilation The absorbed food is transported into tissues and cells of the body where they are used to produce energy for growth and development or stored for future use

Egestion The undigested and unabsorbed residues of food are thrown out of the body

Nutrition

Digestive system

As the complexity of organism increases some of the organs of the body become specialized to perform specific functions

Some of these organs together constitute a complex digestive system

All the processes involved in nutrition in human beings take place by association of digestive organs called the digestive system

Digestive system = alimentary canal + digestive glands

Digestive system

Alimentary canal 1) is a long and muscular tube of varying diameter 2) which extends from the mouth to the anus.

Digestive glands associated with the alimentary canal

1.salivary glands, 2.liver, 3.pancreas, 4.gastric glands (fundic, cardiac, pyloric)

The fundic glands (or oxyntic glands), are found in the fundus and body of the stomach. They are simple almost straight tubes, two or more of which open into a single duct.Oxyntic means acid-secreting and they secrete hydrochloric acid (HCl) and intrinsic factor.

Digestive system

The food that we take is of complex nature. It is converted into simpler molecules with the help of biological catalysts called as enzymes. Enzyme salivary amylase breaks down starch into a simple sugar maltose. Thus digestion starts in the mouth itself.

Mouth Food has to be processed to generate particles with small size. The chewed and crushed food is wetted with saliva secreted by the salivary glands so the food can smoothly pass through the soft lining of the alimentary canal.

Digestive system

Stomach The partly digested food goes down through the oesophagus into a 'J' shaped stomach placed on the left side of the abdomen

The food is pushed forward in the canal due to rhythmic contraction and relaxation of the muscles of the canal called as peristaltic movement.

The gastric glands present in the wall of the stomach release three gastric juices namely hydrochloric acid, enzyme pepsin and mucus

Hydrochloric acid creates acidic conditions which are necessary for the action of the enzyme pepsin which digests proteins

Mucus protects the inner lining of the stomach from the action of acids under normal conditions

Digestive system

Small Intestine The small intestine is the longest part (5 - 6 m) of the alimentary canal fitted into a compact space in the belly by extensive coiling

Digestive system

Although it is much longer than the large intestine, it gets its name from its comparatively smaller diameter

Herbivores (grass eating) need longer intestine, carnivores like tigers (meat eating) have short intestine

The length of small intestine differs in various animals depending on the food they eat

Carbohydrates, fats and proteins are fully digested in the small intestine

Digestive system

Since this action takes place only in alkaline conditions the acidic food received from the stomach has to be first made alkaline

Liver the largest gland in the body secretes bile juice which is stored in the gall bladder

Whenever food enters the small intestine, the gall bladder releases bile into it through a duct

Digestive system

Bile makes the food alkaline and breaks the large fat globules into smaller ones, this increases the enzyme action

Pancreas secretes pancreatic juice. It has digestive enzymes like trypsin (to digest proteins), lipase (to break down fats) pancreatic amylase (to digest carbohydrates)

The bile and the pancreatic juice enter the small intestine through a common duct

Digestive system

Various intestinal juices are also secreted by walls of the small intestine to complete the digestion process of converting proteins to amino acids, complex carbohydrates to glucose, and fats into fatty acids.

The digested food is absorbed by the walls of the small intestine having numerous finger like projections called villi

Digestive system

Villi, which absorb the food are richly supplied with blood vessels

The absorbed food is taken to each and every cell of the body where it is utilized for obtaining energy

Unused glucose is stored in the liver in the form of glycogen

The unabsorbed food is sent to the large intestine

Digestive system

This part of the intestine does not have any digestive function as the digestion is already completed. The walls of the large intestine have villi which absorb most of the water and salts. The rest of the material is removed from the body through the anus. Here too the exit is regulated by the muscle called sphincter.

Large intestine Undigested food and the residue of the digested food pass into the large intestine (about 1.5 m long).

