Eukaryotic Evolution and Classification
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Questions and Answers

What significant evidence for bipedality was preserved in volcanic ash in Laetoli, Tanzania?

  • Tracks left by two australopithecines (correct)
  • Fossilized skulls of early hominids
  • Tools used for hunting
  • Remains of ancient vegetation

Why did bipedality become the primary adaptation for hominids?

  • Improved climbing ability in trees
  • Ability to produce complex tools
  • Reduction of overall heat stress (correct)
  • Increased muscle mass for running

What characteristic distinguishes Australopithecus afarensis as an efficient biped?

  • Pelvis and leg bones resembling a chimpanzee
  • Non-functional valgus angle
  • Humanlike functional morphology (correct)
  • Similar foot structure to modern humans

What is the valgus angle important for in bipedal locomotion?

<p>Aligning the feet under the center of gravity (D)</p> Signup and view all the answers

Which hominid is noted as the first efficient walker despite having a small brain similar to a chimpanzee's?

<p>Homo naledi (D)</p> Signup and view all the answers

What is a key characteristic of tapeworms regarding their digestive system?

<p>They lack a gut system entirely. (A)</p> Signup and view all the answers

What adaptation helps tapeworms maintain their position in the host's gut?

<p>Microtriches that interdigitate with intestinal microvilli. (A)</p> Signup and view all the answers

Which of the following is NOT a feature of parasitic flukes and tapeworms?

<p>Possess a complex nervous system. (D)</p> Signup and view all the answers

What is the primary host for the liver fluke, Fasciola Hepatica?

<p>Water snails are used for larval development. (A)</p> Signup and view all the answers

How do humans typically become infected with beef and pork tapeworms?

<p>By eating raw or undercooked meat. (A)</p> Signup and view all the answers

In the life cycle of Schistosoma, which method is used for entry into the human body?

<p>Entry through the skin. (A)</p> Signup and view all the answers

What mechanism enables the tegument of tapeworms to facilitate nutrient absorption?

<p>It is folded to increase surface area. (D)</p> Signup and view all the answers

What is praziquantel used to treat?

<p>Infections caused by trematodes like Schistosoma. (B)</p> Signup and view all the answers

Where do adult Ascaris lumbricoides nematodes reside in the human body?

<p>Small intestine (D)</p> Signup and view all the answers

What mechanism primarily allows Trichinella spiralis to infect humans?

<p>Consumption of undercooked infected pork (D)</p> Signup and view all the answers

Which of the following is a symptom of Trichinellosis caused by Trichinella spiralis?

<p>Swellings and fever (A)</p> Signup and view all the answers

Which group of parasites causes diseases collectively referred to as filariasis?

<p>Filarial worms (B)</p> Signup and view all the answers

What is a major consequence of lymphatic infection by filarial worms leading to elephantiasis?

<p>Extreme swelling of the lower limbs (C)</p> Signup and view all the answers

Which nematode is known to cause itching and reinfection in children?

<p>Enterobius vermicularis (A)</p> Signup and view all the answers

What is the main transmission method for the parasites causing Bancroftian elephantiasis?

<p>Mosquito bites (C)</p> Signup and view all the answers

What characteristic defines the body structure of nematodes?

<p>Triploblastic and unsegmented with a round cross section (D)</p> Signup and view all the answers

What contributes to tissue destruction and cavity formation in the host lung during TB infection?

<p>Ensuing host immune responses (C)</p> Signup and view all the answers

During what period did most of the evolutionary history of tuberculosis (TB) occur with humans?

<p>Hunter-gatherer times (D)</p> Signup and view all the answers

Which statement about modern TB compared to ancient TB is correct?

<p>Modern TB is associated with a shorter latency period. (A)</p> Signup and view all the answers

What is one of the unique characteristics of TB that allows for its potential resistance to antibiotics?

<p>Presence of a hardy cell wall (D)</p> Signup and view all the answers

What is a key trait of sexual selection as described by Darwin?

<p>Competition between members of the same sex (C)</p> Signup and view all the answers

What does intersexual selection involve?

<p>Females choosing attractive males (C)</p> Signup and view all the answers

Which of the following is an example of intrasexual selection?

<p>Males engaging in physical contests for access to females (C)</p> Signup and view all the answers

What can be inferred about the role of population density in the evolution of TB?

<p>Increased populations selected for less virulent TB strains. (A)</p> Signup and view all the answers

What is the main reason nausea and vomiting in pregnancy peak in the first trimester?

<p>The embryo is in a stage of development where it is most vulnerable. (A)</p> Signup and view all the answers

What do cravings for certain foods during pregnancy indicate?

<p>They are likely for foods that are safe for the mother and embryo. (C)</p> Signup and view all the answers

Which of the following statements is true regarding food aversions in pregnant women?

