Life Processes Notes Class 10 Science Chapter 6 Explanation

CBSE Class 10 Science Notes of Chapter 6 Life Processes, Video Explanation, and Question Answers

Part 1 – Nutrition

Part 2 – Respiration

Part 3 – Transportation

Life Processes Class 10 Notes – Life Processes Class 10 Science Chapter 6 as per NCERT Book used in CBSE and other Schools. The lesson covers the complete explanation of Class 10 Science Chapter 6 Life Processes.

Topics covered in the lesson are Introduction, Breathing and respiration difference, Blood groups, Definition of nutrition, Aerobic respiration, Blood transfusion, Anabolic processes, Anaerobic respiration, Rhesus factor, Types, of nutrients, Different modes of respiration, Heart, Types of nutrition, Characteristics of respiratory organs, ECG, Heterotrophs classification, Respiratory system of man, Blood pressure, Saprophytes, Mechanism of breathing, Lymphatic system, Parasites, Cellular respiration, Transportation in plants, Symbiotic parasites, Respiration in plants, Transportation of water in plants, Holozoic mode, Blood circulatory system, Excretion definition, Digestive system of man, Plasma, Excretory system of man, Associated glands, Red blood cells, Renal failure, Physiology, White blood cells, Osmoregulation, Photosynthesis, Platelets, Nutrition in amoeba, Blood clotting.

Here is the complete explanation of the chapter, along with all the important questions, and NCERT solutions to book questions have also been provided for the ease of students.

Class 10 Science

Chapter 6 – Life Processes (Part 1 – Nutrition)

Also See : CBSE Class 10 Science Syllabus 2021 Session

Life Processes Video Explanation

Life Processes Introduction

Organisms need material from outside in order to grow, develop and synthesize proteins and other substances needed by our body. For this, nutrition is important in our body. So, we can define nutrition as :

Nutrition Definition

It is the process of intake of food to produce energy required for various metabolic activities of the body.

There are two types of metabolic processes occurring in our body : Catabolic and Anabolic

Catabolic process

Catabolic processes include breakdown processes.

Anabolic process

Anabolic process means synthesis processes.

The food that we eat has nutrients in it which provide energy.

Types of nutrients

Different types of nutrients are :

Carbohydrates
Vitamins
Proteins
Fats
Minerals

Types of nutrition

On the basis of how organisms obtain food, they are of two main types:

Autotrophic nutrition
Heterotrophic nutrition

Autotrophic nutrition

It is a type of nutrition in which organisms can make its food with the help of Photosynthesis as they possess Chlorophyll. That is, they have the ability to convert solar energy into chemical energy for food, but this power is only in green plants and not animals or humans as they don’t have any photosynthetic pigment.

For example – In all green plants, the photosynthetic pigments are Chlorophyll, Carotenoids, Phycobilins, etc. Out of all, Chlorophyll a and Chlorophyll b are the best.

Heterotrophic nutrition

It is a type of nutrition in which organisms cannot make their own food as it lacks chlorophyll or any other photosynthetic pigments.

For example – all non green plants & animals

Classification of Heterotrophs

On the basis of how they obtain nutrition from autotrophs, hetrotrophes show different modes of obtaining food: either they act as Parasites, as Saprophytes or show Holozoic mode.

Let us discuss them one by one –

Saprophytes

Saprophytes are the organisms that feed on dead decaying matter. For example- fungi.

They secrete certain enzymes from their body surface that convert complex food into simple form and then they absorb it through general body surface.

Parasites

Parasites are organisms that live in or on the surface of other organisms to fulfill their nutritional requirements. For example – lices in human head.

This relationship can be symbiotic or non symbiotic.

Symbiotic Parasites

Symbiotic parasite is that in which both the partners are mutually benefited like e.coli in human intestine as it obtains its food from our body but in response, secretes certain minerals for our body.