Digestive system

Photosynthesis

Green plants synthesize their food

Photosynthesis They take in carbon dioxide and water and convert them into carbohydrates (glucose) in the presence of chlorophyll and sunlight

Carbohydrates provide energy

Unutilized carbohydrates are stored in the form of starch

Process Carbon dioxide enters into the leaves through tiny pores present on the surface of the leaf called stomata. Water is taken up from the soil. Chlorophyll present in the chloroplasts absorbs the radiant energy from the sunlight

Light energy splits up the water molecules into hydrogen and oxygen, releasing energy in the form of Adenosine TriPhosphate (ATP)

Photosynthesis

The energy produced is used to reduce carbon dioxide to carbohydrates

The above steps may or may not take place one after another immediately

e.g. desert plants take up carbon dioxide at night and prepare an intermediate product which is acted upon during the day by the energy absorbed by chlorophyll

Photosynthesis

Photosynthesis

Site of photosynthesis Mostly in the leaves and to a lesser extent in green stems and floral parts

Photosynthesis takes place only in the presence of chlorophyll

There is an absence of starch in the parts of the leaf which are devoid of chlorophyll

Without carbon dioxide photosynthesis cannot take place

Photosynthesis

Photosynthesis

Raw materials of photosynthesis

carbon dioxide + water

taken in through the stomata of the leaves

With the help of sunlight, chlorophyll, water and carbon dioxide, autotrophs synthesize carbohydrates and meet their energy requirements.

Photosynthesis

Plants also need body building and regulating nutrients like nitrogen, phosphorus, iron, magnesium etc. which are taken up from the soil

Nitrogen is essential for synthesis of proteins

Nitrogen is taken up in the inorganic form or in the form of an organic compound.

Photosynthesis

Respiration Process of release of energy from the assimilated food

Respiration is of two types

1. aerobic presence of oxygen 2. anaerobic absence of oxygen

Respiration involves two distinct phases

1. breathing/ external respiration and 2. cellular/ internal respiration

Respiration

(1) Breathing or external respiration

Breathing involves movement which brings the air into the lungs and expels the air containing more of carbon dioxide from the lungs to the outer environment.

Exchange of gases in and out of the blood also takes place simultaneously.

External respiration is a physical process.

It involves taking in oxygen rich air, absorption of oxygen from it and giving out air containing more carbon dioxide with the help of respiratory organs.

Respiration

(2) Cellular or internal respiration

Takes place in the mitochondria of the cells to release energy in the form of ATP.

Respiration

Exchange of Gases in Animals

Organs of respiration, e.g. gills, lungs, skin, etc.

Aquatic Animals Use oxygen dissolved in water

Solubility of oxygen in water is much lower

Amount of oxygen available is much lesser than air, hence the rate of breathing is faster in aquatic animals

Respiration

Fish take in water through the mouth and release it over the gills

Gills are the site for uptake of the dissolved oxygen into the blood by diffusion

Respiration

Terrestrial Animals Take oxygen from the air

The respiratory organs in different animals are different but process of diffusion is common

These organs have special structures which increase the surface area that is in contact with the oxygen rich atmosphere

But these structures are delicate, so they are placed within the body

A special passage takes the air to these structures

Respiration

Respiratory/ Breathing tract

The human respiratory tract starts with the nostrils

The air passing through the nostrils is filtered by the fine hair that lines the passage

The air also becomes moist and warm

The dust particles are trapped in the mucus

Respiration

Respiratory tract = external nostrils, pharynx, larynx and trachea

Trachea/ wind pipe divided into two bronchi One enters the right lung and the other the left lung

Though conventionally called as respiratory tract, this tract carries out only breathing (part of respiration) so we can also call it as breathing tract

Respiration

Respiration

Respiratory Organs (Breathing Organs)

Lungs They lie in the thoracic cavity on both the sides of the heart

Within each lung the major bronchus divides into two bronchi and further into smaller and smaller bronchioles which finally terminate into balloon like structures called alveoli (singular alveolus; means cavity in Latin)

Role of alveoliAlveoli provide the surface for exchange of gases

The thin walls of the alveoli are closely surrounded by a network of blood capillaries

Respiration

The haemoglobin present in the RBCs of the blood absorbs the oxygen from the air present in the alveoli through the thin walls of the capillaries

At the same time C02 from the blood is released into the alveoli by diffusion, which goes out of the body when we breathe out air

The oxygen is carried to all the tissues of the body which are deficient in oxygen.

