Bio Exam - Digestive System PDF

The Digestive System 1. Outline the way your body physically and chemically digests carbohydrates, protein and fat. Include organs, enzymes and hormones. Be able to label a diagram. Carbohydrate Digestion 1.​ Mouth: Salivary amylase starts breaking down starches into sugars. 2.​ Stomach: No...

The Digestive System 1. Outline the way your body physically and chemically digests carbohydrates, protein and fat. Include organs, enzymes and hormones. Be able to label a diagram. Carbohydrate Digestion 1.​ Mouth: Salivary amylase starts breaking down starches into sugars. 2.​ Stomach: No carbohydrate digestion. 3.​ Small Intestine: ○​ Pancreatic amylase breaks down starch further. ○​ Brush border enzymes (maltase, sucrase, lactase) convert disaccharides to monosaccharides (like glucose). 4.​ Absorption: Glucose is absorbed into the bloodstream. Protein Digestion 1.​ Mouth: No protein digestion. 2.​ Stomach: Pepsin breaks proteins into smaller peptides. 3.​ Small Intestine: ○​ Trypsin and chymotrypsin (from the pancreas) break down peptides further. ○​ Peptidases (from the intestinal lining) break peptides into amino acids. 4.​ Absorption: Amino acids are absorbed into the bloodstream. Fat Digestion 1.​ Mouth: Lingual lipase starts breaking down fats. 2.​ Stomach: Gastric lipase further breaks down fats. 3.​ Small Intestine: ○​ Bile (from the liver) emulsifies fat. ○​ Pancreatic lipase breaks fat into fatty acids and monoglycerides. 4.​ Absorption: Fatty acids and monoglycerides are absorbed into the cells of the small intestine and later enter the lymphatic system. Key Hormones Involved: ​ Gastrin: Stimulates stomach acid and enzyme release. ​ Secretin: Stimulates the pancreas to release bicarbonate. ​ Cholecystokinin (CCK): Stimulates bile release and enzyme release from the pancreas. 2. Make a chart of organ structure and function. Organ Function  Esophagus , Swallowing ​ In mouth food in shaped into a ball (bolus) which tongue moves to back of your throat ​ Entering the Pharynx- the uvula moves up to stop food from entering the trachea ​ The esophagus is a tube surrounded by 2 layers of muscles (circular and lengthwise) ​ The wave of muscle motion that pushed the food down is called peristalsis ​ The waves work continuously to push food throughout the digestive system. Stomach Functions : Structure: ​ To continue mechanical digestion ​ It is a j shaped organ located to the of the food by muscular motion center left side of the abdomen just until the food is not thoroughly below the ribcage broken and mixed with gastric ​ Entrance of food to the stomach is juices controlled by the cardiac sphincter Gastric Juice in Stomach which allows food to enter the ​ Pepsin: an enzyme which breaks stomach but not leave (usually) down protein into groups of amino ​ Exit is controlled by the pyloric acids sphincter which also prevents food ​ Hydrochloric Acid: provides the from leaving before it is ready necessary pH level needed for pepsin to work (pH-2) ​ Renin: A chemical which helps to clot milk into lumps which could be digested easily ​ Mucus: A thick protective layer on the stomach wall, which protects the stomach from acids. Small Intestine: ​ Where majority of the digestion ​ Small Intestine Functions and absorption takes place in our ​ The majority of S.I. is for absorbing body (stomach only absorbs nutrients from the food alcohol & aspirin) ​ The walls of S.I. are folded to form ​ Total length is between 5-7m finger like projections called villi ​ Food requires 7-10 hours to pass ​ The Villi slows down food & through increase the surface area of the ​ It is composed of 3 main parts in intestine to achieve the maximum the following order :duodenum, nutrient absorption ileum and jejunum. ​ Inside the villi are the blood ​ Duodenum: vessels to pick up carbs and amino ​ It is about 20 to 30 cm long acids while the tubes called lacteal ​ It is the most important part of S.I. ducts absorb the fatty acids & ​ This is where most of the digestive glycerol enzymes flow in order to reach the food ​ Several glands along the walls of S.I. produce enzymes to assist with digestion ​ Pancreas: ​ Creates insulin and glycogen two hormones needed to regulate blood sugar ​ Insulin: removes glucose from blood ​ Glucagon: releases glucose from glycogen; get stored in liver and muscles ​ Pancreas: lost of enzymes pancreatic amylase ​ Sodium bicarbonate to neutralize acidic chyme leaving stomach Liver: Produces blue (mixes in fat) Gallbladder: Stores bile and secretes it in the small intestine  large intestine: ​ No nutrient digestion occurs ​ Larger in