Understanding Ecosystems: Structure, Function, and Cycles
An ecosystem can be defined as an open system composed of a physical-chemical part (biotope) and a biotic part (biocenosis), or all living things present in it.
Trophic Levels Within an Ecosystem
- Producers: They are the first trophic level because they are autotrophic organisms, i.e., they produce organic matter from inorganic matter and an energy source.
- Consumers: Part of the organic matter produced by producers serves as food for consumers, which is used for ATP production through cellular respiration
Cellular Reproduction and Genetics: DNA, Meiosis, and Inheritance
DNA and RNA: The Building Blocks of Life
Purines (A, G) have nine atoms in a double-ring structure, while pyrimidines (T, C) have six atoms in a single ring. Adenine (A) pairs with thymine (T) via two hydrogen bonds, whereas guanine (G) pairs with cytosine (C) via three hydrogen bonds, requiring more energy to break. Complementary base pairing dictates that only purine-pyrimidine pairs fit inside the double helix. The 3′ end of a nucleic acid strand is the sugar group.
Ribonucleotides (A, G, C, U)
Read MoreAnatomy of the Human Respiratory and Digestive Systems
Pharynx
The pharynx is a composite input formed by the nasopharynx, oropharynx, and laryngopharynx. It is formed by musculoskeletal tissue and lined by mucous. It is a channel without anterior muscle, located in front of the cervical vertebrae, measuring 14 to 15cm. The pharynx goes to the 6th cervical vertebra.
Pharyngeal Muscles
- Superior constrictor
- Middle constrictor
- Inferior constrictor
Larynx
The larynx has a respiratory function and is located between C3 and C6. It is an odd, symmetric, and superficial
Read MoreATP, Cells, and Cellular Processes: A Comprehensive Look
ATP: The Universal Energy Currency
ATP is a molecule found in all living things and is the main source of energy usable by cells to perform their activities.
The Cell Theory
- The cell is the structural unit of living beings; all living things are made of one or more cells.
- The cell is the functional unit of living things; it is the smallest unit capable of performing the vital functions of a living being.
- All cells come from another pre-existing cell by division.
Basic Structures of Cells
All cells have
Read MoreUnderstanding the Endocrine and Nervous Systems
The Endocrine System
The endocrine system functions as a coordinator, producing chemical messengers called hormones that control the body’s growth, development, and nutrient content. It is also important in the regulation of behavior. The endocrine system consists of a set of glands that secrete their products into the bloodstream.
Human Hormones
Hormones are natural substances, either lipid or protein-based, that travel through the bloodstream. They function as “chemical messengers” that regulate
Read MoreHuman Genetics and Heredity: From Reproduction to Genetic Disorders
Reproduction
Through breeding, new individuals arise that are similar to their progenitors. This ensures the survival of the species.
Asexual Reproduction
Involves a single progenitor and leads to exact copies of itself. The offspring contain the same precise genetic information as the progenitor.
Sexual Reproduction
Involves two progenitors, which contribute specialized cells called gametes that contain hereditary characters. These gametes originate from the two progenitors.
- Female gamete: Egg, oosphere
- Male