Digestive System Overview

Biogeography suggests that species evolve from common ancestors and diverge over time due to geographical separation. The distribution of similar species across continents, which were once joined together, supports the idea of a shared ancestral lineage and the gradual evolution of distinct species as continents drifted apart.

Darwin observed that closely related species within a local environment often displayed distinct characteristics based on their specific habitats. This variation, he argued, arises from the selective pressures of different environments, leading to adaptations that best suit the local conditions.

Natural selection is the process by which organisms with traits better suited to their environment are more likely to survive, reproduce, and pass those advantageous traits to their offspring. This gradual accumulation of beneficial adaptations over generations drives the evolutionary change of a species.

<p>Stabilizing selection favors the average traits within a population, while selecting against extreme traits. This results in a narrowing of the range of variation. For example, human birth weight is a classic example where babies with average weights are typically healthier and have higher survival rates.</p> Signup and view all the answers

<p>Directional selection favors one extreme trait over the other extreme and the average traits. This leads to a shift in the population's characteristics towards that favored extreme over time. An example is the development of antibiotic resistance in bacteria.</p> Signup and view all the answers

<p>Disruptive selection favors both extreme traits while selecting against average traits. This leads to the divergence of the population into two distinct groups with different characteristics. For example, a hypothetical bird species with varied beak sizes - those with very small beaks and very large beaks might be better suited to specialized food sources than birds with average-sized beaks.</p> Signup and view all the answers

<p>Natural selection is not random; it is a process driven by the environmental pressures that favor specific traits. While genetic variations arise randomly, natural selection acts on those variations, selecting for traits that increase an organism's survival and reproduction in a particular environment.</p> Signup and view all the answers

<p>Darwin's theory of natural selection provides a powerful explanation for the diversity of life on Earth. It demonstrates how environmental pressures drive the evolution of species through the gradual accumulation of beneficial adaptations, explaining the remarkable diversity and complexity of life we see today.</p> Signup and view all the answers

<p>The primary function of the small intestine is to absorb nutrients from food.</p> Signup and view all the answers

<p>Villi increase the surface area of the intestine, slowing down food and maximizing nutrient absorption.</p> Signup and view all the answers

<p>The small intestine is between 5-7 meters long, and food takes 7-10 hours to pass through.</p> Signup and view all the answers

<p>The three main parts of the small intestine are the duodenum, jejunum, and ileum.</p> Signup and view all the answers

<p>The duodenum is about 20 to 30 cm long and is where most digestive enzymes flow to aid in the digestion of food.</p> Signup and view all the answers

<p>Symptoms include tiredness, swelling in the upper right abdomen, and yellowing of the skin.</p> Signup and view all the answers

<p>Gallstones are caused by bile crystals forming in the gallbladder and becoming stuck in the duct leading to the intestines.</p> Signup and view all the answers

<p>Primary treatments include eating roughage such as celery and carrots, and using laxatives like Metamucil.</p> Signup and view all the answers

<p>Diarrhea is primarily caused by too much muscle motion in the large intestine, leading to inadequate water reabsorption.</p> Signup and view all the answers

<p>The Archaeopteryx is significant as it is the oldest known fossil bird, showcasing features of both birds and dinosaurs.</p> Signup and view all the answers

<p>Homologous features are body parts that share a common ancestry, such as the forelimbs of mammals.</p> Signup and view all the answers

<p>A vaccine exists as a preventive measure for hepatitis B.</p> Signup and view all the answers

<p>Paleontology is the scientific study of past life forms through the analysis of plant and animal fossils.</p> Signup and view all the answers

<p>Halitosis is characterized by bad breath, commonly caused by poor dental health, cavities, or stomach issues.</p> Signup and view all the answers

<p>Ulcers typically cause abdominal pain and burning sensation especially after eating spicy meals, primarily due to a bacterial infection from H-pylori.</p> Signup and view all the answers

<p>Regular ulcers affect the first few cell layers, bleeding ulcers reach blood vessels causing bleeding, and perforated ulcers create a hole allowing stomach juices to escape.</p> Signup and view all the answers

<p>Mild ulcers are treated with antacids, while severe cases may require medications like Zantac or surgery for perforated ulcers.</p> Signup and view all the answers

<p>Heartburn is marked by irritation and burning sensation in the esophagus, often caused by pregnancy, overweight conditions, or a malfunctioning cardiac sphincter.</p> Signup and view all the answers

<p>Hiatal hernia symptoms include discomfort during meals and heartburn, and in severe cases, it can cause chest pain and shortness of breath similar to a heart attack.</p> Signup and view all the answers

<p>The main treatment for heartburn is to identify and treat its underlying causes, with antacids often helping to alleviate symptoms.</p> Signup and view all the answers

<p>Stress contributes to ulcers in about 15% of cases, whereas the majority are caused by H-pylori infections affecting the stomach lining.</p> Signup and view all the answers

<p>Genetic drift is a random change in allele frequencies due to chance, and it has a more significant effect on small populations because fluctuations can drastically alter allele distribution.</p> Signup and view all the answers

<p>The bottleneck effect occurs when a population size decreases significantly, reducing allele variation and genetic diversity due to the loss of individuals.</p> Signup and view all the answers

<p>The founders effect leads to a reduction in genetic diversity when a small group establishes a new population, as the new gene pool may not represent the diversity of the original population.</p> Signup and view all the answers

<p>Gene flow occurs when individuals from different populations mate, which can increase genetic diversity and introduce new traits into a population.</p> Signup and view all the answers

<p>Natural selection is a non-random process where organisms with advantageous traits are more likely to survive and reproduce, leading to an increase in the frequency of those traits' alleles in the gene pool.</p> Signup and view all the answers