diameter and shorter in length ​ Reabsorbs water from the wastes ​ Contains bacteria called E-Coli which digests some water while producing VitaminK for us (as well as CO2) ​ 10 - 24 hours CCK ( cholecystokinin) ​ It is secreted by duodenum ​ It triggers the release of amino acids and as in duodenum ​ It stops gastric secretion and gastric motility ​ It mainly STIMULATES the production of enzymes and gallbladder contraction ​ It also stimulates the production of bicarbonate, bile secretion and intestinal juice secretion Gastric: ​ It is secreted by stomach ​ It triggers the release of protein( peptide in stomach) ​ It mainly Stimulates gastric secretion but it also stimulates gastric motility ​ It also stimulates the main production of bicarbonate, bile secretion and intestinal juice secretion Secretin: ​ It is secreted by duodenum ​ It triggers the release of bicarb in duodenum (chyme in stomach) ​ It stops gastric secretion and gastric motility ​ It mainly STIMULATES the production of bicarbonate and the secretion of bile ​ It also stimulates the production of enzymes, gallbladder contraction and intestinal juice secretion Define Enzyme: ​ A protein molecule to speed up chemical reactions in the body and it is not consumed in a reaction ​ Enzymes are catalysts, that are never used up in a reaction, it just speeds up the reaction ​ Enzymes are found everywhere in the body ​ Many are in the digestive system  ​ Ex: trypsin, Lactose Functions: ​ Enzymes reduce the amount of energy needed to start a reaction (making it easier for reactions to occur. Activation energy) ​ Enzymes have a spot in their tertiary structure that allows a substrate (molecule they are reacting with) to join (Active site) ​ When joined together they are the enzyme subtract complex ​ Chemical reactions takes place, enzymes and products separate ​ Every enzyme has a specific structure it joins with ​ Ex Lactase reacts upon lactose, sucrase, reacts upon sucrose ​ Enzymes usually combine substrate name with ending -ASE ​ Maltase digests Maltose Factors Affecting Enzyme: ​ As enzymes are proteins, they can also be denatured by temperature changes and pH change ​ Each enzyme will have an optimal temperature and pH change ​ Outside of that range it’s activity will increase 3. Be able to discuss how the structure of organs/organ parts enhances function. 1. Mouth: ​ Structure: The mouth has teeth, a tongue, and salivary glands. ​ Function Enhancement: ○​ Teeth: Teeth are structured for different types of mechanical breakdown (cutting, tearing, grinding), increasing the surface area of food for digestion. ○​ Tongue: Helps mix food with saliva, forming a bolus that is easier to swallow. ○​ Salivary Glands: Produce saliva containing enzymes like amylase, which starts breaking down carbohydrates. The moisture helps soften food for easier swallowing. 2. Esophagus: ​ Structure: A muscular tube with smooth muscle layers. ​ Function Enhancement: ○​ Peristalsis: The muscular layers enable peristalsis, a wave-like motion that pushes food down into the stomach, ensuring the food moves efficiently. 3. Stomach: ​ Structure: The stomach has three layers of smooth muscle and a lining that secretes gastric juices.  ​ Function Enhancement: ○​ Muscle Layers: The three layers (longitudinal, circular, and oblique) allow for strong contractions, which churn and mix food with digestive enzymes and acids. ○​ Gastric Lining: The stomach lining secretes hydrochloric acid and pepsinogen. The acidic environment activates pepsin, which helps break down proteins into smaller peptides. 4. Small Intestine: ​ Structure: The small intestine is long and has many folds, villi, and microvilli. ​ Function Enhancement: ○​ Length: The length of the small intestine (about 20 feet) increases the surface area for nutrient absorption. ○​ Villi and Microvilli: These finger-like projections further increase surface area, allowing for more efficient absorption of nutrients (amino acids, sugars, fatty acids) into the bloodstream. ○​ Circular Folds: These folds slow down the passage of food, allowing more time for digestion and absorption. 5. Large Intestine: ​ Structure: Shorter and wider than the small intestine, with fewer villi. ​ Function Enhancement: ○​ Absorption of Water: The large intestine absorbs water and electrolytes, concentrating waste into solid form. ○​ Bacteria: The colon houses bacteria that help digest fiber and produce certain vitamins (like vitamin K). 