CBSE Class 10 Science Life Processes Notes Set 08

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

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

Examples of Life Processes

• Growth
• Digestion
• Respiration
• Circulation
• Excretion

Nutrition

[The whole process by which an organism obtain 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: Kinds of nutrition in which in organic materials like \( \text{CO}_2 \), water etc are utilized to prepare organic food by the process of photosyntheses.
  Eg. Green Plants
• Hetrotrophic: Kinds of nutrition in which in organisms do not possess the ability to synthesize their own food. They depend on autotrophs for their food supply directly or indirectly.
  eg. Animals, Fungi

Autotrophic Nutrition

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

Autotrophs — Use → Simple in organic material — Convert Into → Complex high energy molecules Carbohydrates

Autotrophic nutrition is fulfilled by the process by which autotrophs take in \( \text{CO}_2 \) and \( \text{H}_2\text{O} \) and convert these into carlohydrates in the presence of chlorophyll, sunlight is called PHOTOSYNTHESIS

Equation:

\[ 6\text{CO}_2 + 12\text{H}_2\text{O} \xrightarrow[\text{Chlorophyle}]{\text{Sunlight}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 + 6\text{H}_2\text{O} \]

Raw Materials for Photosynthesis

• Sunlight
• Chlorophyl → Sunlight absorbed by chlorophyll
• \( \text{CO}_2 \) → enters through Stomata, and Oxygen (\( \text{O}_2 \)) is released as by product through stomata on leaf.
• Water → water + dissolved minerals like Nitrogen phosphorous etc are taken up by the roots from the soil.

Site of Photosynthesis

Chloroplast in the leaf. Chloroplast contain chlorophyll. (green pigment)

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 \( \text{CO}_2 \) to carbohydrates.

STOMATA

Tiny pores present on the surface of the leaves

FUNCTIONS:

1. Exchange of gases \( \text{O}_2 / \text{CO}_2 \)
2. Loses large amount of water [water vapour] during transpiration.

Hetrotrophic nutrition

• HOLOZOIC: Animals take in solid food and breakdown inside the body.
  eg. Amoeba, animals
• SAPROPHTIC: Organisms feed on dead, decaying matter.
  eg. fungi
• PARASITIC: Parasites live inside or outside other organism (host) and derive nutrition from it.
  eg. cuscuta (plant parasite ticks etc.

How do organisms obtain their food

Unicellular / single celled organism : food is taken up through entire surface.

Example : (i) Amoeba. (ii) Paramaecium

NUTRITION IN AMOEBA

• Amoeba → Pseudopodia (extension of cell membrane)
• Capture food
• Take 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) Paramecium: Paramecium → Cilia (present all over the body) → take in food → At a specific spot

Steps in Hologic nutrition

• Ingestion (अंतर्ग्रहण)
• Digestion (पाचन)
• Absorption (अवशोषण)
• Assimilation (स्वांगीकरण)
• Egestion (वहिष्क्षेपण)

NUTRITION IN HUMAN BEINGS

The human digestive system comprises of alimentary canal and associated disgestive glands.

• 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.
  \[ \text{Starch} \xrightarrow{\text{Salivary amylase [Saliva]}} \text{Sugar} \]
• Oesophagus → Taking food from mouth to stomach by Peristaltic movements [contraction and expansion of muscles of the oesophagus]
• Stomach → Gastric glands secrete Gastric juice

Gastric juice:

• PEPSIN: [enzyme that breaks down proteins]
• HCl: [makes medium acidic]
• MUCUS: [Protects inner lining of the stomach]

Small Intestine

Small Intestinal → Intestinal enzyme:

• Carbohydrate → Glucose
• Fats → Fatty acid + Glycerol
• Proteins → Amino acids

Small Intestine → Villi: helps in absorption of food into the blood. [finger like projections]

small intestine → Receives secretion from:

• Liver → Bile-Juice:
  \[ \text{Large fat Globules} \xrightarrow{\text{Emulsify-cation}} \text{Small fat Globules} \]
• Pancreas → Pancreatic juice:
  • Trypsin: Proteins → Peptones
  • Lipase: Fats → Glycerol

Emulsification: The process of breakdown of large fat globules into smaller fat globules by bile juice.