For example – e.coli bacterium (parasite) in human intestine (host)

Holozoic mode

They are organisms that follow five steps in sequence: ingestion, digestion, absorption, assimilation & egestion

For example: man
(Organism showing this mode can be Herbivorous, Carnivorous or Omnivorous)

Digestive System of man

Man is a heterotroph & has a holozoic mode of nutrition. The digestive system of man is divided into two parts:

Alimentary canal

Associated glands

Alimentary Canal is a 9 metre long tube that starts from mouth and ends up at anus.

organs

It has following organs in sequence:

Mouth		Esophagus		Stomach		Small Intestine		Large Intestine		Anus
(Buccal cavity)		(Food pipe)		(J- shaped)		(Long & coiled)		(Short and wide)

Parts of small intestine are Duodenum, Jejunum & Ileum
Parts of large intestine are Caecum, Colon & Rectum

Associated glands

1) Salivary gland- Saliva containing starch is called Ptyalin (Serum Amylase).

2) Gastric gland- They produce various gastric juices like:

Mucus- It lines the stomach wall.
Hydrochloric Acid- It provides an acidic medium.
Pepsinogen- It helps convert proteins to Peptones.
Renin- It helps to change milk to curd.

gland

3) Pancreatic Gland- It produces pancreatic juices.

Amylase- It helps in converting starch to maltose.
Trypsin- It helps in converting Peptones to Peptides.
Lipase- Helps in converting fats to fatty acid & glycerol.

4) Liver produces bile juices which help in digestion of fats.

5) Gland in Ileum prepares erepsin which helps in converting the following-

Peptides to amino acid
Lipase/ fat to fatty acid & glycerin
Maltase/ maltose to glucose
Lactase/ lactose to galactose

Physiology

Ingestion: It is a process in which the food is taken in mouth and churned with the help of teeth.

Digestion: In the mouth, saliva is secreted through salivary gland that contains serum amylase which starts the digestion of starch. The masticated food is rolled into bolus and is swallowed. Then the food, from food pipe, by peristaltic movement passes into the stomach .

In Stomach: When the food goes in the stomach, gastric juices are secreted i.e.,
Mucus- That lines the stomach wall.
Hydrochloric Acid- That provides an acidic medium for Pepsin.
Pepsin- That converts proteins to Peptones.
Renin- That changes milk to curd.

Food remains in the stomach for about 3 hours and then is passed into the duodenum in the form of chyme.

In Duodenum the bile juices, bicarbonates ions from liver & pancreatic juice from pancreas are secreted.
Then the bile juice helps in emulsification of fats.
The bicarbonates ions provide alkaline medium to pancreatic juices.
The pancreatic juices help in converting amylase and starch into maltose.
Also trypsin helps to convert peptones to peptides.
Lipase also helps to convert fat into fatty acid & glycerol.
Then the food passes from jejunum to ileum. In ileum intestinal juice is secreted that completes the digestion and converts food into soluble form i.e. amino acid, fatty acid & glucose..

Absorption:In ileum there are small finger like projections called villi that increase the surface area for absorption. Absorbed food is passed into blood & through blood, diffuses into body cells.

Assimilation:In body cells, energy is produced from absorbed food .
Egestion:The undigested food passes through the large intestine & water absorption take place. This undigested food from caecum passes to colon and then to rectum where it forms faeces and is egested through anus.

Peptic Ulcer: It is a disorder when mucus membrane of stomach gets corroded due to which acid effect reaches stomach wall which leads to ulcers

base

Class 10 Science Chapters

Our Environment	Sources of Energy	Sustainable Management of Natural Resources
Magnetic Effect of Electric Current	The Human Eye and the Colourful World	Reproduction
Heredity and Evolution	Light- Reflection and Refraction	Control and Coordination

Photosynthesis

It is defined as the process of synthesis of food by green plants which takes place with the help of CO₂, H₂O, chlorophyll, in the presence of sunlight.

Raw materials required:

Carbon dioxide which is taken by the plant from atmosphere through stomata.
Water is taken by the plant from soil through roots.
Sunlight which is taken by the plant from the sun.
Chlorophyll, a green pigment that can trap solar energy and convert chemical energy into food. It is present in organelle called chloroplast. This organelle is in palisade cells of mesophyll tissue of leaf.

Mechanism of Photosynthesis

It is divided into two parts which are

Light reaction
Dark reaction

Light reaction: It takes place in grana in the presence of light. It involves:

Photolysis of water – This is done for the breakdown of water into its components in presence of light.