Respiration

Respiration

Fascinating

Alveoli If the alveolar surface of lungs is spread out, it will cover about 80 m2 area

Haemoglobin If haemoglobin was absent and oxygen would have to move only by diffusion from lungs to toes, it would take three years for the oxygen to reach to the toes from the lungs

Respiration

Mechanism of breathing in human beingsAction Inhalation Exhalation muscular diaphragm

contracts relaxes or becomes convex

volume of the thoracic cavity

increases decreases

air pressure inside the cavity

decreases increases

air enters the lungs Leaves the lungsalveolar sacs filled with air rich

in oxygenEmpty the carbon dioxide received from the blood

Respiration

Some facts

A human adult at rest, on an average breathes about 12-20 times per minute, i.e. 28200 times per day

Keep your lungs healthy. Don't smoke. Don't expose yourself to the tobacco smoke given out by cigarette smokers

Avoid being a passive smoker

Respiration

Exchange of gases in plants

Plants are stationary so their energy requirement is less The process of respiration is slower as compared to that of the animals

The process involves exchange of carbon dioxide and oxygen

Respiration

Plants do not have a special respiratory organ and there is very little transport of gases from one part of the plant to another

They have the source of oxygen in their own body as oxygen is released during the process of photosynthesis Large intracellular spaces ensure that all the cells are in contact with the air that enters through the stomatal opening

Respiration

All parts of the plants like root, stem and leaf perform respiration

The gases are exchanged by the process of diffusion

Respiration

Time Day Night C02 02

Photosynthesis Yes No used more releasedRespiration Yes Yes released released

During the day time, photosynthesis and respiration go on simultaneously in a plant

The C02 released during respiration is utilized for photosynthesis and more 02 is released

At night, when there is no photosynthesis, only respiration goes on and more C02 is eliminated

Respiration

Cellular/ Internal respiration

Cellular respiration is a biochemical process in which the simple nutrients like glucose are oxidized within the cells to release energy

This process takes place in the mitochondria of the cells and involves a series of biochemical reactions

The process of cellular respiration varies greatly in different organisms yet the first step is common in all

Respiration

The six carbon molecule (C6H1206) is broken down in the cytoplasm into a three carbon molecule called pyruvate

This process is anaerobic and is called as glycolysis

Respiration

Respiration

Respiration

Respiration

The energy released during cellular respiration is immediately used to synthesize ATP which is used to fuel all other activities in the cell

The energy released during aerobic respiration is more than the energy released during anaerobic respiration

Few intestinal parasites like liverfluke, tapeworm and roundworm respire anaerobically because they live in environments which have less amount of oxygen

Certain cells, such as mammalian RBCs carry out only anaerobic respiration because mitochondria are absent in them

Respiration

Transportation

The substance synthesized or absorbed in one part of the body is moved to the other part of the body by the process of transportation, e.g. carbohydrates, oxygen, etc. 

Transportation in human beingsThe process of transportation of materials in animals is called as circulation

Blood and lymph help in this process

Blood

Blood is the fluid connective tissue in human beings

It carries out the function of transport of various materials in the body

A pumping organ is needed to push the blood around the body along with a network of tubes to reach all the tissues and a system to repair the network from time to time if it is damaged

Transportation

Heart – the involuntary pump

The human heart is a muscular organ which pumps blood

The heart is covered by the pericardial membrane

It is of the size of a human fist and weighs about 360 gm

Transportation

Transportation

As oxygen and carbon dioxide both have to be transported by the blood, the heart has different chambers, the left and the right, to prevent oxygen rich blood from mixing with the blood containing carbon dioxide

The left half carries oxygenated blood. Such separation allows a highly efficient supply of oxygen to the body

Transportation

This is very essential in animals that have high energy needs, such as birds and mammals, which constantly use energy to maintain their body temperature

Each half is further divided into two chambers

The upper one is called atrium and the lower one is termed as the ventricle

The human heart has four chambers

Transportation

Circulation of blood within the heart

Right side Left sideAtrium – deoxygenated blood from the body via vena cava

Atrium – oxygen rich blood from lungs via four pulmonary veins

Valve ValveVentricle - deoxygenated blood Ventricle - oxygenated bloodPulmonary artery – lungs - oxygenation

Aorta – to the body

Transportation

The muscles of the atria are relaxed

The right atrium receives deoxygenated blood collected from different organs of the body via large veins called vena cava

The left atrium too receives oxygen rich blood from the lungs simultaneously through the four pulmonary veins

The atria contract and pour the blood into respective ventricles which expand to receive the blood

Transportation

Left ventricle gets filled with oxygenated blood and right gets filled with deoxygenated blood

Now both the thick walled ventricles contract resulting in pumping out the oxygenated blood to all the parts of the body through the aorta (the largest artery) and the deoxygenated blood from the right ventricle enters the lungs through the pulmonary artery for oxygenation

Transportation

The valves between the atria and ventricles ensure that the blood does not flow backwards

