Life Processes is one of the most important chapters in SSLC Science. In this chapter, students learn about nutrition, respiration, transportation and excretion in living organisms. The chapter also explains nutrition in humans, transport systems in plants and humans, and excretion processes. This article is prepared based on the uploaded LBA document.
Learning Points
This chapter mainly includes:
- Nutrition
- Autotrophic nutrition and heterotrophic nutrition
- How organisms obtain nutrition
- Nutrition in humans
- Transportation in humans and plants
- Excretion in humans and plants
Life Processes
The basic activities performed by living organisms to maintain life are called Life Processes.
Important life processes include:
- Nutrition
- Respiration
- Transportation
- Excretion
These processes are necessary for survival of organisms.
Nutrition
Nutrition is the process by which organisms obtain food and utilize it for growth, repair and energy production.
Types of Nutrition
1. Autotrophic Nutrition
Organisms prepare their own food using sunlight, carbon dioxide and water.
Examples:
- Green plants
- Algae
Photosynthesis is the mode of autotrophic nutrition.
2. Heterotrophic Nutrition
Organisms depend on other organisms for food.
Examples:
- Humans
- Animals
- Parasites
Types of heterotrophic nutrition:
- Holozoic nutrition
- Saprophytic nutrition
- Parasitic nutrition
Photosynthesis
Photosynthesis is the process by which green plants prepare food.
$\ce{6CO2 + 6H2O ->[\text{Sunlight}][\text{Chlorophyll}] C6H12O6 + 6O2}$
Requirements for Photosynthesis
- Sunlight
- Chlorophyll
- Carbon dioxide
- Water
During this process oxygen is released.
Nutrition in Humans
Human digestive system consists of:
- Mouth
- Oesophagus
- Stomach
- Small intestine
- Large intestine
Digestion in Small Intestine
Complete digestion of carbohydrates, proteins and fats occurs in the small intestine.
Functions of Digestive Juices
Saliva
- Contains amylase enzyme
- Converts starch into sugar
Bile Juice
- Neutralizes acidic food
- Helps in digestion of fats
Intestinal Juice
- Completes digestion process
Respiration
Respiration is the process of releasing energy from food.
Types of Respiration
Aerobic Respiration
Occurs in the presence of oxygen.
$\ce{C6H12O6 + 6O2 -> 6CO2 + 6H2O + Energy}$
Anaerobic Respiration
Occurs in absence of oxygen.
In muscles:
$\ce{Glucose -> Lactic Acid + Energy}$
Lactic acid is produced in muscles during heavy exercise.
Transportation in Humans
Transportation is carried out by the circulatory system.
Components:
- Heart
- Blood
- Blood vessels
Blood Components
Red Blood Cells (RBC)
- Contain haemoglobin
- Transport oxygen
White Blood Cells (WBC)
- Protect body from diseases
Platelets
- Help in blood clotting
Plasma
- Transport nutrients and hormones
Lymph
Colourless fluid that helps immunity.
Human Heart and Double Circulation
Human heart has four chambers:
- Right atrium
- Right ventricle
- Left atrium
- Left ventricle
Double circulation means blood passes through the heart twice during one complete circulation.
Advantages:
- Prevents mixing of oxygenated and deoxygenated blood
- Increases efficiency of oxygen supply
Transport in Plants
Plants use vascular tissues for transportation.
Xylem
Function:
- Transports water and minerals from roots to upper parts.
Phloem
Function:
- Transports food prepared during photosynthesis.
Transport of food in plants is called Translocation.
Transpiration
Loss of water through the stomata is called transpiration.
Functions:
- Helps water transport
- Creates suction pressure
- Removes excess water
Plants release excess water through transpiration.
Excretion in Humans
Excretion is removal of metabolic waste materials.
Human excretory system includes:
- Kidneys
- Ureters
- Urinary bladder
- Urethra
The main function of the kidney is excretion.
Nephron
Nephron is the structural and functional unit of the kidney.
Functions:
- Filtration of blood
- Reabsorption of useful substances
- Formation of urine
Excretion in Plants
Plants remove wastes by:
- Storing wastes in leaves and bark
- Transpiration
- Releasing gases through stomata
Important Exam Questions
One Mark Questions
- What is transpiration?
- What is double circulation?
- Define excretion.
- What is nutrition?
Two Mark Questions
- Explain the role of bile juice.
- State importance of transpiration.
- Differentiate arteries and veins.
Three and Four Mark Questions
- Explain nephron structure and function.
- Explain digestion in the small intestine.
- Explain transport of water in plants.
- Explain nutrition in Amoeba.
These questions are repeatedly asked in examinations.
Preparation Tips for Students
- Learn diagrams of heart, nephron and stomata
- Study digestive system carefully
- Practice photosynthesis equation
- Learn differences between xylem and phloem
- Revise double circulation and excretion processes
Conclusion
“Life Processes” is one of the most important scoring chapters in SSLC Science. Students can score high marks by understanding nutrition, respiration, transportation and excretion properly. Regular revision of diagrams and concepts helps in better performance in examinations.
