NCERT Solutions Class 10th Science Chapter – 6 Life Processes Notes

LIFE PROCESSES

• Respiration in Animals
• Nutrition
• Transportation and Circulation
• Excretion

Respiration in Animals

Mechanism of Breathing
• Inspiration
• Gaseous exchange
• Expiration

Part of Respiratory System
• Nostrils
• Trachea
• Bronchi
• Bronchioles
• Lungs
• Alveoli

Nutrition

Autotrophic nutrition in Plants
• Process involved is Photosynthesis

Heterotrophic nutrition in animals.
• Steps included are
• Ingestion
• Digestion
• Absorption
• Egestion

Part of Alimentary Canal in Human.
• Mouth
• Oesophagus
• Stomach Juice
• Small Intestine
• Large Intestine
• Rectum

Transportation and Circulation

Transportation in plants
• Xylem – Transport of water
• Phloem – Transport of food

Circulatory system in humans:
• Blood
• Heart
• Blood vessels

Excretion

In Plants: Process involved is Transpiration

In Humans: Basic unit of Kidney-Nephron Parts of Nephron
• Bowman’s capsule
• Glomerulus
• Proximal convoluted tubule
• Loop of Henle
• Distal convoluted tubule
• Collecting duct

Life processes – All the processes like respiration, digestion, which together keep the living organisms alive and perform the job of body maintenance are called life processes.

All living things perform certain life processes like growth, excretion, respiration, circulation ,Digestion ,etc.

Life processes

• Digestion
• Respiration
• Circulation 
• Excretion

Nutrition

(The whole process by which an organism obtains its food)

Nutrition in Plants
           ↓
Plants are autotrophs.
           ↓
Can make their own food.

Nutrition in Animals
           ↓
Animals are hetrotrophs.
           ↓
Depends on plants or other animals for their food

Modes of Nutrition

Autotrophic Nutrition

The organisms which carry out autotrophic nutrition are called autotrophs (green plants).

Autotrophs Use → Simple inorganic material Convert into → Complex high energy molecules (Carbohydrates)

Autotrophic nutrition is the process by which autotrophs take in CO, and H₂O and convert these into carbohydrates in the presence of chlorophyll, sunlight is called Photosynthesis.

Equations: 6CO_₂ + 12H_₂O Sunlight / Chlorophyll → C₆H_₁₂O₆ + 60_₂ + 6H_₂O

Raw Materials for Photosynthesis

Sunlight

Chlorophyll → Sunlight absorbed by chlorophyll

CO₂ → Enters through stomata and oxygen (O₂) is released as by product through  stomata on leaf.

Water → Water + dissolved minerals like nitrogen, phosphorus etc. are taken up by the roots of the soil.

Main Events of Photosynthesis

• Absorption of light energy by chlorophyll
• Conversion of light energy into chemical energy + splitting (breaking) of water into hydrogen and oxygen
• Reduction of CO₂ to carbohydrates

Stomata – Tiny pores present on the surface of the leaves.

Functions
(a) Exchange of gases O₂/CO₂.
(b) Loses large amount of water (water vapour) during transpiration.

Hetrotrophic Nutrition

How do organisms obtain their food

Unicellular/Single celled organisms – Food is taken up through entire surface. Example
(i) Amoeba
(ii) Paramaecium

Amoeba 

↓
Pseudopodia

↓
extension of
cell membrane

↓
Capture food

↓
Taken in | food vacuole |

↓

Digestion of food
in food vacuole /Diffusion
(of simple substances in cytoplasm)

↓

Undigested food

↓

move to surface of cell and
is thrown out.

(ii) Paramaecium – Which is a unicellular organism takes in food at a specific spot which is moved there by cilia (small hairs present all over)

Nutrition in Human Beings

Mouth – Intake of whole food.

Teeth – Chewing/grinding of food.

Tongue – Rolling of food + Tasting of food + Swallowing/Pushing down of the food.

Salivary Glands – Secrete saliva + Mucus

Starch (Salivary→ amylase [Saliva]) Sugar

Stomach → Gastric glands Secrete→ Gastric juice

Gastric Juice

PEPSIN – (Enzyme that breaks down proteins)

HCI – (Makes medium acidic)

MUCUS – (Protects inner lining of the stomach)

Small Intestine

(a) Intestinal enzyme
↓ convert
Carbohydrate → (Glucose)

Fats → (Fatty acid + Glycerol)

Proteins → (Amino acids)

Small Intestine

(b) Villi (finger like projections) → Helps in absorption of digested food into the blood

Large Intestine

→ Absorb excess of water
→ The rest of the material is removed from the body via the anus.