H₂O

H₂

+

? O2

+

2 e’s

Formation of reduced form of NADP

NADP

+

H₂

NADPH₂

Formation of energy source ATP:

ADP

+

Pi

+

Free energy

ATP

+

H2O

–

Dark reaction: It takes place in absence of light.This reaction is also called Calvin Benson cycle.
In this CO₂ reacts with 2 molecules of NADP and 3 molecules of ATP in the presence of bio-catalyst RUBP to form food in the form of glucose.

CO₂

+

NADPH

+

ATP

+

RUBP

CHO

+

ADP

+

NADP

+

RUBP

Use of RUBP: It is used as a biocatalyst i.e. increases the rate of reaction without undergoing any change in itself.

Factors affecting the process:

light: Increases with increase in light intensity until CO2 becomes limiting.(blue & red light are more effective)
CO2: Increases with increase in the concentration of CO2 but up to a certain level.
H2O: Decreases with decrease in water content
Temperature: Decreases with decrease in temperature as enzyme activity also decreases.(very high temperature lowers photosynthesis)

Nutrition in Amoeba

Amoeba also shows heterotrophic mode of nutrition .

(a) Ingestion: Firstly, amoeba localizes the food and then, to engulf the food, it makes a cup shaped structure (pseudopodia or false feet) around itself and then in the form of a food vacuole it engulfs it.

(b) Digestion: In the food vacuole certain enzymes are secreted that convert complex food materials into simple ones.

(c) Absorption and Assimilation: The digested food is absorbed and is spread in cytoplasm from where it is utilized to produce energy.

(d) Egestion: The leftover remains move near the cell membrane. Then the cell membrane ruptures and the food is thrown out and then again membrane is formed .

Part 2- Respiration

Respiration Introduction

As we all know for survival of any living organism breathing is very important. Not only us every living creature needs to breathe. For this we intake oxygen and give out carbon dioxide. It is essential for us as we know in our body there is absorbed food and in order to get energy we need to break it and for breaking it we need oxygen that is why we need to take oxygen inside and that we can do only by breathing .But many a time we use breathing and respiration in the same manner but actually it is not like that. There is a lot of difference between the meaning of breathing and respiration. Let us see how they differ.

Difference between breathing and respiration

Life Processes Class 10 – Breathing and Respiration are different in many aspects from each other:-

Breathing	Respiration
It is simply exchange of gases i.e. taking in o2 & giving out co2.	It is intake of o2, using it for oxidation of food & giving out co2.
It is a physical process.	It is biochemical process.
There is no energy produced in this.	There is energy produced in this process.
No enzymes are involved.	Enzymes are involved.
It is not a cellular process.	It is a cellular process.

So we conclude that breathing is a sub-part of respiration as it is not concerned with energy production whereas respiration is a wide concept as it includes all the activities like energy production, carbon dioxide production and obviously its removal. Breathing is actually a sub part of it. So now we can define respiration as intake of oxygen, breaking down of food to produce energy and giving out carbon dioxide. Different types of respiration are:

Aerobic
Anaerobic

Aerobic respiration

In this process the respiration takes place in the presence of O2 or oxygen.
For Example : Man

Glucose → Pyruvic acid→ 38 atp + co2 + h2o

In our body cells food is absorbed and to release energy, it needs to be broken down which is done with the help of oxygen that we take in. The food is in the form of glucose which gets converted into pyruvic acid in the cytoplasm of the cell. This process is oxygen independent and is termed as glycolysis.

Then this pyruvic acid, in the presence of oxygen gets converted into energy, carbon dioxide and water vapour. The energy in our body is in chemical form that is ATP(Adenosine TriPhosphate). This conversion of pyruvic acid into energy is called kreb cycle and it occurs in Mitochondria that is the reason why Mitochondria is called the powerhouse of the cell.

In this aerobic respiration we get 38 molecules of ATP when 1 molecule of glucose is oxidized. Those organisms that carry out this type of respiration are called aerobes .

Anaerobic respiration

It takes place in absence of o2.
For example: Some bacteria.

In this, the absorbed food that is glucose is converted into pyruvic acid and it is known as glycolysis and it is also an oxygen independent process. After this the pyruvic acid in the absence of oxygen gets converted into some chemical compound depending upon where this anaerobic respiration is taking place. Along with it carbon dioxide, energy and water vapour are formed as by products. In it 1 molecule of glucose breaks down to form 2 ATP molecules and other by products .