<p>They are associated with harmful substances in certain foods. (D)</p> Signup and view all the answers

How does nausea and vomiting of pregnancy correlate with pregnancy outcomes?

<p>Women with morning sickness have better pregnancy outcomes. (A)</p> Signup and view all the answers

What is the relationship between dietary exposure and nausea during pregnancy?

<p>Women with a varied diet are less likely to experience nausea. (A)</p> Signup and view all the answers

Which of the following predictions is supported by evidence presented in the content?

<p>Nausea in pregnancy is least prevalent in women exposed to safe foods. (B)</p> Signup and view all the answers

What conclusion can be drawn regarding morning sickness during pregnancy?

<p>It may serve as a protective mechanism against harmful foods. (D)</p> Signup and view all the answers

Which of the following foods are pregnant women most likely to develop aversions to?

<p>Meat and vegetables (B)</p> Signup and view all the answers

What distinguishes a phylogram from a cladogram?

<p>Branch lengths have significant meaning in a phylogram. (D)</p> Signup and view all the answers

What subgroup of mammals includes marsupials and placental mammals?

<p>Subclass Theria (C)</p> Signup and view all the answers

Why was morphological comparison inadequate for reconstructing phylogenetic trees?

<p>Rapid changes occurred after the dinosaurs' extinction. (A)</p> Signup and view all the answers

What major shift occurred in the classification of mammals based on DNA research?

<p>The phylogenetic tree moved humans to order euarchonta. (D)</p> Signup and view all the answers

What is a characteristic of the subclass Prototheria?

<p>They produce eggs but also produce milk. (C)</p> Signup and view all the answers

How did researchers determine the relatedness of animals using genetic information?

<p>By comparing the DNA spelling at specific gene points. (B)</p> Signup and view all the answers

What limitation did researchers face when trying to base phylogenetic trees on morphology?

<p>Morphology does not provide data about timelines. (D)</p> Signup and view all the answers

When did the diversification of mammals occur?

<p>After the extinction of dinosaurs. (D)</p> Signup and view all the answers

Flashcards

Tapeworm's digestive system

Tapeworms lack a digestive system. They obtain nutrients directly from their host's digested food.

Tapeworm's adaptation for attachment

Tapeworms have a head structure called a scolex, equipped with hooks and suckers that attach firmly to the host's intestinal lining.

Tapeworm's tegument

The tegument is a tough outer layer that protects the tapeworm from the host's digestive enzymes.

Tapeworm's nutrient absorption

Tapeworms have a folded tegument, increasing surface area for absorbing nutrients and gases from the host's gut.

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Liver flukes

Liver flukes, or Fasciola hepatica, are flatworms that infect the liver of animals, and can be transmitted to humans.

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Liver fluke life cycle

Liver flukes start as eggs in feces, develop in snails, encyst on plants, and infect humans who consume those plants.

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Schistosomiasis

Schistosomiasis is a parasitic disease caused by Schistosoma worms, which enter humans through the skin and migrate to the liver.

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Beef and pork tapeworms

Taenia saginata and Taenia solium are tapeworms that infect humans through the consumption of undercooked meat containing cysts.

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Nematode

A type of roundworm belonging to the phylum Nematoda. They are unsegmented, triploblastic, and have a pseudocoelom.

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Nematode Cuticle

A tough, protective outer layer that covers the nematode's body. It is shed during growth.

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Nematode Reproduction

Most nematodes reproduce sexually, with males and females. Eggs are typically laid, and the larvae hatch and develop into adults.

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Ascaris lumbricoides

A large roundworm that infects humans. It lives in the small intestine and lays eggs that are passed in feces.

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Trichinella spiralis

A nematode that causes trichinosis. It's transmitted by eating undercooked pork.

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Enterobius vermicularis

A nematode commonly known as the pinworm. It infects the intestines and can cause itching around the anus.

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Filariasis

A group of diseases caused by filarial worms, which are transmitted by mosquitos.

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Elephantiasis

A disease caused by filarial worms living in the lymphatic system. It can cause extreme swelling in the limbs and genitals.

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Morning sickness

Nausea and vomiting experienced by some pregnant women, particularly in the first trimester.

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Embryogenesis

The process of development from a fertilized egg to a fully formed embryo.

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First trimester

The first three months of pregnancy, a crucial time for embryonic development.

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Mother's immune vulnerability

The mother's immune system is suppressed during pregnancy to accommodate the growing embryo, making her more susceptible to infections.

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Food aversions in pregnancy

A strong dislike or distaste for certain foods that pregnant women may experience, particularly during the first trimester.

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Secondary plant compounds

Chemicals produced by plants, some of which can be harmful to humans.

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Embryonic organogenesis

The process of developing organs from undifferentiated cells within the embryo.

