Evolutionary Biology: Darwin, Wallace, and Evidence of Evolution
Evolution and Natural Selection
Evolution occurs through mutations. Individuals do not change; they pass changes to their offspring, leading to population change.
Alfred Russell Wallace and Darwin’s Contemporary
Alfred Russell Wallace was a naturalist who independently conceived the theory of natural selection, similar to Darwin’s. Although they corresponded by letters, they never met in person. Wallace’s contributions were not as widely recognized as Darwin’s for several reasons. Wallace mistakenly
Read MoreHuman Circulatory and Excretory Systems Explained
Blood Components and Function
Blood is a red liquid that circulates through blood vessels, carrying oxygen, nutrients, carbon dioxide, and collected waste products. It consists of plasma (55%) and blood cells (45%), totaling approximately 5 liters in the average adult.
Plasma Composition
Plasma is a yellowish liquid containing water, salts, minerals, hormones, and proteins.
Blood Cells: Types and Roles
Blood cells are formed in the bone marrow.
Red Blood Cells (Erythrocytes)
These are the most abundant
Read MoreDefining Life: Core Characteristics and Cellular Basis
Core Characteristics of Living Things
All living things share fundamental characteristics:
- Life Cycle: They have a life cycle that includes birth (origin) and death.
- Chemical Composition: They share a similar chemical composition, primarily based on organic matter.
- Cellular Structure: They are composed of one or more basic units called cells. Cells are the smallest microscopic units considered to be alive.
- Life Functions: They perform essential life functions:
Nutrition
Nutrition is the set of processes
Read MoreCirculatory Systems: Open vs. Closed & Vertebrate Hearts
Circulatory Systems: Open and Closed
Two main types of circulatory systems exist: open and closed. Both share three common elements:
- A fluid (in echinoderms, it’s called hydrolymph; in most invertebrates, hemolymph; and in vertebrates, blood and lymph).
- A network of blood vessels to carry the fluid.
- A heart, a muscular organ that pumps the fluid.
Open Circulatory System
Typical of arthropods and most mollusks (except cephalopods). Blood vessels don’t form a complete network; instead, blood drains into
Read MoreUnderstanding Lipids: Types, Functions, and Classifications
Lipids: An Introduction
Lipids: They do not have a characteristic functional group but are substances of biological origin, soluble in organic solvents and insoluble in water. All lipids share a common carbohydrate-based structure, which explains their insolubility in water.
Biological Functions of Lipids
Biological functions: Lipids serve as the primary energy reserves for living organisms. They are integral components of cell membranes and play a role in regulating cellular and tissue activity.
Lipid
Read MoreHygiene and Skin Lesions
Hygiene and Cleanliness
Hygiene and cleanliness are concepts aimed at preventing disease and preserving health.
Postural Hygiene
Proper posture to avoid injuries during daily activities or work.
Occupational Hygiene
Conservation measures for health in the workplace.
The Necessity of Hygiene as Basic Health
Virginia Henderson framed hygiene within the basic needs of individuals. Maslow set physiological needs, including thermoregulation, as a priority. The skin plays an important, essential role when in
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