Short Notes-Class 10 -Science- Biology-Chapter 5 – Life Processes

Class 10 -Science- Short Notes- Biology-Chapter 5 – Life Processes

Introduction

Living organisms exhibit distinct characteristics:

1. Growth
2. Reproduction
3. Responsiveness to stimuli
4. Need for nutrition

These characteristics differentiate living organisms from non-living entities.

Vital processes essential for maintaining life are termed as life processes.

Life processes continue regardless of the organism’s activity level (active, resting, or asleep).

These processes are fundamental for all living beings, including plants, animals, and humans.

Life processes include:

1. Nutrition
2. Respiration
3. Circulation
4. Excretion

Unicellular organisms carry out all life processes within a single cell.

Multicellular organisms possess specialized systems to execute life processes efficiently.

Earth is the only known planet supporting life.

Organisms live, undergo life cycles, and eventually return to nature.

Living and non-living entities are distinguished based on the execution of life processes.

Maintenance of living organisms is crucial regardless of their state (moving, resting, or sleeping).

Life processes are essential mechanisms sustaining life and ensuring survival.

Nutrition:

• Nutrition is the process of acquiring food necessary for sustenance.
• Two main modes: autotrophic and heterotrophic.
• Autotrophic: Organisms produce their own food using light or chemical energy.
• Heterotrophic: Organisms obtain energy from consuming organic compounds.

Autotrophic Nutrition:

• Organism makes its own food using sunlight or chemicals.
• Plants perform photosynthesis, using light energy.
• Some bacteria utilize chemical energy (chemosynthesis).
• Plants are photoautotrophs; few bacteria are chemoautotrophs.

Photosynthesis:

• Key process by which plants produce food.
• Sunlight and water are used to synthesize carbohydrates.
• Chlorophyll absorbs light energy; splits water into hydrogen and oxygen.
• Carbon dioxide is reduced to carbohydrates, primarily glucose.
• Stomata facilitate gas exchange, primarily carbon dioxide intake.

Stomata:

• Pores on leaves facilitating gas exchange.
• Mostly located on the underside of leaves.
• Guard cells regulate opening and closing of stomata.
• Function influenced by water content of guard cells.

Saprophytic Nutrition:

• Organisms feed on dead and decaying organic matter.
• Food partially digested externally, then absorbed.
• Example: Fungi, which are saprophytes.

Parasitic Nutrition:

• Organisms feed off another organism, causing harm.
• Parasites derive nutrients directly from host.
• Examples: Leeches, Ascaris, and parasitic plants like Cuscuta.
• Leeches are ectoparasites, while Ascaris is an endoparasite.