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Selective advantage

A trait that increases an organism's chances of survival and reproduction in a particular environment.

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Laetoli Footprints

3.6 million-year-old fossilized footprints of two australopithecines found in volcanic ash at Laetoli, Tanzania, providing evidence of bipedalism in early hominids.

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Why Bipedalism?

Bipedalism arose in hominids due to various factors like carrying behavior, reducing heat stress, scavenging and hunting needs, improved vision, and defense against predators.

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Valgus Angle

The angle formed by the femur and tibia, allowing the feet to be positioned under the center of gravity, crucial for efficient bipedal walking.

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Australopithecus afarensis Bipedalism

Australopithecus afarensis developed efficient bipedalism, with a pelvis and leg bones functionally different from chimpanzees. Their morphology was completely human-like.

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Homo naledi: Efficient Walker

Homo naledi was an early hominid that walked upright efficiently, despite having a small brain similar to a chimpanzee's brain size.

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Phylogenetic Tree

A diagram that shows the evolutionary relationships between different species, based on their shared ancestry. It branches off from a common ancestor, with the length of each branch often representing time.

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Cladogram vs. Phylogram

Cladograms only show the branching order of evolutionary relationships, while Phylograms also show the time scale represented by the branch lengths.

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Convergent Evolution

The process where unrelated species evolve similar traits due to adapting to similar environments, which can be misleading when constructing phylogenetic trees.

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Euarchonta

The order that includes primates, tree shrews, and colugos (flying lemurs), based on DNA evidence.

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Morphological Data

Physical characteristics used to categorize species, such as bone structure, teeth shape, or skull features.

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Phylogenetic Data

DNA sequences used to construct phylogenetic trees, providing a more accurate representation of evolutionary relationships.

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Divergence in Phylogenetic Trees

The point in time when two species separated from their common ancestor.

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Mammal Diversification

The rapid evolution of mammals into various forms after the extinction of dinosaurs.

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TB and Host Immune Responses

The host's immune response to tuberculosis (TB) can lead to tissue destruction and lung cavities. This damage helps spread TB, as the cavities release bacteria into the air.

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TB's Evolutionary History

TB has co-evolved with humans for a long time, primarily during the hunter-gatherer era. TB's latent period allows it to survive in humans for years before causing active disease, ensuring continued transmission.

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TB's Adaptation to High Population Density

In crowded environments, TB has evolved to be more virulent and have a shorter latency period, allowing for rapid spread among susceptible hosts.

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TB's Resistance to Antibiotics

TB's unique characteristics, like slow growth and a tough outer layer, make it difficult to treat with antibiotics and contribute to the development of antibiotic resistance.

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Sexual Selection

Sexual selection is a process where individuals with certain traits are more likely to reproduce because those traits are preferred by potential mates.

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Intersexual Selection

Intersexual selection occurs when one sex (usually females) chooses mates based on desirable traits such as appearance, displays, or resources.

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Intrasexual Selection

Intrasexual selection involves competition among members of the same sex for access to mates. This often involves fighting or displays of dominance.

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Wodaabe Clan's Mate Selection

The Wodaabe people of Chad use elaborate rituals and decorations to attract mates. Males emphasize physical attributes like height, facial symmetry, and dental features, which are considered attractive by females.

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Selective Male Choice

In some species, males actively select for specific traits in females. This is often seen through elaborate courtship displays and material offerings.

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Human Mate Selection

Sexual selection is also evident in humans, where individuals seek specific traits in potential partners, often influenced by cultural and societal norms.

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Study Notes

Eukaryotic Evolution

  • 3.5 billion years ago, there was very little oxygen in the atmosphere
  • Prokaryotes developed, increasing atmospheric oxygen
  • This allowed single-celled eukaryotes to develop
  • The ancestor of modern eukaryotes engulfed a heterotrophic aerobic prokaryote via phagocytosis
  • This process made the cell more efficient
  • This was passed down through generations, becoming the mitochondrion
  • Eukaryotic cells can use oxygen

Taxonomy

  • Living organisms are divided into three domains: bacteria, archaea, and eukarya
  • Kingdom Protista is no longer recognized
  • Protists are eukaryotes that are neither plants, animals, nor fungi

Diplomonads

  • Lack plastids and have highly reduced mitochondria
  • Lack DNA, electron transport chain, and enzymes of the citric acid cycle
  • Mostly found in anaerobic environments
  • Two equal-sized nuclei and multiple flagella
  • Example: Giardia (common intestinal parasite, diarrhea, dehydration)

Kinetoplastids

  • Have a single large mitochondrion with a kinetoplast
  • Can be free-living or parasites of animals, plants, and other protists
  • Example: Trypanosoma (parasites of vertebrate blood, cause sleeping sickness in Africa, Chagas disease in South America)