Large intestine

• Absorb excess of water.
• The rest of the material is removed from the body via the anus. (Egestion)

Respiration

Respiration involves:

1. Gaseous exchange : Intake of oxygen from the atmosphere and release of \( \text{CO}_2 \) → Breathing
2. Breakdown of simple food in order to release energy inside the cell → Cellular Respiration

Breakdown of Glucose by various pathways

Glucose (\( \text{C}_6\text{H}_{12}\text{O}_6 \)) [In cytoplasm] → Pyruvic Acid + Energy

• Absence of Oxygen: Ethanol + \( \text{CO}_2 \) + Energy
  (Fermentation : Process of conversion of Pyruvic acid into ethanol, \( \text{CO}_2 \) and energy by Yeast)
• Insufficient Oxygen (In muscles): Lactic acid + Energy
  (Accumulation of lactic acid causes muscle fatigue It occurs after rigorous exercise.)
• Presence of Oxygen (In mitochondria): \( \text{CO}_2 \) + Water + Energy

Respiration Types

Aerobic

• Takes place in the presence of oxygen
• Occurs in mitochondria
• End products are \( \text{CO}_2 \) and \( \text{H}_2\text{O} \)
• More amount of energy is released

Anaerobic

• Takes place in the absence of oxygen
• Occurs in cytoplasm
• End products are alcohol or lactic acid.
• Less amount of energy is released.

Human Respiratory System

Passage of air through the respiratory system:

Nostril → Nasal Passage → Nasal Cavity → Pharynx → Larynx → Trachea → Bronchi → Lungs → Bronchioles → Alveolar → Blood capillaries

Mechanism of Breathing

Inhalation:

• During inhalation the thoracic cavity (chest cavity) expands
• Ribs lift up
• Diaphragm becomes flat in shape
• Volume of lungs increases and air enters the lungs

Exhalation:

• Thoracic cavity contracts
• Ribs move downwards
• Diaphragm becomes dome shaped
• Volume of lungs decreases and air exits from the lungs.

Exchange of Gases between alveolus, blood and tissues

1. Air (rich in \( O_2 \)) (in alveolus) → Blood [through blood vessels] → Binds with Haemoglobin in RBC → \( O_2 \) is released in tissues

2. \( CO_2 \) (from tissue) → \( CO_2 \) released into blood → Dissolved in blood → Blood vessels (in alveoli) → \( CO_2 \) Released in alveolar Sac → Sent out through nostrils

Terrestrial Organisms – 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 occurs through:

1. Stomata in leaves
2. Lenticels in stems
3. General surface of the roots.

Life Process (II) – Transportation and Excretion

Human beings like other multicellular organisms need a regular supply of food, oxygen etc. This function is performed by the circulatory system or Transport system.

The circulatory system in human beings consists of:

• A Pumping Organ: Heart
• Blood vessels: Arteries & Veins
• A circulatory medium: Blood & Lymph

Blood Circulation in Human Heart

Deoxygenated Blood (from body) → Vena Cava → Right Atrium (Relaxed) → Right Atrium (contracts) → Right Ventricle (relaxed) → Right ventricle contracts → Lungs → Oxygenated blood → Left Atrium (relaxed) → Left Atrium (contracts) → Left Ventricle (relaxed) → Left Ventricle (contracts) → Body Parts via AORTA

Blood (A fluid Connective Tissue)

• Solid Component (Blood Corpuscles):
  • R.B.C.s: Carries respiratory gases (\( O_2, CO_2 \)), contains Hb (haemoglobin) which imparts red colour to the blood.
  • Blood Platelets: Helps in blood clotting.
  • W.B.C.: Provide body defence by engulfing the germ cells & producing antibodies.
• Liquid Component (PLASMA): A yellow colour fluid containing 90% water & 10% organic substances like plasma proteins (viz. albumin, globulin) and inorganic-mineral ions.

Lymph: A yellowish fluid that escapes from the blood capillaries into the intercellular spaces. It contains less proteins than blood. Lymph flows from the tissues to the heart, assisting in transportation and destroying germs.