This anaerobic respiration is seen in case of microorganisms helping in breweries for the production of component of hard drinks that is ethanol. In this the chemical compound formed as a result of this respiration is ethanol that is the main constituent of hard drinks .

Glucose → Pyruvic acid → Ethanol + 2 ATP + H2O (fermentation)

Likewise when we are exercising, our energy requirement rises but due to shortage of oxygen supply our muscles start respiring anaerobically and the chemical compound formed is lactic acid. The fate of this lactic acid is that it is sent to the liver where it is stored .

Glucose → pyruvic acid → Lactic acid + 2ATP + H2O (our muscles)

Top
Class 10 Science Chapters, Explanation, Notes

Life Processes	Chemical Reaction and Equation	Carbon and it’s compound
Periodic Classification of Elements	Metals and Non-Metals

Q. Why do we feel tired during vigorous exercise?

A. During exercise our muscles show anaerobic respiration so, energy produced per glucose molecule is only 2 ATP i.e. very less and our energy requirement is high. Therefore, more and more glucose is being oxidized to produce more energy and along with that more lactic acid is produced & this lactic acid gets accumulated in the muscle, leading to tiredness.

Different modes of respiration

Skin ? Cuticular respiration
For example: Earthworm

Tracheal → Tracheal respiration
For example: Grasshopper

Lungs → Pulmonary respiration
For example: Man, Birds, Frog etc

Gills → Branchial respiration
For example: Fishes, Prawns etc

Characteristics of Respiratory Organs

As we have discussed above, different organisms show different modes of respiration that means they possess different respiratory organs. So there must be some characteristics that a respiratory organ must possess which makes them perform their role:

It must be moist as in moist conditions diffusion rate is faster.
It must be thin as it allows better diffusion.
It must have a large surface area as more the surface area more the amount of gas will be diffused.
It must be highly vascular as this also speeds up the diffusion rate as the gases will be quickly taken up by blood.
It must be highly permeable so that the gases can enter and move out quickly.

The respiratory system of man

A human being shows pulmonary respiration i.e. the respiratory organs are the lungs. The respiratory tract includes: nostrils, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles & lungs. External part of the nose has nostrils that leads to nasal cavity. In nasal cavity hairs & mucus glands are present and their function is to clean,moisten & warm the air.This cavity extends up to the pharynx. Air enters from pharynx and goes up to the windpipe(trachea). Trachea is made up of cartilaginous rings that prevent the collapse of tracheal wall in the absence of air. Trachea further divides into two branches called bronchi that further divides into primary,secondary,tertiary bronchi. Bronchioles finally has air sacs (alveoli) at their ends. These air sacs are surrounded by tuft of capillaries. Outer covering of the lungs is called the pleura.

Mechanism of breathing

For the exchange of gases i.e. taking in oxygen and giving out carbon dioxide we have a factor that is responsible for the exchange. The factor is “difference in the pressure of gases inside and outside the body”. Thoracic cavity is a cage like structure present in chest formed of ribs, diaphragm, backbone and the abdominal muscles. During inspiration ribs are pulled forward & upwards, diaphragm becomes flat, abdominal muscles contract. Due to this the size of cavity increases thereby decreasing the pressure of air, but outside the pressure of air is high therefore air from outside moves towards inside. During expiration ribs come back to their original position, diaphragm again becomes dome shaped abdominal muscles relax. Due to this the size of cavity decreases thereby increasing the pressure of air but outside pressure of air is low therefore air from inside moves towards outside.

Cellular respiration

It is defined as respiration at cellular level i.e. in cell. The blood brings oxygen from lungs in the complex form called oxyhb to the tissues. In tissues the content of oxygen is low as compared to blood therefore complex form breaks up & oxygen from blood diffuses into tissues. Inside tissue, the cell uses this oxygen for oxidation of food as a result of which the carbon dioxide concentration in the cell increases. But concentration of carbon dioxide is less in blood therefore carbon dioxide from tissue diffuses into blood where it forms complex carbinohb and is taken to the lungs. From the lungs it is expired out. There are many types of respiratory disorders that a human being can face. One of them is emphysema. It is a disorder in which there is deposition of certain harmful substances in the alveoli. Due to that the oxygen carrying capacity of alveoli gets reduced and person suffers from respiratory disorders. Similar to it we have disorders like asthma ,bronchitis that cause severe problem in respiration .

