Life Processes: Nutrition

• Life processes are the series of actions that are essential to determine if something is alive
• These processes are common to all living organisms.
• The basic life processes include nutrition, respiration, excretion, movement, reproduction, and sensitivity.

Nutrition

• Nutrition is the process of obtaining and utilizing food.
• It involves the intake of nutrients, which are organic and inorganic substances required for energy, growth, and repair.
• Autotrophic nutrition is a mode where organisms produce their own food from simple inorganic substances like carbon dioxide and water, using energy from sunlight (photosynthesis) or chemical reactions (chemosynthesis).
• Plants, algae, and some bacteria are autotrophs.
• Heterotrophic nutrition is a mode where organisms obtain their food from other organisms.
• Animals, fungi, and most bacteria are heterotrophs.
• There are different types of heterotrophic nutrition:
  • Saprophytic: Organisms feed on dead and decaying organic matter (e.g., fungi).
  • Parasitic: Organisms derive their nutrition from another living organism (the host), often causing harm to the host (e.g., tapeworms).
  • Holozoic: Organisms ingest solid or liquid food, which is then digested and absorbed (e.g., humans).

Respiration

• Respiration is the process by which living organisms produce energy from food.
• It involves the breakdown of organic compounds, such as glucose, to release energy in the form of ATP (adenosine triphosphate).
• Aerobic respiration requires oxygen to break down glucose into carbon dioxide, water, and energy.
• Anaerobic respiration does not require oxygen and breaks down glucose into other products such as lactic acid or ethanol, along with energy.
• Gas exchange is an important aspect of respiration, involving the uptake of oxygen and the release of carbon dioxide.
• In animals, gas exchange occurs through various organs like lungs, gills, or skin.
• Plants exchange gases through stomata (small pores on leaves) and lenticels (pores on stems).

Excretion

• Excretion is the process of removing metabolic waste products from the body.
• These waste products are generated as a result of various biochemical reactions.
• Different organisms have different excretory organs:
  • Animals: Kidneys (for urine), lungs (for carbon dioxide), skin (for sweat).
  • Plants: Stomata (for excess water vapor and oxygen), lenticels (for gases), and deposition of waste in vacuoles or shedding of leaves.

Movement

• Movement is a characteristic of living organisms, allowing them to change position or location.
• Locomotion is the movement of an organism from one place to another.
• Animals exhibit various forms of locomotion, such as walking, running, swimming, and flying.
• Plants show growth movements (e.g., bending towards light) but do not exhibit locomotion.

Reproduction

• Reproduction is the process by which living organisms produce offspring, ensuring the continuation of their species.
• Asexual reproduction involves a single parent and produces offspring that are genetically identical to the parent (clones).
• Examples of asexual reproduction include:
  • Binary fission (bacteria)
  • Budding (yeast, hydra)
  • Fragmentation (planaria)
  • Spore formation (fungi)
  • Vegetative propagation (plants).
• Sexual reproduction involves two parents and the fusion of gametes (sex cells) to produce offspring that are genetically different from the parents.
• This process increases genetic variation within a population.

Sensitivity

• Sensitivity (also known as irritability) is the ability of an organism to detect and respond to changes in its internal or external environment.
• Stimuli are changes in the environment that can be detected by organisms.
• Responses are the reactions of organisms to stimuli.
• Animals have a nervous system and sensory organs to detect and respond to stimuli quickly.
• Plants respond to stimuli more slowly through hormones and growth movements.