<p>Stabilizing selection favors average traits, reducing the extremes; for example, human birth weights tend to favor average-sized babies for survival.</p> Signup and view all the answers

<p>Directional selection occurs when one extreme of a trait is favored, leading to evolutionary changes in that direction over time, as seen in antibiotic resistance.</p> Signup and view all the answers

<p>Artificial selection is the intentional breeding of individuals with desired traits by humans, which can rapidly change allele frequencies in a few generations.</p> Signup and view all the answers

<p>Divergent evolution is the process where closely related species evolve different phenotypes due to varying environmental pressures. This results in homologous features being developed in distinct species.</p> Signup and view all the answers

<p>Convergent evolution occurs when unrelated species develop similar phenotypes due to similar environmental pressures. An example is the analogous features seen in sharks and dolphins.</p> Signup and view all the answers

<p>Parallel evolution is the independent evolution of similar phenotypes in related species facing similar environments. Unlike divergent evolution, where the species become more dissimilar, parallel evolution maintains similarity despite separation.</p> Signup and view all the answers

<p>Co-evolution is the process where two or more species influence each other's evolution. An example of mutualism is the relationship between flowers and their pollinators, where both benefit.</p> Signup and view all the answers

<p>Adaptive radiation is the evolution of a single species into multiple distinct species adapted to different environments. The Darwin finches are a classic example, evolving unique traits from a common ancestor to exploit different ecological niches.</p> Signup and view all the answers

<p>Gradual equilibrium describes evolution as a slow and continuous process, while punctuated equilibrium describes periods of rapid change followed by long stability. For example, the transition of horse species reflects gradual equilibrium, whereas trilobites exhibit punctuated equilibrium.</p> Signup and view all the answers

<p>Homologous features arise from a common ancestor and indicate divergent evolution, while analogous features evolve independently in unrelated species due to similar pressures. This distinction is pivotal in classifying evolutionary relationships.</p> Signup and view all the answers

<p>An example of competition in co-evolution is the relationship between lions and hyenas, where both species vie for similar prey resources. This competition drives each species to adapt more efficiently to their environment.</p> Signup and view all the answers

The primary organ where nutrients from food are mainly absorbed into the bloodstream.

Finger-like projections that increase the surface area of the small intestine for efficient absorption of nutrients.

The first part of the small intestine where most digestive enzymes enter, making it crucial for digestion.

Tiny tubes within the villi that absorb fatty acids and glycerol.

The process of taking in nutrients from the food and transferring them into the bloodstream.

The preserved remains of plants and animals found in sediments like sand or mud.

The study of ancient life through the analysis of fossils.

A transitional fossil with bird-like features (feathers and wings) and reptile-like features (teeth and a tail).

Similar structures in different organisms that share a common ancestor.

Structures in different organisms that serve the same function but don't share a common ancestor.

Structures in an organism that no longer serve a purpose but were present in its ancestors.

A type of hepatitis spread through contaminated food and water, curable with treatment.

A type of hepatitis spread through bodily fluids, vaccine preventable.

A condition marked by bad breath, usually caused by poor dental hygiene or underlying issues like cavities or stomach problems.

A sore in the lining of the stomach or duodenum, mainly caused by bacterial infection (H. pylori) or stress, resulting in pain especially after spicy meals or on an empty stomach.

A type of ulcer where the sore has penetrated a blood vessel, leading to bleeding into the stomach or vomiting blood.

An ulcer that has progressed to a hole through the stomach wall, allowing stomach contents to leak into the abdominal cavity.

A condition where stomach acid flows back up into the esophagus, causing a burning sensation.

A condition where a portion of the stomach pushes up into the chest cavity through the esophageal opening in the diaphragm.

A specific type of hiatal hernia where the stomach slides up into the esophagus through the cardiac sphincter.

A specific type of hiatal hernia where a portion of the stomach bulges into the chest cavity beside the esophagus, caused by a weakness in the diaphragm.

The idea that species change over time, with new species arising from existing ones.

The theory that organisms with traits better suited to their environment are more likely to survive, reproduce, and pass those traits to their offspring.

The process by which species vary in different parts of the world, often with similar features in similar environments.

The process by which closely related species living in different habitats within a local environment develop distinct features.

A type of natural selection where the average trait is favored, leading to a decrease in variation within a population.

A type of natural selection where one extreme trait is favored, leading to a shift in the population toward that trait.

A type of natural selection where both extreme traits are favored, leading to greater variation within a population.

The idea that all living organisms on Earth are descended from a common ancestor.

Evolutionary process where closely related species evolve distinct phenotypes due to different environmental pressures.

Evolutionary process where unrelated species evolve similar phenotypes due to similar environments or pressures.

Evolutionary process where related species independently evolve similar phenotypes due to similar environments or pressures.

A close relationship between two species where both benefit, like a flower and its pollinator.

A type of co-evolution where one species (predator) hunts and feeds on another species (prey).

A type of co-evolution where two or more species compete for the same resources, leading to adaptations to reduce overlap or increase efficiency.

A type of co-evolution where one species (parasite) benefits at the expense of another (host), leading to adaptations in both species.

The rapid evolution of a single species into multiple distinct species, often driven by new environmental opportunities.

Random changes in the allele frequencies of a population due to chance events. It has a stronger impact on smaller populations.

A type of genetic drift where a drastic reduction in population size leaves only a few individuals with a limited range of genetic variation.

A type of genetic drift that happens when a small group of individuals establishes a new population, resulting in a reduced gene pool compared to the original population.

The transfer of genetic material (alleles) from one population to another, usually through migration and interbreeding.