Evolutionary Theory: Natural and Sexual Selection
Evolutionary Theory and Evolutionary Psychology
Darwin
Darwin proposed the first evolutionary theory to explain how change might take place over time, especially how seemingly purposeful or functional structures might have arisen.
Adaptation
Improbably usefulness (too precisely functional to have arisen by chance only).
Williams proposed the following criteria for invoking adaptation:
- Reliability: Does the mechanism regularly develop in most or all members of the species across normal environments and
Renal Function and Urine Formation: Key Physiological Processes
Daily Water Losses
- Insensible water loss: Respiratory evaporation and diffusion into the skin.
- Sweat (exercise and temperature).
- Feces.
- Extracellular urine (60%).
- Intracellular (40%).
Renal Function
Excretion of metabolic waste products, foreign chemicals, drugs, and metabolites of the water balance and hormones. Regulation of electrolyte balance. To maintain homeostasis, excretion of water and electrolytes is essential.
Regulation of Arterial Pressure (Long Term)
By regulating excretion of varying amounts
Read MoreCellular Organelles: Peroxisomes, Mitochondria, and Chloroplasts
Peroxisomes and Glyoxysomes
Peroxisomes: These organelles are similar to lysosomes but contain oxidase enzymes instead of hydrolases. Key enzymes include peroxidase and catalase. They facilitate oxidation reactions, similar to those in mitochondria, but the released energy is dissipated as heat. Peroxisomes also detoxify harmful substances.
Glyoxysomes: A specialized type of peroxisome found in plants, containing enzymes for the glyoxylic acid cycle. This cycle enables the synthesis of carbohydrates
Read MoreMeiosis: Understanding the Phases of Cell Division
Digestive System in Vertebrates: From Oral Cavity to Midgut
Oral Cavity
The oral cavity, or mouth, is surrounded by folds of skin called lips, except in turtles and birds. Inside the mouth, there are teeth. In some species, all teeth are the same, while in others, the upper teeth have different shapes. Their function is to cut, grind, and crush food (mechanical digestion). The tongue is also found in the mouth. It contains a large number of taste buds, and its function is to mix food and facilitate its transit into the pharynx. In fish, the tongue is not
Read MoreSexual and Asexual Reproduction in Living Organisms
Reproduction in Living Organisms
Reproduction is the process by which living things produce new generations of individuals of the same species. The new living things can arise from individual cells, groups of cells, or portions of the parent organisms.
Unicellular Organisms
In unicellular living things, the cell is the full body and divides to give rise to new organisms.
Multicellular Organisms
In multicellular living beings, their constituent cells originate apart from others by successive division.
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