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Important Videos Links

Respiration in plants

In plants we have already discussed that photosynthesis take place and during that carbon dioxide is taken in and oxygen is given out. For the exchange the stomata are present in a leaf which is surrounded by guard cells that encloses a pore. When this pore opens the gaseous exchange occurs. But at night when there is no sun the plant instead of photosynthesis carry out respiration just like animals i.e. take in oxygen and give out carbon dioxide. This exchange also occurs through the stomata in the same way like the other respiratory parts in plants.

Lenticels: In the bark of the tree there are loosely arranged mass of cells that allow gaseous exchange. They also have pores through which the exchange occurs .

Pneumatophores: These are the breathing roots present in the plants growing in saline water. These roots help in the gaseous exchange.

Life Processes Class 10 Extra questions-

Q1) Write down the difference between direct respiration and indirect respiration?

Ans) Direct respiration: In this gaseous exchange occurs directly through body cells by means of diffusion. The blood is not involved in respiration.. For example: amoeba
Indirect respiration : In this the gases are carried by means of blood. It also involves special organs like lungs etc.The blood transport the gases to all the body cells.For example: man.

Q2) Write down the difference between respiration in plants & animals?

Ans : Plants Animals
.

In plants the different parts of the plant like root,stem etc respire separately.	In animals respiration occurs as a unit.
In plant there is a little transport of gases.	In animals the gases are transported to a long distance in the body.
In plants the rate of respiration is slow.	In animals the rate of respiration is higher.
In plants there is almost no heat produced.	In animals there is heat produced.
In plants the anaerobic respiration produces ethanol & co2.	In animals the anaerobic respiration produces lactic acid & co2.

Q3) How do the roots of a plant respire?

Ans) When the roots are young they obtain O2 from soil particles with the help of root hairs and is transported to all cells of root by means of diffusion. In a similar way CO2 is given out. When the roots get older they respire through loosely arranged cells called lenticels as they lack root hairs.

Q4) How do plants growing in saline soil respire?

Ans) They respire through special respiratory roots called pneumatophores. Each pneumatophore bears pores or lenticels that helps in the gaseous exchanges.

Q5) How do leaves & stem respire?

Ans) The leaves and stem respire with the help of stomata & lenticels.

Q6) How do fish respire?

Ans) Fish respire with the help of gills. There are four gills on each side of the body. The gills are enclosed in a chamber called gill chamber in form of gill filaments that bears pore called operculum. The gill filaments are richly supplied with blood. The direction of blood is opposite to the direction of water current. During breathing the rhythmic movements of mouth ,operculum allows availability of water to the gills from which they extract dissolved o2 & release co2 in water.

Related – MCQs for Life Processes Class 10

Q7) Why fish die when taken out in air?

Ans) The reasons why fish die when taken out in the air are:
(i) Because the mouth & operculum can not show muscular movements in air.
(ii) The gill filaments stick to each other therefore surface area for gaseous exchange gets reduced.

Q8) Write about the functions of epiglottis?

Ans) Epiglottis is a flap like structure that covers the glottis to prevent entry of food into the trachea while swallowing the food.

Part 3 – Transportation

Introduction

In our body, transporting system is as essential as food, hormones, gases, etc. For this, we need to have some system that can transport these things from one part of the body to other parts.
There are two circulatory systems:

Blood circulatory system
Lymphatic system

Blood Circulatory System

In this system the fluid that transports substances is blood. Let us know about blood first. Blood is formed of two components :-

Plasma
Blood cells

Plasma

It is a yellow coloured fluid that is 90% water and rest 10% is organic and inorganic substances like nutrients, gases, hormones, etc. That is the reason plasma acts as a nutritive medium for blood cells. Types of blood cells are:

Red blood cells
White blood cells
Platelets

Red blood cells

They are the cells that have a disc like shape. These are incomplete cells with no nucleus, mitochondria and endoplasmic reticulum. These cells are the smallest cells of our body. These cells have a red colour pigment made up of iron called hemoglobin. The function of haemoglobin is to transport gases by forming complexes i.e oxyhb and carbinohb. These cells are synthesized in the bone marrow of adults and in infants they are synthesized in the spleen from stem cells. The lifespan of these cells is 120 days. These cells are also known as erythrocytes.

