The Genesis of Life: From Primordial Soup to Complex Organisms
Act II. The Life
Scene I. The Early Word
Pasteur, Darwin, and the Origin of Life
What roles did Pasteur and Darwin play in explaining the origin of life?
Pasteur demonstrated that microscopic germs are everywhere. In an experiment, he isolated a meat and vegetable broth, boiled it for sterilization, and concluded that life does not arise spontaneously but is a process that takes time.
Darwin championed the principle of evolution, where species are modified by natural selection—nature selects the fittest
Read MoreAnimal Digestive and Respiratory Systems
Stomach
The stomach is a dilated section of the digestive tract that stores food temporarily before it moves to the intestine in a more broken-down state.
Stomach Variations in Vertebrates
- Fish, Amphibians, and Reptiles: Spindle-shaped stomach.
- Birds: Divided into a muscular gizzard, specializing in food trituration, and a glandular section.
- Mammals: Highly folded stomach structure.
- Ruminant Mammals: Complex stomach divided into four chambers: rumen, reticulum, omasum, and abomasum. Unchewed grass is
Human Body Systems: Digestion, Respiration, Circulation
The Digestive System
The digestive system is responsible for transforming food into simpler substances that can be used by the cells. It is made up of the digestive tract and digestive glands.
Digestive functions:
- Ingestion
- Digestion
- Absorption
- Egestion
Chewing is a mechanical action by which food is shredded. Insalivation is the process of wrapping food in saliva.
The Respiratory System
The respiratory system is responsible for taking oxygen from the air outside, taking it to the blood, and removing carbon
Read MorePulmonary and Plant Respiration: A Detailed Analysis
Pulmonary Respiration
In pulmonary respiration, gas exchange takes place in specialized cavities with highly vascularized, thin walls called lungs. These cavities are connected to the outside through:
- Nostrils: Where air is heated and cleaned of impurities.
- Pharynx: Connects the nasal passages, mouth, and throat.
- Larynx: Reinforced by cartilage and contains the vocal cords.
- Trachea: A tube reinforced with cartilaginous rings, serving as a cleaning area, which bifurcates into the bronchi.
- Bronchi, Bronchioles,
Animal and Plant Nutrition: Processes and Adaptations
Nutrition
Nutrition describes the processes by which living things take in external substances and turn them into matter and energy.
Autotrophs
Autotrophs produce their own organic matter from inorganic substances taken from the environment. They can be:
- Photosynthetic: Obtain energy from sunlight.
- Chemosynthetic: Obtain energy from chemical reactions.
Heterotrophs
Heterotrophs feed on other organisms or their remains. They can be carnivores, herbivores, omnivores, filter feeders, scavengers, etc.