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Evidence of Evolution: Understanding Natural Selection and Adaptation

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Artificial Selection and Evolution

Possible Misconceptions

  • Populations evolve, not individual organisms. Individuals may have certain heritable variations, but they do not evolve these traits during their lifetime.

Evidence of Evolution

The Study of Fossils

Support for Evolution

  • Charles Darwin proposed a possible explanation for the origin of species, explaining various data and suggesting areas for further research.
  • The theory of evolution suggests that all organisms on Earth share a common ancestor.

Fossil Record

  • Fossils provide significant evidence of evolutionary change, offering a record of species that existed long ago.
  • Ancient species often show similarities to species living today.
  • Not all extinct fossils have modern counterparts, and some ancient
... Continue reading "Evidence of Evolution: Understanding Natural Selection and Adaptation" »

Understanding Rheumatic Fever: Causes, Symptoms, and Complications

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Rheumatic Fever

Is a multisystem inflammatory disease that can involve the heart, joints, skin, and brain. The disease develops after a streptococcal infection (A beta-hemolytic – Streptococcus pyogenes) – mostly pharyngitis

Clinical Features

  • Occur most often in children
  • Develop 2-4 weeks after streptococcal infection
  • Fever, malaise, and increased erythrocyte sedimentation rate
  • Rheumatic heart disease – pancarditis; inflammation of the entire heart (3 layers)

Pericarditis

Leads to serous effusions

Myocarditis

Leads to cardiac failure

Endocarditis

Leads to valvular damage

  • Rheumatic endocarditis – mitral and aortic valves (mostly); the valves become thickened, fibrotic, deformed, & calcification (may)
  • Joint involvement – arthralgia, arthritis,
... Continue reading "Understanding Rheumatic Fever: Causes, Symptoms, and Complications" »

Understanding the Lymphatic System: Functions, Lymphocytes, and Composition

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1. Know the functions of the lymphatic system

· Produce, maintain, and distribute lymphocytes and other lymphoid cells that provide defense against infections and foreign substances PRIMARY FUNCTION. Return of excess fluid to bloodstream. Transport of lipids absorbed in digestive tract

2. Know the three subtypes of lymphocytes and what type of immunity each is responsible for

· T cells à Cell-mediated immunity (4+ subtypes)

  • Cytotoxic T Cells (Tc) - direct cellular attack
  • Helper T Cells (TH) and Suppressor T Cells (TS) - regulatory roles
  • Memory T Cells.

B Cells à Antibody-mediated immunity

  • Antibodies (immunoglobulins)
  • Antigen - usually proteins (specific chemical targets)

· NK Cells à Immunological surveillance

3. Know where the three types of lymphocytes

... Continue reading "Understanding the Lymphatic System: Functions, Lymphocytes, and Composition" »

Cell Biology: Structure, Function, and Division

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Cell Structure and Function

A cell is the smallest structural and functional unit of life that can carry out the three vital functions: nutrition, reproduction, and interaction.

  • Nutrition: obtaining energy, renewing the cellular structure, and obtaining biomolecules.
  • Interaction: cells can adapt to changes in their environment and continue performing the activities they need to live.
  • Reproduction: formation of new cells.

Types of Cells

Prokaryotic Cells

Prokaryotic cells do not have membrane-bound structures, are relatively small, have a single circular chromosome, have isolated ribosomes in their cytoplasm, and have cavities in their cytoplasm that function as mitochondria. Organisms belonging to the Monera kingdom have prokaryotic cells.

Eukaryotic

... Continue reading "Cell Biology: Structure, Function, and Division" »

English Phonetics: Consonants and Articulation

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Vowels and Consonants

A vowel is a sound produced without any closure in the mouth or throat. There's no obstruction in the buccal cavity. A consonant, conversely, involves at least one stoppage of airflow during vocalization.

Places of Articulation

The place of articulation describes where the obstruction occurs in the vocal tract. It's the point of contact between an active articulator (usually part of the tongue) and a passive articulator (typically part of the roof of the mouth).