Thus the deoxygenated blood enters the right part of the heart and again after oxygenation it enters the left part of the heart so the blood goes through the heart twice during each cycle

This is known as double circulation

Transportation

Double circulationTransportation

The body temperature of cold blooded animals varies according to environmental temperature

Such animals can tolerate some mixing of oxygenated and deoxygenated blood

Such animals have three chambered heart e.g. amphibians and many reptiles

Fish have only a two chambered heart so blood goes through the heart only once

Transportation

Transportation

Blood pressureThe force exerted by the blood on the wall of a blood vessel is called the blood pressure

This pressure is greater in the arteries than the veins

The pressure in the artery during ventricular contraction is called the systolic pressure and the pressure in the artery during ventricular relaxation is called diastolic pressure

Transportation

The normal systolic pressure is 120 mm of Hg and diastolic pressure is 80 mm of Hg

Blood pressure is measured by an instrument called as Sphygmomanometer

High blood pressure is also called Hypertension

Transportation

Capillaries and veins

Arteries carry blood away from the heart and have to tolerate the force exerted by the blood which is under high pressure exerted by the heart

The walls of the arteries are thick and elastic

Veins collect the blood from different parts of the body and bring it back to the heart. They do not need thick walls as blood is no longer under high pressure; instead they have valves to prevent the backward flow of blood

Transportation

On reaching the tissues arteries divide and redivide into smaller and smaller vessels called capillaries to bring the blood in contact with individual cells

Exchange of material between the blood and the surrounding cells takes place across the thin walls of the capillaries

The capillaries join together to form veins which take the blood away from the organ but towards the heart

Transportation

Repair of damaged network by the blood platelets

A cut damages the network of blood vessels

A leakage in such a closed system would lead to loss of blood and loss of pressure and thus reduce the efficiency of the pumping system

The blood platelets do the work of plugging these leaks by clotting the blood at the point of injury

Transportation

Lymph

When blood flows in the capillaries, some amount of the water, proteins and dissolved solutes are filtered out from the blood plasma into the tissue spaces

It forms the tissue fluid

It is similar to blood plasma except that it has very less amount of proteins in it because the capillary wall is impermeable to plasma proteins

Transportation

Some amount of this fluid enters small channels called lymph vessels and the fluid now is known as lymph

This light yellow fluid flows only in one direction that is from tissues to the heart

Role Lymph helps to destroy potentially dangerous bacteria and cancer cells and filter waste and toxins. It is also responsible for working with the circulatory system to help deliver hormones and nutrients to the tissues of the body. (https://www.sharecare.com/health/immune-lymphatic-system-health/what-role-lymph-my-body)

Transportation

Transportation in plants

Plants are stationary, they also have many dead cells in their body therefore their energy requirement is less and their transport system is quite slow

Plants need inorganic material like nitrogen, phosphorus, magnesium, manganese, sodium, etc.

Transportation

Soil is the nearest and the richest source of these minerals

Roots absorb them and transport them

Special tissues like xylem (carries water) and phloem (carries food) are present

All the parts of the plant are interconnected with these conducting tissues

Transportation

Transport of water in plants1) Root pressureRoot cells are in contact with water and minerals present in the soil

Due to the difference in concentration, water molecules and minerals enter the cells of roots

The cells at the surface become turgid and exert pressure on neighbouring cells called as root pressure

The minerals and water reach the root xylem and is pushed further and further to eliminate this difference

This steady movement creates a column of water that is steadily pushed upwards

Transportation

However this pressure by itself is unlikely to be enough to move the water up in tall trees though it is adequate in small plants like herbs and shrubs or even small trees

2) TranspirationThe loss of water in the form of water vapour from the aerial parts of the plants, like stomata of leaves, is known as transpiration

Evaporation of water from the leaves to atmosphere results in a decrease in the water potential of the epidermal cells

The water which is lost is replaced by the water from xylem vessels in the leaf

Transportation

Gradually it creates suction which pulls water from xylem cells of roots which in turn absorb more water

Thus the pull due to transpiration helps in absorption and movement of water and dissolved minerals in tall plants during the day when the stomata are open, while effect of root pressure is important during night

Root pressure TranspirationNight Day

An oak tree may transpire from its leaves 151,000 litres of water per yearAn acre of corn crop gives off 11,400 - 15,100 litres of water each day

Transportation

Transport of food and other substances

Translocation Food manufactured in the cells of the leaves is transported to each cell of the plant