Respiration

Nostril
↓
Nasal Passage
↓
Nasal Cavity
↓
Pharynx
↓
Larynx
↓
Trachea
↓
Bronchi
↓
Bronchioles
↓
Alveoli
↓
Blood capillaries

Lungs

Bronchi
 ↓
Bronchioles
  ↓
Alveoli
  ↓
Blood capillaries

Mechanism of Breathing

Exchange of gases between alveolus, blood and tissues

(i) Air (rich in O_₂) → Blood → Binds with haemoglobin in RBC → O₂ is released in (in alveolus) (through blood vessels) tissues

(ii) CO₂ → Released in blood→ Dissolved in blood→ Blood vessels→ Released in alveolar sac → Sent out through nostrils (from tissue)

Terrestrial – Use atmospheric oxygen for respiration

Aquatic organisms – Use dissolved oxygen for respiration

Respiration in plants

Respiration in plants is simpler than the respiration in animals. Gaseous exchange occur through:
(a) Stomata in leaves
(b) Lenticels in stems
(c) General surface of the root

Transportation

Human beings like other multicellular organism need regular supply of food, oxygen etc. This function is performed by circulatory system.

The circulatory system in human beings consists of

Heart → (A pumping organ)

Arteries and Veins → (Blood vessels)

Blood and lymph → (A circulatory medium)

Diagram to show blood circulation in human body

Double circulation

Blood travels twice through the heart in one complete cycle of the body.

Direction of blood flow through human heart

• Pulmonary Circulation – Blood moves from the heart to the lungs and back to the heart.
• Systemic Circulation – Blood moves from the heart to rest of the body and back to the heart.

Blood

(A fluid connective tissue)

Granular component (Blood corpuscles)

R.B.C

• Carries gas (O₂,CO₂)
• Contain Hb impart red colour to the blood

Blood Platelets

helps in blood clotting

W.B.C

Provide body by engulfing the germs & producing antibodies

Liquid Component (Plasma)

A yellow colour fluid contain 90% water & 10% organic substances like – plasma, proteins viz. albumin, globulin, inorganic – mineral ions.

Blood Vessels

Transportation in plant

There are two main conducting Pathways in a plant

Transpiration is the process of loss of water as vapour from aerial parts of the plant.

Function

(a) Absorption and upward movement of water and minerals by creating Osmotic pressure pull.
(b) Helps in temperature regulation in plant.
Transport of food from leaves (food factory) to different part of the plant is called Translocation.

EXCRETORY SYSTEM IN HUMAN

Excretory/urinary system consists of

The human excretory system

EXCRETION
1. The metabolic activities in the body generates many kinds of wastes including nitrogenous wastes which are harmful for the body and hence needed to be removed. Excretion is a process by which these wastes are removed from our body.

Material excretion

• Nitrogenous wastes
• Excess of water
• Gases
• Salts

Nitrogenous wastes

• Urea
• Uric Acid
• Urine

Excess of water

• Sweat
• Urine

2. Unicellular organisms remove these wastes by simple diffusion.

Formation of Urine

1. Each kidney contains many filtration units called as nephrons.

2. Nephrons are made up of a cluster of thin walled capillaries called glomerulus which is associated with a cup like structure called as Bowman’s capsule and the long tube which terminates through this capsule.

3. The renal artery brings oxygenated blood to the kidneys along with the nitrogenous wastes like urea and uric acid and many other substances.

4. The blood gets filtered through the glomerulus and this filtrate enters the tubular part of nephron.

5. As this filtrate moves down the tubular part, glucose, amino acids, salts and excess of water gets selectively reabsorbed by the blood vessels surrounding these tubules.

6. The amount of water reabsorbed depends upon

• How much excess of water is there in the body and,
• How much nitrogenous wastes need to be excreted out.

7. So the fluid now flowing in the tubular part is urine which gets collected in collecting ducts of nephrons.

8. These collecting ducts together leave the kidney at a common point by forming the ureter.

9. Each ureter drains the urine in the urinary bladder where it is stored until the pressure of expanded bladder leads to an urge to pass it out through urethra.

10. This bladder is a muscular structure which is under nervous control.

11. 180 litres of filtrate is formed daily but only 2 litres is excreted out as urine so the rest is reabsorbed in the body.

Functions of Nephron

• Excretion of nitrogenous wastes.
• To maintain the water and ionic balance (osmic regulation).

Structure of a Nephron

The urine formation involves three steps

1. Glomerular filtration – Nitrogenous wastes, glucose water, amino acid filter from the blood into Bowman Capsule of the nephron.

2. Tubular reabsorption Now, useful substances from the filtrate are reabsorbed back by capillaries surrounding the nephron.

3. Secretion – Urea, extra water and salts are secreted into the tubule which open up into the collecting duct & then into the ureter.

Artificial Kidney

Hemodialysis – The process of purifying blood by an artificial kidney. It is meant for kidney failure patients.

Excretion in Plants

Plants use different strategies for excretion of different products:

• Oxygen and carbon dioxide is diffused through stomata.
• Excess water is removed by transpiration.
• Plants can even loose some of their old parts like old leaves and bark of tree.
• Other waste products like raisins and gums especially in old xylem cells which can also be lost by plants.
• Plants also secrete some waste substances into the soil around them.