White blood cells

These cells are irregular in shape and are complete cells enclosing all organelles. These cells do not have any pigment in them and that is the reason they have no colour. These cells have a lifespan of about 2 to 4 weeks. They are also called as leukocytes. They are also called as soldiers of our body as they protect our body from infection causing agents. Either they engulf infection causing agent or they secrete certain proteins that make infection causing agent harmless.

Platelets

They are tiny fragments that may or may not have a nucleus. Their function is to secrete certain proteins that helps in blood clotting. Their life span is 60 to 120 days. They are also called thrombocytes.

Blood Clotting

We have seen many a time that our vessel gets punctured due to one or more reasons and bleeding starts but with time the bleeding stops also. It occurs through the process of blood clotting .
It is defined as the transformation of liquid state of blood into jelly like state on exposure to air. Mechanisms:

a) Injury + platelets → Thromboplastin (inactive enzyme)

b) Prothrombin → Thrombin (active enzyme)

c) Fibrinogen → Fibrin

d) Fibrin + rbc → Blood clot

in beginning this clot is soft in nature then in few seconds it turns into hard clod and then a yellow colored fluid is secreted called serum which is plasma without fibrinogen.
the whole process takes 2 to 3 minutes.

Some important terms

Antigens: They are infection causing agents that can harm the body.

Antibodies: They are the proteins synthesized in our body that fight against antigens and make them harmless.

Blood groups

We have noticed that we have different blood groups. Even in the same family you get to see different blood groups. So let us study first the types and then we will study about its reason.

There are four major types of blood groups:

blood group	antigen	antibody
a	a	b
b	b	a
ab	a, b	–
o	none	all

Blood transfusion

It is the process of who can receive blood from whom and who can donate to whom. It is the process of transfer of blood from a healthy person to a sick person. The one who donates is the donor and the one who receives is the recipient.
When blood is to be transfused, some special precautions are to be taken. These precautions are given below:

The blood groups must be same
The blood should be disease free
If the two things are verified, still for precaution sake, a compatibility test is carried out:
Take a drop of donor’s blood on a slide, then add a drop of recipient’s blood to it. Leave it undisturbed for some time. Then observe it under the microscope. If clusters of red blood cells are seen, then blood is in-compatible and if clusters of red blood cells are not seen then blood is compatible.

Blood compatibility

Blood group AB is universal recipient as it has no antibodies.
Blood group O is the universal donor as it has all antibodies.

Rhesus factor

It is an antigen that may be present in our blood. The blood that carries the antigen is rh+ve and the other which does not possess is rh-ve. The blood that is +ve is compatible with it and for others it is a harmful antigen. Heart is a muscular walled organ that pumps blood to all the body parts. It is just like a clenched fist.It is roughly divided into two sides. The vessels that are associated with heart are:

Heart

Arteries- These are vessels that are thick walled and carry pure blood from the heart to all parts of the body.

Veins- These are thin walled vessels that carry impure blood from all body parts to the heart.

Capillaries- These are very thin walled vessels that are actually junctions between arteries and veins through which the exchange of substances occur.

left side- deals with pure blood
right side- deals with impure blood

The outer-covering of heart is pericardium and in heart special type of muscles are present that are non fatigue called cardiac muscle.

The heart is divided into 4 chambers:

2 atrium
2 ventricles

The two atria are separated by inter auricular septum and two ventricles are separated by inter ventricular septum and auricle and ventricle by an inter a-v septum. In right atrium a cup shaped structure called s-a node (sinu-auricular) is present whose function is to generate electric impulses in the heart. The pure blood through the pulmonary vein flows from lungs to left auricle, as the volume of blood increases, pressure increases in left auricle. Due to this a-v septum valves open and blood flows from left auricle to left ventricle. As volume of blood increases in left ventricle, pressure increases. Due to this a-v septum valves close and semilunar of aorta opens. This blood flows into

Aorta → Arteries → Capillaries.

Through capillaries the exchange of substances occur an| now in capillaries, the impure blood is transferred from small veins to the bigger veins.

The three bigger veins are formed:

1.superior vena-cava
2.inferior vena –cava
3 posterior vena cava

All these veins unite to form a common vein that opens up into the right atrium. The blood flows into the right atrium, volume increases pressure increases. then a-v septum valves open and blood flows into the right ventricle. then, by pulmonary artery, it is carried to the lungs for oxygenation. As we know that blood flows twice through heart therefore the circulation it is called “double circulation.”