Blood Vessels

• Arteries:
  1. Carry oxygenated blood from heart to body parts except pulmonary artery.
  2. Also called distributing vessels.
  3. Thick and elastic.
• Veins:
  1. Carry deoxygenated blood from body parts to heart except pulmonary vein.
  2. Also called collecting vessels.
  3. Thin and less elastic.

Transportation in Plants

There are two main conducting pathways in a plant:

• Xylem:
  1. Carries water & minerals from the roots to other parts of the plant.
  2. No energy is used.
• Phloem:
  1. Carries product of photosynthesis from leaves to other parts of the plant.
  2. Energy is used from ATP.

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

Functions of Transpiration:

1. Absorption and upward movement of water and minerals by creating a PULL (transpirational pull).
2. Helps in temperature regulation in plants.

Translocation: Transport of food from leaves (food factory) to different parts of the plant is called Translocation.

Excretion

The process of the removal of the harmful metabolic wastes from the body.

Excretory system of human beings includes:

1. A pair of kidneys
2. A Urinary Bladder
3. A pair of Ureters
4. A Urethra

Urine produced in the kidneys passes through the ureters into the urinary bladder where it is stored until it is released through the urethra.

The purpose of making urine is to filter out waste products from the blood, i.e., urea which is produced in the liver.

Each kidney has large numbers of filtration units called nephrons.

The urine formation involves three steps:

1. Glomerular Filtration: Nitrogenous wastes, glucose, water, and amino acids filter from the blood into the Bowman's Capsule of the nephron.
2. Tubular reabsorption: Now, useful substances from the filtrate are reabsorbed back by capillaries surrounding the nephron.
3. Secretion: Extra water and salts are secreted into the tubule which opens up into the collecting duct & then into the ureter.

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

Excretion in Plants

• Oxygen, \( CO_2 \), & \( H_2O \) are excreted through stomata (Transpiration).
• Other wastes may be stored in leaves, bark, etc., which fall off from the plant.
• Plants excrete some waste into the soil around them.
• Gums and resins are stored in old xylem.
• Some metabolic wastes are in the form of crystals of calcium oxalates in the leaves of colocasia and stem of zamikand.

Life Processes - Exercise (Question Bank)

Very Short Answers (1 Mark)

Question. State one difference between autotrophic and heterotrophic mode of nutrition.
Answer: Autotrophic nutrition involves synthesizing organic food from simple inorganic raw materials using light or chemical energy, whereas heterotrophic nutrition involves obtaining complex prepared organic food from other organisms.

Question. What will happen to a plant if the xylem is removed.
Answer: If the xylem is removed, the transport of water and minerals from the roots to the aerial parts of the plant will stop, leading to wilting and the eventual death of the plant.

Question. What is the role of saliva in the digestion of food?
Answer: Saliva contains salivary amylase, an enzyme that digests starch into simpler sugars like maltose. It also moistens and lubricates food for easy swallowing.

Question. Name the tissue that transports water and minerals in plants.
Answer: Xylem.

Question. What is the role of acid in our stomach?
Answer: Hydrochloric acid (\( HCl \)) creates an acidic environment that activates the protein-digesting enzyme pepsin and kills harmful bacteria ingested with food.

Question. What is emulsification
Answer: Emulsification is the process of breaking down large fat globules into smaller fat globules by bile salts, increasing the surface area for lipase enzymes to digest fats.

Question. Name the organelle in which photosynthesis occur.
Answer: Chloroplast.

Question. Name the largest artery in the human body.
Answer: Aorta.

Question. Define transpiration
Answer: Transpiration is the loss of water in the form of water vapor from the aerial parts of the plant, mainly through the stomata of leaves.

Question. What are structural and functional unit of kidneys called.
Answer: Nephrons.

Short Answers (2 Marks or 3 Marks)

Question. How is small intestine designed to absorb digested food?
Answer: The inner wall of the small intestine features numerous finger-like projections called villi, which significantly increase the surface area for absorption. These villi are richly supplied with blood vessels that transport the absorbed nutrients to different parts of the body.

Question. What are stomata? Draw a labelled diagram of stomata.
Answer: Stomata are tiny microscopic pores located on the epidermal layer of leaves and young stems. They regulate gas exchange (\( CO_2 \) and \( O_2 \)) and the loss of water vapor during transpiration. Each stoma is surrounded by a pair of guard cells that control its opening and closing. (To draw the diagram, sketch a central pore surrounded by two kidney-shaped guard cells containing chloroplasts, bounded by epidermal cells).

