Class 7 Unit-5 (Life Processes)

 

Unit-5 (Life Processes)

Introduction

Life processes are the essential functions that living organisms perform to maintain life, ensuring survival, growth, and reproduction.

 

Transportation

The process of supplying required substances to the cells and transporting unnecessary substances from the cells to the related excretory organs is called transportation.

 

Transportation in plants

Transportation in plants is the process by which water, minerals, and food are moved from one part of the plant to another. This helps the plant to grow and stay healthy.

Transport of Water and Minerals:

• Done by xylem.
• Water and minerals are absorbed by roots from the soil and moved up to stems and leaves.
• This process is called upward transport.

Transport of Food:

• Done by phloem.
• Food made in the leaves during photosynthesis is sent to all parts of the plant (roots, stems, fruits).
• This process is called translocation.

 

Transportation in Animals

Transportation in animals is the process of carrying food, oxygen, hormones, and waste materials to different parts of the body with the help of a transport system.

In Simple Animals (like amoeba, sponges, hydra):

• They do not have blood.
• Substances move in and out of the body by diffusion (direct exchange with surroundings).

In Higher Animals (like humans):

• They have a circulatory system made up of blood, blood vessels, and the heart.

1. Blood:

• A liquid that transports oxygen, nutrients, hormones, and waste.
• It has plasma, red blood cells (RBCs), white blood cells (WBCs), and platelets.

2. Heart:

• A muscular organ that pumps blood throughout the body.

3. Blood Vessels:

• Arteries carry blood away from the heart.
• Veins carry blood back to the heart.
• Capillaries help exchange materials between blood and body cells.

 

Excretion

Excretion is the process by which living organisms remove waste products formed in their body during different activities like respiration, digestion, and other chemical reactions. These wastes can be harmful if they are not removed.

 

Excretion in plants

·   Plants excrete oxygen (during photosynthesis) and carbon dioxide (during respiration).

·   Some wastes are stored in leaves, bark, or old parts that later fall off.

·   Some plants release waste as gums, resins, and latex.

 

Excretion in Humans:

• Main excretory organ is the kidney.
• Kidneys filter blood and remove urea, extra water, and salts in the form of urine.
• Other organs of excretion:
• Lungs → remove carbon dioxide.
• Skin → removes sweat (water and salts).
• Liver → breaks down harmful substances.

 

Absorption

Absorption is the process by which digested food is taken into the blood or body cells. After digestion, the small and soluble food molecules are absorbed and used by the body for energy, growth, and repair.

 

Absorption in Humans:

• Takes place mainly in the small intestine.
• The inner wall of the small intestine has many finger-like projections called villi.
• Villi increase the surface area and absorb digested food into the blood.
• The absorbed nutrients are then transported to all parts of the body.

 

Absorption in Plants:

• Plant roots absorb water and minerals from the soil.
• This happens through root hairs by the process of diffusion, osmosis, and active transport.
• The absorbed materials are then transported to other parts by xylem.

 

Respiration

Respiration is the process by which living organisms break down food (glucose) to release energy. This energy is used for growth, movement, repair, and all other life activities.

Types of Respiration:

1. Aerobic Respiration

o Takes place in the presence of oxygen.

o Glucose → Energy + Carbon dioxide + Water.

o Example: Humans and most animals.

2. Anaerobic Respiration

o Takes place without oxygen.

o Glucose → Energy + Alcohol/Acid + Carbon dioxide.

o Example: Yeast (produces alcohol), some bacteria, muscle cells during heavy exercise.

 

Respiration in Animals

-Animals take in oxygen and give out carbon dioxide

  during respiration.

-Different animals use different organs for breathing:

• Humans and mammals → lungs
• Fish → gills
• Insects → spiracles and trachea
• Earthworm → skin

-Oxygen is carried by the blood to all body cells.

-Energy produced is used for movement, growth, repair, and survival.

 

Respiration in Humans:

• We breathe in oxygen through the lungs.
• Oxygen breaks down food in the cells and releases energy.
• Carbon dioxide is given out as waste.

 

Respiration in Plants:

• Plants also respire all the time.
• They take in oxygen and release carbon dioxide through stomata in leaves and lenticels in stems.

 

Importance of the respiration process 

·   Respiration gives energy to the body.

·   Energy helps us move, grow, and repair our body.

·   It keeps our organs and cells working properly.

·   Respiration helps balance oxygen and carbon dioxide in the body.