Evolutionary Theories: From Lamarck to Punctuated Equilibrium
Hypotheses of Evolution
Lamarckism
Lamarck’s transformisme theory proposed that organisms evolve through the inheritance of acquired characteristics. For example, a worm transforming into a beetle over time or an animal adapting to a contaminated environment.
Evidence of Evolution
Darwin posited that living beings are products of a process involving successive modifications from a common ancestor, driven by natural selection.
Paleontological Evidence
Fossil remains of extinct flora and fauna demonstrate
Read MoreHuman Body Systems: Diseases, Illnesses & Health
Health and IllnessWhat is Health?Health, as the absence of illness, is the state of well-being of the body. When healthy, the body carries out all its functions correctly. Healthy habits help us stay healthy and prevent illnesses. A healthy diet is one of the most important habits. What is Illness?An illness is an abnormal process that alters, modifies, or prevents the activity of part of our body or the complete organism.
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Bacterial Genetics and Physiology
Transposable Elements: Transposons
The genes in living organisms are not static and may change their sequence under certain conditions, for example, through insertion sequences.
- Insertion occurs through single-strand breakage by the enzyme transposase.
- Transposons, or “jumping genes,” are DNA segments that can move within the genome, or between chromosomal DNA and plasmids.
- The transposon attaches to the ends of single strands and repairs them after replication.
- Transposition is important because these
Circulatory Systems: Human and Vertebrate Blood Flow
There are two types of circulatory systems:
Closed circulatory system: It consists of a series of blood vessels through which the blood travels continuously. Materials carried by the blood reach the tissues through diffusion. It is characteristic of annelids, cephalopods, and vertebrates.
Open circulatory system: The blood pumped by the heart travels through blood vessels, which supply blood directly to the cells, returning by different mechanisms. This type of system is present in arthropods and
Read MoreHuman Reproduction and Development Stages
Human Reproduction
Females produce female gametes (eggs) and males produce male gametes (sperm). These two cells join to form a zygote.
Internal Fertilization
The egg and sperm unite in the female’s reproductive tract, and the new human being develops there.
Reproduction Steps
- Gamete Production: Specialized reproductive organs produce gametes.
- Fertilization: The union of both gametes inside the female reproductive tract forms the zygote.
- Zygote Development: Within the female reproductive tract, the zygote
Understanding the Human Nervous System: Structure and Function
The Nervous System: Receiving and Responding to Stimuli
The nervous system receives and responds to stimuli, maintaining the body’s homeostasis. It coordinates the activities of tissues, organs, and systems.
Neurons: The Building Blocks
Neurons are the primary cells responsible for transmitting nerve impulses. They consist of:
- Cell Body: Contains the nucleus and cytoplasm.
- Dendrites: Short, numerous extensions that capture nerve impulses.
- Axon: A long extension that conducts impulses to distant areas,