  • Bilabial: Both lips.
  • Labio-dental: Upper lip and upper front teeth.
  • Dental: Tongue tip/blade and upper front teeth.
  • Alveolar: Tongue tip/blade and alveolar ridge.
  • Post-alveolar: Tongue blade and back of the alveolar ridge.
  • Palatal: Tongue front and hard palate.
  • Velar: Tongue
... Continue reading "English Phonetics: Consonants and Articulation" »

Understanding the Circulatory and Respiratory Systems

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Blood Flow and the Circulatory System

Blood flow refers to the circulation of blood pumped by the heart through the circulatory system. In humans, blood circulation is:

  • Double: Blood passes through the heart twice in every complete cycle.
  • Complete: Oxygen-rich blood and carbon dioxide-rich blood do not mix because the two sides of the heart are separated by the septum.

Pulmonary Circuit

The pulmonary circuit, or shorter circuit, is the path blood takes between the heart and the lungs. The right side of the heart pumps blood through this circuit.

  1. Blood carrying carbon dioxide, waste, and nutrients picked up throughout the body enters the right atrium through the inferior vena cava and then passes into the right ventricle.
  2. The blood leaves the right
... Continue reading "Understanding the Circulatory and Respiratory Systems" »

Understanding the Human Senses and Their Disorders

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Sense of Smell: Enables the body to detect chemical molecules in the air. Molecules are detected by chemoreceptors in the nasal cavities. Sensations they receive are called smells.

Types of Nasal Mucous Membranes:

  • Respiratory Mucous Membrane: Has blood vessels that warm inhaled air and hairs that trap dust particles.
  • Olfactory Mucous Membrane: Contains the olfactory receptors. Chemoreceptors converge in the olfactory bulb. Receptors transmit impulses along the olfactory nerve to the brain when stimulated by chemicals.

Sense of Taste: Enables the body to detect flavors. Four basic tastes: sweet, salty, sour, and bitter. Chemoreceptors respond to chemicals dissolved in saliva, located mainly on the tongue, but also on the palate, pharynx, and larynx.... Continue reading "Understanding the Human Senses and Their Disorders" »

Cheat sheet

Classified in Biology

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Chapter 1

Gross/macroscopic Anatomy: study of large, visible structures   Microscopic Anatomy: study of structures too small to be seen by the naked eye   cycology: microscopic study of cells   histology: microscopic study of tissues   embryology: study of developments before birth  Developmental Anatomy studies anatomical and physiological developments throughout life
requirements for life are 1)Maintenance of Boundaries(homeostasis) 2) movement 3)responsiveness 4) Digestion 5) Excretion 6)Metabolism 7)Growth 8)Reproduction  Necessary for survival 1)Nutrients 2)Oxygen 3)Water-70% 4)Normal Body Temp.-98.6F or 37C   

Population Genetics: An Evolutionary Overview

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Population Genetics

Microevolution

Change in the collective genetic material of a population.

Bell Curve

Shows the frequency of a trait in a population.

Gene Pool

Describes the total genetic information available in a population.

Hardy-Weinberg Genetic Equilibrium

Principle based on a set of assumptions about an ideal hypothetical population that is not evolving.

Immigration

Movement of individuals into a population.

Emigration

Movement of individuals out of a population.

Gene Flow

Process of genes moving from one population to another.

Sexual Selection

Tendency of females to choose the males they mate with based on certain traits.

Stabilizing Selection

Individuals with the average form of a trait have the highest fitness.

Disruptive Selection

Individuals with... Continue reading "Population Genetics: An Evolutionary Overview" »

Stages of Cell Division and Meiosis

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Name the stage of cell division in which paired homologous chromosomes get shortened and thickened?

Ans: Pachytene is the stage of cell division in which paired homologous chromosomes get shortened and thickened.

Which structure of animal cell forms the asters of spindle?

Ans: Centrosome is that structure of animal cell which forms the asters of spindle.

Name the cells in which meiosis occurs?

Ans: Meiosis occurs in the reproductive cells or germ cells.

At which stage of meiosis crossing over of genetic material takes place?

Ans: Pachytene is the stage of meiosis in which crossing over of genetic material takes place.

What is Go phase?

Ans: A stage when cell cycle is arrested during interphase is called Go phase.

Name the cell division concerned with

... Continue reading "Stages of Cell Division and Meiosis" »