6. Liver: ​ Structure: The liver is a large organ with a network of cells and blood vessels. ​ Function Enhancement: ○​ Bile Production: The liver produces bile, which is stored in the gallbladder and released into the small intestine. Bile emulsifies fats, breaking them into smaller droplets, making it easier for enzymes to digest them. ○​ Metabolism: The liver also processes nutrients absorbed from the small intestine, converting them into forms that can be used by the body or stored for future use. 7. Pancreas: ​ Structure: The pancreas has exocrine cells that secrete digestive enzymes and endocrine cells that release hormones. ​ Function Enhancement:  ○​ Digestive Enzymes: The pancreas secretes enzymes like amylase (for carbohydrates), lipase (for fats), and proteases (for proteins), which aid in digestion in the small intestine. ○​ Bicarbonate Production: The pancreas also produces bicarbonate to neutralize stomach acid, creating an optimal pH for enzymes to function. 8. Gallbladder: ​ Structure: A small, pear-shaped organ located under the liver. ​ Function Enhancement: ○​ Bile Storage: The gallbladder stores bile produced by the liver and releases it when needed to emulsify fats in the small intestine. 4. What are the four types of teeth? How is their structure tied to their function? Enamel- very hard outer lining Dentin- bone like inner core of teeth Crown- the part above the gum Root - the part above the gum Structure & Functions: Incisor - bite Canine - tear Premolar - tear and crush Molar- grind 5. Be able to identify disorders discussed in class. 1.​ Halitosis ​ Symptoms- bad breath ​ Causes - ​ Poor dental health ​ Maybe a sign of cavity or stomach trouble ​ Treatment - ​ Better dental habits or have your teeth checked for a cavity or have your stomach checked 2.​ Ulcers ​ Symptoms- ​ Abdominal pain, burning after a spicy meal or when stomach is empty ​ Causes - ​ Stress about 15%, 85% are due to a bacterial infection( H-polyric) that causes the mucus lining to become thin and the stomach acids attack the muscle lining and then the pepsins attacks protein in the muscle lining  ​ 3 types: ​ Regular- ulcer affects the first few layers of cells in the stomach lining ​ Bleeding- ulcer has penetrated to blood vessels so blood builds up in the stomach or maybe thrown up ​ Perforated- A hole has been eaten completely through the stomach and the juices can escape into the abdominal cavity ​ Treatment - ​ For mild cases- taking antacids (Mcalox) ​ In more severe cases, medications(like Zantac) will be used to control the amount of acid made by the stomach ​ Antibiotics are used to eliminate H-pylori when its presence is confirmed ​ Perforated ulcers require emergency surgery 3.​ Heartburn (aka Acid Reflux Disorder) ​ Symptoms- ​ Stomach acid moves up the esophagus causing it to feel irritated (burning sensation) ​ Causes - ​ Pregnancy, cardiac sphincter not working, overweight ​ Treatment - ​ The main treatment is to find and treat the cause but the symptoms are generally treated by antacids 4.​ Hiatal Hernia ​ Symptoms- ​ Bulky and uncomfortable feelings usually during a meal, heartburn as well. ​ Severe cases may feel like a heart attack (trouble breathing, pain in chest and left arm) ​ Causes - ​ Part of the stomach is pulled up into the chest cavity either through the cardiac sphincter into the esophagus (sliding the hernia) or besides the esophagus through a weakness in the diaphragm. It can put pressure on the heart ​ Treatment - ​ Involves watching what and when you eat, dropping some weight and use of medications to control the attacks. ​ Surgery can be used to repair the more severe cases 5.​ Crohn's disease ​ Symptoms-  ​ Combinations of severe pain, bloating or swelling the abdomen, nausea, lack of appetite. ​ Causes - ​ Is believed to be hereditary - results in the severe inflammation of the portion of large intestine (rarely small intestine) which block the food and limit the ability of the intestines to absorb the nutrients ​ Treatment - ​ Involves support care- inflammatory drugs, painkillers and possible feeding by I.V until the problem subsides ​ Surgery can be used to remove inflamed portions 6.​ Appendicitis- Appendix ​ Symptoms- ​ nausea and vomiting ​ Severe pain in lower right abdomen ​ Causes - ​ Opening to the appendix has become blocked and the appendix has become infected and swollen. If left untreated, it will burst ​ Treatment - ​ Antibiotics for mild cases ​ Surgery for severe cases 7.​ Diabetes - Blood ​ Symptoms- ​ Extreme thirst, weight loss, tiredness, vision trouble, slow healing or sore ​ Type 1 ​ Is usually hereditary, pancreas suddenly fails to produce insulin ​ Type 2 ​ Pancreas wears out slowly and produces smaller and smaller quantities of insulin. Treatment involves weight control, possibly insulin pills or insulin shots or insulin pumps. ​ Gestational Diabetes ​ Occurs in about 4-8% of pregnant women. Occurs because of the weight change in pregnancy stresses their pancreas and they become temporarily diabetic. The majority of these women go back to normal after the baby has been born 8.