Question. Write the equation for the process of breakdown of glucose in a cell
i) in the presence of oxygen
ii) in the absence of oxygen.
Answer:
i) In the presence of oxygen (Aerobic respiration):
\( \text{Glucose} \xrightarrow{\text{In cytoplasm}} \text{Pyruvate + Energy} \xrightarrow[\text{Oxygen (In mitochondria)}]{\text{In presence of}} 6CO_2 + 6H_2O + \text{Energy (38 ATP)} \)

ii) In the absence of oxygen (Anaerobic respiration in yeast):
\( \text{Glucose} \xrightarrow{\text{In cytoplasm}} \text{Pyruvate + Energy} \xrightarrow{\text{In absence of Oxygen}} \text{Ethanol} + CO_2 + \text{Energy (2 ATP)} \)

Question. Write the difference between inhalation and exhalation.
Answer:
- Inhalation: The thoracic cavity expands, ribs lift up, the diaphragm contracts and becomes flat, increasing lung volume so air rushes into the lungs.
- Exhalation: The thoracic cavity contracts, ribs move downwards, the diaphragm relaxes and becomes dome-shaped, decreasing lung volume so air exits from the lungs.

Question. List the three events which occur during photo synthesis.
Answer:
i) Absorption of light energy by chlorophyll.
ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
iii) Reduction of carbon dioxide to carbohydrates (glucose).

Question. How does transpiration helps in upward transport of substances.
Answer: Evaporation of water from the stomata creates a continuous suction pull (transpiration pull) inside the xylem vessels. This pull draws water and dissolved minerals from the root cells upwards through the stem to the leaves.

Question. Describe the process of double circulation in human beings.
Answer: Double circulation means that blood travels through the heart twice during each complete cycle through the body. It consists of two pathways:
i) Pulmonary Circulation: Deoxygenated blood is pumped from the right ventricle of the heart to the lungs for oxygenation and then oxygenated blood returns to the left atrium of the heart.
ii) Systemic Circulation: Oxygenated blood is pumped from the left ventricle to the rest of the body through the aorta, and deoxygenated blood is collected from body parts and brought back to the right atrium via the vena cava.

Question. Write the functions of the components of blood.
Answer:
- Red Blood Cells (RBCs): Transport oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs via hemoglobin.
- White Blood Cells (WBCs): Provide defense against pathogens by engulfing germs and synthesizing antibodies.
- Blood Platelets: Prevent excessive bleeding by initiating the clotting mechanism of blood at injury sites.
- Plasma: Transports dissolved nutrients, carbon dioxide, nitrogenous wastes, hormones, and salts throughout the body.

Long Answers (5 Marks)

Question. Explain the process of digestion of food in mouth stomach and small intestine in human body. Draw a well labelled diagram.
Answer:
- Mouth: Teeth mechanically break and chew the food. Saliva secreted by salivary glands contains salivary amylase, which digests complex starch into maltose (sugar).
- Stomach: The muscular walls of the stomach churn food. Gastric glands secrete gastric juice containing hydrochloric acid (creates acidic pH and kills bacteria), pepsin (digests proteins into peptones), and mucus (protects the inner stomach lining from acid damage).
- Small Intestine: This is the site of complete digestion. It receives bile juice from the liver (emulsifies fats) and pancreatic juice from the pancreas (contains trypsin for protein digestion and lipase for fat digestion). Intestinal juice completes the breakdown of carbohydrates into glucose, proteins into amino acids, and fats into fatty acids and glycerol.

Question. Draw a diagram showing Human Respiratory system. Label the following parts
i) Larynx
ii) Trachea
iii) Bronchus
iv) Lungs
Answer: To draw the Human Respiratory system, include the following structures in order:
i) Larynx: Located at the top of the windpipe (voice box).
ii) Trachea: The windpipe supported by rings of cartilage preventing collapse.
iii) Bronchus: The bifurcation of the trachea entering into each of the two lungs.
iv) Lungs: The two major breathing organs containing networks of bronchioles and alveoli where gaseous exchange occurs.