Notes, summaries, assignments, exams, and problems for Biology

The Interaction in Living Things

The interaction functions are those enabling a living being to receive information from the outside to the inside, and respond to it. A stimulus is a change in the environment surrounding a body or inside it.

There are two types of responses:

• Static: There is no movement.
• Dynamic or taxis: Movement occurs in response to a stimulus.

The Interaction in Plants

• Tropism: Movements related to plant growth or its parts. They are slow and irreversible responses.
• Nasties: Rapid and temporary changes in certain parts of the plant.
• Photoperiodism: Responses due to changes in illumination that occur throughout the seasons.

The Relationship in Animals (1)

Many animals have developed sophisticated sensory organs that detect specific... Continue reading "Interaction: Stimulus and Response in Living Things" »

Genetic Problems and Mutations

There are several ways in which a gene may be defective and cause a failure in the process of creating a protein by the cell. In general, this is due to a change in the gene known as a mutation. The negative change or mutation can occur in three basic ways: one in which the order of the components of the gene has changed, another where components of the gene are lacking, and another where the complete gene is missing or does not exist on the chromosome.

To understand this, we use an analogy where a gene is a recipe and the components are the words of that recipe. Negative changes to the recipe would be such that the words are changed in order, words are missing, or whole sections are absent. Worse yet, the whole... Continue reading "Genetic Mutations and the Foundations of Heredity" »

Ecosystems: An Overview

Ecology is the science that studies the characteristics of living beings, their environment, and the relationships they build with each other and their surroundings.

What is an Ecosystem?

An ecosystem consists of a fragment of the biosphere where living organisms interact and form relationships.

Biotope

The biotope is the physical environment or place where living things develop, including the environmental conditions that characterize it.

Biocenosis

Biocenosis refers to the set of living organisms within a given ecosystem.

The Biotope: Terrestrial and Aquatic Environments

The terrestrial environment is located on the surface of the continents, while the aquatic environment is made up of water.

Abiotic Factors

Abiotic factors are... Continue reading "Understanding Ecosystems: Biotope, Biocenosis, and Dynamics" »

Human Tissue Types: Location and Function

Epithelial Tissue: This tissue is found on the body's exterior surfaces, lining internal cavities (such as blood vessels), and in glands. Its cells are directly linked, without any intermolecular substance between them. The primary function is to coat and protect the body's exterior and internal cavities.

Connective Tissue: Located around organs, tendons, ligaments, in the dermis of the skin, and bone marrow. It consists of several cell types and connects other organs, muscles, and bones. It also fuels the dermal tissue and generates red blood cells.

Adipose Tissue: Found under the skin and around certain organs (like the kidney or heart). It is composed of round cells that store fat. Its functions include... Continue reading "Human Tissue Types and Cellular Components: Functions" »

Cranial Bones

Sphenoid Bone

The sphenoid bone, shaped like a wedge in the middle of the skull base, presents a body, two lesser wings, two greater wings, and two pterygoid processes. Its upper body contains a cavity that houses the pituitary gland. It participates in the formation of the orbital cavity and contains the sphenoid sinus within its body.

Occipital Bone

It features a large opening, the foramen magnum, which allows for the continuity of the brainstem with the spinal cord. On both sides of the foramen magnum are the occipital condyles, which articulate with the atlas.

Temporal Bone

It has three main parts: the squamous part (forming part of the cranial vault), the petrous part (housing portions of the ear canal, middle ear, inner ear, and... Continue reading "Human Skeletal Anatomy: Skull, Spine, and Thorax Bones" »

Understanding Plant Fundamentals

Plants are multicellular organisms characterized by being anchored to the ground by roots, which absorb water and mineral salts. Chlorophyll, a green pigment, captures light energy. The primary products of photosynthesis are carbohydrates, with oxygen produced as a secondary byproduct.

Plant Transport Systems

Most plants, with the exception of mosses, possess vascular tissues, similar to human blood vessels, through which sap flows. There are two main types of sap:

• Raw sap: A mixture of water and dissolved minerals, it rises from the roots through the xylem.
• Elaborate sap: Containing carbohydrates produced during photosynthesis, it flows through the phloem.

Plant Classification

Plants are broadly categorized into two... Continue reading "Plant Biology: Structure, Function, and Diversity" »

Human Tissue Types

Connective Tissue

Connective tissue consists of specialized cells embedded in an intercellular substance containing fibers like collagen. Key types include:

• Connective Tissue Proper: Binds and supports other tissues and organs, such as tendons and ligaments.
• Adipose Tissue: Composed of adipocytes filled with fat, providing lipid reserves, organ protection, and thermal insulation.
• Cartilage: Made of chondrocytes within a solid intercellular substance, forming structures like the nose, trachea, and ear cartilage.
• Bone Tissue: Composed of osteocytes that develop a strong intercellular substance with mineral salts of calcium and phosphorus, forming bones.
• Blood: Considered by many as a connective tissue with plasma as its intercellular

The Large Intestine

The large intestine is divided into:

• Cecum (Blind): Located after the ileum, contains the appendix.
• Colon: Divided into ascending, transverse, descending, and sigmoid sections.

Functions of the Large Intestine

• Absorbs water, forming feces. Feces consist of undigested food, few nutrients, and bile pigments.
• Synthesizes vitamins created by the intestinal flora. These flora digest substances we cannot and synthesize vitamins for us, a symbiotic relationship.

Rectum and Anal Canal

• Rectum: 15-20 cm in length.
• Anal Canal: 3 cm, opening to the outside through the anus.
• Anus: Contains two sphincters (muscle loops), one involuntary and one voluntary.

The Liver

The liver is located in the upper right quadrant, weighs approximately 1.5 kg, and... Continue reading "Digestive System, Breathing & Oxygen Administration: A Concise Review" »

Understanding Human Reproduction:
The process of human reproduction involves sexual reproduction. Females produce female gametes (eggs) and males produce male gametes (sperm). These two types of cells unite to form a zygote.
Fertilization is internal; the egg and sperm unite in the reproductive tract of women.
The reproduction process includes the following events:

• Production of gametes in specialized reproductive organs.
• Fertilization, which is the union of two gametes within the female reproductive tract to form the zygote.
• Development of the zygote within the female reproductive tract, where the zygote becomes an embryo and then a fetus.
• Birth of a fully formed baby.
• Development of children, including the maturation of their sexual organs

Physiological Adjustments to Regular Physical Exercise

Cardiovascular System Adaptations

• Increased coronary flow, capillary permeability, and capillary density.

Adaptive Responses of Blood Pressure to Exercise

• Increased blood pressure during exercise and decreased resting blood pressure.

Adaptations in the Respiratory System to Exercise

• Increased frequency and depth of respiration.

Blood Flow Distribution During Exercise

• Increased blood flow in active muscles at the expense of inactive organs.

Cardiac Adaptations: Concentric Hypertrophy

• Corresponds to concentric hypertrophy of the heart, often induced by strength training.

Functions of Respiratory System Adaptations

• To meet O2 demands, eliminate excess CO2, and regulate pH.

Cardiac Output Responses to Exercise

• Trained