Plant Biology and Horticultural Practices
Vascular cambium is the lateral meristem in stems that produces xylem and phloem. Spongy mesophyll is a type of loosely organized tissue that allows for air exchange within the leaf. Commensalism is a symbiotic relationship where one organism benefits and the other is not harmed. A lenticel is a rough area on some stems that serves as a breathing pore for gas exchange. Photosynthesis is not a root function. A sugar beet is a modified root that has two functions: storage and propagation. Stomata
Read MoreDigestive and Respiratory Systems: Functions and Processes
The Digestive System
It consists of the gastrointestinal tract and accessory glands. The gastrointestinal tract is a long tube that varies along its route, widening in some places and narrowing in others. It begins at the mouth and ends at the anus. The following parts are distinguished:
- Pharynx
- Esophagus
- Intestine
The accessory glands are organs that pour their secretions into the digestive tube. These are:
- Salivary glands (located in the mouth)
- Stomach
- Intestinal glands (in the intestine)
- Liver
- Pancreas
The
Read MoreCellular Nutrition: Autotrophs, Heterotrophs, and Respiration
Cells need organic substances for two main purposes:
- Building and Repair: To rebuild structures, grow, and reproduce.
- Energy Production: To carry out activities such as movement and exchanging substances with the environment.
Living organisms obtain nutrition in two primary ways:
Autotrophic Nutrition
Autotrophs are able to capture energy from sunlight and use it to produce organic matter from inorganic substances. They take in raw materials to construct their own nutritional matter.
Heterotrophic Nutrition
Heterotrophs
Read MoreThe 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