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

Changes achieved through the development, acquisition, or loss of organs are maintained and transmitted to offspring, which preserves and increases these traits through successive generations. This concept is known as the inheritance of acquired characteristics. However, analysis of these proposals has not demonstrated any inherent tendency or impulse towards complexity in living things. In light of developments in genetics, the inheritance of acquired characteristics is not supported.

Natural Selection: Darwin and Wallace

Darwinian theory posits that in a changing world, organisms also change over time. Some features disappear, and new ones emerge. This process of change is gradual and continuous. Organisms with similarities are related and... Continue reading "Evolutionary Theories: Darwinism, Neo-Darwinism, and Hominid Origins" »

Biological Foundations

Photosynthesis: Energy Capture

Photosynthesis is a vital process that enables plants to convert light energy into chemical energy. This fundamental process, crucial for life, relies on the presence of leaves and pigments to capture solar energy.

Cellular Structures & Nutrient Transport

Unicellular vs. Multicellular Organisms

Unicellular organisms are in direct contact with their external environment. In contrast, multicellular organisms do not have all their cells in direct contact with the outside world, facing challenges in spreading nutrients across individual cells.

Therefore, multicellular organisms require internal transport systems (like 'pipes' or circulatory systems) to distribute nutrients to all cells not in... Continue reading "Biological Foundations and Wastewater Treatment Essentials" »

Core Concepts in Biotechnology and Genetics

Genetic Code

The genetic code is the set of rules by which information encoded in messenger RNA (mRNA) sequences is translated into amino acid sequences during protein synthesis. It dictates which amino acids correspond to each codon, allowing them to join together in the correct position to form a protein.

Biotechnology

Biotechnology involves the use of living organisms, or parts of organisms, or modified products derived from them, to improve plants or animals, or to develop microorganisms for specific objectives.

Plasmids

Plasmids are circular DNA molecules, independent of the chromosomal DNA, that often carry genetic information useful to the host organism, typically found in bacteria and yeasts.

Bacteriophage

The Digestive System: Functions and Anatomy

The digestive system is responsible for several key functions:

• Food intake: Consuming food.
• Nutrient preparation: Breaking down nutrients through mechanical and chemical digestion.
• Absorption: Absorbing nutrients into surrounding tissues.
• Elimination: Eliminating undigested waste.

Components of the Digestive System

The digestive system consists of the following organs:

• Mouth
• Pharynx
• Esophagus
• Stomach
• Intestines:
  • Duodenum
  • Jejunum
  • Ileum
  • Large Intestine (Cecum, Appendix, Ascending Colon, Transverse Colon, Descending Colon, Sigmoid Colon, Rectum, Anal Canal, Anus)

The entire system is lined with the peritoneum, a serous membrane.

Accessory Glands

Several accessory glands aid in digestion:

• Minor and major salivary glands

Endocrine System Fundamentals

What is Endocrinology?

Endocrinology is the science studying the function and pathology of the ductless or endocrine glands, whose secretions are called hormones.

Components of the Endocrine System

The endocrine system is a control system responsible for various bodily functions. It maintains the body's internal environment, participates in growth, sexual differentiation, and reproduction, and intervenes in reactions. Closely related chemically with the nervous system, the endocrine system functions in an integrated way. Endocrine interrelations between glands are most often governed by the hypothalamic-pituitary axis.

The main endocrine glands include the pituitary gland, thyroid gland, endocrine pancreas, parathyroid... Continue reading "Endocrine System and Hormone Function" »

Unit 5: Cell Nutrition

All living beings need food used as follows:

• For growth: it provides the substances needed for making new cells and tissues.
• As a source of energy: required for the chemical reactions which take place in living organisms to keep them alive.
• For replacement: of worn and damaged tissues, for example, red blood cells that break down each day and to replace the skin which is worn away and to repair wounds.

Nutrition can be defined as obtaining organic substances and mineral ions from which organisms obtain their energy and their raw materials for growth and tissue repair. Several systems are involved in cell nutrition: this process is carried out by organ systems which working together allow cells to obtain matter and energy.

• Digestive

Health and Disease: A Comprehensive Overview

Health Encompasses: Sickness absence and well-being in physical, mental, emotional, social, spiritual, sexual, and environmental aspects.

Risk Factors for Health

• Food rich in fat and/or sugar
• Tobacco and/or drug use
• Lack of hygiene
• Stress

International Sanitary Conference (Paris, 1851)

Accomplishments:

• Development of public health policies with laws governing food handling and potable water.
• Creation of the National Institute of Health.
• Methods for preventative health planning, including vaccination and infection control.
• Improved diagnostic techniques.
• Drug development.
• Promotion of better nutritional habits for a healthy life.

Infectious Diseases

Infectious diseases are caused by microorganisms and are transmitted... Continue reading "Health and Disease: Factors, Prevention, and Immunity" »

Asexual Reproduction in Cormophytes

Asexual reproduction in cormophytes involves specific vegetative organs such as stolons, rhizomes, tubers, and bulbs.

• Runners: These are side branches emerging from the base of the stems with horizontal growth. Roots emit buds, giving rise to new independent individuals.
• Rhizomes: Underground stems that grow horizontally in the soil and accumulate reserve substances. Ground stems can emerge from buds, eventually taking root and separating from the main rhizome.
• Tubers: Very enlarged underground stems that store food. They can be separated from the main plant to form separate plants.
• Bulbs: Underground stems that are more or less spherical, with fleshy, layered storage. Smaller bulbs are often formed with buds

As a result of cephalocaudal and lateral folding, a portion of the yolk sac lined by endoderm is incorporated into the embryo to form the primitive gut. The primitive gut is divided into three parts: foregut, midgut, and hindgut. The midgut communicates with the yolk sac through the temporary omphalomesenteric duct.

Foregut Development

It extends from the oropharyngeal membrane to the second portion of the duodenum (ampulla of Vater).

Esophagus Formation

Its primordium arises from the tracheoesophageal septum around the 4th week. The endoderm proliferates to temporarily occlude the lumen. At the end of the embryonic period, the lumen recanalizes, and the endoderm differentiates into stratified squamous epithelium. The muscle of the upper 1/3 is... Continue reading "Digestive System Embryology" »

Understanding Plant Biology: Structure, Function, and Diversity

Autotrophs and Photosynthesis

Plants are autotrophic organisms, meaning they produce their own food. They are typically fixed in place and do not move actively. Their characteristic green color is due to a vital substance called chlorophyll.

Photosynthesis: This fundamental process allows plants to harness sunlight as energy. Chlorophyll captures this solar energy, enabling plants to produce organic substances from inorganic compounds absorbed from their environment (like water and minerals).

Plant Anatomy: Vegetative and Reproductive Organs

Vegetative Organs

The vegetative body of plants consists of specialized organs essential for growth and survival:

• Root: This part grows into the