ECG (Electro Cardio Graph)

It is an instrument used to record electric impulses generated in the heart. In it the ecg machine is used to which electrodes are attached. These electrodes are further attached to the chest of the patient by fixing a gel. Then the patient is said to relax. The impulses are recorded and they appear on a sheet of paper in the form of graph called electrocardiogram.

Blood Pressure

It is the pressure that blood exerts on the walls of the vessel. It is measured by an instrument called a sphygmomanometer. The blood pressure is more in arteries than in veins. There are two types of pressures:

1.systolic (pressure generated due to contraction).
2.diastolic pressure (pressure generated due to relaxation).

The normal blood pressure is 120/80 mm of mercury. High blood pressure is called hypertension.

Lymphatic system

The fluid in it that transports substances is lymph. This system consists of the following:
1. Lymph vessels
2. Lymph capillaries
3. Lymph

The lymph capillaries are present all over in the blood like blood capillaries but they are blunt from one end. These capillaries unite together to form lymph vessels. In lymph vessels, at certain places, lymph nodes are present which consist of lymphocytes that function like white blood cells. In these vessels the lymph fluid flows.
The functions of lymph are:

1. It carries digested and absorbed fat from the intestine.
2. It drains the excess fluid from the extracellular space back into the blood.

Transportation in plants

In plants also transportation is required but not that complicated. Transportation is important but is not too complex. For this transportation two systems are present in the plants:
1. Xylem
2.Phloem

These are also known as vascular bundles. Xylem helps in the transportation of water and minerals whereas the phloem helps in translocation. Xylem is made up of four kinds of cells. it is formed of the following 4 cells:

Tracheid
Vessels
Parenchyma
Xylem fibres

Out of all, only parenchyma is living and all the other components are dead. Let us study all the components:

1) Xylem vessels : These are formed of the dead cells joined end to end forming a long tube. These tubes have open ends. It is made up of lignin. It has certain pits where lignin is absent.

2) Tracheids: They are spindle shaped vessels with closed ends having pits in them.

3) Parenchyma: They are the living cells with nucleus.

Transportation of water in plants

Ascent of sap is the continuous channel formed for the transportation of water and minerals from roots to aerial parts of plant. The factor that is responsible is “transpiration pull”. As the stomatal pores open, water starts transpiring due to which they withdraw water from epidermal cells which further withdraw from underlying cells. Ultimately, the hydrostatic pressure of xylem vessel of the leafs fall. But the hydrostatic pressure is still high in xylem vessels of root so the water starts moving from xylem vessel of root to vessel of leaf now the pressure in x. Vessel of root falls. Therefore, they withdraw water from underlying cells.

Part 4- Excretion

Definition of excretion

It is defined as “the removal of nitrogenous waste from the body.” Nitrogenous waste can be
Urea (ureotelic) e.g. man
Uric acid (uricotelic) e.g. birds
Ammonia (ammonotelic) e.g. insects

Excretory system of man

Excretory system of a man consists of a pair of kidneys, ureters, urinary bladder and urethras. Kidneys are bean shaped and located just above the waist. Nephron are structural and functional unit of kidneys i.e. kidney is formed of cells called nephrons. Urine formation is broadly divided into three steps:-

Filtration
Reabsorption
Collection

Filtration- The blood flows through the glomerulus under great pressure which is because efferent arteriole is narrow. All the substances useful and non useful present in blood is filtered and enter from glomerulus into bowman’s capsule through pores.called fenestrae. Then this substance passes from bowman’s capsule to pct and finally reaches loop of henle. Capillary blood that is left is regarded as a waste product. Water absorption take place in this region. Therefore water and waste product forms urine.
Collection: The urine then pass from distal convoluted tubule. Small convoluted tubule forms bigger collecting tubule. Finally they pour their secretion into renal pyramids. Urine from renal pyramids goes into ureter. Through ureter, urine reaches urine bladder where urine is stored temporarily & is excreted out through the urethra. The process of urine out of the urethra is called urination. Function of Henle’s loop is to concentrate the urine.

Renal failure

Renal failure can occur due to many reasons like:

Accident or injury
Disease etc.