​ Hepatitis - liver ​ Symptoms- ​ Tiredness and swelling in the upper right abdomen, yellowing ​ Causes - ​ 5 different letters listed below:  ​ A - spread orally ​ B,C,D,E - transmitted by blood fluid (blood, saliva) ​ Treatment - ​ Cure exists for type A, a vaccine exists for type B 9.​ Gallstones - gallbladder ​ Symptoms- ​ Sharp and severe pain in the upper right abdomen ​ Causes - ​ Bile crystals have formed in the gallbladder and have become stuck in the duct leading from the GB to intestines ​ Treatment - ​ Lasers can be used to try to shatter the stone or the GB surgically 10.​Diarrhea ​ Symptoms- ​ Belly cramps or pain. ​ Blood in the stool. ​ Causes - ​ Too much muscle motion in the large intestine (prevents water from being reabsorbed, so wates stay liquid ​ Treatment - ​ Drugs like imodium or cornstarch water, limits sugar 24h 11.​Constipation ​ Symptoms- ​ Too much water is absorbed due to muscle motion ​ Causes - ​ Not enough motion in Large intestine ( too much water gets absorbed, wastes become excessive hard) ​ Treatment - ​ Eats a lot of roughage like celery and carrots, prunes, ex lax, metamucil Evolution 1. Know key terms like fossils, paleontology, archaeopteryx, Homologous features, Analogous features, Vestigial features, Fossil- fossils are the preserved remains of plants and animals whose bodies were buried in sediments, such as sand and mud, under ancient seas, lakes and rivers. Paleontology - scientific study of life of the geologic past that involves the analysis of plant and animal fossils, including those of microscopic size, preserved in rocks. the branch of science concerned with fossil animals and plants. Archaeopteryx- the oldest known fossil bird, of the late Jurassic period. It had feathers, wings, and hollow bones like a bird, but teeth, a bony tail, and legs like a small coelurosaur dinosaur. Homologous structures - structures in different organisms that have similar anatomy and a recent shared ancestry but different functions Analogous structures - refers to the parts that have similar functions but different anatomical structures and no recent shared ancestry. (wing bat, birds, butterfly) Vestigial structures - anatomical parts that appear to have no functions. Ex- thumbs on dog paws, hip bone in whales, bats having eyes 2. Know early ideas about evolution. ​ Evidence for evolution - Molecular similarities ○​ DNA sequence - humans and chimpanzees share roughly about 98 to 99% of DNA sequence ○​ Pseudogenes - non functional sequence of DNA that have lost their ability to code for proteins due to mutation, similarities seen between species ○​ Similar amino acid sequence between species ○​ These similarities are evidence of evolutionary relationships and that species evolved from a common ancestor gradually over a long period of time ​ Evidence for evolution - Anatomical similarities ○​ Homologous structures - structures in different organisms that have similar anatomy and a recent shared ancestry but different functions ○​ Analogous structures - refers to the parts that have similar functions but different anatomical structures and no recent shared ancestry. (wing bat, birds, butterfly) ○​ Vestigial structures - anatomical parts that appear to have no functions. Ex- thumbs on dog paws, hip bone in whales, bats having eyes ​ Evidence for evolution - Development similarities ○​ In the embryonic stage many organisms have anatomical features that are similar to other organisms but these disappear before birth ​ Evidence for evolution - Fossil records ​ These provide a timeline of evidence of evolution, showing how species have changed over time and adapted to their environments, including through transitional forms. They also have allowed scientists to study extinct species, support common ancestry through comparative anatomy, and highlight evolutionary adaptations, such as marine fossils found in dry regions. ​ Evidence for evolution - Biogeography ○​ Similar species are found around the world as the scientists believed all the continents were joined together (pangea), millions of years ago but they continents got split over time and the animals which were from same species lived in different parts got spread around the world 3. Know Darwin’s Theory of Natural Selection. ​ Darwin’s observations: ​ Species vary globally ○​ Distantly related species living in similar habitats around the world act similarly. Ex- rhea, ostrich ○​ Some areas have very unique organisms not present anywhere else. Ex- kangaroos in Australia ​ Species vary locally ○​ Related animals that lived in different habitats within a local environment had different features. Ex- galapagos islands ( very different climate - related animals had different features) ○​ Galapagos tortoise - tortoise varied locally. These islands have very different climates. Tortoise adapted differently to the climate they lived in. ​ Darwin’s theory ○​ All species of organisms living on the earth today are descended from an ancestral species ○​ Species evolve overtime ○​ The mechanism that causes the species to change is called natural selection ​ Natural selection - is not random. Organisms with traits better suited for the environment are more likely to survive and reproduce and pass on their traits to their offsprings. The fittest individuals have the reproductive advantage so the frequency of their allele in the gene pool is higher. Selective pressure in the environment change the relevant frequencies of phenotypes in a population: ​ Stabilizing selection - this happens when the average traits are best suited for survival and the extreme traits are less helpful. Ex - human birth weight, average sized babies have least problems ​ Directional selection - this happens when an extreme trait is best for survival causing the population to change in that direction over time ex antibiotic resistance ​ Disruptive selection - this happens when extreme traits on both the ends are better for the survival than the average traits, leading to two very different groups in population 4. Know Modern Synthesis, Random Change in DNA, Genetic Drift, Gene Flow. ​ Genetic Drift: ​ Random change in the allele sequence due to chance. It has a much greater effect on small populations  ​ Bottleneck effect: occurs when a population decreases generally due to a natural disaster. This decrease in population reduces variation in alleles, decreasing genetic diversity ​ Founders effect: a reduction in genetic diversity that occurs when a small group of individuals establishes a new population. ​ Gene flow: ​ The moment of alleles from one population to another ​ Happens when individuals from different populations mate and produce offsprings, sharing their genetic material ​ Can lead to increase in genetic diversity and sometimes introduce new traits to the population ​ Ex birds from one group migrate to another island and breed with a different group 5. Be able to explain patterns of selection. ○​ Natural selection - is not random. Organisms with traits better suited for the environment are more likely to survive and reproduce and pass on their traits to their offsprings. The fittest individuals have the reproductive advantage so the frequency of their allele in the gene pool is higher. Selective pressure in the environment change the relevant frequencies of phenotypes in a population: ○​ Stabilizing selection - this happens when the average traits are best suited for survival and the extreme traits are less helpful. Ex - human birth weight, average sized babies have least problems ○​ Directional selection - this happens when an extreme trait is best for survival causing the population to change in that direction over time ex antibiotic resistance ○​ Disruptive selection - this happens when extreme traits on both the ends are better for the survival than the average traits, leading to two very different groups in population ○​ Sexual selection- not random mates are often chosen based on their phenotypes. Other individuals in the species screen, or select their traits. ○​ Artificial selection - Not random humans have been modifying species for thousands of years. Can be fast - only a few generation traits that are selected from can occur at a high frequency. Can have unintended consequences, usually in the form of genetic diseases. Ex all dogs come from the wolves. 