Apicomplexans

  • Placed in Alveolata clade, which has membrane-bound sacs under the plasma membrane
  • All are animal parasites
  • Example: Plasmodium (causes malaria)

Rhizopodia/Amoebozoans

  • Live in any moist/aquatic habitat
  • Ectocommensal or endosymbiotic
  • Example: Entamoeba histolytica (causes amoebic dysentery)

Platyhelminthes

  • Triploblastic, acoelomate, bilaterally symmetrical, unsegmented worms
  • Parasitic or free-living
  • Incomplete gut or no gut system
  • Example: Flukes and tapeworms

Nematodes

  • Triploblastic, pseudocoelomate, bilaterally symmetrical
  • Have a complete gut
  • Free-living in most moist aquatic habitats, soil
  • Example: Ascaris lumbricoides (intestinal parasite), Trichinella spiralis (causes trichinosis), Enterobius vermicularis (pinworm), and filarial worms (cause elephantiasis)

Arthropoda Characteristics And Phobias

  • Triploblastic, coelomate, bilaterally symmetrical
  • Body divided into segments (tagmata)
  • Hard exoskeleton (chitin), shed periodically
  • Insect nuisance
  • Some species are numerous
  • Some are pests
  • Arachnophobia: fear of spiders; Entomophobia: fear of insects

Arthropoda Venoms

  • Insects sting to defend nest
  • Worker bees and wasps have unbarbed stingers, therefore can reuse them
  • Honeybee stingers are barbed; therefore, unable to reuse them
  • Wasp venom causes vasodilation and muscle relaxation
  • Insect venoms could be polypeptides

Insects as disease vectors

  • Insects transmit various diseases, from protists to viruses and nematodes
  • Mechanical and biological transmission
  • Example: mosquitos transmit malaria, yellow fever

Specific Disease Types

  • Pediculosis (body lice): Infestation of hair with lice
  • Scabies (scabies mite): Burrows in skin causing itching, rashes
  • Schistosomiasis (trematodes): Enters body through skin
  • Filariasis: Enters via mosquito bite, causes swelling in lymphatic system (elephantiasis)
  • Malaria (Plasmodium): Transmitted by Anopheles mosquito

Host-Parasite Interactions

  • Parasites need the host to survive for transmission & reproduce
  • Naive body reacts with a strong inflammatory response
  • Selection has shaped hosts to downregulate response
  • Host & parasite coevolve
  • Example: Multiple sclerosis, symptoms reduced in patients with worm infections

The Limits of Natural Selection

  • Humans' unique characteristics
  • Primitive vs. derived traits
  • There are many differences between apes and monkeys
  • Humans are larger and heavier
  • Humans are often able to walk on two legs
  • Humans have a broader chest
  • Humans rely more on vision, less on smell
  • Humans have larger brains relative to body size
  • We use tools and have complex social lives

Evolution

  • DNA suggests humans are 96% identical to apes
  • Evolutionary changes in traits, genetic variation, and reproductive success
  • Examples: Bipedalism, large brains, tool use
  • Natural selection edits/selects existing traits

Human Evolutionary Biology

  • Evolution is descent with modification
  • Natural selection to occur there must be variation in traits, variable reproductive success among those with different traits, and heritability for traits
  • Human traits: variations in reproductive success, age at reproduction, physical characteristics, and behavior

Evolutionary Trade-offs

  • Trade-offs between traits/characteristics
  • Examples: Bipedalism in humans versus strength
  • Vitamin C path: Humans lose the synthesis of vitamin C
  • Humans must have a vitamin C diet

Comparative Genomics

  • Mutations in the genetic code
  • Point mutations: Changes in one base pair
  • Wild-type genes: Most common alleles
  • Types of mutations
  • Silent substitution: No effect on protein
  • Missense mutation: Different amino acid
  • Nonsense mutation: Premature stop codon
  • Deletions/insertions: Shift in reading frame

The Human Genome Project

  • Aimed to map and sequence the human DNA
  • Aims to chart variations in DNA
  • Aims to map human genes
  • Began to label the functions of genes, other parts of genome
  • Sequence the genomes of other model organisms

Tree of Life

  • Molecular mechanisms allowing mammals extraordinary longevity
  • Telomeres: Contribute to aging because they shorten with each cell replication
  • Bats: maintain telomere lengths without telomerase (which lengths telomeres but causes cancer)

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Description

Explore the fascinating journey of eukaryotic evolution, detailing the origins of eukaryotic cells and their classifications. Understand the significance of prokaryotes in the increase of atmospheric oxygen and learn about distinct eukaryotic groups like diplomonads and kinetoplastids. Test your knowledge on the taxonomy of living organisms and their adaptations.

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