So either transplantation is done or person is put on artificial kidney i.e.on dialysis. Dialysis is a process of separating small molecules from large ones using semi-permeable membrane. it is also called haemo-dialysis.

Dialysis machine consists of cellulose tubes and has dialysing solution filled in chamber. Blood from renal artery passes from cellulose tube, impure substances diffuse out into dialysing solution, & pure substances diffuse into blood. Hence, blood gets purified and is put back into renal vein.

Osmoregulation

It is the process of maintaining water and ionic balance in the body. Osmo receptors are the cells present in blood that are sensitive to alteration. Any alteration makes osmo receptors active and they generate an impulse to the brain. Brain analyses, interprets & sends message to prostaglandin. Prostaglandin in response secrete antidiuretic hormone. Antidiuretic hormone diffuses into blood and via blood reaches the kidney where it acts on loop of henle of nephron. If water content is high, then antidiuretic hormone makes the loop of henle more permeable to water. So that more under is removed from the body and urine will be diluted in that case. If water content is low, then antidiuretic hormone makes loops of henle less permeable to water so that more & more water is retained, thereby the urine is concentrated. Some waste products are stored in leaves & bark and are removed as they shed. Raphides are the spine like structure that store excretory products of certain plants, fruit, vegetables like yam (jimikand).

Life Processes NCERT Book Solutions

Q. Choose the correct option
1. The kidneys in human beings are a part of the system for
(a) nutrition.
(b) respiration.
(c) excretion.
(d) transportation.

Ans : (c) excretion

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.

Ans : (a) transport of water.

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

Ans : (d) all of the above

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

Ans : (b) Mitochondria

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

Ans: Fats are emulsified by bile juice and then converted into fatty acids and glycerol by lipase of pancreas and intestinal juice. It occurs in the small intestine.

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

Ans: It helps in the lubrication and mastication of food.

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

Ans: The necessary conditions for autotrophic nutrition are-
1. Carbon dioxide 2. Light 3. Water 4. Chlorophyll
The bi products are food in the form of glucose and oxygen gas.

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

Aerobic	Anaerobic
It occurs in the presence of oxygen.	It occurs in the absence of oxygen.
It consists of 2 steps: Glycolysis and kreb cycle.	It consist of glycolysis but not krebs cycle.
In it 1 glucose molecule produce more energy that is 38 ATP. It produce energy and carbon dioxide as a bi product.	1 glucose molecule comparatively produce less energy that is only 2 ATP. It produces energy , carbon dioxide and also some chemical compound
Example: Man	Example: Bacteria

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

Ans : Alveoli are surrounded by tuft of capillaries and moreover, they have balloon like structure to maximize the exchange of energy.

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

Ans : Deficiency of haemoglobin can lead to Anemia.

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

Ans : The pure blood through the pulmonary vein flows from lungs to left auricle, as the volume of blood increases, pressure increases in left auricle. Due to this, A-V septum valves open and blood flows from left auricle to left ventricle. As volume of blood increases in left ventricle, pressure increases. Due to this A-V septum valves close and semilunar of aorta opens. This blood flows into
aorta → arteries → capillaries.
Through capillaries exchange of substances occur and now in capillaries, the impure blood is transferred into small veins → bigger veins.

The three bigger veins are formed
1. Superior vena-cava
2. Vena –cava
3. Posterior vena cava

All these veins unite to form a common vein that opens up into the right atrium. The blood flows into the right atrium, volume increases and the pressure increases. Then A-V septum valves open and blood flows into the right ventricle.Then, by pulmonary artery, it is carried to the lungs for oxygenation. As blood flows twice through heart, therefore, the circulation is called double circulation. It is necessary in order to separate oxygenated blood from deoxygenated blood which makes our circulatory system an efficient system.

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

Ans :Xylem : It helps in transportation of water and minerals.
Phloem : It helps in translocation of food.

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

Alveoli	Nephron
It is the smallest unit of respiratory system. It consists of a sac which can hold gases and allow their exchange with blood.	It is the smallest unit of the excretory system. It consists of glomerulus and associated tubules.
It is balloon shaped and it helps in the exchange of gases.	It is more like a tube and helps in excretion.
It supplies blood to pulmonary venules.	It supplies blood to renal veins.
It is found in lungs.	It is found in the kidneys.

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