6. Formation of a species. ​ Prezygotic barriers - a barrier that either impedes mating between species or prevent fertilization of eggs ○​ Behavioral isolation - difference in mating calls or mating rituals. Ex courtship rituals of elk, birds song  ○​ Temporal isolation - mating occurs at different times of the year or day. Ex: orchids - times of the day, ○​ Habitat isolation - differences in using resources and living spaces within the same habitat. Ex: cichlids- feeding on different sources within the same habitat ○​ Mechanical Isolation- where species can attempt mating but fail because they are automatically incompatible. Ex- dogs - size incompatible, Damselflies - different shaped reproductive organs ○​ Gemate isolation - when the sperm and eggs of different species are incompatible preventing fertilization. Ex coal protein , flowers - pollen vs stigma, sea urchin - red vs purple ​ Postzygotic barriers - a barrier that prevents hybrid zygotes developing viable, fertile individuals ○​ Hybrid sterility - when the offspring of the cross between 2 individuals is infertile. Ex mule (horse and donkey) ○​ Hybrid inviability - when a hybrid cannot develop into a healthy adult or the zygote dies shortly after fertilization. Ex- sheep and goat has a shorter life span ○​ Hybrid breakdown - when the first generation (F1) is viable and fertile but when the hybrid species mate with each other, or another parental species, the next generation F2 is weak or infertile. Ex- cotton and rice ​ Allopatric speciation (aka geographic isolation) ○​ Physical barriers like a mountain, ocean or canyon that separates populations may eventually lead to an inability to interbreed because the gene pool has been too different. Both groups are reproductively related ​ Sympatric speciation ○​ Same geographic location but reproductively isolated ○​ Happens due to prezygotic and postzygotic barriers ​ Peripatric speciation ○​ A small population becomes isolated on the edge of the main population leading to rapid genetic drift ​ Parapatric speciation ○​ Adjacent population evolves into distinct species while maintaining a shared border where interbreeding is limited 7. Know Human Evolution ​ Human evolution ​ Australopithecus ○​ Binocular vision (eyes to the front) ○​ Opposite thumbs (muscle grasping easier) ○​ Were knuckle walkers (were more upright than previous species)  ​ After Australopithecus (different generation) ○​ Was so different that it becomes its own genus known as homo ○​ Walked completely upright ○​ Reduced body fur ○​ Enlargement of the brain case in the skull ○​ Reduction in the size of the jaw and its supporting muscles ​ Homo - Habilis ​ Enlarged brain case ​ First primate descent to use stone tools ​ Fossils found primarily in Africa ​ Homo - Erectus ​ Walked completely upright ​ Used tools ​ Fire for the first time ​ Emigrated to Europe and Asia ​ Homo - Neanderthalis ​ About 600,000 years ago were an offshoot of homo - erectus ​ Thick bone structures ​ Greater muscle mass ​ Practiced complex speech and funeral rituals ​ Homo - Sapiens ​ Brain case enlargement ​ Complete smaller teeth ​ Forward looking eyes ​ These are modern humans (diverged for roughly 130000 years ago) 8. Adaptive Radiation, Convergent, Divergent Evolution. ​ Divergent evolution ○​ Closely related species that have evolved different phenotypes ○​ Happens due to different environments or pressures ○​ Homologous features are generally seen in distinct species ○​ Ex grand canyon squirrels ​ Convergent evolution ○​ Unrelated or independent species that have independently evolved similar phenotypes ○​ Happens due to similar but unrelated environments or pressure ○​ Analogous features are usually seen in distinctly related or unrelated species (similar phenotypes ) ○​ Ex sharks (fish) and dolphins (mammal) live in similar habitats and have analogous features ​ Parallel evolution  ○​ Related species that have independently evolved similar phenotypes ○​ Happens due to similar environments or pressures ○​ Ex flightless birds ​ Co - Evolution ○​ Mutualism: A relationship where both species benefit from each other's pressure. Ex flowers and pollinators ○​ Predators or prey - A relationship where one species (predators) hunts and feeds on another prey. Rough skinned newts and California's red-sided garter snakes ○​ Competition - A relationship where two or more species are competing for the same resources, driving adaptation to reduce overlap or increase efficiency. Ex- lions and hyenas, squirrels and birds ○​ Parasite or Host - A relationship where one species (parasite) benefits at expense of another (host), leading to defensive and offensive adaptations. Ex- cuckoo birds and host birds, ticks and mammals ​ Adaptive radiation - when a single species evolve into multiple distant species; ex- darwin finches (divergent evolution) ​ Gradual equilibrium- evolution as a slow and continuous process of change; transition of horse species from small multi toed animals to large single toed for 50 million years ​ Punctuated equilibrium - evolution occurs in rapid burst of change followed by long periods of stability ​ Triloboats, which show sudden changes in morphology after millions of years after radiation