Besides amino acids excess food is taken to the storage organs like roots, fruits and seeds

This process is called translocation and it takes place through phloem in upward as well as downward direction

Transportation

Translocation is not a simple physical process but needs energy which is obtained from ATP

When food material like sucrose is transferred to phloem tissue, using ATP, the concentration of water molecules decreases in that area

This results in the movement of water into the cells due to osmosis

The increased contents within the cells exert a high amount of pressure on their wall

Transportation

This pressure moves the food materials to the adjacent cells with low pressure

This allows the phloem to move material according to the plant's needs

In the flowering season, sugar stored in the roots or stem is translocated to the buds for growing them into flowers

Transportation

Excretion

Biochemical reactions constantly occur in the cells of a living organism. However, these reactions produce not only the required substances but also produce several unwanted harmful products like urea, uric acid, ammonia, etc.

These unwanted and harmful waste products need to be eliminated from the body. Different organisms employ different strategies for this.

Excretion in human beings

The excretory system in human beings

• a pair of kidneys, • a pair of ureters, • urinary bladder and • urethra

Excretion

Kidneys remove the waste products from the blood and urine

Kidneys are two bean shaped structures located at the back of the abdomen, one on either side of the vertebral column

The basic filtration unit in the kidney is a cluster of thin walled blood capillaries called as a nephron

Excretion

Excretion

Each nephron has a cup shaped thin walled upper end called Bowman's capsule which contains a bundle of blood capillaries called glomerulus Urea formed in the liver enters the blood

When blood containing urea enters the glomerulus it gets filtered through glomerular capillaries

Excretion

Excretion

The selectively permeable wall of the Bowman's capsule allows the water molecules and small molecules of the other substances to pass through them and forms glomerular filtrate

The blood, free from these materials is taken to the heart through the renal vein

The glomerular filtrate collected in the Bowman's capsule further passes through the nephron tubule where reabsorption of water and useful molecules takes place

Excretion

The remaining fluid containing the waste forms the urine which eventually enters a long tube called the ureter

It is further stored in the urinary bladder and from there it is thrown out through the urethra

As the bladder is muscular it is under the control of the nerves

As a result we can usually control the urge to urinateThough the kidneys are the major excretory organs in a human being the skin and the lungs also help in the process of excretion

Excretion

Right kidney is placed slightly lower than left kidney

Each kidney has approximately a million nephrons

An average person has around 5 litres of blood which the kidneys filter about 400 times in a day

Kidneys filter out about 190 litres of filtrate daily to produce 1-1.9 litres of urine, rest is absorbed

Excretion

HaemodialysisMany factors  like  injury,  infections or restricted blood flow to kidneys reduce the activity of kidneys

This leads to accumulation of poisonous wastes in the body which may lead to death

In  case  of  kidney  failure  an  artificial  device  is  used  to remove  the  nitrogenous  waste  products  from  the  blood This process is called dialysis

At one time 500 ml of blood is passed through the dialyzing machine

The  purified  blood  is  pumped  back  into  the  body  of  the patient

Excretion

Excretion

Excretion in Plants

Excretion in plants is much simpler than that of animals

No definite excretory system or organ is present in plants for removal of wastes

Gaseous excretory materials are eliminated by diffusion

Excretion

Many plant waste products are stored in the vacuoles of the leaves, flowers, fruits and even in the bark that falls off

Other waste products are stored as resins and gum in old xylem

Gum Resin

Excretion

Gums ResinsContain high amounts of sugar  Soluble in water, either dissolving entirely or swellingExude naturally from the stems or in response to wounding of the plantCommon in plants of dry regions

UseAdhesives, in printing and finishing textiles, sizing for paper, paint and candy industries

Usually secreted in definite cavities or passagesFrequently oozes out through the bark and hardens on exposure to airResins, unlike  gums, are insoluble in water

UseDissolved in solvents and surfaces are painted; for waterproof coatings, decorative coatings

http://www.faculty.ucr.edu/~legneref/botany/gumresin.htm

Excretion

Plants also excrete some waste substances into the soil around them

In some plants waste is in the form of needle-shaped calcium oxalate crystals called as raphides

Excretion

Some plant wastes are very useful to human beings e.g. rubber latex, gum, resins and essential oils like eucalyptus or sandalwood oil

Rubber latex

An oil is "essential" in the sense that it contains the "essence of" the plant's fragrance

Excretion

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